GTA
Airguns by Make and Model => Daisy Airguns => Topic started by: Rob M on August 20, 2016, 02:15:56 AM
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after making 2 flat tops , i couldnt figure out the ideal stroke range.So with this its took me 5 minutes to get dialed in to where my harder shooting non adjustable is .. the pump arm is flexing by pump 6, and im pretty sure im maxing out a lot of components i need to reinforce. Took all night to make it , revise it and so on..i never thought an 880 could bark this loud with any mod
The .250 rolled rod on the pump linkage has an aluminum shaft going all the way to the roll pin threaded in 10-24.. thats adjustable.. the piston end also has 10-24 threads but will be red thread locked tonight.. after numerous shots the piston doesnt rotate back in the threaded rod , soonce its set and iit the tube , it doest change position.. Boring topic perhaps , if someone wants to test my other piston design and post numbers on it , u need a chrony, a stock 880 and some spare time ( and some integrity to actually post and nOT JUST TAKE THE FREE PISTON_)
(http://i746.photobucket.com/albums/xx102/robnewyork50/adjustable%20880.jpg) (http://s746.photobucket.com/user/robnewyork50/media/adjustable%20880.jpg.html)
FINAL NUMbER 910FPS 23 PUMPS 7.9 ( for now)
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That's pretty nifty. Have you measured the increase in FPS yet?
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heres a video of it firing at 2000 psi.............910FPS WAS FINAL 23 PUMPS
https://www.youtube.com/watch?v=iGHzBu6GbD0 (https://www.youtube.com/watch?v=iGHzBu6GbD0)
i shipped one to avator( bill) to test out and chronograph, he only has the regular flat top , not the adjustable so im awaiting his results today or tommor whenever he has time. The gains as u see in the video are huge with adjustable
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That's quite an impressive noise... And that's just a youtube vid- which never does the sound justice.
I have a video of a .50 Quakenbush booming away, and the video doesn't do it justice AT ALL.
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yes sir , it sounded like a 22 rimfire in real life lol. I may sell a select few after avators test run, im hoping he gets about 775 on 10 pumps , and over 900 fps on 20.. ive been making em non stop, testing different designs. Im also in the process of planning( read building) a long stroke conversion KIT ( more air per stroke , longer tube , different pump geometry) this way when u want 10 pump power , you only have to pump 6 time ( 47percent swept colume gain )
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Your prob thinking , why, whats the end goal lol.( its a 40 dollar gun) Well , 880fps , 10 pumps and reliable with about an extra 40 invested is the goal.. There is nothing i know of on the market like that , and i think the 880 is the perfect platform.. Most people say it wont be reliable. but so far there is no evidence of that.
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I think it's a good platform. Tom (StonyKill) convinced me of that. I was getting pretty good with mine until I screwed up the trigger and bought an HW95... and then a Gladius... and inherited a 1322, and haven't messed with it since.
Time to get back to the 880 and fiddle with that trigger again.
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The fine polishing of the trigger is a great mod but from what im gatheting if you want mega power the flat spring aids in the hammer release. Meaning u will get valve lock at some point thats yet to be determined. Mine fires at any pressure ..but the trigger isnt modded. Others report valve lock at 15 pumps with the stock piston.. Chrony numbers saturday night.
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How are those chrony numbers?
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nt
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895fps with the crosman premiers is the max at 20 pumps , theres a thread in the american gate to see the other numbers..Heres the new design , it circumvents the need for a roller pin, and should offer better stabilty to the piston head,. Im not sure if it will increase muzzle velocity yet
(http://i746.photobucket.com/albums/xx102/robnewyork50/newpist%20on%20design.jpg) (http://s746.photobucket.com/user/robnewyork50/media/newpist%20on%20design.jpg.html)
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after making 2 flat tops , i couldnt figure out the ideal stroke range.So with this its took me 5 minutes to get dialed in to where my harder shooting non adjustable is ..
Hey Rob,
What was the final optimal amount of clearance between the piston head and the valve?
I'm going to make a metal piston for a Umarex NXG pumper and may just make it one-piece instead of adjustable.
Thanks.
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the one piece was harder to get right , the dimensions of the piston i sent to BIll ( avator) were the closest to ideal ..You could email me since that was the last of the one piece pistons i made at the time
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the one piece was harder to get right , the dimensions of the piston i sent to BIll ( avator) were the closest to ideal ..You could email me since that was the last of the one piece pistons i made at the time
Thanks, Rob. The Umarex piston isn't the same as the Daisy one so I'll have to get my dimensions from the stock piston. I am looking for the amount of clearance between the piston and the valve at the bottom of the stroke. I didn't know if they should touch, or if a few thou clearance is needed.
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from what i found to get max stroke, the lever doesnt wanna full shut with ease on the first stroke , i dont know the exact stroke distance.
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from what i found to get max stroke, the lever doesnt wanna full shut with ease on the first stroke , i dont know the exact stroke distance.
Ok, thanks, that's about where I ended up tonight. My version is the 490 fps restricted output rifle. As such, it had 0.175" clearance between the piston and valve. I found a piece of UDPE and screwed it to the end to take up the space. I then machined it down to where the lever would lightly snap close.
It's not a metal piston, but this was quick and easy and it's fun to experiment. I'll build a proper metal piston later and compare the results.
Sorry for the "non-Daisy" thread hijack, but your results are encouraging and I want to see how it works with the cheap Umarex I bought.
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sounds good , no worry about the thread.. post results when you get them,/.Im sure there are serious gains to be made on that version
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Results with 8.5 grain Crosman wadcutters:
10 pumps = 570 fps
15 pumps = 630 fps
Then I blew the seals out when I went over 15 pumps. They were not the original metric o-rings, but .75" o.d. ones I bought at the local hardware.
Time now to research the best o-rings and build a piston like you have done.
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so thats a big gain over stock.. Few hints, double orings, and more oring radius contact with the tube wall..
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so thats a big gain over stock.. Few hints, double orings, and more oring radius contact with the tube wall..
Yep. :D
One problem I see is that the valve body OD uses two o-rings spaced an inch apart. A double o-ring piston head won't do much good if the valve body OD can't hold the pressure the piston can provide.
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is the valve the same as the daisy?/ im not familiar but the daisy valve has proven to hold 2200psi
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No, it's not the same.
Not mine, but here's a pic:
http://www.gatewaytoairguns.org/GTA/index.php?topic=81275.msg776203#msg776203 (http://www.gatewaytoairguns.org/GTA/index.php?topic=81275.msg776203#msg776203)
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pretty cool.. the similar" abutement "plug is threaded,, I cant tell how the air is retained( how it gets into the valve) i see the checkvalve to release the air..
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I took a couple pics of mine:
Exploded view:
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20160919_214955_012-1_zpshqyjbhhm.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20160919_214955_012-1_zpshqyjbhhm.jpg.html)
Where air enters the valve:
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20160919_212626_005-1_zpsztmzic2j.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20160919_212626_005-1_zpsztmzic2j.jpg.html)
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so the check valve is much like a crosman, all inline.. Im not seeing why its not sealing.the rubber grommet on the compression tube side needs to sit quite flush to get a good seal..wayy simpler smarter setup than the 880
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is there anything retaining the rubber grommet in the forward position to ensure a seal
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i guess thats the reason for the spring shape to seat the grommet
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i guess thats the reason for the spring shape to seat the grommet
Yes, the spring seats in that cup-shaped grommet. I think the reason it started failing to hold full pressure was because the o-rings were cheap and soft. They looked like air was blowing past. I ordered some Viton o-rings in the proper metric size as well as some -113 size in Viton/90.
I'm also going to polish the holes/slots in the tube again and make sure I didn't leave any rough edges.
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yea, thats a factory leak.. once u get it sealed i bet the gun can push 800 fps
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looks like u have 880 valve volume or more
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heck thread the cap to the valve where the check grommet is and u have a tethered pcp!
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http://www.ebay.com/itm/G7-HPA-paintball-tank-regulator-One-Way-fill-nipple-1-8-npt-Stainless-10400-/171410216987?hash=item27e8d8581b:g:azMAAOSwBLlVQTxS (http://www.ebay.com/itm/G7-HPA-paintball-tank-regulator-One-Way-fill-nipple-1-8-npt-Stainless-10400-/171410216987?hash=item27e8d8581b:g:azMAAOSwBLlVQTxS)
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Hmmmm....I don't know if I should thank you for that suggestion or not. ;D
First I want to build an adjustable piston and see what it will do with good seals.
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yep, agreed.. i could have tethered my 880 once i had the 1/8th npt threads in it , but its more fun to see what u can really squeeze out of the pumper. I really think thise valve has more potential for power than the 880.. So if i got to 910 fps the skies the limit here.Im being the devils advocate but i wonder if the factory installed weak seals to regulate the max pressure in the valve?????????????????
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yep, agreed.. i could have tethered my 880 once i had the 1/8th npt threads in it , but its more fun to see what u can really squeeze out of the pumper. I really think thise valve has more potential for power than the 880.. So if i got to 910 fps the skies the limit here.Im being the devils advocate but i wonder if the factory installed weak seals to regulate the max pressure in the valve?????????????????
The seals that failed were cheapo -113 sized seals from the local hardware store. The factory seals were cut badly from installation and I didn't try them with my modified piston. Every slot and hole in the tube had razor sharp edges.
But, yes, I wonder how much pressure this valve will hold safely and how much I'm generating? Obviously I want to stay on the safe side.
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Whats the piston size, and whats the pump arm made of ?? I caN telll you really fast what pressures u wont hit!
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so the pump tube wasnt holding air , and the valve actually was ?? im confused now
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Pump arm is plastic, piston size is about .765. IIRC
Valve was holding air but I think my leakage was between the pump tube and piston and pump tube and valve body.
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I will share a tid bit with you that sounds odd.. MOST people dont understand pumpers AT ALL..Yes, we all get swept volume, bore diameter, piston facial pressure, camover, material strength, pump arm geometry, valve volume, transfer port flow, flat top pistons etc. But theres a good reason why Guys like LD and Phil are currently building pumpers that bend the rules. I could list all the misconceptions I know of , but thats really scratching the surface/
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Pump arm is plastic, piston size is about .765. IIRC
Valve was holding air but I think my leakage was between the pump tube and piston and pump tube and valve body.
sounds like u need more radius wall engagement from ur orings, i had the same problem with early designs on the 880.. the natural tendency for the piston to "yaw" or "cant" during higher pump numbers seems to cause some back leakage.In other words if the 113 has an i.d of .625 and o.d of .750 , u kinda want the oring gland to be .640 in diameter so that wall engagement is a bit more.. Hassle to load the piston sure, but same ease of pumping with a better seal
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oh yea, you wont be able to pump anything beyond 1800psi , the pump arm will snap or bend so hard the piston wont push anymore air into the valve ( thre back pressure will outweigh ur pump efforts)
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I can see that. It bends already. Until I learn more, I'll just consider it a safety feature. Lol
Thanks for your help! I'm just starting out. At this point I'm reading everything I can and experimenting with this rifle and a Benji 392.
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I just measured the volume of my valve. It's 2.2 cc.
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did u use water ?? .13 cubic inches, less than half what i imagined the 880 valve being..but still makes sense
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Yes, I used water dropped from a medical syringe.
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awesome, im sure my .3 cu inches was wayy off and its closer to your number on the 880
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Update: I installed the Viton seals, tried a few test pumps, and heard it leaking. I used some soapy water and traced the leak to the intake cup seal. I pulled it apart and found black Pelgun oil. I cleaned everything spotless and installed new o-rings. This time I lubed with a scant amount of silicon oil. I could still hear it leaking but decided to see if a few shots would seat the leaking seal. 10 pumps with a 7.9 gr CPHP gave me 590 fps. 15 pumps gave me 625 fps. So did 30 pumps, so I've reached the limit until I can fix the leak and build an adjustable piston head.
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Im guessing the pumps stopped adding up as the leak got worse?
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Actually, the leak seemed to lessen the more I shot it. I had to put my ear right on the tube slot and it was very faint. I think the piece I added to the end of the tube may not be quite long enough? Then again, maybe it just wouldn't hold more than a certain pressure?
Anyway, I think I'll machine a plastic intake valve like on a Benjamin 392 later on this winter. For now I'm going to pick up a Daisy 880 and do the tried and true mods like a lot of you guys here have proven worked.
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id love to see where the leak is , the gun should be as capable as the 880 based on stroke volume and the appearance of valve volume. but there may be a choke point in the tp , who knows
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id love to see where the leak is , the gun should be as capable as the 880 based on stroke volume and the appearance of valve volume. but there may be a choke point in the tp , who knows
I pumped it up and removed the valve assembly from the tube. I then used soapy water at every point I thought it might leak. When I put it on the intake port small bubbles formed. Based on this, it has to be the cup seal.
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interesting,,would the pressure of a washer/shim hellp flatten it to hit the wall better
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interesting,,would the pressure of a washer/shim hellp flatten it to hit the wall better
I don't know. I'll visit a few hardware stores this week and see what I can find.
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i mean even with no mods it still needs to seal.. if you could return exchange i would.. nice looking gun to mod
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I wouldn't feel right returning it. I've modified the piston head, used way more pumps than recommended, and used Pelgun oil rather than silicone oil, so maybe I damaged it. Besides, I'd hate to deprive myself the joy of figuring out this problem. :D
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okay.i didnt know what ya did was irreversible.. keep me updated on what ya figure out
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okay.i didnt know what ya did was irreversible.. keep me updated on what ya figure out
I filled the pocket in the piston head with epoxy and then screwed a piece of plastic on the face to take up the space between the piston and valve.
I'll let you know what I figure out with the leak.
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So, I gave it 10 pumps, removed the valve, and submerged it in water. It bubbled from both the front intake and rear rod. I used some valve lapping compound on the rear ball/seat and polished the intake bore with 800 grit. I also polished the rod that goes through the center of the cup seal. Also took the shine off the surface of the cup seal with 800 grit
Leak fixed. ;D
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wow, probably a dam spec of dust causing the leak !!!!!!! time to max it it out and see what it will push stock or otherwise
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Love to have one of these adjustable pistons. I'd have to put the stock trigger back in mine, which I need to do anyway.
How much have you gotten out of yours so far?
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Ive been using the last design pictured for a while now , since i posted it.. I was planning on selling a few But i simply could not come up with one simple design that was gaurenteed to do well in every single gun so i opted not to..To test it , i replaced thee compression tube and tried all the same settings, and sometimes it was perfect and others it needed to be pulled and adjusted.I do know that the max of the stock gun in any variation with no increase in valve volume is 910fps with 7.9
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I built this today. Results to follow tomorrow.
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20160929_194932-1_zpsxahsfbyp.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20160929_194932-1_zpsxahsfbyp.jpg.html)
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that look awesome mman, cannot wait to see results. i like the use of the higher quality orings.
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Thanks. The o-rings are Viton 70 in the original metric size. I also have some -113 Viton 90 o-rings that fit a bit tighter that I'll try if these don't hold up.
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yep.. it becomes a tight fit with the dual orings but a really good seal if there were any imperfections in the compression tube. Im actually building a 1 inch bore pumper from scratch right now , and finding more and more that the rigidity of the pump assembly from the handle to to top of the piston really dictates how much energy you can get from it.. your setup looks quite solid so hopefully we will see some good numbers
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Im actually building a 1 inch bore pumper from scratch right now
Interesting. Do you have a build thread anywhere? Coincidentally, I found a piece of 1" brass tubing in my dad's scrap pile this week and now the gears are turning...
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no build thread , but you can see the valve i made here
http://www.network54.com/Forum/275684/message/1475020298/so+i+made+my+own+valve++for+a+new+project+%28pics%29 (http://www.network54.com/Forum/275684/message/1475020298/so+i+made+my+own+valve++for+a+new+project+%28pics%29)
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Looks great. Are you planing on a two-stage pump?
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not on this one, this will just be a big bore(.30) sidelever pumper, keeping pump strokes to a minimum. I do have plans for a 2 stage system but not sure what platform yet.Its soo complex the only guy i know to pull it off so far is ron on the green forum circa 2006 i think
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the funny part there was he was able to pump the gun to 6000 psi ! yes 6000 psi lol.the valve split into 2 and the sheer heat above 4500 was melting the check valve
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Wow, that's impressive. My goals are more modest. I'd like one pump for plinking (450ish fps in 22) and four or five pumps for 800ish fps for hunting.
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and the biggest challenge there , like it was with the 880 was the swept volume of each stroke.. were the frame not soo restrictive ive had simply added a 1 inch id compression tube on the 880 and instead of needing 23 pumps to hit 910fps , i may have been able to get there in 7-9 pumps.. and modest power at 3-4 pumps.Granted, id have snapped more pump arms than i did lol. Theres soo many pumper possibilities and like you already know , 2 stage is mecca. Is there room in the frame for a bigger comp tube on your new gun , i never looked closely
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heres the plans for 6000psi pumper
http://www.network54.com/Forum/275684/message/1255819561/telescoping+piston+pics (http://www.network54.com/Forum/275684/message/1255819561/telescoping+piston+pics)
most people wouldnt even believe this is possible with a pumper.
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Yes, I think there is room for a bigger tube on the NXG. Now there is another idea swimming around in my head. Lol.
Thanks for the link. The two stage pump uses a ball lock system like is used on the tractor hydraulic couplings I'm familiar with.
