GTA
All Springer/NP/PCP Air Gun Discussion General => "Bob and Lloyds Workshop" => Topic started by: rsterne on December 01, 2012, 08:32:04 PM
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A short while ago I built a .25 cal Carbine Pumper based on a shortened Disco Tube, the linkage from a Benji 392, and an MRod barrel.... While working on it, I started collecting ideas and parts for a rifle version using a full length Disco tube and a .25 cal choked Lothar Walther barrel.... Instead of having an auxilliary reservoir made from a 16 gr. CO2 bulb under the main tube, this gun would have an internal reservoir and a separate check valve.... After about a week in the shop, here are the main internal parts....
(http://i378.photobucket.com/albums/oo221/rsterne/Millenium%20Pumper/IMG_2827.jpg)
The pump linkage is an extended Billet linkage from Mac1 Airguns.... It is stronger, and 3" longer than stock, although it maintains the same 7.6" stroke, giving a swept volume in the Disco tube of 54 cc.... I wanted to mount the pivot pin as far forward as possible, so instead of shortening the Disco tube I made a threaded end plug to help spread the end load of the pivot pin into the tube.... The smaller stub on the front will mount a barrel band.... The piston is the same as the one I made for the Carbine.... Immediately behind that is a check valve, sealed both sides with O-rings, mounted into two new holes in the Disco tube and secured with high tensile 8-32 low profile SHCSs.... There is a 2.5" long, full diameter, (18cc) air chamber between the check valve and the extended front end on the valve.... The valve extension is 3/8" ID for most of its length, providing additional volume, and enough wall thickness to mount the gauge and a male Foster fitting on the left side just behind the gauge location.... That will enable the gun to be filled from a tank or stirrup pump, both easier than the onboard pump, whose main purpose is for topping up in the field.... Also shown is an MRod trigger with Challenger trigger guard.... Everything will be mounted in a inletted Boyd's Blaster stock from Norm at Discos-R-Us in Nutmeg laminate....
(http://i378.photobucket.com/albums/oo221/rsterne/Millenium%20Pumper/IMG_2831.jpg)
In the second photo are details of some of the parts.... The front plug was pretty tricky to machine.... I had to turn and thread it, mount it in the already slotted Disco tube, and then machine the slot and drill the pivot hole in the proper orientation.... It worked out beautifully, and the tube is full wall thickness at the pin location.... Below that is the check valve.... It is a simple aluminum housing, drilled through, and carrying a shortened check valve pin from a male Foster fitting, retained by a piano wire pin.... I tried one in my Carbine and it functioned perfectly, and the thin pin diameter left room for the screws on both sides.... Beside the check valve is the valve poppet and spring.... You can see how I have streamlined the head of the poppet, and narrowed the stem behind it.... The front of the valve spring has been expanded to 9/32" ID, to match the spring seat ID in the extended valve front end, for additional flow.... The brass part is a custom gauge mount I made from brass pipe fittings.... I used a 1/8" male to 3/8" female adapter and a 3/8" male to 1/8" female, then bored them out for additional volume, and threaded them together and sealed it with solder.... The Blaster stock is plenty deep enough for that assembly, and it added over 3 cc more volume to the valve.... The total volume is now 28.5 cc, slightly bigger than the Carbine was.... The Disco valve has been bored out inside to 0.62" ID, the throat drilled to 0.25", and the exhaust port milled out to 0.203" on a 20 degree angle.... It still needs a little TLC with a Dremel to round and smooth the inside corner.... The porting is 16% larger in area than what I used in the Carbine.... That combined with the longer barrel and slightly larger valve volume should gain a bit of velocity.... I'm hoping for about 10% higher FPE in this version at the same pressures.... With the additional leverage of the extended linkage, the effort should be the same at about 1800 psi as it was at 1500 in the Carbine.... so I have little doubt the peak power of this rifle will be higher....
This project resulted from my joining the Green Forum because of interest in their "Millenium Pumper" project, the concept of which was to bring MSPs into the 21st Century.... There was no concensus of opinion over what it should be like, so I undertook this project as my own interpretation of what could be done easily, starting with mostly Crosman parts and adding a few custom bits into the mix.... There are lots of other interpretations of the idea possible.... this just represents mine....
Bob
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it never ceases to amaze me the talent that some people possess. i can't wait to see the finished rifle.
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IMPRESSIVE!!Can't wait ts see the final results.
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Well, it holds air!.... I got the main tube assembly done and pressured tested to 2000 psi.... I can actually still use the pump at that pressure, and it doesn't seem much harder to pump than the Carbine at 1500.... which means hard, but not impossible....
(http://i378.photobucket.com/albums/oo221/rsterne/Millenium%20Pumper/IMG_2837.jpg)
I made and installed the hammer and the RVA, lengthened the rear of the bolt slot in the breech 0.10", faced 0.030" off the back of the valve and shortened the valve stem about 1/16" so that it is flush with the back of the valve when the valve spring goes coil bound.... Those modifications, along with the changes I made to the cocking slot in the tube and the bolt allow the maximum possible hammer travel, which works out to about 0.8".... No matter how the travel is adjusted, the cocking pin can't hit anything....
There are basically two areas left to work on.... The Lothar Walther barrel has to be machined to fit into the breech, I have to make a chambering reamer and cut the chamber and a groove for the O-ring, make a .25 cal bolt, machine the transfer port and crown, and make a barrel band.... On the Boyd's Blaster stock, I have to cut a hole for the gauge and relieve a few spots for the MRod trigger.... and then the major job of converting the forestock into the pump handle.... The stock will then need final sanding an finishing.... I'm really looking forward to seeing how this new pumper will perform....
Bob
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You like those pumpers don't ya. Beautiful job. I can't wait to see how we'll it performs. No doubt it will be a hammer.
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Bob, your project is progressing nicely. Your interpretation has taken the pumper to new heights and pressures with beautiful workmanship and engineering. Be careful, you're are dangerously close to building every part of your gun!
Tom
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or at least REBUILDING it.... *LOL*....
Bob
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I completed the barrel work today.... I made a chambering reamer from O1 Drill Rod, hardened and tempered it, and then used it to cut the chamber to just past the transfer port location.... I then machined in the barrel port and a rebate in the end for the O-ring to seal the bolt.... It will be pinched between the barrel and the breech.... The barrel OD was reduced to 7/16" to fit the Crosman steel breech....