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phils design is similar and still in the works.. the only challenge with the bigger comporession tube is obviously sealing it to the back of the gun( the valve area) so if its .730 now and you jump to .860 you will simply need to machine a spacer that seals to those orings, and most likely interference fit to the tube wall itelf for the sake of keeping it compact and air tight.. As the bore goes up the swept volume goes up exponentially..So really even a small gain like .050 is pretty substantial ( too lazy to do math lol
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895fps with the crosman premiers is the max at 20 pumps , theres a thread in the american gate to see the other numbers..Heres the new design , it circumvents the need for a roller pin, and should offer better stabilty to the piston head,. Im not sure if it will increase muzzle velocity yet
(http://i746.photobucket.com/albums/xx102/robnewyork50/newpist%20on%20design.jpg) (http://s746.photobucket.com/user/robnewyork50/media/newpist%20on%20design.jpg.html)
Do you have any drawings of this? Maybe I could make my own - even if all I have is a wood turning lathe...
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i think i have one of the old designs in my toolbox.it may need shimming, and needs fatter orings , i dont know what size,but if ya have a kit sitting around it you will have them.. PM me and Ill mail it out, obviously i havent tested this one and cannot recall if it worked as is or how it fit so for FREE i dont expect any negative backlast on the forum ( on PM its fine)
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its one of the them with the drilled shank insert , not the cup design as seen in the picture.
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That's very generous of you Rob! Thank you!
I'll send you the "flame-letter" on a PM. ;)
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Results are in: 915 fps on 22 pumps. :o
Just kidding. Lol ;D
Real numbers with 7.9 gr CPHP:
3 pumps - 450 fps
10 pumps - 675 fps
15 pumps - 750 fps
25 pumps - 780 fps
30 pumps - 810 fps
I adjusted the piston several times and this was the best. The pump arm was flexing and I had firm contact between piston/valve. I tried the firmer/fatter -113 Viton 90 seals and there was no change, except for the pumping friction, so I think I'm getting a good seal.
I didn't go past 30 pumps because I didn't want to destroy my rifle just yet. ;) I have a few more things I'd like to try.
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those are REALLY good numbers. i think you said the gun was supposed to push 500 fps stock?? or am i confused.. 810 is faster than a stock 397! Now to get the number of pumps down.. wish you were closer, wed convert it to big bore stroker in no time since ive already dont the leg work researching where to get the tube and what sizes are ideal.what was the gun pushing on 10 pumps before the mod??
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Yes, it was suppose to push 490 stock, but this is the reduced power version. The normal version claims 800, but online reviews have it around 100 fps faster than my reduced power version. I think the only difference is mine has a shorter piston that stops .175 short of the valve. Nevertheless, mine started out shooting 10.5 gr pellets at 450 with 10 pumps before the mod. IIRC.
I'd like to try the larger tube. Any info would be greatly appreciated.
But next up I want to see what reducing valve volume does.
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the valve is soo small ill tell you what will happen.. from pump 1-5 the velocity will go up , or stay about the same. from pumps 10 up you will either not be able to pump anymore, or the velocity will not climb.. your new max numbers will likely be closer to 700 fps, but with less strokes. u can try it and see what happens. But ur wayy better off pushing higher pressure with a very solid pump arm mechanism
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I'm sure you're right, but it sure is fun to experiment. Sounds like I'll need to build a new cocking arm. ;)
Anyway, curiosity got the best of me and I picked up the full power version of my rifle today. Kmart had them for $35.
The piston looks a lot like my modified one - plastic back half that connects to the pump arm with one o-ring and a foam wiper, and a front half with an aluminum head with one o-ring.
30 pumps gives 720 fps, 10 pumps gives 630 fps. I'll bet a few layers of aluminum tape would have it right up there with the adjustable piston.
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maybe .. the dual orings u have is a bit of an advantage.. give it a go.. seems like u already spanked the stock numers
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ok yea , id just reinforce the pump arm with a strip of steel till the connection point blows up like mine did lol
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I made a reducer. It reduced the valve volume by .9 cc.
From the 4th pump onward it pumps about as hard as the previous version at 10 pumps.
Results:
1 pump - 262
2 pumps - 388
3 pumps - 470
5 pumps - 532
6 pumps - 585
7 pumps - 600
8 pumps - 625
10 pumps - 650
15 pumps - 690
30 pumps - 709
40 pumps - 702
So, I actually lost speed from 6 pumps on. 5 pumps were the same. I'm sure barrel length comes in to play now with the small volume of air.
It is crazy quiet at 4 pumps and below; the hammer strike and valve reset are louder than the shot. This would be a great mod for basement shooting or bird pesting at close range It is also much quieter for the rest of the shots.
Now I'll increase valve volume a little at a time and see if there is a sweet spot.
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/2016-10-01%2010.48.31_zpsxtetuuom.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/2016-10-01%2010.48.31_zpsxtetuuom.jpg.html)
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/2016-10-01%2010.49.14_zpsoepuxsmk.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/2016-10-01%2010.49.14_zpsoepuxsmk.jpg.html)
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I made a reducer. It reduced the valve volume by .9 cc.
From the 4th pump onward it pumps about as hard as the previous version at 10 pumps.
Results:
1 pump - 262
2 pumps - 388
3 pumps - 470
5 pumps - 532
6 pumps - 585
7 pumps - 600
8 pumps - 625
10 pumps - 650
15 pumps - 690
30 pumps - 709
40 pumps - 702
So, I actually lost speed from 6 pumps on. 5 pumps were the same. I'm sure barrel length comes in to play now with the small volume of air.
It is crazy quiet at 4 pumps and below; the hammer strike and valve reset are louder than the shot. This would be a great mod for basement shooting or bird pesting at close range It is also much quieter for the rest of the shots.
Now I'll increase valve volume a little at a time and see if there is a sweet spot.
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/2016-10-01%2010.48.31_zpsxtetuuom.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/2016-10-01%2010.48.31_zpsxtetuuom.jpg.html)
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/2016-10-01%2010.49.14_zpsoepuxsmk.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/2016-10-01%2010.49.14_zpsoepuxsmk.jpg.html)
so in other words, my prediction was SPOT On?? lol, awesome , cool, that ya tried
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i think increasing the valve 40% will get ya to 900fps , or better, but the pump count may not go up..
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so in other words, my prediction was SPOT On?? lol, awesome , cool, that ya tried
Yep! Except that pumping wasn't as hard as I thought and the pump arm didn't break - yet. Lol
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lol. well im excited to see what the valve increase does.. i dont see why you cannot get 900-1000 fps.. when i had one with added valve volume , i didnt have a chrony but heres the video
https://www.youtube.com/watch?v=iGHzBu6GbD0 (https://www.youtube.com/watch?v=iGHzBu6GbD0)
seriously think i was hitting 1000fps
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Nice! That sounds like a .22 rimfire.
I'll have to ponder a way to increase the valve volume. I'll bet those threads are metric and I don't have any way to cut them.
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the sloppy idea is a dremel./Yes in real life it sounded like a 22 and i have a 22 so I know. lol/the way i did mine was add a gauge , so the channel leading to the valve was the additional volume. if ur not used to tapping NPT threads, DONT DO IT>> Anyway , id bore the rear valve plug on the lathe. drill bit and a boring bar could get some small gains.. then combined with dremel in the wall of the valve, u might have an easy time. You can thread metric on an imperial lathe, just need to know what ur doing.but id go the bore route.
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id have to see it in real life to have more ideas i guesss
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I've been looking and thinking, and I just don't see much excess material. I think I can unscrew the halves about .040" and then remove a couple threads from the male end, but that would only get me a 10 percent increase. I can bore it thinner in some areas, but I don't want to make a hand grenade. I think my time would be better spent fitting a larger tube like you originally suggested.
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the interior wall on the daisy 880 is super thick . .400 roughly, so adding volume was no issue.. another idea, drill and tap a hole. then plug it only at the end. essentially what i had done with the gauge , but you would just have a plug.. the bigger tube would get the pump count down dramatically, but without a seriously solid pump mechanism and rigid piston assembly, it will not hit higher pressure. ( again more valve volume would be huge gains, especially combined with the bigger compression tube) if you can , share a pic of the compression tube configuration
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i looked it up on your other thread, thats a wayyyy better design than the 880. the cap that holds the check valve could surely use some boring.. and the valve body itself could use the drill/ plug method if you are confident in sealing it.the compression tube looks like real steel too, lol, thats a big difference. the 88o tube is a 4 inch piece of thin thin wall aluminum
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I'll get some pics tomorrow, but it's a metal tube. As to the valve, there is no where on it that is .400 thick. Locations on the inside where it gets thick correspond with grooves or cuts on the outside.
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i saw there are slots and screw holes externally.theres definately ways to add volume, but having the pump compression tube bigger is a leap in the right direction no matter what to reduce the stroke count.. be nice getting 800 fos at 10 pumps or less
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I really wanna see you get to 1000 fps so i can go grab one and do the conversion with your r+d LMBO
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I enlarged the volume some. I cut about a thread off the valve and cut a slight chamfer. I also machined a new inlet valve plug. It increased the valve volume by .25 cc. I put it and the old one (separately) in a graduated cylinder to measure their displacement.
So what do think happened?
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20161002_154724-1_zps1lpepfuh.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20161002_154724-1_zps1lpepfuh.jpg.html)
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the velocity dropped pumps one to 15 , or it leaks?
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It really didn't make much difference from the original valve. At 10 pumps it was 2 fps faster, and at 30 pumps it was 20 fps less.
I tried five different sized valves: -.9cc, -6cc, -.3cc, stock, and + .5 cc (estimate). Looking at all my numbers, there wasn't much difference in the last three sizes. Time to find a bigger and/or longer tube.
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thats really odd, seems to me the piston is no longer compressing air at a certain point.. how in the world it lost velocity at 30 pumps is beyond me. What percentage of the valve volume was added with the last mod, Im guessing by how small it sounds , that it wasnt significant enough to impact the velocity
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thats really odd, seems to me the piston is no longer compressing air at a certain point.. how in the world it lost velocity at 30 pumps is beyond me. What percentage of the valve volume was added with the last mod, Im guessing by how small it sounds , that it wasnt significant enough to impact the velocity
I think I added around 15 percent. Maybe the o-rings are getting worn? I haven't changed them during this valve volume test series, so maybe they are getting worn?
Here are some pics of the action. If nothing else I could gain a little with a longer tube with a shorter cocking arm slot.
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20161002_141404-1_zpshdbgtacj.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20161002_141404-1_zpshdbgtacj.jpg.html)
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20161002_141419-1_zpsfpttucdh.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20161002_141419-1_zpsfpttucdh.jpg.html)
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20161002_141537-1_zpsfit8fn3a.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20161002_141537-1_zpsfit8fn3a.jpg.html)
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20161002_142114-1_zpsc9wiiika.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20161002_142114-1_zpsc9wiiika.jpg.html)
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the tube plays a big role in the chassis of the gun , unlike the 880// longer stroke means minimal gains , and changing the pump geometry, its actually harder to do on some models.. the toggle ( connects the piston rod to pump arm) would need to be elongated..WHAT I would do// Chop the tube 1 inch in front of where the valve connects. machine a derin rod step up with 4 orings. ( 2 on the stock tube side , 2 on the new tube side so .750 to 1 inch adapter) drill right through the adapter with 1/16th but to keep headspace at nothing.. make sure the adapter on the valve old tube side fills the void till its flush with valve face. now take ur pump assembly , add a 1 inch piston and transfer to the new one inch tube// Sounds complex but its a one day project .
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in other words , ur just doing a step up from the old tube which stays the same at the back, to the new tube which is big bore. the new tube and old tube would be pinned to the adapter, and the front of the new tube would be secured via the rigidity of the connection and perhaps stabilized by the barrel shroud
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my 1 inch pumper is pure beast to pump ( even with an extended sidelever) , so id probably shoot for .860 bore give or take
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Sounds like a good plan. Do you think 1020 DOM A513 tubing would be strong enough? 1" od with a .065 wall thickness has an id of .870.
My tube has an OD of .908. I thought about turning down the short valve section to fit inside the 1" tube and then silver solder and screw them together.
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yes, the dom will be ample strong.. Your idea might impede the other functions of the back half of the tube..If not ( you know better than I ) go for it.. Dom is cheap and .870 sounds awesome.. Were it not for the sidelever long arm im not even sure i could pump my build more than 2-3 strokes lol.
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Whats the i.d of the stock tube , at .908 od the id must be closer to .800.
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i see how ur idea could work , but i see it as a lot of milling and drilling , and too much effort compared to turning an aluminum or delrin adapter, when u set aside the chopped section from the pump tube, do not forget to duplicate the stroke length and geometry obviously , u want to be as close as possible to the stock configuration, just bigger piston moving in a bigger tube ;D
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im still trying to figure out why the gun isnt topped out at a lower pump count. the daisy is beyong difficult to pump at 17 and by 20 you can feel your no longer doing much to compress air, just burning calories.. Im wondering why its letting u pump 30 times before hitting max velocity.does it feel extremely hard to pump after a certain number
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im still trying to figure out why the gun isnt topped out at a lower pump count. the daisy is beyong difficult to pump at 17 and by 20 you can feel your no longer doing much to compress air, just burning calories.. Im wondering why its letting u pump 30 times before hitting max velocity.does it feel extremely hard to pump after a certain number
Too funny. I was just thinking about this exact thing. Why is pump 40 the same difficulty as pump 15? Something is just not right. I wonder if I'm getting flex at the the back of the piston since it is made of plastic? Or... is the valve face slightly off perpendicular and leaving a wedge of air that can't be stuffed into the piston? I'm going to eliminate these two variables before going with the larger tubing. BTW, my current ID is close to .780 (can't remember exactly right now.)
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ive found with my pumper experiments ur dead on.. the yaw and cant of the piston assembly is ur biggest issue and the bigger the piston or the stiffer the piston , the more this becomes a problem.. tighten up every dam link, make the piston one long a's solid rod of aluminum.. or keep the adjustable screw section really dam short.
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No one believes it but on crosmans, even tihgtening up the play in the pump arm pivot of the tube leads to gains for this exact reason.. MAtter of fact the reason for the piston cup assembly is to avoid overpumping lol. The designers intended it so the piston will push no more air after X numver of pumps
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another idea while ur at it, u can extend the valve by simply getting a home depot coupler male to female in that thead , then turning it down on the lathe .. just as an aside
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another idea while ur at it, u can extend the valve by simply getting a home depot coupler male to female in that thead , then turning it down on the lathe .. just as an aside
That's a good idea. This weekend I measured the thread pitch to see if it was metric. It is 1.0 mm. I didn't measure the diameter, but I know the o-rings have a 15mm ID, so likely it is a M14-1.0 thread. I'm searching for an adapter in that size but haven't had any luck yet.
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male to female 14-1.0, im looking
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i think its 1.5mm pitch , double check
http://www.ebay.com/itm/Steel-Adaptor-M14-x-1-5-Female-to-M14x1-5-Male-Fittings-HEX-22-L-43mm-1-7inch-/322245392493?hash=item4b0752786d:g:0tQAAOSw9IpXw8wg&vxp=mtr (http://www.ebay.com/itm/Steel-Adaptor-M14-x-1-5-Female-to-M14x1-5-Male-Fittings-HEX-22-L-43mm-1-7inch-/322245392493?hash=item4b0752786d:g:0tQAAOSw9IpXw8wg&vxp=mtr)
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not to assume u dont know, but measure the major thread to the next major thread on an even plane./
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http://www.mcmaster.com/#steel-pipe-fittings/=14g01ky (http://www.mcmaster.com/#steel-pipe-fittings/=14g01ky)
ANOTHER IN 1.5
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MAN THAT will be a lot of extra air , lol.. the gun will sound like a 12 gauge on 25 pumps @ But it will be adjustable when u have it threaded all the way down im sure it will not even double the volume
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Thanks for looking. I'll double check the measurements, but I'm positive it's a 1.0 thread. I used a thread gauge when I measured it.
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thats really odd man,no one makes anything in 1.0 .. its hard enough to find a tap in 1.0 nevermind a coupler.thats 25.4 threads per inch , super fine thread for that diameter.
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tap is 8 bux, then ud have to turn the A threads on the lathe.
makes it a big project compared to a wham bam
http://www.ebay.com/itm/M1-M16-Industrial-HSS-Metric-Taper-Plug-Tap-Right-Hand-Thread-Drill-Bits-Set-US-/331769989528?var=&hash=item4d3f084998:m:m7lnSs1coT1LryrDW9vB1Ug (http://www.ebay.com/itm/M1-M16-Industrial-HSS-Metric-Taper-Plug-Tap-Right-Hand-Thread-Drill-Bits-Set-US-/331769989528?var=&hash=item4d3f084998:m:m7lnSs1coT1LryrDW9vB1Ug)
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I got the piston in the mail yesterday Rob. Thanks! I'm anxious to try it out. (But, it's been so long since I've been into my 880, I've forgotten what all of it looks like. I'll have to get familiar again.)
The threaded rod is a bit off-axis in the bottom of the piston. Will that cause problems? Or will the pivot action in the roll pin connection give me some fudge room?
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i never noticed apparently.. yes, it should shoot straight due to the natural flex in the entire pump assembly... That was an early proto and all i had left. if you have a 10-24 nut you may wanna put one behind the piston .. With all the designs, even the last one the gains really come from pumps 12-20 ,,. make sure you keep it well oiled , but dont drown it.I can only imagine something was out of spec and thats why it was thrown in the drawer.I probably made 10 designs or more in a month lol
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tap is 8 bux, then ud have to turn the A threads on the lathe.
makes it a big project compared to a wham bam
Yea, I think I'm just going to machine an all-metal piston, square the valve face, and except what I get. I would rather put my time and money towards building an all-new design with a good receiver and trigger than sink a lot more into the plastic rifle I have now.
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if i wasnt swamped in projects, id get the gun and see where it goes.i think even with the limited valve volume and a super rigid pump mechanism , based on the numbers you have gotten thus far, that you can crack the 900fps mark no problem! the further you start from scratch , the more headaches, i can promise that.Im still wondering why they used 1mm thread.. The drill and tap valve anlargement idea should still be on the table , its by far the easiest way to gain volume. Heck you could thread in this and triple the volume with 10 minutes and a tap
http://www.aerotechnic.com/store/index.php?main_page=product_info&cPath=6_29&products_id=144 (http://www.aerotechnic.com/store/index.php?main_page=product_info&cPath=6_29&products_id=144)
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or any hollow plug for that matter. But first things first, the piston needs to be all metal and super rigid.. and take any slack out of the pump arm and connection points.
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Hmmm... that threaded reservoir idea has some potential....
But first, I'm going to be sure everything I have now is optimal. Two other potential problems could be scratches in the pump tube and ensure that I have a perfect gland cut. I made a square bottom in my piston and I wonder if it should have been round to hold more pressure? However, I did duplicate the factory piston gland.
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im not sure.. sqare bottom glands got me to 2200 psi.. slightly more than optimal oring engagement on the wall is always good too , so i usually have the gland about .010 less shallow than suggested/.i might try my 880 in the old configuration again where it sounded like a 22, just to see what the chrony says now having the 24 inch barrel installed.
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heres my little valve extension with gauge i made. letting the the red thread lock cure in the sun.. it probably adds 4 cc's//
(http://i746.photobucket.com/albums/xx102/robnewyork50/for%20bhm.jpg) (http://s746.photobucket.com/user/robnewyork50/media/for%20bhm.jpg.html)
also serves the purpose of having a 3000 psi gauge
(http://i746.photobucket.com/albums/xx102/robnewyork50/gauge%20block.jpg) (http://s746.photobucket.com/user/robnewyork50/media/gauge%20block.jpg.html)
(http://i746.photobucket.com/albums/xx102/robnewyork50/gaudy%20gauge.jpg) (http://s746.photobucket.com/user/robnewyork50/media/gaudy%20gauge.jpg.html)
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Nice. So you know pressure increase for each pump. How much does it go up from pumps 20 to 23?
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ive done this before, if you look at old threads on my 880 experiemts.. PUmp 1-10 are about 100 psi per pump with modified piston.. pump 15is about 1600psi and then it declines fast. pump 20 is only 1850 iish , pump 23 hits 2000psi, and 2200 psi was like 26 with the last few pumps being rapid and heated. ( the compression at that point makes the air tremndously hot and also heats the valvve. I havent tested the new setup, because by the time the thread lock set, it was too late to get the chrony outside.. Plus i wanna make a new piston design.. hoping tommor ill try to bust 1000 fps.. BTW the non linear gains had to do with heat accumulation, obviously if i let the air cool after each pump the numbers would have been different
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I cant find all the details i recall typing , but heres the thread from the old design with perhaps less additional volume
http://www.gatewaytoairguns.org/GTA/index.php?topic=113523.0 (http://www.gatewaytoairguns.org/GTA/index.php?topic=113523.0)
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what cossed my mind is making an insert in the compression tube that will house a smaller piston. still single stage but ill be able to pump to wayyy higher pressure wiith the stock pump arm , granted it will take 40 pumps to get there but even at .500 piston the force required would be half, so getting to 3000psi should be easy
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Yea, one thing I like about this NXG is how easy it is to pump. I'd rather pump it 30 times than my Benji 392 12 times.
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yep the 880 is very easy too , till i get to 15 ish.. any news on the piston design??
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It will be this weekend before I get a chance to do anything. I was on vacation last week and had time to play.
But I'm going to make a rock-solid piston and "lap" it to the valve face.
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sounds good , hopefully ill either test out the 880 as is tommor, or put together the small pump pump setup and see what kinda pressure i can pump with a 1/2 inch piston
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I glued a piece of 320 grit sandpaper on the piston face, pushed the piston assembly down the tube, and gave it a few turns. The valve came out evenly sanded, but the piston came out looking like this:
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20161006_215511-1_zpsbe9dmu5x.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20161006_215511-1_zpsbe9dmu5x.jpg.html)
Heavy-duty piston with a square face coming soon...
Or maybe I should glue sandpaper to the valve face and sand the piston square first and see how that works?
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im not sure what ur trying to do lol! i think ur trying to get the 2 faces to sit flush to each other. what id do is simply look for all losses of rigidty in the pump mechanism
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i didnt get &^^& accomplished because i never made it to the store to get new orings., And my lathe threw a belt so essentially a wasted day of my life.hopefully tomorr goes better.the one thing i did do was make a new piston design , then overcut the depth on the oring gland and have to throw it in the trash.. after that i was fed up and done for the day
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The pic is my piston face covered with sand paper. The left side is aluminum dust from sanding the valve face and the right side is virgin sandpaper. So, my piston touches the valve only on one side and I have a wedge of air that never gets squeezed into the valve.
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i see now.. ur eliminating all headspace
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Exactly. I measured and one side is about .012 shorter than the other.
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have you figured a way to make a more rigid piston assembly ?? I was trying to do my piston reduction last night, then i ran the numbers before i started. Basically , id lose half my swept volume even going to .500..So id be be pumping 40 plus times per shot , even though id obviously reach insanely high pressures, Anyway , off to get materials and orings finally today to test the new gauge block.. Ill post pics if all goes well and maybe chrony data
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I'm going to make the entire thing out of aluminum and drill and tap the entire piston before I separate the halves. Also going to use a 3/8 bolt instead of 1/4.
Looking forward to seeing your results. But I agree about the 1/2" piston. I'd like the easy force, but don't want to pump more than about 15 times....and 10 would be better.
Things are slow for me right now because I'm building a pond and the weather is good, but winter is coming.
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Cool..i made an entirely new flat top piston one piece assembly today with 1/4 set screws locking it to the pump rod so theres no flex at all.. Come to find out my valve isnt sealing up by the transfer to the barrel. With this new rigidity i should be able to pump to higher pressure than ever before. If i can get it to seal.yea. the small piston was too many strokes to pirse although pumping to 3000psi would have been a breeze.
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I finally had time to play on the lathe and mill and came up with a solid piston. This design utilizes my new "Tit Top Technology" ;) to eliminate as much headspace as possible.
I made it exactly as long as the old one was and it's a nice snug fit as the lever is closed. I figured that if I needed to adjust the length a few thou then I could unscrew the valve slightly or sand the face.
Chrono results tomorrow, but for now, it pumps much harder than the old piston after about 5 pumps. It strains the lever at 10 pumps and at 15 pumps it's really hard and bends the lever significantly.
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20161019_224023-1_zpswizpptmx.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20161019_224023-1_zpswizpptmx.jpg.html)
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A very professional looking piece of work...PHIL
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Thanks, Phil! Hopefully it works well.
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friggen awesome man@@@@@@@@@@@@@@@@ looks great, and very rigid.. it sounds like the pump effort i had on my 880 with the first piston i made, it was pretty dam hard by pump 8.. Cannot wait for the chony results. post the numbers here and in a new thread. (or dont if you do not want emails asking for the pistons )
ive been working on wrapping up the Multi stroke p17.. probably be another week.. I might sell a few but for now im keeping it quiet till i get some really high chrony numbers. will that front pin knock the check seal out of place?? cool idea
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Thanks. The front pin is not long enough to touch the check valve. I measured and then double checked before I put it all together. No way I'll sell any pistons - I enjoy tinkering, but that sounds too much like work. ;) I figure that if I can get it to work I'll post a thread in the China Gate so others can improve their NXG.
I'd like to see details about your Multi stroke P17. Those things are only $35 at Amazon....
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lol, the details.. you might get emailed details, but nothing public but numbers :D no matter the skillset , its a very hard conversion for reasons people dont think of .., thats why only one gun has ever been done sucessfully, and hes a brilliant designer beyond explanation..
i really think you may be able to crack into the 900s now.. the biggest challenge will be not breaking the pump arm.(i broke 2)What ya can do as opposed to making them for people, if enough ask, post the blueprints, let them find their own machinist..
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lol, the details.. you might get emailed details, but nothing public but numbers :D no matter the skillset , its a very hard conversion for reasons people dont think of .., thats why only one gun has ever been done sucessfully, and hes a brilliant designer beyond explanation..
i really think you may be able to crack into the 900s now.. the biggest challenge will be not breaking the pump arm.(i broke 2)What ya can do as opposed to making them for people, if enough ask, post the blueprints, let them find their own machinist..
And you too, Rob! If you finalize a design, I'd love to have a drawing... I've been too busy trying to get my HW95 working to work on the 880. (And of course I suddenly have 5 woodworking projects to do in addition to my assembly line Model Ts).
One of these days I'll get around to putting that piston in. When I do, I'll let you know what happens.
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Results are in:
5 pumps = 550 fps
10 pumps = 700 fps
15 pumps = 765 fps
20 pumps = 800 fps
25 pumps = 805 fps
30 pumps = 804 fps
Kind of puzzled why it flatlined at 800 fps. Valve volume? I looked at the o-rings and they appear to be sealing well. I'm tempted to drill a few holes in the sides of the valve body (at the hex area) to get more capacity. Do you think the pump tube and o-rings would hold the pressure?
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20161002_142136-1_zpsvnmyou0l.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20161002_142136-1_zpsvnmyou0l.jpg.html)
I'll be more than happy to share any piston dimensions with anyone who wants them, but mostly it's just a solid version of the factory piston with two o-rings, a tit to reduce headspace, and lengthened to contact the valve body.
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Results are in:
5 pumps = 550 fps
10 pumps = 700 fps
15 pumps = 765 fps
20 pumps = 800 fps
25 pumps = 805 fps
30 pumps = 804 fps
Kind of puzzled why it flatlined at 800 fps. Valve volume? I looked at the o-rings and they appear to be sealing well. I'm tempted to drill a few holes in the sides of the valve body (at the hex area) to get more capacity. Do you think the pump tube and o-rings would hold the pressure?
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20161002_142136-1_zpsvnmyou0l.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20161002_142136-1_zpsvnmyou0l.jpg.html)
I'll be more than happy to share any piston dimensions with anyone who wants them, but mostly it's just a solid version of the factory piston with two o-rings, a tit to reduce headspace, and lengthened to contact the valve body.
You're not working with an 880 though, are you? Seems like you were working on something similar...
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Okay , 800 flatline at 20 pumps essentially. the valve volume is the issue ( one issue..) no DONT randomly drill unless u are gonna plug it with additional volume as we have discussed.the other issue might be the valves ability to breath into the barrel , im actually positive thats one issue.. make a plug, or just buy a 1/8th npt plug at home depot, drill a hole and add some volume.. seal it with red locktite, although NPT seals itself anyway.Is there a way to drill the transfer port to the barrel?? there really isnt on the 880 without compromising the seal of the valve. More volume is in order, think before you drill. ;D
Underdog , let me know how the 880 goes, the p17 conversion will have some details posted in the coming week.i dont want to share anything till i have the chrony numbers .. Its very difficult to pull off, hence we dont see them at all.Its the hardest mod ive ever done for a dozen reasons
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There is a rubber plug on the underside of the valve. I think they drilled the transfer port and then installed the plug.
Underdog - This is a Umarex NXG APX. Rod said he didn't mind me posting in this thread.
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So your sole option is additional volume , if you dont understand the hollow plug idea, i made a drawing .. it should really be about a 5 minute mod.. the key is , in my experience, using a smaller thread connection to the valve wall. this way u can run the tap in with a drill , and disrupt less internally. a very simple combo if you have a 10-32 tap is these 2 items
http://www.ebay.com/itm/2-Glycerin-Filled-Stainless-Steel-Gauge-1-8-NPT-Lower-Mount-0-3000-PSI-/181677210228?hash=item2a4cce3a74:g:le0AAOSwNSxU76Qo (http://www.ebay.com/itm/2-Glycerin-Filled-Stainless-Steel-Gauge-1-8-NPT-Lower-Mount-0-3000-PSI-/181677210228?hash=item2a4cce3a74:g:le0AAOSwNSxU76Qo)
http://www.ebay.com/itm/1pk-1-8-NPT-Female-to-10-32-UNF-Male-Brass-Pipe-Adapter-MettleAir-120-AU10-/190751234882?hash=item2c69a8db42:m:mDBJ77y7FOsWIBmbjAqtALQ&vxp=mtr (http://www.ebay.com/itm/1pk-1-8-NPT-Female-to-10-32-UNF-Male-Brass-Pipe-Adapter-MettleAir-120-AU10-/190751234882?hash=item2c69a8db42:m:mDBJ77y7FOsWIBmbjAqtALQ&vxp=mtr)
now u have more volume and a massive good quality gauge
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but wayy better option is a hollow home machined plug with good internal volume.like the aluminum one i made last week
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Yea, I need to build a new valve front. I'm rebuilding a South Bend 9 lathe right now. I think they make a set of gears for cutting metric threads. I'll have to look into it.
Tonight I drilled out the plug and enlarged the transfer port slightly ~ maybe .010". I can go more if need be, but thought I'd take it slowly. I plugged the hole with JB weld.
I also thinned and polished the exhaust valve shaft.
Results tomorrow after work.
BTW, that plug and gauge look interesting. I'm curious to know how much pressure is in there.
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sounds great.. the .010 might make all the difference. yes, extending the valve plug is one method , the only thing i dont like about that is the fact it shortens your potential piston stroke.. your idea about drilling the hex between the 2 orings might work , just make sure the hole is a threadable size so u can plug it if it does leak.. Rebuilding the SB9 will be well worth it when done, and yes, youtube will have the proper gear combo..Theres also a few online calculators, I have one i used last week for doing 10 pitch ( you put in all the gears, it generates a combo)
oh yea, the plug gauge combo is nice., id bet your pumping 2000 psi ..
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start at 8:30 in the video
https://www.youtube.com/watch?v=PbpYqUccOd4 (https://www.youtube.com/watch?v=PbpYqUccOd4)
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start at 8:30 in the video
https://www.youtube.com/watch?v=PbpYqUccOd4 (https://www.youtube.com/watch?v=PbpYqUccOd4)
Thanks. I'll check it out.
Btw, When I build a new valve front I won't make it longer - I'll make the i.d. fatter in the middle by eliminating the hex part.
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Brilliant@@@@@@ very good idea. that will asdd substantial volume.. while rebuilding the SB , what machine are you working with??
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I'm using a half-worn out SB Heavy 10. I'm going to rebuild it after the 9.
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cool/. when I lived in NYC , I could have gotten almost any quality lathe for 1000 bux or less .. It was insane how low people would sell.. now living in central LA , the very few lathes on craigslist are soo wildly overpriced, its actually a better deal buying new from grizzly.Im not sure if its only because there are more people in northern cities, or because there was more industries that had machines 50 yrs ago and the market is still flooded.
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Likely a combination of both. Many schools had lathes too and got rid of them when computers became the big thing.
Anyway, I shot a few over the chrono today after work. I gained 10-15 fps in the 10-15 pump region. Then again, the air is colder and dryer today so that could account for the difference.
Like you said before; needs more volume.
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10-15 fps is a good thing ,especially for .010 port job..( i meant 1000 bux above, im sure you caught that lol) is there any more porting that can be done safely or are you maxed out ??
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I figured you typed an extra zero in your lathe price. :D
Anyway, the port is .140" now. I think I may be able to go out another .010, but it's close to the breech sealing surface in the barrel as it is, AND I think the exhaust valve shaft is the limiting point now.
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okay.. I wouldnt push the porting too much further in that case. with the added volume, the gun will get soo loud its actually kinda funny.Sounds to me the exhaust arrangement is also quite different than the 880.140 is is still pretty small but its all in relation to the valve size, not sure there will be too much more to gain , especially as you approach .177 port.. if you had a gauge, and body armor, you could always wrap the valve in small diameter copper tubing , then run boiling water through the tubing and pump till you hit 3000 psi (-;
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Body armor? :o :D :D
I've been thinking about it and I think I've reached a good balance point. With over 700fps @ 10, 775fps@15, and slightly over 800fps @ 20, it's not loud, I'm not breaking the pump arm, and it has enough power for small pests. I think I'll turn now to accuracy and finish this project. After I get my lathe rebuilt I'll start working on a pump .22 from scratch. Everything will be solid metal and bolt together so I can play with valve size, tranfer ports, etc, etc.
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I personally think you still need to do the volume mod, its a 20 minute mod with a plug from home depot. costs almost nothing if you make the plug, and seriously I think 900 plus fps will be effortless with a 20% GAIN.. no to mention your hex drill idea which is free. just my opinion, i was close to quitting the 880 well before I got 910 fps.. i have a pic of my 1 inch tube pumper, need to finish one day
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(http://i746.photobucket.com/albums/xx102/robnewyork50/pumper2.jpg) (http://s746.photobucket.com/user/robnewyork50/media/pumper2.jpg.html)
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Nice work! How hard is it to pump?
Yea, I can't give up this close. ;) One problem with the plug is that the inside of that hex area is where the check valve cup washer seals. A plug would ruin the sealing surface.
I'm mulling over some other ideas....
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Its quite difficult to pump to be honest ., pump 1 is like pump 6 on a 392 with the same length lever. thats the reason its sidelver.. with the temporary extension bar on there, its fairly easy to get to 3 pumps.at first I had a 392 valve with spacers in it , then i needed to make a valve from scratch , the 392 valve was simply wayy to small in volume.Im wrapped up in other things now , ill get back to it soon.. I will say this , starting a gun from scratch ( not converting an existing gun ) is soo many man hours its no wonder only a few guys do it , and charge accordingly. Anyway, in regard to your gun , the longer the stem going into the valve , the more variety of places it can be mounted. If you notice with my 1/4-20 to 1/8th npt adapter i made, the threaded 1/4 rod is pretty long so i was able to thread into the valve from outside the gun.. A famed navy seal Robert O'neill once said " most people quit when there 98% to their goal , they just dont know it "
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No doubt building a gun from scratch is a huge project. I'm looking forward to seeing your finished project.