(http://i378.photobucket.com/albums/oo221/rsterne/Millenium%20Pumper/IMG_2872.jpg)
The reamer has a 0.246" pilot that just rides on the lands in the LW barrel.... It has a 2* taper to create the leade, and then the chamber is 0.254".... The chamber is machined to just past the front of the transfer port, with the leade in front of that.... I also did a target crown on the muzzle....
(http://i378.photobucket.com/albums/oo221/rsterne/Millenium%20Pumper/IMG_2861.jpg)
The barrel port is 0.188" wide by 0.219" long at the bore, tapering to a 0.204" circle where it mates to the transfer port, which will be made from a piece of 5/16" Teflon rod.... After finishing the machining, I used JB Bore Paste to lap the bore and the chamber, followed by a polish with their polishing compound.... The results are a mirror finish inside.... LW sure do make a beautiful barrel....
Bob
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Looking really nice there Bob !!
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Excellent workmanship!
Nice reamer. Do you use by hand or chuck super slow?
beautiful crown too. It looks a lot like crown on the RainStorm but with and addition of a counter bore. Is that for protection or does it serve some other function?
Tom
Tom
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That is some excellent barrel work. Nicely done.
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I used 164 RPM but the lube was still smoking.... so next time I'll engage the back gear and drop it under 100.... You can change the aggresiveness of the reamer by how far past the centerline you maching the cutting edge.... On center it barely rubs off material, I used about 0.005" below to give a bit of rake to the cutting edge.... I've been told ~0.020" is the maximum.... Sometimes when you harden the reamer it warps a fraction and the "following" edge shades the cutting edge and it won't cut.... If that is the case, you just grind a bit off the corner of the following edge.... It can speed up the cutting dramatically.... in this case, I had so little material to remove it wasn't an issue.... After oil hardening, I tempered the reamer in an oven at 470*F for 30 minutes.... hence the nice dark straw colour....
The crown is at 90* to the bore, so the gasses can expand immediately without affecting the base of the bullet.... The disadvantage is that it is prone to damage, and that is the reason for the raised edge, to protect it.... I used to do all my crowns at 11*, but if you think about it, unless you indicate on the bore, even at that shallow angle you could have the crown closer to the breech on one side than the other, allowing the gasses to escape (a fraction) earlier on one side, possibly tipping the base of the bullet.... With a 90* to the bore, even if the bore is not concentric in the lathe, the release point for the gasses at the edge is the same all the way around.... Besides, it looks cool.... *grin*.... and it's actually easier....
Bob
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Yes, the in-your-face rifling is cool looking for sure and the fist detail I noticed. You read so much from BR shooters about this or that angle and wonder how they can quantify such small changes. The 90deg. makes perfect sense to me.
Thanks for the reamer tips, I was planning on single pointing my leade (advantage of CNC) but I think the reamer a will give better surface finish and require less cleanup.
Tom
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I got the main fitting of the stock done today.... When I ordered the Boyd's Blaster stock from Norm at Discos-R-Us I wasn't sure what I was going to use it for, so I had it inletted for a Disco without gauge.... I had to modify the inletting slightly for the MRod trigger, and I used a 1" Forstner bit to drill the gauge hole.... I also had to grind a small groove in the top left side to accomodate the Foster QD fitting.... The Challenger trigger guard came too close to my fingers on the pistol grip, so I had to shorten it a bit.... Fortunately, it doesn't have a "back end" so that wasn't a problem.... I've cut off the forearm off to make the pump handle, but haven't cut the groove yet for the pump linkage....
(http://i378.photobucket.com/albums/oo221/rsterne/Millenium%20Pumper/IMG_2875.jpg)
The other thing on today's agenda was to make the barrel bands.... The front one (right in the photo) fits on the 5/8" stub on the front of the front pivot block, so the outside of the band is the same diameter as the OD of the main tube.... The rear barrel band is designed to sit immediately in front of the gauge, and clamp the front of the breech in place for extra stability....
(http://i378.photobucket.com/albums/oo221/rsterne/Millenium%20Pumper/IMG_2877.jpg)
The Crosman steel breech's main weakness is the 4-48 screw in the loading port.... There is nothing forward of that to hold the breech and barrel in place.... I would have had the band right up against the front of the breech, but because of my oversized gauge mount I had to have a 1/4" gap between the band and the breech.... The band is made in two parts, the lower one will stay on the main tube, located with a set screw.... The upper half will sit on the barrel, just in front of the breech.... You remove the two clamping screws to remove the barrel and breech from the gun.... When you replace the breech and tighten the screws, it pulls down on the barrel, clamping the front of the breech securely against the main tube.... The top of the barrel band is flush with the top of the breech....
The only major jobs left are to cut the slot in the forearm for the pump linkage and make the .25 cal extended probe bolt.... With a little luck I'll get those done tomorrow and then I can give the stock a final sanding and start finishing it with Watco Danish Oil.... This thing isn't far from initial testing.... I just need Lloyd's MRod trigger shim....
Bob
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Hubba-hubba!!!!!
drools...:)
cheers,
Douglas
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Absolutely outstanding Bob.
Gene
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I tethered my "Millenium Pumper" today, running it regulated at 2000 psi to find out what it can do.... How does over 1000 fps with JSB 25.4 gr. Kings sound (over 57FPE) ?.... I initially set the hammer travel plunger flush with the end of the hammer, which gives me a travel of about 0.6", roughly the same as a stock Disco.... I can increase the travel 5 turns (24 TPI) or about 0.2" from there.... I ran through the entire range of RVA travel from coil bind out 12 turns (16 TPI) which is 0.75" of preload adjustment.... I then increased the travel 3 turns (0.125") and repeated the procedure.... Here are the results....
(http://i378.photobucket.com/albums/oo221/rsterne/Millenium%20Pumper/MilleniumPumper2000Preload.jpg)
First comment is that coil bind occurs 2 turns further out on the RVA with the additional 1/8" of hammer travel, which makes perfect sense.... I noticed that at high preload the increased travel actually lost a few fps, and I was wondering if the outside rim of the hammer was hitting the valve, limiting the lift in that situation.... I selected three different RVA settings, and ran the hammer travel through it's range to find out, with the following results....