You're right - I need to finish this.
So, what do you think of this idea:
Step one: Drill the valve on each flat like is pictured here. The drill is angled to avoid the intake check valve.:
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20161021_210623-1_zpsqnp3x4g1.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20161021_210623-1_zpsqnp3x4g1.jpg.html)
Step two: Machine a steel bushing with about a .125 wall thickness. (I'll call this my anti-shrapnel bushing. ;)) Make the I.D. a slight press fit with the tube O.D. press in place over the valve and secure with green Loctite. The bushing is represented in this pic with masking tape:
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20161022_162024-1_zpseqb9zdqi.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20161022_162024-1_zpseqb9zdqi.jpg.html)
The actual bushing would not extend as far forward as the masking tape. Maybe .50" in front of the valve face. For that matter, I could make the wall thick enough to hold a pressure gauge and machine a groove for clearance under the barrel and cocking arm.
What do you thinK?
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if everything is locked in place annd u can get good thread engagement on that angle then fine.. It looks challenging from the picture though.. id rather attack the side of the gun for a good drill spot, right through the plastics and into the valve.I LIKE THE LOOKS OF THE BIG HOLE IN THE SIDE. whatever you are comfortable with. heres the msp p17
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(http://i746.photobucket.com/albums/xx102/robnewyork50/p17%20msp.jpg) (http://s746.photobucket.com/user/robnewyork50/media/p17%20msp.jpg.html)
pumping it is plain exausting , pump 1 is easy , pump 2 is the as stock , and pump 3 is incredibly hard. went out back to chrono and the sun was gone too far down.. my caldwell reads anything so i knew it was a lighting issue.. this conversion is not practical.. i was gonna make and sell a few, but it needs an adjustable piston no matter what.. 1/4-20 rod isnt strong enough so i need to change that to 5/16 stainless. Im pretty strong and only 35, I just cant see any old timers enjoying this at all. Not to mention , no matter how u dial the piston , it draws back to far and pops loose when u open the gun fully.. Yes, i can spring load the piston and make it telescopic under load, but again , were back to a lot more work to make it practical.
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That's too bad about the P17. I wondered if it would be hard to pump with that short of a lever. I'm a semi-old timer with a bad shoulder so that would be too much for me. I'd still like to see what it's putting out at the chrono, though.
On my valve that big hole is behind the exhaust valve so I can't put an adapter in there.
But, that's not what I was aiming to do. My thought was that the holes would connect the large area between the o-rings with the valve chamber. The sleeve on the outside would increase the thickness of the pump tube so it could contain the pressure safely. So the pump tube between those o-rings become part of the valve. It's like a skeleton valve in a 392.
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On your gun , Im fairly confident the tube wall of the pump would handle whatever the valve will , the reason is adiabatic heating.. while you are pumping , the air in the rear portion of the tube is super hot after a few strokes, so the tube wall pressure is often in excess of what the valve will see ( now you have expansion and cooling post check valve ) So , yes that will work as long as it seals
My p17, its really powerful, i do know that .. chrony results tommorow.. Im hoping it shoots 600fps with 7.9 , i too have a bad shoulder from pumping the dam gun (-'
Lots of people are really interested in this gun being msp , but in order to make it relaible enough for retail , theyd also need to be quite expensive I assume ( money in time , not materials) .. I know stalwart is working on a conversion , but i think he will hesitate to go commerical when he realizes how much strain it puts on the gun chassis
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If you're like me, in twenty years you'll be telling the shoulder surgeon you don't know what you did to hurt your shoulder. Lol
Going commercial: I think it would be tough when you're starting out with a low-cost gun. Most of the cheap stuff is marginally built and a lot of guys don't/can't fit things precisely. By the time I get this NXG shooting hard it will be half worn out.
I see what you mean about the tube already being subject to those pressures. I think I'll give it a shot. At the worst I'll have to build another valve front - or scrap out a $29 rifle. As I see it, an o-ring seals the two valve halves, so it should seal in this case. They also make some of those super-duper x-rings. Maybe that would work if these don't.
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yep,my shoulders will not last long at this rate.. From what im picturing , all you need to do is drill one small breather hole to take up that vacant volume in the rear portion of the tube.. the stock orings already in place are creating a seal as is.if these orings dont hold, look at the next size up as far as thickness. for example , on the p17 it comes stock with 117 rings., and on the valve wall im using 210 orings ( twice as thick and .015 taller )
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matter of fact i just used this dual oring method like youre planning to seal off the pinning screws on my p17 so the pressured air never sees the screw holes
(http://i746.photobucket.com/albums/xx102/robnewyork50/check%20valve%20bhh.jpg) (http://s746.photobucket.com/user/robnewyork50/media/check%20valve%20bhh.jpg.html)
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Good point. I think it will work. I'm using .750 O.D. o-rings instead of the factory metric and it's a tight fit to get them in there.
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sounds good , slight interference is always good , just lube em up real well and make sure the seating location is glass smooth
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im sure u inferred this but there is no need to drill your tube , just the valve for the dual oring seal
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Yep! The tube becomes the valve wall. That's why I was going to put a sleeve on the outside of the tube - it would make the new valve wall stronger.
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ok , just making sure that unless ur installing the gauge , theres no need to drill the tube/ Airguns are hard enough to keep sealed in stock config lol
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So, I drilled the valve at two places with a .125" drill. I put the holes on an angle like in my photo. I ran out of the the oversize 90 Duro SAE o-rings, so I had to use stock metric sizes in 70 Duro.
Results:
No leaks,
No explosion,
10 pumps I'm down about 35fps,
15 pumps I'm about the same,
20 pumps I'm gaining a little ground,
25 pumps and I have a 30 fps gain,
30 pumps and it's at 850fps
from there it slowly improves with a peak of 893 fps at 45 pumps.
I tried for 900fps, but couldn't quite make it - even with 60 pumps. The rifle was getting hot and I was loosing velocity. I lubed the piston o-rings, but it didn't make any difference.
I'm letting it cool now and will try again later. If my arms are up to it. Lol
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hahahahahaaa, thats friggen awesome ! congrats ! so , what id do since u gained sooo much volume , is throw a spacer in there to reduce it back down a bit.. check ur piston orings, make sure all is well lubed.. and try to bore the transfer port another .010.. this way you get to 900 ish in less pumps /./ WAS it loud??
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if you gained ground at 20 pumps , it seems like most of the real compression was done by that point.. i think a few tweaks will have u at 900 inside 30 pumps
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hahahahahaaa, thats friggen awesome ! congrats ! so , what id do since u gained sooo much volume , is throw a spacer in there to reduce it back down a bit.. check ur piston orings, make sure all is well lubed.. and try to bore the transfer port another .010.. this way you get to 900 ish in less pumps /./ WAS it loud??
Open transfer port more and play with finding optimal valve volume for 20 and fewer pumps - I was thinking the same thing.
It was louder, but not loud. I was surprised.
I'm going to have to order more o-rings - I've trashed about 40 of them. Lol
But first I have something else to build:
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20161023_180316-1_zpsnobj88gd.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20161023_180316-1_zpsnobj88gd.jpg.html)
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sadly , that exact breaking point looks quite familiar.. harbor frieght has entire oring sets in metric and sae for 5.99 , 200 piece. I have several lol.the max, if anything like the 880 should come around 23 pumps, so in reality, if you were getting to 893, you should be able to do it by 25 pumps if all is correct
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since ur gun is rated soo low from the factory, im sure the hammer and trasfer port are slightly restricted not allowing you to dump the full charge quickly..
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since ur gun is rated soo low from the factory, im sure the hammer and trasfer port are slightly restricted not allowing you to dump the full charge quickly..
I'm not so sure about that. I think the difference is in the piston. I bought the full-powered version a couple of weeks ago and it had a full length piston. It made about as much power as my first piston did when I added a piece of plastic to take up the headspace. From the factory, mine had about .175" headspace plus a .2x.25 hole in the face of the piston. I didn't take the rifle apart to check the internals, however, and my son took it with him after a visit, so I can't look at it now.
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aside from the transfer port, what else do you think is a limiting factor? I do think a heavier hammer spring would gain you another 20-40 fps if you happen to have a thicker one laying around.. does your machined piston eliminate head sPACE?? i know on the 880 having the piston literally crashing into the valve check block at the very end of the stroke created the best numbers.. ( i do mean barely , it was probably impacting .030 before the lever closed)
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I just took it apart and found a thick layer of blackened silicone oil on the valve and piston face. I think the oil was keeping the piston and valve from touching and causing the hole in the lever to stretch until it broke. I put the lever pieces back together and it looks like the hole elongated before it broke. Maybe that accounted for my decreasing velocity? On the good side, none of that blacken oil had migrated past the o-rings so I believe I was getting a good seal.
During shooting today I checked and the valve was not retaining air. Would a stiffer spring do anything in that case?
So, build a new arm, reduce the amount of oil, and make sure the valve and piston touch. Then try again with about half of my additional volume.
I had the piston and valve face touching when I installed the new piston. I can adjust headspace slightly by loosening the valve half.
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the elongagting of the hole in the toggle created headspace over time, as did the accumulation of grease.. So thats a big reason you stopped building pressure at some point ( pump30 ish ) As for The hammer spring. people call it lock time but yes.. As the pressure increases, the hammer spring may still be able to blow open the valve, But is it doing it quick enough to make use of the new found volume?? So you may be reaching this fine balance point where the pressure is low enough to let the valve blow open( barely ) , but its not doing it quickly enough because of the( well beyond stock) back pressure. If that makes any sense?
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for example , the 880 trigger is brutal at about 8 lbs , but a good amount of that sprung weight is the hammer spring.. So it had no issue at all dumping 2200 psi.. Could i have made gains with an even heavier spring, perhaps , guys with far less mods gained 20-30 fps by making the hammer violent.. I will say this , ive moved on from the 880, but when someone comes along and slings a 7.9 from an 880 at 911 fps , ill be right back at it with a 2 stage piston! . I simply dont see that happening ;D ( thats not cockiness, I hope someone does make a 1000fps 880
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in other news, the p17 set up for 3 -4 pump max is brutal, on the 4 th pump , the effort is about 100 lbs.. my hands are destroyed. The bad part is its impossible to take the tube off and add some more valve volume, so each revision requires a new gun.. on 3 pumps i got a lame 480fps with 7.9 grain..if the roll pin in the piston would stay in place for pump 4, im pretty sure i could crack 600 fps( blood adds 20 fps)My new idea, if i decide to pursue it , is a true 10 pump msp gun.. the idea being that the gun would not need to exceed stock pressures by much , but the volume would be triple.Thats the only confuration the gun would have mass appeal , and a key reason i believe a prominent builder has taken soo long to get the system to market.A very bright and sneaky way around this entire challenge would be to make a sleeve reducing the piston bore to .700 from .985..the sleeve at the rear could also be the check valve, This way the pumping effort to accomplish 3000psi weould be substantially reduced . Lets look at piston face pressures to get to 3000psi .. with the stock piston , its impossible. ( .4925x.4925X pi X 3000psi =2284lbs /15:MA =152lbs effort for one pump , NOT HAPPENING, the gun breaks at 100 lbs , i KNOW
for .700 the face piston pressure would be .350X.350XpiX3000=1154lbs at piston , given a mechanical advantage of 15:1 reduction , were at 77lbs effort. Very doable since i know i was pushing 100 lbs effort today.. The downfall to this design is that even with double valve volume , (ill have to do actual compression model math ) you would have to pump about 20 times to reach the peak pressure. Whereas with the full size stock piston , 8 pumps would give pretty dam good speed with normal effort. All a balance, as usual
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the elongagting of the hole in the toggle created headspace over time, as did the accumulation of grease.. So thats a big reason you stopped building pressure at some point ( pump30 ish ) As for The hammer spring. people call it lock time but yes.. As the pressure increases, the hammer spring may still be able to blow open the valve, But is it doing it quick enough to make use of the new found volume?? So you may be reaching this fine balance point where the pressure is low enough to let the valve blow open( barely ) , but its not doing it quickly enough because of the( well beyond stock) back pressure. If that makes any sense?
Yea, that makes sense. A quicker spurt rather than a longer squeeze of air. I'll poke around and see if I can find a stronger spring.
So, sounds like I need to get an 880 and see if I can get 911 fps....Lol ;D
Bummer about the P17, but you're right about balance. As I was pumping 40-60 times for each shot I realized that I'd rather have 750fps at 12 pumps than 900 at 40. But it's been a great learning exercise.
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yessir , it seems like ur heading in the right direction , hopefully you will have a 750 fps 12 pump gun in the near future , then when u wanna go crazy pump to 20 and get 900s.
The 880 is wayy easier to start out with , shoots 700 out of the box.. But obviously , its pretty close to max potential out of the box also.. so even 200 fps was hard fought gains.. i think the gun maxed about 815 before any additional volume was added, i could be wrong.
This p17 would be my 3rd design if i continue, nice part is ill still have less than 100 bux invested in all 3 guns total. lol. If i do the third, I know now exactly what i need to do to have the effort real low , and the numbers really high.. Little things i learned like check valve spring pressure and geometry payoff huge for the next build..Heck , if i made 2 of the new design and sold one id break even on the deal.And if we didnt experiement, and just talked about it , there would be nothing worth reading on any of the forums.It would just be " look at my 100 yard groups !" that no one really believes
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how will u fix the pump arm.?? some aluminum angle might do the trick>> if not super glue?? lol
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And if we didnt experiement, and just talked about it , there would be nothing worth reading on any of the forums.
Absolutely! I can only shoot so much before I get bored. When I'm experimenting it keeps me thinking.
I'm still chewing on my plans for a new pump arm, but anything worth doing is worth over-doing, lol, so I'll likely make it from solid aluminum. Or at least the part that connects the tube and piston linkage. A lot of it will depend on what I can find in the scrap pile, but I guarantee that it won't be the weak link. Lol.
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It would just be " look at my 100 yard groups !" that no one really believes
And "it put three through the same hole once I threw out the two shots I pulled...."
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lol, i was gonna say , if you have some plate aluminum , u could outline the forst six inches of the arm , mill it shape it , etc.. then connect to the plastic part. Or , in the dream world , You could mill the entire pump arm from 6061! that would be a pretty cool looking piece with some mothers polish ;D. Anyway , what i was thicking was a steel backplate the lenght of the arm , lets say 1/4 plate bolted in 4 places to the arm.. then send a piecce clear through the plate, through the plastic , and drill the pivot hole in that ( i was thinking some threaded rod etc, make use of the steel backstrap somehow
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It would just be " look at my 100 yard groups !" that no one really believes
And "it put three through the same hole once I threw out the two shots I pulled...."
Im always shocked , Navy seal and army ranger snipers have great resumes, but end up on airgun forums (-'
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i was more than excited to see the adjustable piston head, and even more excited to see the high levels of fps on an 880. i have been messing with my 880 for quite some time and did all the mods that i have seen on GTA. so far the mods that i did were
- smooth and reduce trigger pull (remove material)
- tape mod
- opened the transfer port slightly and polished it
- replaced seals with thicker o-rings
- flat top piston mod with JB weld
- and various other cosmetics
lately i also came to the conclusion that valve volume was a problem restricting performance so I began to increase volume. to do this I used a dremil and jewelers files and I took the valve piston and removed material by creating a ramp on the top (side view of valve) removing material from the base (nipple from casting) and creating a ramp on the bottom leading air up toward the transfer port. Also on the valve where the spring sits i removed material by creating a ramp on top and on the bottom to further direct the flow of air. on the inside before reaching the transfer port seal, i opened up the port to direct air above the transfer port seal rather than having the air fight its way around it. also I removed the stock bolt probe tip and replaced it with a longer and thinner probe to allow the pellet to be further in the barrel and reduce air restriction from the probe.
after this the volume increase I noticed more power. do not have a chrony, but i use a thick piece of hard particle board. before the volume mod a gold flight 8.9 pellet entered .110 at 6 yards after the volume increase it went .140 then came the stroke increase mod.
i did this by cutting .300 of the end of the piston arm above the rollers and shaved the pump arm link to curve and allow the piston to extend an additional .300 out of the tube. using jb weld and plastic from a soda bottle to sit agains the inside of the pump tube i extend the tube by an additional .25 for added air. some sanding on the fore arm above the pivot point and now I am able to compress more air. after this mod the same pellet was able to enter the same piece of wood .280 double what it did before.
to be able to dump all the air I use an additional 880 trigger spring under the loading port from where the flat spring is removed. with the reduction in trigger pull mod, the additional spring tension is not even noticeable.
very happy to see how hard it sinks allow hard pellets and it nearly obliterates lead pellets. I will post pictures soon of my mods.
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sounds great, im sure u have seen this 2000PSI SHOT
https://www.youtube.com/watch?v=iGHzBu6GbD0 (https://www.youtube.com/watch?v=iGHzBu6GbD0)
910fps was the best i got , but i think it was shooting hotter when i had the old setup seen in the vid
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the 2 biggest restraints on the gun are swept volume , and valve volume. alter those to an extreme and you have a gun that makes a 397 look weak // the problem is the swept volume is not easily altered, and therefore the max power didnt come on till 23 pumps.
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the result of my 880 with the additional .300 stroke resulted in .250 in tube additional volume resulted in what I think was me breaking the sound barrier with a PBA raptor at 24 pumps. at this point it no longer makes the hiss noise suggesting that it is no longer taking in air to overcome the pressure in the valve. my goal was not to shoot the fastest, but it was pretty impressive hearing that come from my little 880.
have you considered using an o-ring with a backup teflon seal for added pressure. or maybe a double lip o-ring that is used in hydraulics for pressures of up to 6000 psi.