(http://i378.photobucket.com/albums/oo221/rsterne/Millenium%20Pumper/MilleniumPumper2000Travel.jpg)
4 turns out on the RVA is the most preload I can use that will not cause the spring to go coil bound with the maximum hammer travel (5 turns).... You will note that there is a small but definite LOSS in velocity with increased travel.... At 9 turns out, the velocity increases as you increase travel, reaching a peak at 4 turns, and then drops.... At 12 turns out (minimum preload), the velocity increases steeply as the travel increases.... That is as per the expected behaviour, as not only does this style travel adjuster increase the travel, but as the preload is constant, it also increases the cocked spring force, so with light preloads, you're getting twice the bang for the buck, and power increases steeply....
For both the 4 turn and 9 turn out RVA settings, there is a downturn in velocity at 4 turns out.... My assumption is that is the point where the outer rim of the hammer is hitting the back of the valve, limiting valve lift.... It would appear, therefore, that is the maximum travel the gun can make use of without further modifying the back of the valve to allow the momentum of the hammer to carry it further.... Is this worth doing?.... Considering I will never run the gun at those high power levels, probably not.... The efficiency would be terrible at the long dwells associated with that much lift.... At 2000 psi, I would likely not run this gun at over 950 fps even if it was tethered.... That means at least 9 turns out on the RVA at minimum hammer travel, even less if the travel is increased.... A good solution, at least for further testing, would seem to be to set the travel at 4 turns, giving a hammer travel of about 0.77".... This will result in very low preload on the hammer spring.... I may well need to try a shorter and/or weaker spring as I'm running out of room to decrease the preload to allow tuning the gun.... This problem will increase at lower pressures....
I'm going to have to ponder these results for a while to decide where to go from here.... I'll probably do some testing at 1600 psi to accumulate more information before making any changes....
Bob
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I did some experimenting at 1550 psi (couldn't be bothered resetting the reg to 1600).... I had to swap out the QB hammer spring for a weaker one as I couldn't dial it to a light enough hit.... The new spring is 2.0" long made from 0.045" wire.... I tried three different stroke lengths, with the following results....
(http://i378.photobucket.com/albums/oo221/rsterne/Millenium%20Pumper/MilleniumPumper1550Preload.jpg)
What is interesting is that at maximum stroke, the velocity DROPS as you increase the preload to maximum.... The only thing I can think of is that the hammer is hitting the valve with enough force (less air pressure, remember) to rebound off it, shortening the dwell and reducing the velocity.... At one turn out from maximum stroke, the velocity has it's normal "plateau" or nearly so, and since I am going to be detuning the spring preload the hammer should never come in contact with the valve.... so that is the setting I used for the remainer of the testing....
I filled the gun to 1600 psi and bled and disconnected the fill whip so that the gun was operating on only the 28.5 cc of air inside the valve for the next tests.... The maximum velocity for a single shot at that pressure was 922 fps (48.0 FPE) with the 25.4 gr. JSB Kings.... That compares to 836 fps (39.4 FPE) at 1500 psi with the previous Carbine pumper I built recently.... so I've picked up over 20% in FPE with the longer barrel, bigger valve, larger ports, and a 100 psi increase in pressure.... I didn't spend much time trying for a two-shot setup, but I did manage 2 shots within 5% averaging 44 FPE at an efficiency of 1.0 FPE/CI.... I did play around until I got a good 3-shot tune at 38 FPE (808/834/813 fps) with an efficiency of 1.21 FPE/ CI.... That compares to the 3-shot tune at 31 FPE with the Carbine at 1400 psi with an efficiency of 1.10 FPE/CI....
I then filled the gun to 1800 psi and repeated the above procedure.... I never tried for maximum velocity, but I got 2 shots at 45 FPE with an efficiency of 1.00 FPE/CI.... and a 3-shot tune of just over 40 FPE (835/868/840) with an efficiency of 1.13 FPE/CI.... Those three shots used exactly half of the air in the valve, the ending pressure was 900 psi.... The setting required was about 4 turns out from coil bound with the 2.00 " x 0.045" wire spring, and the travel was 1 turn less than maximum....
Considering these are just preliminary results, I'm very pleased.... I have no idea yet how many pumps (or how hard) it will be to get to 1800 psi.... but based on the extra leverage the effort should actually be less than to reach 1500 with the Carbine.... I've won't be doing any pumping until the stock is finished and installed, which is 4 more days of oiling and sanding....
Bob
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Bob,
Nice work, and obviously an effort driven by personal satisfaction. The best kind.
The leading edge of the hammer can impact the back end of the valve and I ran into that with my 80fpe disco a while back. There are a couple of remedies that will work, but your choice. The extra stroke length usually adds a nice boost to the power levels.
Lloyd
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I measured the pump leverage on the extended Billet linkage compared to the stock linkage I used on the Carbine.... When you measure from the main pivot to the center of your hand, the new gun is 16.5" compared to 12.5" on the Carbine.... Since the pump stroke is the same (and the link pivot in the same place), that means this rifle should require the same effort at 2000 psi as the Carbine did at 1500.... The 3-shot tune I had on the Carbine started at 1400 psi, so I decided to tune this gun for a 3-shot string at 1800 psi.... Once I made that decision, and based on the previous testing, I went through a series of RVA settings at various hammer stroke lengths at 1800 psi to develop a baseline....
(http://i378.photobucket.com/albums/oo221/rsterne/Millenium%20Pumper/MilleniumPumper1800Preload.jpg)
I observed the same strange behaviour as previously at maximum hammer travel, so I took some measurements.... It turns out that when the hammer is adjusted for maximum stroke length, it can only open the valve 0.10" before it hits the back of the valve body.... Under normal operating conditions, this is not an issue, but a combination of maximum hammer stroke plus maximum hammer spring preload causes this collision to reduce the dwell, and hence the velocity.... However, since I would never run this gun at over about 950 fps (wasteful of air) I can run the maximum hammer stroke without a problem.... Each turn less on hammer stroke requires about a half turn more preload on the spring.... This increases the cocking effort and the load on the sear, and is likely to increase the possibility of hammer bounce.... so I maxed out the hammer stroke (to minimize the preload) and started looking for suitable tunes....
I wanted three tunes, one with a single shot at high power without wasting too much air.... a second one where you had two shots of equal velocity.... and the main one I was interested in, a 3-shot tune where the three shots were within a 4% maximum ES.... Here are the results, using 25.4 gr. JSB Kings....
(http://i378.photobucket.com/albums/oo221/rsterne/Millenium%20Pumper/MilleniumPumper1800Strings.jpg)
The graph shows the velocity of the following shots so you can see what is happening.... The single high power shot worked out to 951 fps (51 FPE) and used 500 psi of air (0.85 FPE/CI).... The 2-shot string was 898 fps (45+ FPE) and used 730 psi (1.04 FPE/CI).... The 3-shot string averaged 846 fps (40+ FPE) and used 900 psi (1.12 FPE/CI).... If you needed a 4th shot, it would be about 725 fps (30 FPE), plenty good enough for a close follow-up or Coup de Gras....
How does this compare with the Carbine I built previously?.... That gun maxed out at 837 fps (40 FPE) for a single shot, delivered two at 796 fps (36 FPE) , or three shots at 739 fps (31 FPE).... so I've picked up about 100 fps and 10 FPE across the board.... To say I'm pleased would be an understatement.... Another couple of days of oiling and sanding the stock and I'll be able to try pumping this beast....
Bob
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OK, OK, the lightbulb just went on.... The downturn of the maximum travel curves at maximum preload is the "bstaley" effect showing up.... I was just slow to recognize it.... I was thinking of it backwards.... Once you run enough preload it is possible to drive the hammer into the back of the valve IF the stroke adjuster is fully inside the hammer (maximum throw).... Here is the data replotted for the maximum preload with the 2.00" x 0.045" spring at coil bind....
(http://i378.photobucket.com/albums/oo221/rsterne/Millenium%20Pumper/MilleniumPumperStrikerDepth.jpg)
What is happening is that if the center of the hammer face (the striker part) is recessed as far as it can go, it is limiting the valve lift to 0.100".... That is what is happening at the "Maximum" setting in the above graph.... As you move the striker forward (towards the hammer face) it opens the valve further (eg. at 1 turn).... At 2 or more turns, the hammer is no longer hitting the valve body, so the velocity limits at it's usual "plateau" like I'm used to seeing.... If I continued reducing the recess in the front of the hammer (which also reduces hammer throw) I would again see a velocity loss....
I'm going to have to ponder this for a while....
Bob
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looking at your graph
maximum means flush or sticking out of the hammer correct?
each less turn means the further in/more reccessed the striker is??
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On that last graph, "Maximum" means maximum stroke/travel.... ie fully recessed (about 0.20") into the face of the hammer.... The fact that the face is so deeply recessed limits how far the valve can open before the rim of the hammer face hits the back of the valve body.... That in turn, limits the velocity....
Bob
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My version of the Millenium Pumper is finally finished.... It uses a .25 cal Lothar Walther barrel, a Disco main tube, and a Mac1 extended Billet linkage, and weighs 7.25 lbs. without the scope, which is a Leapers 4-16 x 40 AO MilDot.... Here's what it looks like....
(http://i378.photobucket.com/albums/oo221/rsterne/Millenium%20Pumper/IMG_2889_zpsc0710b62.jpg)
The Boyd's Blaster thumbhole stock has a swell in the forearm right where you grip it for pumping, and was a perfect choice.... The pump stroke is long, but significantly easier at 1800 psi than the Carbine was at 1500.... I have pumped the gun by hand to 2000 psi, and I would consider that a safe upper limit.... Over 60 FPE with EunJins should be pretty easy at that pressure....
(http://i378.photobucket.com/albums/oo221/rsterne/Millenium%20Pumper/IMG_2893_zps50d6fe30.jpg)
The pump actually works better than the one in the Carbine did, filling the 28.5 cc valve faster than the Carbine did its 27 cc valve.... It takes 80 pumps to fill to 1800 psi from empty.... The second graph shows the number of pumps to refill after each shot when the gun is set up for three shots of 40 FPE.... This gun actually takes fewer pumps while producing 40 FPE per shot than the Carbine did at 30 FPE per shot....
(http://i378.photobucket.com/albums/oo221/rsterne/Millenium%20Pumper/MilleniumPumperPressure_zps12009273.jpg)
Filling to 1800 psi gives a choice of three different tunes just by resetting the RVA.... I can get 1 shot at 950 fps (51 FPE), 2 shots at 898 fps (45.4 FPE), or 3 shots at an average of 846 fps (40.4 FPE) within 30 fps (less than a 4% ES).... While the gun can be pumped to 2000 psi, I feel that these three settings give the best balance between power and pumping....
(http://i378.photobucket.com/albums/oo221/rsterne/Millenium%20Pumper/MilleniumPumper1800Strings.jpg)
The graph above shows the velocity of the "next" shot in each string.... You can see that the 4th shot when the gun is set up for three shots of 40 FPE is still about 30 FPE.... plenty good enough for a close follow-up or a coup de gras.... I'm extremely pleased with the way this project turned out.... It surpassed all my expectations, and performs better than I could have ever dreamed or hoped for....
Bob
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WOW Bob! Great design, engineering, and execution! You've got it all in this one.
Very nice.
Lloyd
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looking good!
very nice shooter!
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Somebody asked what the FPE was if I maxed out the settings at 2000 psi.... With 42.4 gr. EunJin Points, it hit 858 fps, which works out to 69.3 FPE.... Mind you, it took half the air in the valve to do that, and MAN was it LOUD !!!
Bob
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WOW super nice. I will trade you one of my kids for this rifle ;D
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Great project Bob. Is it any harder or easier to use that than a benj hand pump? Wondering if you may have to switch arms every 20 pumps or so.
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Bob,
You do a great job at not only reaching your functional requirements, but looking good while doing it!
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Awesome rifle Bob. Have you shot any targets yet ?
Scotty
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Snow everywhere here, so only indoors.... At 7 yards it just makes one pencil sized hole.... In my experience, LW barrels are never a problem....
Bob
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This thread has been incredibly fascinating! Thank you very much for taking the time to share the details of your project. Finished product looks amazing! Hope it performs as well as it looks!
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I want one! Seriously, I want one!