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man id love to know what it does over the chrony/?? also , yes it will get pretty loud.. what is ur piston setup?? i dont recall.. I never had air getting past the piston , i simply started breaking pump arms first
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sorry the piston is a stock piston with the dimple filled with JB weld and a thicker o-ring. the sound I was referring too is when you pump it and start to extend the pump it makes a hiss as it draws in air for the stroke. it normally will spring out a certain amount and more with each stroke as the pressure in the valve increases. toward the end of a max out pumping cycle the arm springs nearly all the way out. i pumped it until the hiss was no longer heard at extending the arm guessing that the piston was no longer able to overcome the pressure in the valve.
picture of my valve volume mod. basically was leading toward redirecting air rather than increasing volume but it results one in the same.
the added spring opens the valve ( to my knowledge) at the same rate despite the amount of pumps rather than using a single heavier spring.
I will post a pic of the extension of the tube and internals soon after my class ends and I have time to get back into it.
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very cool! usually when the balance was reached, and it no longer took on air ( hiss ) it meant that i could no longer build pressure on my gauge, and not pump past it.. ideally , a 2 stage would be used ( which i have a design for ) to kepp pushing air past the 2200 psi mark
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Nice work, and nice rifle. Where did you get the metal parts? Old guns on ebay?
Looking forward to the pics.
If you are going to be a hard-core experimenter, you have to get a chronograph. ;)
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Nice work, and nice rifle. Where did you get the metal parts? Old guns on ebay?
Looking forward to the pics.
If you are going to be a hard-core experimenter, you have to get a chronograph. ;)
bought them in a parts lot with metal receivers, metal pump arms, old forearm stocks without the diamonds, and one full set of wood parts for a 177x. i have enough parts to build three all metal 880's.
i know that i need to have a chrony until then it is all speculation in what I think i'm doing. its on my list of things to get until then i'm working strictly with penetration tests. looking to make ballistic gel soon and test the depth of the shots from 1-20 pumps.
does anyone know where to buy a tube that is equivalent to the ID of a stock daisy pump tube. I believe that a QB78 co2 tube has the same ID.
I would love to see that side level pumper build.
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the side lever is on the shelf right now , been too busy making stuff for other people ..the closest i.d is .732, or 1 inch by .134 wall.. its not cheap.. and needs to be turned down to .815.. if you see a cheaper way , or source.. let me know.
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i had actually planned on a stroker kit for the 880, and the tube was the biggest hassle point since turning a bunch of steel dom tube to .815 wasnt my idea of fun.. plus need to spend 50 up front
http://www.ebay.com/itm/DOM-STEEL-TUBING-1-x-134-x-60-ALLOY-1020-1026-/310345332562?hash=item484205f752:g:4S4AAOxyVX1RxIRt (http://www.ebay.com/itm/DOM-STEEL-TUBING-1-x-134-x-60-ALLOY-1020-1026-/310345332562?hash=item484205f752:g:4S4AAOxyVX1RxIRt)
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I have also played with the idea of doing the mods that i have done and am doing to increase the stroke by the .460 stroke and also if you look into the valve, the piston that holds the cup seal can be moved in by .250 leaving .050 of space before the cup seal will contact the valve-body. this would allow for an adjustable piston to enter the valve .250 with the added .460 that I have learned yielding a .710 stroke almost 3/4 of an inch of added compression. the piston would need to be modified to enter in or even be adjustable and the spring would need to be cut to reduce coil bind under the cup.
i tried my best let me see if the drawing would work.
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also the idea of just drilling a new pin hole to move the seal piston in and extending the stroke arm can work and if it doesn't one could just cut it tap it and put the adjustable eye and lock nut. the reduced volume can be replaced by porting the internals of the valve returning back to stock or even increasing the volume which the cut on the piston would already remove mass from the inside allowing for a large reservoir and added stroke for pressure.
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ok got the design
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i see what ay mean..my adjustable piston was actually crashing into the check wall when dialed in for max power. so it took a bit of extra pressure at the end of the stroke.. Now, i wasnt really gaining much off it , but there was a difference in how fast the gun built pressure. I added massive volume when i added the gauge , and thats when i made the youtube video of it sounding like a 22. with no volume mods is when i got the 910 fps on 23 pumps.. the biggest challenge is the swept voluime which u seem to be attacking.wouldnt simply sawing off a large portion of the abutement metal block do both tricks for more swept volume while keeping valve volume? i do plan on attacking another one when i have time ..id actually cut the back half and add a stronger spring to it
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as an aside, i truly feel without some serious design changes including a smaller center piston ( 2 stage ) it will be impossible to pump the gun beyong 2200 psi.. the math basically says its impossible with the .730 piston.. or atleast with the current linkage.. u would need a way to take absolutely all slop and yaw out of the pump assembly , and possibly with a metal pump arm hit 3000#
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working on it.
how did you install your gauge, and is there a way to make it sit more flush to the receiver.
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theres a pocket in the side of the cast right behind the check valve.. theres no vital components there so i drilled and tapped right there. shop vacuumed out the debris.. made an extension , and used red loctiite to seal it.. the first one i did i drilled right into the main valve area, and threaded the side of the gun for 1/8th npt,.. and hooked the gauge right to it.. sounds dumber but it was simpler.. hardeest part was getting the plastic shell drilled in the same spot after.. ideally, u wanna tap into the non action part of the valve closest to the check wall..For the flush one , see my 2000psi 880 post in daisy forum.. thats where i drilled a small hole right down to the spring in the check valve( blow open spring _) , then drilled the 1/8npt hole with an 11/32 bit as i recall,,. tapped it , and threaded the gauge in.. much simpler, only one possible leak point ( the gauge thread area) Because it was npt , it held air after i hand tightened it , no sealer needed
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Hey rob, i was wondering what your 880 was grouping at I understand that high pressure is great for more power, but was wanting to know at what pump numbers your 880 groups best at, i was having some inconsistency in accuracy. I tried all levels of pumping 10-12-15 and it seamed to group about 1-1/2 inches. i remembered that I increased the volume and pump stroke and tried a lower number of pumps. as i went lower the groups got closer until at 7 pumps it puts them in a 1/2'' group at 5 yards. Not sure whats going on i figured that the increased volume is either matching the volume of the barrel and is expelling too much air causing my 7.9g pellet to go wild. Im sure that a heavier pellet would be more accurate at higher pumps. Im curious to see what your 880 groups best as i know you have pumped it up to high PSI. strange because my stock 922 at 12 pumps puts 5 pellets in 3 holes at 5 yards. still working on tuning for accuracy so starting close and going out further tomorrow. also what do I have to do to get one of them pistons off of you. ;)
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i had installed a 24inch crosman barrel, and tried the stock barrel.. the more the barrel was braced in the shroud the better both shot.. it actually did not matter whether it was shooting 700 or 895 fps from my tests.. but getting the barrel pinned in place was huge
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Ok Rob, so i went back into the 880 and looked into my tape mod job and it was good, snug in the front sight, and snug in my mid mount but than i realized that the front sight was not tight enough in the barrel shroud and I fixed it with a bit of tape. more investigation lead me to think that it was shooting great before the wood furnishing and i discovered that the forearm pieces were leaving about .050 after the screws were tightened and let the barrel shroud float even after the gun was put together. a washer under each one relieved the play and now is back to dime sized groups at 7 pumps of 15 pumps she's happy, I'm happy ;D
your crosman barrel did you turn it yourself or buy it like that.
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i turned the crosman barrel.. it was too long and knocked the fps down 40fps.. i was also thinking about this last night, how to firm up the barrrel.. and put it under tesnsion. i was thinkin about a threaded adapter replacing the front sight , that screws onto the barrel ( after threading it 5/16-18 ) essentially pulling the barrel hard torward dead center..wish id thought of it before i sold mine
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Well it's ugly, but I think it will be strong enough. Testing to resume this week.
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20161204_163151-1_zpsagqy1tmb.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20161204_163151-1_zpsagqy1tmb.jpg.html)
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that looks great, some black paint ur good to go@@@@@@@@@
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Disclaimer: I could not get outside before dark and I couldn't get my chrono to work tonight in the basement. I was able to get my son's chrono to work with LED shop lights as long as I shot very close to the sensors. However, my ears are ringing a little from the muzzle blast so I know I was getting some serious air. I only took a few shots
So,
938 fps on 45 pumps with 7.9 gr CPHP pellets. 15.44 ft/lbs
Observations:
Pumping pressure was very hard from 20 pumps on up. Velocity seemed to rise in a linear way as I tried it at 20, 25, 30, 35, 40 pumps.
O-rings were stock size metric o-rings, but Viton 70 Duro.
Valve modification worked and tube held the pressure.
Time now to reduce the valve volume and see what I can get out of 15 pumps.
Or maybe I'll play with a stronger hammer spring and enlarge the transfer port a few thou and see if I can hit 1000 fps. ;)
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hahahahahaaa, wow @@@@@@@@@@@@@@@ you need to start an entire new thread when you get it shooting 1000 !@ i would do a small reduction , and try to get it pretty fsast at 20 pumps or so.. what were thhe numbers on the wway up to 45 pumps ??yep, if u could transfer the air faster, 1000 is right there
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I didn't write the numbers down on the way to max, but I think it hit a little over 800 at 20 pumps. From there it just kept climbing every 5 pumps, but I didn't write it down or commit it to memory. I also didn't check for retained air.
Hopefully tomorrow I'll be able to use my chrono in the daylight and keep better notes.
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makes sense// heavier hammer spring would make sure of the air.. but since its a dump valve, all the air was almost certainly dumped.. getting that air out to the barrel faster will be key..skys the limit, which is kinda what i predicted when u started out...too bad we can get a few thou stroke added on , that would reduce pump count
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you could hook ur shop compressor to it.. 5 strokes or so ud be maxed out!!!!!!!!!!! precharge the tube to 100 psi (-'
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Yea, that would be a learning experience. Just be hard to take in the woods. ;)
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Just a thought, but this rifle has a big fat magnetic probe on the bolt. I need to thin that down some.
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thats a huge factor along with the TP.. make one from steel rod , like coat hanger
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I did the same with my 880. took the barrel out and looked at the bolt to see how far it pushed the pellet into the barrel and noticed how the magnet probe was almost shrouding the entire transfer port. pulled it out and replaced it with a used rivet pin that was .030 longer and ground it down about 2/3 of what the original probe was. don't have a crony, but after this i did notice the pellet strike my target with a little more power such as watching my pellet trap rock a little harder.
I know high pressure is a concern of making the pellet fly faster but i believe that more volume would help keep the average pressure constant as the pellet travels down the barrel thus creating more energy and reducing the drag after pressure decreases as it expands in the barrel. a port job definitely helps to redirect flow to push the pellet.
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Last night I used a dremel and reduced the diameter of the bolt probe. Today after work I shot of few over the chrono. Temp was about 35 degrees and the light was fading fast so I only shot one pellet at each data point.
10 pumps - 679
15 pumps - 750
20 pumps - 819
25 pumps - 866
30 pumps - 872
40 pumps - 907
50 pumps - 939
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holy &^^&@@@@@@@@@@@@@ we need a way to increase the swept volume.. One way is to machine the face of the valve down a few thousandths.. .060 or so so as to not compromise the burst
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what baffles me is theres actually gains in the last 10 pumps
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holy &^^&@@@@@@@@@@@@@ we need a way to increase the swept volume.. One way is to machine the face of the valve down a few thousandths.. .060 or so so as to not compromise the burst
Actually, it's already been done. When I made the new pump arm I drilled the piston arm hole slightly farther from the pivot than stock. It ended up putting the piston about 1/16" farther down the tube. I faced the front of the valve by sanding it on a piece of glass. Bottom line - the valve face and piston face are flat, mate perfectly, and I have about 1/16" more stroke.
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okay.. we will have to find a way to get more volume ,. even if you could get 900fps off 20 pumps , it would be golden
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I need a new tube. The slot for the pump arm is a half inch longer than it needs to be.
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I need a new tube. The slot for the pump arm is a half inch longer than it needs to be.
new pump tube ??? what size steel , im not good at much but i can scour the web for delrin , steel and aluminum tube
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It's metric. .907 o.d. x .787 i.d. Or 23mm x 20mm.
The trouble is I'm approaching the point of diminishing returns because I'm going to have all this time and money in a hopped up power plant that will be attached to a crappy plastic shell that won't hold a scope and has a crappy plastic trigger.
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those sizes are cheap.. but i see ur point.. Why no scope?? thats odd>id get to tuning it for 800 fps or more at 20 pumps.
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http://www.ebay.com/itm/6061-T6-Aluminum-Seamless-Tubing-OD-24mm-ID-20mm-Length-0-5m-1-64-ft-EA-D-/181557631286?hash=item2a45ad9936:g:wkMAAOSwFTRTrTy9 (http://www.ebay.com/itm/6061-T6-Aluminum-Seamless-Tubing-OD-24mm-ID-20mm-Length-0-5m-1-64-ft-EA-D-/181557631286?hash=item2a45ad9936:g:wkMAAOSwFTRTrTy9)
turn this down 1mm , you have a new longer comp tube and extra
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The scope rail is undersize and normal rings don't fit. The whole clamshell is flexy too.
I think I'm going to reduce my extra valve volume a bit and see what happens. Since I'm using the tube as the valve wall I don't think I want to use aluminum. Although I don't know the burst pressure of aluminum. It may be fine.
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the burst pressure on that tubing would be roughly 3500psi .. (with 1mm or .040 wall. )
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believe it or not the thomas FT 3500 dollar gun has a 6061 tube , I know i couldnt believe it either. 2024 is way better for the application.. Anyway, yep, fine tuning.. the scope rail thing has me baffled. if you have some jb weld, id bed both insides off the clam , get it stiff. then use a weaver to 11mm rail adapter ( 3 bux on ebay) and mill one side down 1 mm to really grab the clamshell rail
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Yea, the scope rail could be shimmed/epoxied to work fine.
I think that tube could be left full thickness in the area surrounding the valve and all the way to the pump arm pivot. It would only need to be machined where the trigger group and butt stock attaches. I'll have to think on it a bit.
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i know how you feel.. every 10 bux i put into the 880 killed me.. Heres the real reason.. After you strip and reassemnble these guns 20 times, theyre never the same.. If you took what ya know now , and applied it all at once to a new gun, getting a 15 dollar tube would seem like nothing.. I know exactly how it felt when people were asking, " why not 25 cal on the 880" .. well yea , 35 bux is nothing for a machine tool, but for an 880 its a fortune
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Exactly. The screws are made of cheese and screwed into soft aluminum or plastic, and no matter how careful you are, things wear out just from taking it apart so many times.
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yep.. were i to do an 880 again, id do all my mods at once, and actually have a relaible sturdy 900 fps pumper..heck i probably would do 25 caliber.. But ive been too busy..
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Yea, you should do it. I'm going to get an 880 and work it over like you did just to have an air rifle I can actually use. What were you getting at 15 pumps?
In other news, today I flared a pellet for a tight fit and pumped it up in the basement with 65 degree air rather than the 25 degree air outside. 960 fps. But really , who cares when I have to do that much pumping. I'm going to limit myself to 20 pumps and see what I can get with that.
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add a delrin spacer , pump 20 chrono , and repeat till u hit the high of 20 pumps ( reducting volume gradually )
15 pumps was 805 ish
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To bring this thread back on track, today Santa brought me a Daisy 880. Looks like I'll be making an adjustable piston.
I also figured out why you broke pump arms so quickly while I was able to use/abuse my Umarex NXG for so long before it finally gave up. The Daisy pump arm is vastly inferior to the NXG. I've used sporks at KFC that are stronger than the Daisy pump arm. ;)
Baseline power from the 880 with CPHP 7.9gr:
10 pumps = ~650 fps
15 pumps = ~700 fps
20 pumps = ~750 fps
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thats great@@ a tad low on prelim numbers, i think my lasst one was 671 10 pumps same pells.yes, the spork pump arm is a joke.. the old metal ones are the opposite, and overkill
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you say the old metal pump arms are a bit overkill, i feel it is better to have it and not need it than need it and not have it. still working on raising the funds for a crony i decided to use my modified 880 on 10 pumps only as it is very accurate, and seams to have the power i need. plus my added stroke helps possibly bump up what I'm actually pumping. seams to shoot hard and is dead on, all I need. if you do a search you can find the old metal pump arms for pretty cheep.
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yep.. if he posts a wtb he will find one, i did.. Funny, i had my 880 shooting 910 fps, but none of the 3 guns were ever accurate. my idea to thread and tension the barrel came after my 880 craze,. basically the barrel would be threaded 1/4-28 and a nut on the front of the shroud would slip in , grab the thread and then the user would turn the front nut to tension the barrel.. pretty dam simple.. Maybe one of these days ill get back to it.
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Good to know that metal pump arms are out there. I might build one and try to coax a little more stroke out of it. My goal for this rifle is to have reliable shooter and not seek max power.
Interesting idea about the threaded muzzle.
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i think the adjustable piston with the stock felt oil wipe on it will make the gun a good reliable 800 fps shooter.
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that was my idea, a god reliable shooter hence the wood stock and forearm and the metal receiver and pump arm. i am swapping out the barrel shroud for another older daisy shroud that i have that has an internal sleeve that feels heavier, but would protect the barrel that much more than the thin metal new barrel shroud. mine became inaccurate after the mods that i did, it used to shoot the CPHP pretty well, and after the chamber volume increase and stroke increase they just pepper the target. i now shoot the Beeman pointed at 8.53 grain as opposed of the 7.9 CPHP. also shoots the gold flights as they are also 8.5 grains. the heavier pellet makes a huge difference.
I have used plumbers tape on the barrel to help it seal and gives it a good fit. looking at possibly making a billet piston arm to increase durability.
love my little daisy.