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Very cool thread. Thanks. ;D
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This is, literally, the most amazing display of airgun engineering skill displayed by a single person I've ver seen.
I am in awe.
Thank you.
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Seeing this thread resurface made me smile.... The gun is now residing with a friend who had a heart attack over the winter, and has renewed his waning interest in airguns, much to his wife's chagrin.... The funds recovered (and more) have gone into my .30 cal Disco Double project.... so the gun continues to bring pleasure to both of us.... For sure it's the hardest hitting pumper either of us have ever seen.... and with only 12 pumps for a single 40 FPE shot doesn't wear you out too bad....
Bob
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It's nice to hear your efforts have found a nice home :) Guns never seem to loose value, it seems this is true for many AGs as well.
Tom
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VERY NICE and VERY VERY Impressive numbers!!
CW
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I gotta tune my psychic antenna...I completely missed your thoughts considering parting with it...LOL I would have walked out to pick it up...in winter, in sandals.
cheers,
Douglas
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Don't feel bad, Douglas.... It was requested long before it was even finished.... *grin*.... However, people should have figured out by now that I very seldom keep my projects, I allow them to find a good home and then roll the funds back into the next project.... The Hayabusa is the exception, as it's a project without end (at least for now).... I do keep a few "Hunters" of course....
Bob
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Wow..
<speechless>
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Bob, thank you for starting this thread. I am planning to build air conserving pumper so this thread is big help for me. My goal is two shots around 20 FPE in 177 cal. with the least number of charging pump A couple of question, if you don't mind:
1) how to calculate yield strength of pressurized vessel ? I'm still undecided whether using the pump tube directly for reservoir as you did, or using modded brass valve (e.g. benjamin AC397). Whichever is stronger.
2) did your millenium pumper experience tube bending at maximum charge? I prefer barrel band for easier tinkering but I think soldered barrel (392/397 style) resists bending better.
thank you.
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Here is a calculator for working pressure.... http://www.engineersedge.com/pipe_bust_calc.htm (http://www.engineersedge.com/pipe_bust_calc.htm)
You need to know the tensile or yield strength of the material.... using tensile will give the burst point, using yield will give the point at which it deforms and doesn't return to the original size.... You have to input the safety factor.... 3:1 on burst or 4:1 on yield is what I use on my own projects.... This only gives the data for the tubing, you have to work out the end plugs separately, and that can get fairly complex, depending on whether they are threaded in or secured with screws....
I didn't notice any bending on the main tube of my Millenium Pumper, even at 2000 psi....
Bob
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Here is a calculator for working pressure....
You need to know the tensile or yield strength of the material.... using tensile will give the burst point, using yield will give the point at which it deforms and doesn't return to the original size.... You have to input the safety factor.... 3:1 on burst or 4:1 on yield is what I use on my own projects.... This only gives the data for the tubing, you have to work out the end plugs separately, and that can get fairly complex, depending on whether they are threaded in or secured with screws....
I didn't notice any bending on the main tube of my Millenium Pumper, even at 2000 psi....
Bob
Thanks for the link and answer Bob. I'll do some number crunching before proceeding.
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:o :o :o :o :o :o :o :o :o :o :o :o :o :o :o :o :o :o :o :o :o
ABSOLUTELY FREAKING BEAUTIFUL!!!!!
I too am speechless.
That beauty and power, would easily get in the $600 range or even more!
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I sold the original for more than that, and I figure I might have made $1 an hour.... *LOL*.... The money just got rolled into my .30 cal Disco Double anyway....
Bob
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wheres the thread for your carbine? i can't seem to find it
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http://www.gatewaytoairguns.org/GTA/index.php?topic=37401 (http://www.gatewaytoairguns.org/GTA/index.php?topic=37401)
Bob
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This is indeed impressive. I love a good .25 cal as much as the next guy. What would REALLY impress me is a .177 caliber rifle that can attain somewhere in the 12ftlb range of power with a SINGLE pump of the arm. Now that would be something. You could built an FT rifle that would be self contained and super precise on a platform like that. Do you think that is at all possible? I know Daystate made the Sportsman rifle that was similar but I cannot recall how many pumps it took to get that much power. I was at an FT shoot one time where a fellow nobody knew showed up with one and nearly cleaned the course on the first day and was doing the same on the next day but something happened to the gun or his scope as I recall. Pretty interesting. Nice and thanks for sharing the knowledge. I may have to try to build the dream gun here after I finish my FT PCP. Peace
Pete
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I don't think what you want is possible, for the following reasons.... SSPs, by definition, are a "pump and dump" design.... That puts them at a disadvantage because the valve is still open for the last half of the pellet travel down the barrel, where most of the air is wasted.... Even if it were possible to achieve an efficiency of 1 FPE/CI (as is typical with many PCPs), you would have to compress 12 CI of air to achieve the 12 FPE output you want.... That is nearly as much air as contained in a Marauder reservoir.... Let's say you used a pump with an ID of 1", you would need a stroke of about 15".... If you managed to achieve 1500 psi, the force on the piston would be about 1200 lbs.... By comparison, at the end of the 80 pumps it takes to fill my Pumper to 1800 psi, the force is less than 800 lbs, and the piston stroke is about 7.5".... For an SSP to compress the air you would need in one stroke you would need twice the stroke at 1.5 times the force.... or using the same stroke (and therefore pump length), the force would have to double that to about 2400 lbs.... three times what my gun requires.... I know for a fact I couldn't pump it....
Bob
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Honestly man I dunno all the particulars of the system because I have only really built a bunch of PCP airguns from scratch not any single or multi stroke guns. However I will just throw this out to ya. Watch this video for a moment.
http://www.youtube.com/watch?v=hgXR4t2yc1M# (http://www.youtube.com/watch?v=hgXR4t2yc1M#)
That is a FWB 600 series single stroke pneumatic rifle. That rifle generates energies in the range spoken of here....
http://www.network54.com/Forum/79537/thread/1339377368/Single+stroke+Pneumatic+at+altitude+question (http://www.network54.com/Forum/79537/thread/1339377368/Single+stroke+Pneumatic+at+altitude+question)
Approx. 550-575 fps with 7.9 grain pellets or so. What I am saying is that if you watch that video the gun which by all accounts is a fine piece of german engineering of course is BUILT to be super easy to cock in order to not tax the shooter too much during a match.