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Wow, that was easy. I did a few mods and new results (with CPHP 7.9 gr) are:
10 pumps = 742 fps
12 pumps = 788 fps
15 pumps = 825 fps
I quit at this point because it's cold and snowing outside and I didn't want to break the pump arm yet. At this point it is relatively easy to pump and I think it will last a long time if I don't go further.
I didn't build a new piston, but I filled the old one with JB weld and sanded it completely flat. I then put a flat washer behind the piston head with a thickness equal to the material I removed from the piston face. Then I used a round file and extended the grove in the attaching shaft to let the piston assembly go towards the valve face about another .050". This lets the piston and valve contact firmly and the rubber bumper take up some shock and pressure.
I also made a longer/smaller dia. bolt probe, cut the breech end of the barrel to remove a sloppy leade, and opened the transfer port to .125".
This design is really efficient compared to the NXG.
I think I'm going to stop messing with this one and just have a nice rifle.
But I can't help but wondering:
A. Make a steel pump tube. I'll bet with a thinner wall and taking up all the space in the metal channel I could gain .040" in diameter.
B. Adjustable piston with about .010" clearance to the tube wall. The stock has a bunch of slop. I think Daisy doesn't want any chance of the piston hitting that soft aluminum tube. I'll bet the current system is wasting at least a pump's worth of air with all of the space.
C. Tweak stroke length. Maybe make a new thinner abutment out of ss or brass and then see if I can get a little more at the other end.
D. Metal pump arm, obviously. ;)
Guess I'll have to buy another 880. ;)
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those are very good numbers , and similar to what i was getting.. I wanted 20 pumps to be 900 fps with 7.9s , never got there, 895 was max.. at 23 pumps i hit 910 fps, but that was a custom piston.. You surely made more headway than most without machining any serious parts.
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My plan with this mod was to optimize the way every stock Daisy part functioned to make it efficient as possible. It paid off more than I thought it would.
So now I'm looking at my NXG project with this in mind. The breech has a sloppy, crooked throat and the probe doesn't push the pellet in far enough to seat firmly in the rifling. Last night I made an extended probe and now I'll cut off the bad part of the barrel and make a new tighter leade. Maybe I can hit 1000 fps after all. :D
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well i certainly think the ngx is the more classical approach as far as the valve - piston relationship
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Agreed. Seems like the dump valve is more efficient, however.
Anyway, I went back out and tried more pumps.
20 pumps = 869 fps
23 pumps = 864 fps
So it looks like I've hit the limit with what I currently have. I could tell I was really straining the pump arm starting at pump 17.
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nice numbers, I am going to be buying a few abutments and going to experiment with them to see what I can do with them to increase stroke and also make them a bit thinner to make reduce clearance from piston to seal. if I am successful, I will be able to increase the stroke of the gun by one whole inch and would use less strokes to reach a good power to stroke ratio. Once again i have not crony, but I have some old sheets of meta and did some testing at 10 pumps and with the bee man pointed they would pancake agains it leaving a flat lead disk. I shot some lead free gold flights at it and id would leave a decent dent and on occasion would leave a small break in the metal, i pumped it to 15 pumps and it blew right through it I need to measure the metal that i was using. i was impressed to see it actually hit that hard. going to try the stroke mod to my .22 daisy and do the same test at 10 pumps to see what I can get out of it. love to see all the work that everyone is doing with their 880's took a rabbit the other day at 10 yards with 10 pumps with the Beeman pointed and had a pass through on a head shot I was happy to see that it has the power to do so, made lunch that much more enjoyable. I would love to get 800+ fps with 8.5 grain pellets.
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Agreed. Seems like the dump valve is more efficient, however.
Anyway, I went back out and tried more pumps.
20 pumps = 869 fps
23 pumps = 864 fps
So it looks like I've hit the limit with what I currently have. I could tell I was really straining the pump arm starting at pump 17.
you need a custom piston , make it smooth as glass and duel oring..those numbers will skyrocket
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you need a custom piston , make it smooth as glass and duel oring..those numbers will skyrocket
Yea, I'm fighting the urge...
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I will be able to increase the stroke of the gun by one whole inch
I'm interested. 8 pumps would be like 10, 12 would be like 15.
I would love to get 800+ fps with 8.5 grain pellets.
You might already be there, but without a chrono it's hard to tell how much you've improved your velocity.
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you need a custom piston , make it smooth as glass and duel oring..those numbers will skyrocket
Yea, I'm fighting the urge...
mine was never a problem till it scuffed the tube wall
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mine was never a problem till it scuffed the tube wall
How much clearance did you have?
I'm thinking that I'd need the absolute minimal amount of piston in front of the first o-ring and behind the second o-ring. That would keep it from hitting the tube wall.
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yep.. not much clearance and the dual oring helps to prevent impact.. i think they were in the .720 range so .015 clearance or .0075 per side??
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if you break all edges( chamfer ) on the piston including the oring glands, then smooth everything w 220 grit it wont matter,
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I ordered some DOM steel tubing today. Plans are to make a double o-ring adjustable piston riding in a .760" I.D. tube with as long as stroke as I can make it. And, of course, make a metal pump arm.
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hahahaahaa.. the challenge will be turning the tube down to .815 o.d.. sounds good to me .. i always wanted to do a larger bore., but the frame was a massive restricting factor
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the challenge will be turning the tube down to .815 o.d..
Or milling four flats on the tube...
and/or milling slots in the tube to get a little bigger tube in there...
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or making a square piston ;D
yes, theres numerous possibilities, the length was one challenge, the diameter was perhaps the bigger one.. I wanted to make a stroker kit for the masses, but the mods needed to the cosmetics for the additional 2 inch stroke was too much.. Not to mention the .732 i.d SS tube was 54 dollars for a few feet.
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Ok, back to the APX NXG pumper. Just like I did with the 880, I cut off the barrel breech end that had the sloppy, crooked throat and made a tight throat. I also made an extended thinner bolt probe and used JB weld to seal everything when I reinstalled the barrel. I also opened up the exhaust passage in the valve.
Results - No gain. 900 fps at 50 pumps. It's loud. I'm wearing ear muffs while shooting in the basement.
I reduced my valve volume to near the original volume and it didn't make much difference. And it's still loud.
I compared it to my 880 and the 880 is 40 fps faster at 10-20 pumps. And the 880 is very quiet.
I'm going to look for a stiffer hammer spring.
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very interesting.. I wonder whats causing the difference?? 50 pumps is insane so we know dam well half those are wasted energy either via leaking or the max pressure is reached and the piston orings let the air pass.
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No doubt a lot of wasted air. I've looked for leakage, but can't hear anything. I don't see any signs of blow-by either. The face of the piston and valve both have dark oily residue, but none has made it past the first o-ring.
I'm not kidding when I say it's loud. I have to wear hearing protection when I shoot it in the basement. Too bad I don't have a 24" barrel to try.
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thats soo weird, only a guage would tell the story i guess
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I pulled apart the NXG tonight. I found that I had increased headspace due to wear in the new aluminum pump arm.
I also decided to increase the flow of air from the new section of the valve by drilling a hole in each of the six flats instead of the two I had.
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20170108_195402-1_zpswimwvkvb.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20170108_195402-1_zpswimwvkvb.jpg.html)
When I took it apart I noticed that the cup seal had some scratches. When I drilled the holes before I didn't deburr them properly.
So I drilled new holes, deburred, and then sanded the scratches out of the cup seal and polished it smooth with 1000 grit.
O-rings looked a little worn so I replaced them. Also unscrewed the valve halves to reduce headspace.
Results - 25 pumps = 895 fps. 7.9gr CPHP
Then it wouldn't hold pressure. I took it apart and the little intake plunger I made was hung up. I made the clearance too tight and I'll have to sand it down a few thousands and break the edges a little better. After I get it working smoothly I'm going to reduce the valve volume slightly and see if I can get the number of pumps down.
Then for comparison I grabbed the Daisy 880. 25 pumps = 852 fps. For the little work I did, that thing really puts out the power.
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holy COW ! ALL THESE minor innefficiencies add up soo fast its scary.. so essentially, the flow from the new volume was soo restricted, it actually did nothing for the shot because the pellet already left the barrel , but u still got the huge BANG after the shot.. Incredible.. fyi my best was 910 on 23 pumps with the same pellet, ur right on my heels ( dangit
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fyi my best was 910 on 23 pumps with the same pellet, ur right on my heels ( dangit
Yep. Stay tuned. Lol.
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it seems like the nxg has more promise till you do a custom piston for the 880
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Tonight's results:
I broke the corners on my intake valve and polished it well. Now it doesn't stick.
I reassembled and changed my lube to the Daisy recommended non-detergent 30 weight.
23 pumps = 903 fps
30 pumps = 939 fps with retained air.
I tore it back down and reduced the valve volume by adding an o-ring like this:
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20170109_202302-1_zps9h1hlwcz.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20170109_202302-1_zps9h1hlwcz.jpg.html)
A little superglue holds it in place.
Then I relubed, reassembled, gave it 23 pumps, and got this:
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20170109_203508-1_zpstl4jtzdx.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20170109_203508-1_zpstl4jtzdx.jpg.html)
I tried a few more pumps and it retains air. I kept trying to find the max and now it leaks like crazy. I'll tear it down, reseal and try it with another o-ring to restrict the volume.
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incredible ! seems like the extra volume needs to be escaping faster ! well you now own the RECORD for crappy pumpers ! you still need to get the 880 to do 910 to motivate me enuff to build a 1000 fps version!
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MAYBE dremel or mill out an entire wall from the polygon, seems like the added volume might not be doing anything at this point
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MAYBE dremel or mill out an entire wall from the polygon, seems like the added volume might not be doing anything at this point
Yea, my velocity increased when I reduced volume so no point in adding more volume. At this point I want to see what it will max at 20 pumps. A reliable 850 fps at 15 pumps would suit me fine.
Before that I need to find a stronger hammer spring and see if I can hit 1000.
"Record for crappy pumpers"? LMBO ;D ;D ;D ;D
Still waiting on tubing for the 880... brace yourself. lol
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sounds good.. YES the hammer opening faster will be a good improvement.. I think the added volume may help were it reaching the barrel fast enough.. tough call.. since when u started the added volume seemed to help.. But now that you are building higher pressure it doesnt help.
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I see what you mean about getting rid of the air faster. I'll open up those six holes a little and see what happens.
I took it apart a few minutes ago. Looks like I used a little too much oil. I cleaned it up and it seals fine now. I did notice that the plastic ball that seals the exhaust port is now getting egg shaped. The heat and pressure is distorting it. I don't think it was designed for this. ;)
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haahahahaaa.. a guy on the green years ago made a 2 stage pumper pistol , needless to say it would pump to 6000 psi.. But he could never use the power because the check valve would start to melt beyond 4500 psi
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id bet right now you are pumping to 2000psi or so
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I think this is the last gasp for the NXG.
I opened the transfer ports I drilled to enlarge the valve volume and installed a stronger hammer spring. It's really hard to cock now.
It didn't change much. I experimented with more pumps and with 30 pumps I got one shot of 897 fps followed by a second shot of 591.
I then experimented with changing valve volume by removing and adding o-rings. Larger volume retained air at a lower number of pumps and smaller volume gave reduced velocity.
I finished the tin of 500 pellets I was using for testing. I'll bet I averaged at least 20 pumps per pellet. Plus I tried a few other brands/weights.
Now my new aluminum pump arm has slop where the piston linkage attaches. So now I have excess headspace. The exhaust ball valve is a grooved egg shape instead of a ball. I think I've pushed it hard. ;D
I learned a lot. Time now to see what I can get out of the 880 in as few pumps as possible. I think I'm going to set my limit at 12 ft lbs. Tubing should be here this week. ;)
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hahahaa, im wondering how the heck the npx was retaining air , thought it was a dump valve?? anyway, i was pushing 14 fpe or so with the 880, 12 would have been fine..the biggest challenge u face is installing the new comp tube , not only getting it in there but getting it to seal to thee abutement and the valve face! thats why i was helbent on getting the .732 tube in stainless, it required no mods at all
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hahahaa, im wondering how the heck the npx was retaining air , thought it was a dump valve??
Not sure what you call it, but it's the white ball thing here:
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20160919_214955_012-1_zpshqyjbhhm.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20160919_214955_012-1_zpshqyjbhhm.jpg.html)
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thats a traditional crosman like valve.. cut a few coils off the valve spring and watch the velocity skyrocket !!!!!!!!!!!!!!!!!
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u could even put your stock hammer spring back in and see huge gains, No wonder there was confusion about the velocities.. 1000 fps should be easy
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thats a traditional crosman like valve.. cut a few coils off the valve spring and watch the velocity skyrocket !!!!!!!!!!!!!!!!!
I don't think there is much to be gained there. I made a new intake plunger and it reduced the spring preload. There is barely enough pressure to push the cup seal back in place. Here's the stock intake plunger compared to the one I made:
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20161002_154724-1_zps1lpepfuh.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20161002_154724-1_zps1lpepfuh.jpg.html)
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weird.. even with the heavier hammer spring it wont dump the full charge?
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Nope. I just looked at it and I think I can clip one coil off the spring. I think I can sand down the diameter of the ball too. Maybe that will help airflow.
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yep, anything to increase flow and duration of the valve being open.. Kinda not worthy its serving both purposes
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Ok, I clipped a coil and sanded the ball down to the smallest diameter I could. The spring barely compresses when I put everything back together.
Not much difference. It will hold another pump or two before retaining air. Velocity is about the same, but I didn't have the same pellets so I calculated energy and worked backwards to extrapolate the velocity as if I had been using the CPHP 7.9 gr. As it was, I was getting 804 fps using Winchester 9.7 gr domed.
But it's worn out. Piston linkage hole in pump arm continues to grow and headspace is increasing. I put all the parts in a box and I'm going to use the barrel for another project. I got a lot of fun out of the $29.27 this rifle cost.
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you really stretched that 30 bux, literally and figuratively !
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...I didn't mention that I burned through almost that much in o-rings...Lol
Also forgot to say... Thanks for your helpful advice!
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NO problem.. this thread is not dead, U need to make a nice piston for the 880 and break 910 fps
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Yep. But my goal for the Daisy is fewer pumps to 12 ft lbs and end up with a gun that will last.
Right after I put the NXG pieces in a box I got the 880 back out and took it apart. My tubing arrived today and now I'm in the thinking stage. ;) :D
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lol, my numbers are well recorded, ill be able to compare our 15 pump notes! with the new tube you will need a piston anyway, no?
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... with the new tube you will need a piston anyway, no?
Yes. I'm going to make a double o-ring but keep the Daisy rubber bumper design in some form. I think the zero headspace I used before caused the rapid pump arm wear. It just takes a thin film of oil on the piston face and suddenly I have an interference fit.
Anyway, one of the negative points of the 880 is that it uses cheap, soft steel for the frame.
But one of the positive points is the cheap, soft steel....
So what you see here is a .870" I.D x 1" O.D. pipe stuffed inside the frame. I heated and bent the bottom lips out straight, then used a punch to make an arch in the top of the frame, and then hammered the tubing inside and formed the steel into a tube around the new tube. I didn't use the actual tube for all the blacksmith work, but a piece of thick wall tube with the same O.D. instead. What you see in the pic is the actual tube.
Yea, I'll have to do a lot of fitting of the parts that attach, machine an adapter to fit the original valve, bend and tweak the frame some more, and maybe it won't work at all....
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20170118_211356-1_zpsljv8r25y.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20170118_211356-1_zpsljv8r25y.jpg.html)
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20170118_211455-1_zpsmj4me7wg.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20170118_211455-1_zpsmj4me7wg.jpg.html)
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well, u have certainly dug yourself a large pile of work! The good news is , when u get it working , 4 pumps will have the swept volume of almost 7 pumps previosly.. So 12 pumps will have the valve maxed out shooting 900fps or so.. lotta work , i commend the effort
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Do you think an aluminum pump arm will hold up, or should I make one out of steel?
I wonder how hard it will be to pump at stroke 12?
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You may want to look into PPE (Personal Protective Equipment) I would thing at least a helmit and athletic cup.... lol
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You may want to look into PPE (Personal Protective Equipment) I would thing at least a helmit and athletic cup.... lol
Lol. ;D
But:
I've expressed that I'm interested in getting about 12 ft lbs and plenty of guys here push their 880s to that level. Rob installed a gauge and pushed it well beyond that point. I assume he has all his male bits and no head injury. ;)
And I'm using a steel tube with a .065" wall instead of the stock aluminum with a .035" wall.
Seems like I'm not pushing it too much.
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I've been following the thread since it began. I think I was the first to get one of Rob's piston heads. I tested them in the older Ted Williams and 881 but the brass tube with the slots in them just kept chewing up the o-rings. I didn't have anything newer at the time except for Betty Lou's Metal/Metal 880 and I feared for my life when I thought about fooling with it. I have a few options now and I may pull them back out for another go round. We use our 880s for accurate plinking at 30 - 35 yds. Rarely do we put more than 6 pumps in them. I do enjoy tinkering though.
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hey bill , hope all is well!@
as far as the pump arm concern , i think aluminum is fine is you can mill one.. I think the pumping effort will be like a 392 on 12 pumps , mine was when i got to the 20s and urs will be there by 12 pumps , or less according to the math..I think any wood or plastic in the pump arm design will be the downfall. ALSO ,any oppportunity to use bigger screws at stripping points or bulging points will make a world of difference.I still have all my body parts, even after installing a gauge and adding tremendous volume to the 880.. Neighbors likely thought it was a 22, i still regret not having a chrony when i started , i was getting the best results when i made the youtube video , and after that when I was getting 910 fps it sounded substantially weaker and the pump tube was already beat to heck.