Now take your average FT springer like an HW97 rifle. Probably guessing somewhere in the neighborhood of 25 pounds cocking force for a single stroke. It seems to me that all we are talking about is a rifle that would be cocked with similar force that generates only another 200-250 fps with the same pellet to be in the 12 ft lbs range. That does not seem like it would be all that difficult if you accepted a force of cocking of double what the match gun needs. *(&^ even if you had to cock it two times to get there it would be just fine as the Whiscombe rifles which of course are completely different but use two or three strokes to fully compress both spring pistons. Lost of folks use them in FT competitions. I know if I could shoot a 12ftlb rifle that was quality built like a PCP and needed to be cocked twice to get that power level I would be pretty pleased with it.
What I don't know to speak intelligently about this is the match guns firing chamber volume and pressure to generate the lower power. If you knew that you could probably figure out the necessary volume and pressure to generate the 12 ftlbs and work backwards from there. Like I said you probably know more than I do about the MSP guns but it sure seems doable. You would really have something interesting if it were possible and I think it is.
I even have some tubing out in the shop I could use for the cocking pressure tube and materials to build the rest of it too. Maybe I need to go get myself a MSP cheapie gun and tear it apart and learn about it some. I just was speaking to my friend Art who is an engineer that works with pressure systems all the time and a pretty smart fellow about it and he said he would be willing to help me figure it out. Do you have any ideas about it? Peace
Pete
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Bob, I'm just starting an engineering degree, and this post is inspiring. A project like this is what I hope to be able to accomplish once I'm through with school. I'd love to be able to not only conceptually design something, but actually put that plan into action. Thanks (and if you ever feel like doing a short video showcasing that gun it'd be awesome)
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That FWB 600 has an energy of 5.3-5.8 FPE, which is a LONG way from 12, like less than half.... Once you talk about more than one cocking stroke.... or retaining air in the valve, so that you can have several cocking strokes to fill the gun and then 1 or 2 to top it up between shots, you have a competely different situation.... Springers use adiabatic compression and the heat generated to increase energy, again a totally different concept.... My response was directed at the original concept of an SSP of 12 FPE.... I think it would take a Gorilla to cock it....
Bob
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and we shall name it The Ahnold Gun....
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That FWB 600 has an energy of 5.3-5.8 FPE, which is a LONG way from 12, like less than half.... Once you talk about more than one cocking stroke.... or retaining air in the valve, so that you can have several cocking strokes to fill the gun and then 1 or 2 to top it up between shots, you have a competely different situation.... Springers use adiabatic compression and the heat generated to increase energy, again a totally different concept.... My response was directed at the original concept of an SSP of 12 FPE.... I think it would take a Gorilla to cock it....
Bob
Okay man thanks. I understand how a springer works have owned and tuned many. My comments were pertaining to the force of what would be a comfortable stroke for a shooter not comparing the two vastly different power plants. I was just hoping to open an intelligent conversation about the idea. Good luck with your project. Peace
Pete
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Hello Bob, could you point me to your complete build? Or even search terms hints.....
Interested in revisiting a build.....
Walter......
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Walter, from Post #48 (above), a link to the Carbine, the predecessor to this build.... http://www.gatewaytoairguns.org/GTA/index.php?topic=37401 (http://www.gatewaytoairguns.org/GTA/index.php?topic=37401) .... the rest of the info is all in this thread....
Bob
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Tag for review later... Looking for a high-quality multi Pumper. I know there's one out there for about four hundred bucks, forget the name but it's a bit bulky
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That FWB 600 has an energy of 5.3-5.8 FPE, which is a LONG way from 12, like less than half.... Once you talk about more than one cocking stroke.... or retaining air in the valve, so that you can have several cocking strokes to fill the gun and then 1 or 2 to top it up between shots, you have a competely different situation.... Springers use adiabatic compression and the heat generated to increase energy, again a totally different concept.... My response was directed at the original concept of an SSP of 12 FPE.... I think it would take a Gorilla to cock it....
Bob
Bob i might have missed something but Numerous SSPs have been built to 12fpe with not much cocking effort.. heres Phils who is also a member here
https://www.youtube.com/watch?v=R0fJrfe-oOg (https://www.youtube.com/watch?v=R0fJrfe-oOg)
james perotti and a few others have also built 12fpe SSps. if there was a larger market im sure wed see all kinds of multistage SSPs.. but there isnt
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Yep, I'm out of date, and I apologize.... Like you say, if the market was there, both those and the Millenium Pumper and/or Carbine would be available for purchase....
Bob
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Bob i might have missed something but Numerous SSPs have been built to 12fpe with not much cocking effort.. heres Phils who is also a member here
james perotti and a few others have also built 12fpe SSps. if there was a larger market im sure wed see all kinds of multistage SSPs.. but there isnt
Are there any links to these builds? This is the first I'm seeing it, and I'm extremely interesting in building a SSP 12 fpe rifle
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Phil has a few videos on his yt page i think .. james perottis is here
https://www.tapatalk.com/groups/thegreencrosmanforum/here-is-james-perotti-s-ssp-pictures-stunning-t44499.html (https://www.tapatalk.com/groups/thegreencrosmanforum/here-is-james-perotti-s-ssp-pictures-stunning-t44499.html)
the paradigm which was never mass produced is here
https://www.youtube.com/watch?v=7VkmHk6RwUA (https://www.youtube.com/watch?v=7VkmHk6RwUA)
there were a few more produced in the mid 90s but the names are not popping into my head.