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were i to start over.. heres a simple list id do , and the price would more than the double the guns cost.. this would be the combo for 1100 fps with a 7.9grain IMO
first , get an old scool metal pump arm for the new gun
Next, id make an adjustable piston with 2 113 orings.smooth it out super nice with 400 grit
Next id order .732 id stainless tube , id then turn it down to fit the frame , and duplicate the tube , just .500 longer.
Then , id get another 3000 psi gauge off amazon , drill my 11/32 hole in the special spot right behind the abutement where you CANNOT hit anything vital , theres nothing there. This would serve as my gauge and Volume increase.
with these mods, I think 1000 would be super easy , 1100 would be pushing the frame and everything to the brink , and likely ID need to pump well beyond my old 2000psi , probably 2400 but the all metal zero slop pump assembly plus the added strokje length would make it possible;
Some people would say " rob , thats impossible , youre an idiot " .. But these same folks never had one pushing 910 fps and sounding like a 22 rimfire either. ;D
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http://www.ebay.com/itm/DOM-STEEL-TUBING-1-x-134-x-60-ALLOY-1020-1026-/310345332562?hash=item484205f752:g:4S4AAOxyVX1RxIRt (http://www.ebay.com/itm/DOM-STEEL-TUBING-1-x-134-x-60-ALLOY-1020-1026-/310345332562?hash=item484205f752:g:4S4AAOxyVX1RxIRt)
this is the cheapest section of .732 tube i could find, its DOM
even 10 inches from the metal supplier is 40 bux shipped
http://www.onlinemetals.com/merchant.cfm?pid=14868&step=4&showunits=inches&id=902&top_cat=1 (http://www.onlinemetals.com/merchant.cfm?pid=14868&step=4&showunits=inches&id=902&top_cat=1)
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A huge factor would not be human strength , it would always be the rigidity of the pump assembly to allow it to pump beyond 2200 psi.. And anyone looking for power from an 880 , I think thats the number one culprit for losses.
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All very interesting but I just woke up from working the night shift last night to a box dropped off by UPS containing my most recent purchase. Another unmolested metal/metal 880. Time to go molest it. Just the typical mods for this one:
Remove the flat spring
Polish the trigger contact points and take a bit off of the sear hook to shorten the pull
Open the pellet port on the clams for easier loading of the Winnie Domes.
Fill the stock with silicon caulk
Clean and tape the straw barrel
Glue the BB door closed and JB Weld the BB rabbit hole
Might put that adjustable double o-ring piston pump head in if the tube isn't slotted.
Then we'll see where we are.. If anything is significant I'll begin a thread.
Once again, my goal is not to break any power records. Just an accurate fun shooting plinker without spending more money than the end result is worth.
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I made some progress today.
I turned an aluminum sleeve and inserted a section of the original pump tube. I used Loctite 609 and a press fit. I heated the sleeve and tapped the valve tube in place. Then faced it off. Here are the two parts together:
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20170205_195259-1_zpsrrx5mjgq.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20170205_195259-1_zpsrrx5mjgq.jpg.html)
Then I heated the new steel pump tube and used the same heat/hammer/Loctite 609 method to insert this into the new pump tube. Here are the three parts together. I don't think I'll get any air leakage.
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20170205_201535-1_zpskhyzpjgt.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20170205_201535-1_zpskhyzpjgt.jpg.html)
So now this will fit on the valve assembly and the original tube/sleeve assembly will stop flush with the end of the abutment. The piston face will contact the abutment and tube/sleeve at the same time.
For those concerned with safety, the pressure will be contained by the original tube, an aluminum sleeve press fit over it, and a .065" steel tube press fit over that. I think that will be safe.
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very cool.. i get it now.. so the piston will still run its full length stroke..very cool./ No pressure concerns , the stock compresion tube can handle it and thats basically paper
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very cool! Im assuming the pics are the end of the new tube where it adjoins to the valve..
Yep.
And, yes, the piston will run it's full stroke the same as a stock piston.
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u gotta ,make a big ole piston now
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u gotta ,make a big ole piston now
Yep. After these interference fits I made today machining a piston sounds easy.
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hahahaahaa, yes,, just make sure the piston connection points are within a good tolerance.this should be pretty cool..
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i actually keep seatching for the .732 id tube on ebay.. I guesss i could always make some with a boring bar and the steady rest
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i actually keep seatching for the .732 id tube on ebay.. I guesss i could always make some with a boring bar and the steady rest
I need a better lathe/boring bar set-up before I attempt something like that. I think it would be tough to get the surface finish I need on tube that long.
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Yes, would not be easy,even with aluminum..youd need a way to follow up after the machining to hone the tube.. like a custom made 200 grit sanding bit in the tailstock at high rpm
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actually one way it would be easy is in the spindle bore.. have the work almost level with the chuck ( just enough proud to indicate) run the boring bar in 2.5, flip it , do the same , and your have a mirror finish on aluminum.. Bad news for me is my spindle bore is only .78 , if it were an inch , I could make custom long tubes.
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Would a brake cylinder hone give a suitable finish to the bore?
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anything designed for honing would probably do it.. it needs to be glass smooth for the orings to run smoothly
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Oh. okay. A brake hone won't provide a glass smooth finish. Well, not unless different stones are fitted.
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after its machined it would be pretty dam smooth already.. Im betting it wouldnt need a hone if someone has the spindle bore to hold the tube..
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I made a piston tonight. That small spot in the center is where my live center was.
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20170210_213733-1_zpsdisxq7sv.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20170210_213733-1_zpsdisxq7sv.jpg.html)
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20170210_213805-1_zpsy8kgyapl.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20170210_213805-1_zpsy8kgyapl.jpg.html)
I tried it, but didn't have much pressure build up. It felt rough and when I removed it I had grit from some of my machining, grinding, sanding. I also think I made the piston too tight. I have about .005 clearance from the piston to the tube wall.
So I'll pull it apart and clean/polish/reseal.
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looks great, need to chamfer all edges including oring gland edges..huge!!!!!!!!!!!!
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need to chamfer all edges including oring gland edges
Yes, I was in a hurry and forgot.
I realized why I had grit - I neglected to clean the inner frame channel in front of the tube and the piston picked up some grit as I assembled it. Hopefully I didn't hurt my tube.
Never time to do it right, always time to do it over....
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im the same way.,and the piston chamfering at the oring glands is the biggest issue.. Ran into that with the first MSP p17, and the 880those endges will bite when the piston is cambered even the tiniest amount u cannot even see.
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I pulled it apart and carefully cleaned everything. I also reduced the diameter of the piston by .010", broke all the corners, and polished it with 800 grit. It now glides smoothly in the pump tube.
But I'm not getting the pressure I expected. Three pumps will get me over 500 fps, but I hit a wall and another 10 pumps will only get me over 600 fps. The pump handle is hitting the enlarged pump tube right at the point the linkage is starting to cam over, so I think I have excessive headspace. That will be the next issue to tackle.
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sounds good, 3 pumps is very impressive,.headspace could be huge
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pics when u can
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I used a heat gun and formed the pump arm to the frame. It didn't make much difference.
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20170214_203740-1_zpsjgxwpbhm.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20170214_203740-1_zpsjgxwpbhm.jpg.html)
Then I added a piece of credit card to the front of the piston to close up the head space.
It didn't make much difference either.
Here's a pic of the piston after I polished it and it made about a 100 strokes. No signs of rubbing .
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20170214_204046-1_zpsghdtcoqw.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20170214_204046-1_zpsghdtcoqw.jpg.html)
So I pulled the piston out and pinned it in place. The rubber bumper system no longer works.
That was it.
New numbers with 7.9 gr CPHP:
Strokes FPS
1 312
2 456
3 540
4 606
5 660
6 698
7 732
8 750
9 782
10 793
11 803
12 813
Pumping was way easier than I expected and I haven't broken the pump tube yet. I think that more power could be had with a larger valve volume, but I'm making more power at 6 pumps that the stock rifle did with 10.
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HOLY COW<u need to make a new post new topic " daisy 880,700fps on 6 PUMPS.. this is insane @@@@@@@@ i wanna see it push 900!
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stack steel washers in between the pump arm stem and the piston, every bit of rigidity ( think machining) will make an improvement
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stack steel washers in between the pump arm stem and the piston, every bit of rigidity ( think machining) will make an improvement
Yea, I see your point. I just now pulled out the piston to take a look and noticed a couple of small rub marks on the back part of the piston. The only way that could have touched the tube would be if the piston shaft flexed. I'll turn a bushing on the lathe.
I really wondering why someone doesn't make a pumper with better performance with fewer pumps. Based on this experience, a .875 id tube, 4" stroke, and lengthen the pump arm about 4" to make it slightly easier to pump. Even at 12 pumps this thing is way easier to pump than my 392 at 8.
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it makes no sense to me either since grown men are buying them.. you recall my 1 inch piston pumper???????? it wasnt hard and i was using no handle on it.. needless to say 1 stroke was 3 392 strokes .. oh and sidelever frees up inches of stroke too.. boggles the mind
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(http://i746.photobucket.com/albums/xx102/robnewyork50/pumper2.jpg) (http://s746.photobucket.com/user/robnewyork50/media/pumper2.jpg.html)
wish id finished it, be selling em by now
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Well, dust it off and get back to it. ;) :D
What was it that caused you to stop?
I'm about ready to put the cheap stuff away and start from scratch.
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what stopped me.. I started with a factory gun linkage, the 392.. Far too flimsy, so that would have to be made from scratch.. I was using a 392 valve, those are not so good so i had to make a bigger one from scratch.. So i already had most of it built only to realize, I really needed to start over with all heavier duty stuff to really make it worth while
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all that was left was mounting a breech , barrel, and getting the hammer spring sorted out..But the 392 linkage was gonna fail past pump 3 which is about the same air pressure as pump 10 on the 392 factory gun.. Pumping effort was far less with the long sidearm.. ( lots of mechanical advantage
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and now that you did this experiment, you see what I mean about no one understanding pumpers. Ask anyone about a 1 inch pumper and they will automatically say " the effort to pump it would make it useless".. OR , " a pumper could never push 25 cal at pcp speeds"/// All bs misconceptions and wives tales that have been proven wrong by the best of builders like Bob sterne, James perotti, LD, Phil Riggs, and very few others.
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I think part of the problem is that there is more money in selling many cheap guns than there would be in selling a few quality guns with a heavy-duty parts.
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yep.. theyre making the springers and walmart pumpers for pennies on the dollar.. theyd need to sell a lot of 25 cal pumpers to be worth it..
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Nothing like having a "one off" like you have there. Something you did. And I'm sure you gained a ton of knowledge along the way. I bet it answered a lot of questions for other tinkerers too. Thanks for sharing it. 700 fps at 6 pumps ? Yeah, I'm in for that.. another 6 pumps for another 200 fps? I'll probably go in the house and grab another gun.
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I think part of the problem is that there is more money in selling many cheap guns than there would be in selling a few quality guns with a heavy-duty parts.
I agree it's probably not a viable option for the big manufacturers, but this is how guys have made a cottage industry of reworking lesser airguns into improved versions. I don't know if enough folks would buy the parts to modify this gun or not, but it's a cool exercise! This is reminiscent of my having modified Daisy spring air lever guns (details over at THR in the Air Guns forum under "Putting a little more power in a cheap Daisy" or something like that). In my case, the plunger tube was (is) the weak link. Making a stiffer one is, at least for now, beyond my capabilities so I stalled at 350 fps on a ~250 fps baseline. I decided there was not enough interest in hotrodding a Red Ryder to warrant pursuing better parts, but in this case who knows?
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Nothing like having a "one off" like you have there. Something you did. And I'm sure you gained a ton of knowledge along the way. I bet it answered a lot of questions for other tinkerers too. Thanks for sharing it. 700 fps at 6 pumps ? Yeah, I'm in for that.. another 6 pumps for another 200 fps? I'll probably go in the house and grab another gun.
Thanks, it's more about learning and tinkering than actually having a nice powerful gun. I agree that past 6 or 7 pumps it's not really worth the extra effort, but, the goal of this large tube project was reducing pumps rather than searching for absolute power. Still, I may enlarge the valve a little and see what happens. It sure is hard to resist those "Whatifs" when they crawl inside my head. ;)
Anyway, just to put this in perspective, here are the stock numbers vs the modified:
Stock Modified
10 = 650 fps 5 = 660
15 = 700 fps 6 = 698
20 = 750 fps 8 = 750
I didn't make it to 12 fpe, but I cut the number of pumps in half. With a metal pump arm I think it could reliably handle 8 pumps over the long haul.
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very nice.. once u stiffen all the moving parts and such, i dont see why you cannot get 900 fps on pump 12
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Nothing like having a "one off" like you have there. Something you did. And I'm sure you gained a ton of knowledge along the way. I bet it answered a lot of questions for other tinkerers too. Thanks for sharing it. 700 fps at 6 pumps ? Yeah, I'm in for that.. another 6 pumps for another 200 fps? I'll probably go in the house and grab another gun.
Thanks, it's more about learning and tinkering than actually having a nice powerful gun. I agree that past 6 or 7 pumps it's not really worth the extra effort, but, the goal of this large tube project was reducing pumps rather than searching for absolute power. Still, I may enlarge the valve a little and see what happens. It sure is hard to resist those "Whatifs" when they crawl inside my head. ;)
Anyway, just to put this in perspective, here are the stock numbers vs the modified:
Stock Modified
10 = 650 fps 5 = 660
15 = 700 fps 6 = 698
20 = 750 fps 8 = 750
I didn't make it to 12 fpe, but I cut the number of pumps in half. With a metal pump arm I think it could reliably handle 8 pumps over the long haul.
Oh yes, I am absolutely all for more power with less pumps. betty Lou and I have a matching set of Metal/Metal 880s now. We shoot paper flys at 10 meters with 4 pumps and paintballs and beer cans at 5 - 6 pumps. Between us it is not uncommon to burn a tin of 500 winnies in an evening. Even at 1 pump less per shot, that is huge.
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A mod like this would be perfect for that type of shooting, but I'm not sure the tube would fit under the metal clamshells. I'm going to have to get the heat gun out and make a bulge in the plastic ones I'm using.
Tonight I used washers and made the piston rigid. Nothing changed. I adjusted it so the head space was as close to nothing as I could get without a hard snap shut. I erred on the side of longevity and lost less than 10 fps.
Then I tried the 9.7 gr Winnie domes:
1 = 292
2 = 417
3 = 497
4 = 551
5 = 602
6 = 634
7 = 658
8 = 691
9 = 708
10 = 724
11 = 733
10.3 fpe in 8 pumps.
11.3 fpe in 10 pumps. Not bad.
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I meant to say we shoot the paint balls and beer cans off of 3" drywall screws with 5 - 6 pumps at 25 - 30 meters.
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if you dont want the slapping noise, you may want to add a rubber piece of inner tube or something similar to the piston face.. This will also aid in headspace.
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if you dont want the slapping noise, you may want to add a rubber piece of inner tube or something similar to the piston face.. This will also aid in headspace.
It wasn't the noise, it was stress caused by an interference fit between the piston and valve. I have them very lightly touching when the pump handle closes. In the past when I had the hard fit it caused things to wear and break.
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I meant to say we shoot the paint balls and beer cans off of 3" drywall screws with 5 - 6 pumps at 25 - 30 meters.
Are you sure you're not just looking for an excuse to brag? ;D Seriously though, going with the posted stock numbers, that is alot of pumping.
I just read this whole thread today and am trying to figure how all this information can be applied to my 1377. Not being the sharpest tool in the shed, all I've managed is to get an oring around the pump cup. I haven't figured out where I'm supposed to shim or what to pin. I hit the mark I wanted with Davio's help and parts, but now I kinda want to go a little further.
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:-\ If it were my intent to brag I would have to brag on Betty Lou. She still out shoots me 2 to 1. :o
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:-\ If it were my intent to brag I would have to brag on Betty Lou. She still out shoots me 2 to 1. :o
;D I understand, Sir.
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if you dont want the slapping noise, you may want to add a rubber piece of inner tube or something similar to the piston face.. This will also aid in headspace.
It wasn't the noise, it was stress caused by an interference fit between the piston and valve. I have them very lightly touching when the pump handle closes. In the past when I had the hard fit it caused things to wear and break.
well it really goes to show when your pushing that much power how everything needs to be rigid and with a certain tolerance.. Just like we discussed in regard to my 1 inch pumper.. I quickly realized i could never push the platform with the stuff I had.. But , at 6 pumps and 700 fps , i guess you dont need to push this platform to the max ( but ID prefer if ya did lol, just to hit 911 fps
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ALSo, it looks like with 10.3s or heavier you will hit 12 fpe at 12 pumps..
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I quickly realized i could never push the platform with the stuff I had..
Exactly. That's why I backed off a touch.
But , at 6 pumps and 700 fps , i guess you dont need to push this platform to the max ( but ID prefer if ya did lol, just to hit 911 fps
Yea, I'm going to open up the valve a little this weekend. I seem to remember some threads around here about taking a dremel to the valve.
So, I just tried 12 pumps:
9.7 Win Dome = 744 and 11.93 fpe.
10.66 H&N Barracuda = 722 and 12.34 fpe :D :D
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PULLING my chain man
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howd u get the extra 150 fps from the last post??
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Lol. Ooops. Typo. I corrected my numbers. I had the fps wrong.