Are there any links to these builds? This is the first I'm seeing it, and I'm extremely interesting in building a SSP 12 fpe rifle
[/quote]
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the bowkett was another one
https://www.gatewaytoairguns.org/GTA/index.php?topic=118868.20 (https://www.gatewaytoairguns.org/GTA/index.php?topic=118868.20)
the parker hale dragon can also be found in that thread with a sophisticated linkage
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Theres also a guy on YouTube that achieved 16 fpe with a SSP. He dressed her up nice too, in a nice FT style wood stock. Too bad it hasn’t come to the market yet
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Theres also a guy on YouTube that achieved 16 fpe with a SSP. He dressed her up nice too, in a nice FT style wood stock. Too bad it hasn’t come to the market yet
saw that.. if he reached out to the bigger companies it kinda proves they have no interest.. for what reason idk
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saw that.. if he reached out to the bigger companies it kinda proves they have no interest.. for what reason idk
He claims that it only costs him about $250 in raw materials to build it. That’s with a walnut stocks. Now, if a big manufacturer got their hands on it they could cut that cost in half by using cnc machines. If a 16fpe SSP was brought to market at $300-400, I would rather buy it than a ATI Nova freedom. SSPs seem easier to work on than the problematic seals of the ATI pump
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With China in the mix spa or crosman could likely make on for 50 dollars each .. so there would be good margin. the catch being that theyd have to make 10s of thousands of them to get the prices low.. likewise theyd have to anticipate 10s of thousands of sales. which apprently they dont.. Walmart springers sell soo many its actually amazing how cheap the refurbs go for.. Kinda demonstrates how cheaply theyre being made to begin with.. From an amatuer machinist standpoint , when looking at a red ryder on the shelves for 24.99 its just mind bending they can make all the precision parts needed, then package it , ship it , give walmart a cut , and still make a profit.
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I don't see how using a CNC will reduce the cost of the raw materials, only bulk purchasing can do that.... The $250 for raw materials, including the walnut for the stock, I would assume would not include the time to machine the parts (ie the term "raw").... Yes, CNC machines can make parts in much less time, but they are many more times the price, so have to charge more per hour to pay for themselves....
Tooling up to mass produce such a niche gun as a custom SSP is likely just not worth the cost and risk for the limited sales potential.... The original .25 Carbine MSP that I built, however, would use mostly existing Crosman/Benjamin parts.... Even then, there was no interest, even with all the development work done, and the details spelled out in the thread, all at no charge.... Go figure !!!!
Bob
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@Rob M It is mind boggling that a Red Ryder can cost 24 bucks considering if you were to try and make one you’d be hard pressed to pay $24 for materials let alone the hours of labor. Amazing what big corporations can do with cnc machines and bulk pricing
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yes.. economies of scale is fascinating..Id love to see how fast the chinese can make a wooden stock .. I know they have 4 axis axis machines that do all the hogging work but what about sanding , staining , clearcoating , etc..Not to mention some wood stocks go on 99 dollar guns..
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@rsterne Using a cnc machine will not reduce cost of material. When I mentioned a large company making them on CNC’s I assumed that every large company buys in bulk, I didn’t see the need to bring it up.
The cost of cnc machines would be a factor for a certain amount of time depending on how much/fast they can generate profits.
After the initial cost is covered, whew! some serious profits start rolling in; it also gives them the leverage to offer their products at the lowest price possible, as seen with the $24 red ryder
Rsterne, I am a fan of your work on the pumpers especially the millennial pumper. If I remember correctly you said it could be configured to put out 12 fpe with one pump! I would gladly pay $400-$500 for such a pumper.
It’s blows my mind that no one has picked that up, being that you can make it from crosman parts! Now, I could understand if it was a complicated differential piston pumper that this Hawaiian guy made some years back, but your .25 MSP is a practical product that should be brought to market IMO.
Out of curiosity, why do you consider the MSP a niche gun?
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@Rob M I’m going to have to put that on the bucket list: Fly to China to see the production methods in their airgun factories
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@Rob M I’m going to have to put that on the bucket list: Fly to China to see the production methods in their airgun factories
its already on mine!
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...The original .25 Carbine MSP that I built, however, would use mostly existing Crosman/Benjamin parts.... Even then, there was no interest, even with all the development work done, and the details spelled out in the thread, all at no charge.... Go figure !!!!
Bob
Oh, I don't know about that Bob, I still plan on building my own- It's just that my machines still aren't up and running yet! ;D
Or did you mean "no interest" from Crosman?
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I meant that I consider the SSP to be a niche gun.... and yes, Rob, I meant no interest by Crosman....
Bob
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My mistake, I meant to write:” Why do you consider the SSP a niche gun?
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short story regarding the SSP.
in 1995 Gm rolled out the EV1 electric car.. One year later they rounded up all the cars and crushed em.. The car had nothing wrong with it , it functioned just like a telsa nowadays as far as charging and so on.. AS it turned out , the cost of educating the consumer on electric vehicles was more than the cost to actually make them.. In other words, since the public didnt understand the process of driving and living with the EV1 there was no point in making more or maintaining the existing ones for many years to come..
Most airgunners are casuals , they enjoy walmart shelf guns.. They have no conception of an SSP or its benefits.. Half this forum might not understand the mechanical aspect of an ssp or the accuracy and consistency potential ( better than a PCP fyi)
So theres no point in rolling out a 400 dollar gun that takes one stroke when the 89.99 springer next to it also takes one stroke.
There are numerous inventions out there better than what the public uses everyday , but if Joe public doesnt understand it the value is zero.
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I see where you’re coming from. But I look at rifles like the Diana 48-56 with its side lever and think this SSP is not much different than a side lever Diana in that they both have clunky cocking mechanisms. I could imagine the criticisms guys had about the side levers when they first hit the market. I just think that if a clunky Diana side lever can be accepted into the AG community there’s hope for the SSP and MSP. Perhaps, they were accepted so easily because of Diana’s rock solid reputation for producing heirloom quality pieces. Especially if what you say is true about the SSP being more accurate and consistent than pcps. A rifle like that would be a real eye opener at FT matches. Maybe if Greg Suave was to win a few FT matches with an SSP it would draw enough interest from the AG community
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yea.. the SSP design has advantages over almost all other designs..AS for the diana reference , In the springer realm , sidelevers and underlevers are held in high regard due to the fixed barrel.. not necessarily the ease of operation.. I dont think anyone would take issue with the operation of an ssp at all , but explaining to them why theyre gonna cost extra would be an issue. Lets not forget plenty of SSPs are available right now , from daisy 953s all the way up to the older anshunz rifles costing 600-1300 used.. also the FWB 601 . all are target guns though and lack the power for hunting ( aside from birds maybe
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The only thing that SSPs and Springers have in common is that they both only take one stroke.... Springers compress and heat the air on firing, SSPs compress it into a valve and then it expands and cools on firing.... Thermodynamically, and efficiency-wise, about as far apart as you can get.... SSPs are great at delivering a consistent velocity/FPE, without the recoil of Springers.... which is why they dominated 10M competition between the days of Springers and PCPs....