Back to second place behind you. ;) ;) ;D ;D
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14.53 fpe was my record, just checked. @ PHEWWWWWWWWWWWW, my walmart is 24.7 and 4 miles away , i was debating taking the wifes car
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PHEWWWWWWWWWWWW, my walmart is 24.7 and 4 miles away , i was debating taking the wifes car
Lol. I have three more refurbs to experiment with... ;)
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well , now you know exactly what needs to be done to hit 1000.. everything need to be rigid, need a metal pump arm from an older gun , the piston u have bottoming out on the abutement valve face, and some additional volume in the valve.. ANd perhaps a final addition to preload on the hammer .pretty simple formula with the big piston.. with the small one theres a few other tweaks needed to make 1000 , not many to get to 900 plus
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I enlarged the valve by taking a little off here and there. I also opened the channel that connects the abutment area to the valve area below the transfer port.
Velocity was about equal at 10 pumps but lost a few fps below that and gained a few fps above that. By "a few" I mean single digits.
12 pumps and 9.7 gr Win domes = 748 and 12.05 fpe
Then I decided to go for broke (literally) ;)
20 pumps, 10.66 gr H&N Barracuda = 786 fps and 14.63 fpe
20 pumps, 9.7 gr Win domes = 799 and 13.75 fpe
20 pumps, 7.9 gr CPHP = 881 and 13.62 fpe
22 pumps, 7.9 gr CPHP = 873 and 13.37 fpe
21 pumps, 7.9 gr CPHP = 854 and 12.8 fpe
See what is happening? The pump arm is giving out and power is going down as the hole is elongating and creating headspace.
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good numbers , but were back to rigidity in the linkage again.. By pump 14 u shouldnt even be able to pump without snapping the arm like a twig..whatever lil sneaky ways to get a solid stroke will make all the difference,. bushings washers whatever
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good numbers , but were back to rigidity in the linkage again.. By pump 14 u shouldnt even be able to pump without snapping the arm like a twig..whatever lil sneaky ways to get a solid stroke will make all the difference,. bushings washers whatever
Yep, and I think the frame is flexing too.
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good numbers , but were back to rigidity in the linkage again.. By pump 14 u shouldnt even be able to pump without snapping the arm like a twig..whatever lil sneaky ways to get a solid stroke will make all the difference,. bushings washers whatever
Yep, and I think the frame is flexing too.
yep.. my pump arm would flex past stroke 7, But i never really had problems with the rigidity for 2 reasons.1 becuse i was pushing a smaller piston , and 2 because I had an adjustable piston.. So as it broke in and created headspace I just adjusted it back out the 1/8th inch or whatever for max compression again... I guess a third reason I nevr had issues was i simply broke the pump arm first (-;
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I just hit 15.24 fpe. ;D ;D ;D
841 fps with 9.7 gr Win Domes,
with 23 pumps,
with only lightly modified stock parts - Not my big bore and not using a custom piston.
I made the piston flat-topped, added a washer to reduce the amount of squish in the piston bumper assembly, increased hammer travel, used a nut to add preload to the hammer spring, drilled the transfer port to .140, reduced probe diameter, reduced the leade in the breech, and opened the transition from the abutment chamber to the main valve chamber.
Amazing how all the little things add up.
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wow, id love to see pictures@ also , you need to spit a 7.9 outa there and see if you get 911 fps >:( if i still had mine , id certainly be outside testing with a 9.7 LMBO..
sounds like the 2 mods that made a huge difference were the TP and the hammer strength
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you need to spit a 7.9 outa there and see if you get 911 fps
You know what they say, be careful what you ask for...because you just might get it. Lol ;D ;D ;D ;D
Here is a 7.9 CPHP with 23 pumps:
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20170311_124512-1_zpshxx1pn1z.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20170311_124512-1_zpshxx1pn1z.jpg.html)
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holy COWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW, you now hold the official 880 speed record.. ID love to see these mods.. What i find most interesting is that you did not use a custom piston to acheive these results.. You should make a new post detailing the entire " how to " on the mods, and the phenomonal results.
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opened the transition from the abutment chamber to the main valve chamber. """
what does this mean?? i assume you machined the rear portion of the abutement
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I have one more refurb 880 to go through. I thought I'd take pics at each step of the way and make a thread.
One thing to note is that the fastest shots happen with a fresh lube and a cold gun. As I continue to shoot it settles down to about 25 fps slower. On the other hand, I'm using a tube that had a scratch from the factory and I sanded it out by hand with 400 and then 800 grit wrapped on a stick. So the wall finish is not finely polished and no doubt a few thou bigger.
Most importantly is that 10 pumps gives over 10 fpe easily and without strain. Add 3 more pumps and it's 12 fpe. So it's a reliable, accurate rifle at that power level.
I did not machine the rear part of the abutment. I'll post a pic later.
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Sounds liek you found the ultimate power tune, and apparently no machining required
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I figured it was the same as porting an engine: more flow=more power.
Sorry about the poor pics, but it was hard getting light down there and my phone cam to focus.
Stock:
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20170311_142258-1_zpsa4yjfvuo.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20170311_142258-1_zpsa4yjfvuo.jpg.html)
Ported:
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20170311_143514-1_zpsqlvbzugm.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20170311_143514-1_zpsqlvbzugm.jpg.html)
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so , you added a small bit of volume , increased the flow of that air, and then added hammer to get it into the barrel faster.. Awesome.. the .140 tp kinda finishes the job.. very cool
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so , you added a small bit of volume , increased the flow of that air, and then added hammer to get it into the barrel faster.. Awesome.. the .140 tp kinda finishes the job.. very cool
Yea, that was my thinking. I'll bet you could add your adjustable piston and metal pump arm and hit 1000 fps.
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If you flatten the flooring wider (looking like a sideways D ) and put a radi on the edge like a waterfall it will flow even better Put a washer on the seat to protect it a from damage..i did the same porting on my 901.when I was looking at the port on mine I could see it was restricted by the poppet. There was little room for air to go down and around the poppet. Mine was way narrowed than the on in your pick it was as wide as the poppet.BTW do you have any picks of the pistion and rod that you modified.
I was not trying for a big power increase I was trying to fix my vertical point of impact that I was getting.i just went in and debur the portl a little.I might go back in and make it a little bigger and drill out the transfer port.
If I could figure out how to cut the seat lower so I would have more valve travel I think that could make some more power .I added the travel to my hammer already but I think it could use some more.
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If you flatten the flooring wider (looking like a sideways D ) and put a radi on the edge like a waterfall it will flow even better
Put a washer on the seat to protect it a from damage..
Thanks for the advice. I was worried about the seat and stopped before I really wanted to because I was afraid of slipping with my Dremel.
Here's the piston. Just fill the center depression with JB Weld and then sand it flat until the step is gone:
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20170210_213805-2_zpss424th76.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20170210_213805-2_zpss424th76.jpg.html)
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thats the most common mod.. What did you do with the bumper rubber thing
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Yea I would like how you rigged the washer on the pistion too.
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thats the most common mod.. What did you do with the bumper rubber thing
I put a washer behind the piston so that the bumper has preload and is harder to compress. My reasoning is that it would mean more air going into the valve. I could be wrong, but the lever snaps shut with the slightest of pressure so I doubt it's hurting anything.
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20170311_190144-1_zpsquedamkf.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20170311_190144-1_zpsquedamkf.jpg.html)
Here's a pic of the hammer spring spacer. I drilled the nut to sit on the trigger nub and then drilled one side to create a cup for the spring to sit in. Drill a little at a time until the trigger cocks. Edit: You'll need to sand/file/grind a little off the sides of the nut to get clearance for the stock.
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20170311_185716-1_zpsi1vyjj2w.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20170311_185716-1_zpsi1vyjj2w.jpg.html)
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very nicely done simple mods.. Ive seen guys stack washers to replace the rubber bumber and get good results, but seems like ur mod is better
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Thanks. Yea, nothing big - just little tweaks here and there and they eventually add up.
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drilling the TP sounds like the hardest part, very vital seal area ..
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Thanks for the pics ,the nut idea brilliant!
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drilling the TP sounds like the hardest part, very vital seal area ..
It is tricky. You have to squinch your cheeks together tightly. I used a cordless hand drill and went slow and easy. I think I drilled it in a couple steps and with the barrel out.
Thanks for the pics ,the nut idea brilliant!
Thanks.
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Drill the transfer port Is scary to me. Thats why I have not done it yet.i read somewhere if you put pellet in breach above the port and drll it wont make a burr and help drilling too deep.to the other side.
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figured as much because the area still needs to be super smooth to maintain a seal.this short list seems like the new standard pwer mods.. My question is , can it keep up with the big tube pump for pump
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I was also thinking if I drill the tp bigger and the hole was not perfict round. I have a lot of steel sling shot ammo that I could use to remake a round seat. Just drop a ball that is big as the poppet a few light taps it should make a perfit seat..just a idea here thinking out loud.
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Maybe stick a wood dowel in the "chamber" area to keep from hitting the other side and keep the burr at a minimum? I use a dental pick to smooth out the sharp edge from drilling.
No way will this keep up with the big bore pump for pump, BUT, the frame just can't handle the stress and actually stretches and increases head space in the big bore. However, the goal of the big bore was to reduce the number of pumps at normal power levels.
I really think this design is best suited for 10 pump/10+fpe with an occasional 13 pump/12 fpe shot for hunting.
...and experimenting. ;)
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Here's some ideas for drilling the transfer port:
Build a simple jig. Note: I just whipped this out quickly to show the idea. I didn't take the time to make it accurate enough to use.
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20170311_210300-1_zpsbqcwqtaj.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20170311_210300-1_zpsbqcwqtaj.jpg.html)
Or find a washer or something round to fit in the chamber. Note: Be sure it doesn't rotate if it's on the o-ring sealing surface. I'm going to use a wrap of tape.
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20170311_210325-1_zps7c5sqllb.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20170311_210325-1_zps7c5sqllb.jpg.html)
This is actually a strap button for a guitar. It fits perfectly. Two wraps of masking tape on the od makes for a snug fit in the valve, and the id allows a few thou clearance for my .140 drill bit. Talk about luck. Lol
(http://i424.photobucket.com/albums/pp330/305178/Mobile%20Uploads/20170311_210400-1_zpsotlosibp.jpg) (http://s424.photobucket.com/user/305178/media/Mobile%20Uploads/20170311_210400-1_zpsotlosibp.jpg.html)
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Note about the hammer spring spacer: You may need to sand/file/grind a little off the sides of the nut to get clearance for the stock.
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do you think more volume would get u 1000 fps with 7.9s?? also , do u think its even maxed out at 24 pumps?>
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Maybe I missed something but, why the nut under the hammer spring instead of a stiffer spring?
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Maybe I missed something but, why the nut under the hammer spring instead of a stiffer spring?
The nut was laying there on my bench and a stiffer spring is at the hardware store. ;)
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Maybe I missed something but, why the nut under the hammer spring instead of a stiffer spring?
The nut was laying there on my bench and a stiffer spring is at the hardware store. ;)
LMBO... I was sitting here visualizing all the times I've messed with the Daisy 880 and for the life of me I couldn't get my head around this and what the shim would do that a stiffer spring wouldn't. I was in the process of going back thru the pages trying to find the answer when you responded. Thanks
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do you think more volume would get u 1000 fps with 7.9s?? also , do u think its even maxed out at 24 pumps?>
Likely so, but I don't think the rest of the parts can handle the strain for very long. I pumped beyond 23 pumps and didn't gain anything. I took everything apart after my "record attempt" (Lol) and found the pin that holds the abutment to the valve was bent slightly from all the pressure.
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LMBO... I was sitting here visualizing all the times I've messed with the Daisy 880 and for the life of me I couldn't get my head around this and what the shim would do that a stiffer spring wouldn't. I was in the process of going back thru the pages trying to find the answer when you responded. Thanks
Lol, yep, it was just easy, cheap, and available. How's the foam barrel shroud coming along?
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do you think more volume would get u 1000 fps with 7.9s?? also , do u think its even maxed out at 24 pumps?>
Likely so, but I don't think the rest of the parts can handle the strain for very long. I pumped beyond 23 pumps and didn't gain anything. I took everything apart after my "record attempt" (Lol) and found the pin that holds the abutment to the valve was bent slightly from all the pressure.
very interesting , I also had a slightly curved pin after my 2000psi plus testing
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Honestly, I haven't even messed with it. I made a trade for a .22 Marauder and I can't put it down. I commend you guys for picking a project and sticking with it. Tons of info can be gleaned from threads like this one. The guys in the big money machine shops are doing amazing RnD and it's very interest to read the results but you guys are "toolbox tinkering". Go to Walmart and spend $40 on a gun, stop at the local hardware for a couple springs and washers that Walmart didn't have then head out to the shed/garage and have at it. If it don't work.. so what. More parts for the next project.
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very interesting , I also had a slightly curved pin after my 2000psi plus testing
So Bill was right - we should have been wearing our helmets and titanium cups. :o That pin was yielding to the pressure.
I'm going to stick to the 10-12 fpe range from now on.
Bill - Yep. These things are cheap, easy, fun, and a good break from the more expensive projects. So far I've resisted the PCP stuff, but the price is coming down...
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bigger pin, harder material. even bigger diamter same material..I think your TP opening is the biggest gain.. as weve seen previosly, all the volume in the world wont let the air flow fast enough out of the valve.. well, hammer and TP
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what im wondering is why the giant piston build u have wont push the same numbers.. only guess is the tp
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Yes, it has a .125 TP, no hammer mods, and I didn't enlarge the port from the abutment chamber to the valve chamber as much.
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For giggles and grins, I bet a 4gr pellet at 23 pumps would give you your record of at least 1020fps. I got a feeling the numbers you have now will be on top for a long time. Until someone comes up with a steel valve and stouter pump. Awesome job.
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BHH has been extremely persistent, gone through a few guns , and done crazy mods to pass my 910 record.. Like you said , 923 will be very hard to beat .. ( until i get another 880 (-;
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I guess I need to take a leap and do the tp bigger. My 901 still dont make the power that my 880 has with just a slot fill.no porting. Today I check how little force it takes to compress the pistion.. the washer mod I think is the way to go.there will still some give.i am not looking to max out anyway. If I can get the power of my 397 with a budget air rifle. That lighter and easyer to pump is win win to me.
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BHH has been extremely persistent, gone through a few guns , and done crazy mods to pass my 910 record.. Like you said , 923 will be very hard to beat .. ( until i get another 880 (-;
8) ;D
Is it unfair of me to root for both sides?
;D
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If I can get the power of my 397 with a budget air rifle. That lighter and easyer to pump is win win to me.
I have a 392. The 880 is sooo much easier to pump. I pump it with a thumb and two fingers holding the handle. 10 pumps gets about 10.5 fpe and 12 pumps nearly 12 fpe. How much are you getting out of your 397?
8) ;D
Is it unfair of me to root for both sides?
;D
We're all on the same team here as far as I'm concerned. I'm looking forward to watching Rob break 1000. :D
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I thought about the 397, rebuild my buddys 347 , man by pump 8 it was a beast... and took 10 pumps to hit 730fps
Yes, root for both lol.. Without a serious compresssion tube mod like BHH did, no one will ever get 700 fps on 6 pumps again , just not enough swept volume/. But as far as the max velocity an 880 can do , were no where close.
BHH, im in the middle of the high pressure 1377, but it wont be long till 924fps calls my name, walmart is only 4.6 miles away ;D
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Well I dont have a chrony but I have a 397 and a 392.the 397 just has a ported exhaust.the 392 got ported cut the check valve by 1/3 extra oring..the 397 will pump to 10 and the 392 can Pump to 12. Before holding air. How I can tell on power is the stack magzine test, how.many spins on my spiner and if I can see the pellet Iin flight.iwill tell you once you get over 4 pumps you better have some strength. Over 8 pumps the arm could bend anytime. I useally dont go over 8 pumps 4 to 6 keep the poi the same for under 20 yard shots.there both are more accurate than my dasiys right now but there close. It just the pumping when the grandsons and nephews come over and shoot with me . They like to go on way longer than I do. The the crosmans are a workout.lol.my nephew has a 880 and thats I got turn on to daisys it was so easy to pump and pretty accurate.
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yep, the linkage on those guns is right at the brink.. definately not made for overpumping at all
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I did the mods to my 392. It creaks and groans when I pump it. With 14.3 gr CPHP it gets 400 fps with two pumps, 700 with 8, and 800 and retained air with 12 pumps. I removed the handle and will make a longer one that extends to in front of the trigger guard to get more leverage.
I bought a 1377 too and picked up a Powermaster 66 at a pawn shop. I plan to marry the two and give the PM tube a 90 degree twist and make a side pumping carbine.
I wish I could find a good cheap .22 barrel for the 880. I'd like to try that first.
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lol, i also bought a 1077 brand new last night.. I dont even know why but ebay has em direct from crosman cheaper than all the other sites
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Don't look now but I think Rob may be headed down the HPA road.
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Don't look now but I think Rob may be headed down the HPA road.
hahhahhaaa.. no pcps here. no interest.. i had a mrod 25cal 6 yrs ago , and was pumpin it mid summer.. I spent all my time pumping and no time shooting
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Rob, did you ever sell the piston mod to the public?
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It is a potential performance upgrade to purchase the piston/pump rod assy for the Winnie 1977 from Daisy.
Them relocate the pivot pin hole to work in the 880.......
Can be modded to work properly in brass tube models..
Dual O-rings and a square wire coil spring instead of the ribber bumper....
I may market these once I fixture for the pivot pin hole..........
So little to do...so much time! Wait...reverse that... (Willie Wonla)
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Rob, did you ever sell the piston mod to the public?
No i never did , these were my early days of modding .. replacing the rubber bumper with steel washers is a better mod anyway , someone years ago had their gun shooting a bit faster than mine at the time , 915 fps or so. That being said , he and I both broke quite a few plastic pump levers as i recall.
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Rob, did you ever sell the piston mod to the public?
https://www.gatewaytoairguns.org/GTA/index.php?topic=203896.0 (https://www.gatewaytoairguns.org/GTA/index.php?topic=203896.0)