There are a lot of inexpensive SSPs available, to fill the low-power, no-recoil market, and being low power, they are easy to cock.... What I should have said is that higher powered SSPs are a niche market.... and I'll add that is just my opinion, nothing more....
Bob
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I was not aware of those SSPs existing. Do you guys think a high power SSP, with a lothar Walther barrel, would keep up with the rifles that are used today for FT?
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I was not aware of those SSPs existing. Do you guys think a high power SSP, with a lothar Walther barrel, would keep up with the rifles that are used today for FT?
unless the rules were 12fpe like europe.. in that case yes.. very much so
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I agree, at 12 FPE an SSP should be doable in .22 cal, not so sure about .177 cal.... I don't think you could build an SSP to deliver 20 FPE in .177 cal, however.... at least not one you would want to cock 60 times during an FT event....
The SSPs that were used in Olympic competition were 500-600 fps with maybe an 8.4 gr. pellet in .177 cal.... so 8 FPE or less.... IIRC....
Bob
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Man, I wish my shooting skills were up to par like some of you guys. I would buy that high power SSP from the YouTube guy and shoot it at the FT competitions myself. Sometimes people just need a demonstration of what a product can do before they open up their wallets
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Rsterne, have you built any SSPs?
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Man, I wish my shooting skills were up to par like some of you guys. I would buy that high power SSP from the YouTube guy and shoot it at the FT competitions myself. Sometimes people just need a demonstration of what a product can do before they open up their wallets
i actually dont believe the youtube guys numbers unless he has some top secret contraption inside the gun that engineers never thought of... I do believe Phil Riggs 13.5 fpe build.
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i actually dont believe the youtube guys numbers unless he has some top secret contraption inside the gun that engineers never thought of... I do believe Phil Riggs 13.5 fpe build.
If he is lying it would be the dumbest thing a person could do that’s trying to sell their idea to a manufacturer. They would quickly realize that he is a phony and show him the exit. I could understand some guys on YouTube who make a video of them shooting an egg from 381 yards offhand, but I think this guy is the real deal. I bet many people wouldn’t have thought Rsterne could reach such numbers with his pumpers
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Nope, never owned one, except a Daisy 953.... and of course a Red-Rider....
Bob
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If he is lying it would be the dumbest thing a person could do that’s trying to sell their idea to a manufacturer. They would quickly realize that he is a phony and show him the exit. I could understand some guys on YouTube who make a video of them shooting an egg from 381 yards offhand, but I think this guy is the real deal. I bet many people wouldn’t have thought Rsterne could reach such numbers with his pumpers
hes just using far less swept volume ( air ) than other designs that are making 60% less power.. My suspicion is based on plain math.. Bobs build was self explanatory and made sense before he built it
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Seems the big air rifle manufacturers rather develop their own ideas and not be handed the golden egg on a platter ::)
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Seems the big air rifle manufacturers rather develop their own ideas and not be handed the golden egg on a platter ::)
Isn't this always the case though? Look at how much stuff is talked about and developed here. That's just THIS airgun forum. The majority of what we talk about is modifying existing guns. We all add our input about various guns. Changes are made, guns are modified and tested. Yet manufacturers fail to reach out. Even when they do, they nearly always miss the mark with the product(s) they bring out. Guns that could have been made cheaper and use existing parts, guns that use wonky barrel specs... The grunt work is done for them, yet they miss the mark time and again. I just don't understand it.
But I digress... and apologize for the rant.
I do plan on making MY version of the Millennium Pumper... But mine will have certain design elements of a Crosman 1400 and some parts from a QB. I can't wait to build it!!
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hes just using far less swept volume ( air ) than other designs that are making 60% less power.. My suspicion is based on plain math.. Bobs build was self explanatory and made sense before he built it
Assuming he’s using the same SSP technology as the other designs, that 60% less sweep would in fact make him full of it
Pardon the newb question: Do SSPs pump air on the upstroke as well as the down stroke?
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hes just using far less swept volume ( air ) than other designs that are making 60% less power.. My suspicion is based on plain math.. Bobs build was self explanatory and made sense before he built it
Assuming he’s using the same SSP technology as the other designs, that 60% less sweep would in fact make him full of it
Pardon the newb question: Do SSPs pump air on the upstroke as well as the down stroke?
generally no.. but thats a good question since mutistage pumps like the FX indy do pump on both strokes.( thats the only one i can think of )
keep in mind forum members have done a lot of thinking over the last 19 years.. On the yellow we had a Nasa engineer as a member.. I still speak to him on occassion.. Weve also had hundreds of brilliant machinists who could literally make anything they dreamed of.. And yet this random guy on youtube achieved far better results with less effort than 19 yrs of think tanks.
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Yep, I'm out of date, and I apologize.... Like you say, if the market was there, both those and the Millenium Pumper and/or Carbine would be available for purchase....
Bob
Very nice work. Did you actually try and market/manufacture this one or other of your projects?
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I have no interest in going back to work at 71 yo.... I did the development, Crosman is aware of it, and decided not to use it.... Their loss, IMO....
Bob
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I have no interest in going back to work at 71 yo.... I did the development, Crosman is aware of it, and decided not to use it.... Their loss, IMO....
Bob
I am sorry to see you giving up. I am about the same age and in fact working on a new ideas just because I am retiring from "real" work...
If something is developed it does not mean that there is not room for further innovations. Every perfect design can be made better.
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I have no interest in "marketing/manufacturing" one of my project guns.... The best way to make a small fortune in airguns is to start with a large one.... ::)
I'll stick with what I do best.... developing ideas and trying to improve airgunning in general.... I will leave it to others to go broke trying to make and sell them.... I've seen it too many times for it to hold any interest for me.... ;)
Bob
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I have no interest in "marketing/manufacturing" one of my project guns.... The best way to make a small fortune in airguns is to start with a large one.... ::)
I'll stick with what I do best.... developing ideas and trying to improve airgunning in general.... I will leave it to others to go broke trying to make and sell them.... I've seen it too many times for it to hold any interest for me.... ;)
Bob
I am glad to hear that you are not giving up the developments; you have great ideas and a lot of experience. As for the business venture, I do (mostly) share your sentiments.