GTA
Airguns by Make and Model => Crosman Airguns => Topic started by: Spooner on April 01, 2021, 02:44:50 PM
-
I have read in some posts where some of you pin your valves. if the front trigger frame screw goes through the 13xx pump tube and threads into the front of the valve, can the valve still move back?
-
depending on the pressure yes.. That screw could fail and make the valve a bullet.. Generally , for applications over 1000 psi , people use several pins.. Even with a regulated drop bottle conversion , if the reg fails , the system should be able to withstand the pressure for the split second it presumably takes for the burst disc to fail... 3 pins is the norm, but others have done 2-5 with varying size screws and locations.
-
depending on the pressure yes.. That screw could fail and make the valve a bullet.. Generally , for applications over 1000 psi , people use several pins.. Even with a regulated drop bottle conversion , if the reg fails , the system should be able to withstand the pressure for the split second it presumably takes for the burst disc to fail... 3 pins is the norm, but others have done 2-5 with varying size screws and locations.
Thanks Rob. im researching this. but generallly... i will never go above 10 pumps, maybe 12 on the rare occasion, but my norm is to shoot at 6 pumps. i tried 20 pumps when checking chrony readings and was not comfortable with that many pumps and honestly... its a lot more pumping than i want to do. ;)
-
The 13XX has a piece of tube bent in behind the valve to locate it.... in addition to the trigger frame screw.... I don't recall ever seeing anyone pin a 13XX valve, but of course no harm in doing so.... If you have a stock pump cup and plastic piston I don't think you could ever develop enough pressure to cause the valve to move back.... JMO....
Bob
-
Our own Mr. Gary/Wyoman does it.
I emulated his method and had mine drilled and tapped (2 tiny stainless 6-32 set screws) with the valve installed inside the tube.
Do it top and bottom so that the set screws stay hidden when the breech and trigger assembly are installed.
It is a very solid mod.
-
Pinning the valve in a 13xx medium power pumper is redundant.
The raised stake and grip frame screw are more than adequate to prevent valve movement.
The 766/2100/2200 valves are not pinned and generate much higher pressure and velocity than a 13xx.
-
I would not argue with Mr. Ron, as he is an expert when it comes to these stuff.
To clarify, I did the valve pinning method on my two 2400KT CO2 carbines.
The valve cap is very thick, so that is where my machinist friend drilled and tapped.
-
sorry , i thought this was a PCP project , if its a pumper , theres no need.
-
I have pinned a 1322 valve along the lines of what Wyoman does. I did this after reading rsterne's post of the pressure that can be obtained with an FTP. I did not perform the full PCP-like pinning. That is to say, having the machine screw head into both the tube and the valve body. Just simple drill and tap threads into the air tube and valve body. Redundant? Don't know - but as a member has said, can't have too much valve retention.
-
Been there, done that, and I guess made one of the t-shirts, lol.
Drill is 1/8", depth is 1/4", location is 180° from the grip frame screw, tap is 8-32...
(https://i.imgur.com/5JnuXBY.jpg)
(https://i.imgur.com/VP76Xcc.jpg)
(https://i.imgur.com/eDyFsKi.jpg)
(https://i.imgur.com/Tg48Zx6.jpg)
(https://i.imgur.com/rYspi15.jpg)
(https://i.imgur.com/MEEBhlh.jpg)
Results from the experiment 9 years ago:
(https://i.imgur.com/sWNxwrK.jpg)
The barrel was a stock Crosman 10.25"
Not the least bit surprising when you look at the physics... only the bottom of the valve is retained. Even at only 500 psi, there is 150 lb of force on the piston. This force will cause deflection until the reaction is in equilibrium. The deflection opens up headspace, even if it's elastic in nature.
And reports as early as 2006 showed the soft aluminum valve with stress related issues... gouging of the back of the valve (by the tube indent) and shearing of the female threads (grip frame screw).
But by all means, please do the testing and reports... hth-
Wyo
-
Instead of pinning the valve, I pressed a steel ring onto the soft aluminum valve. The steel ring now contacts the tube indent.
-
I agree, if you are using an F-T-P where you can develop a lot more pressure than with a stock piston and cup, there could be some flex and movement at the higher pressures.... Gary's data would certainly confirm that, so even if safety is not an issue, there is a bit of extra performance to be had by pinning, by the looks of it.... 8)
Bob
-
this is great information... thank you all, i greatly appreciate it and thank you Gary for chiming in with the pictures, graphs, and sizes. ;D 8)
all i have at my disposal is a cordless drill, but i do have two sets of taps and can get any size of set screw i need at work. this is a simple enough mod to do but i may ask my friend in the tooling department at work if he could do this. he has precision equipment and could do it in minutes if he is willing to do so. my whole goal here is to do this one as right as possible. these valve tops must be pretty thick, i've never had one open, but at a 1/4" drill depth they must be?
i didnt do this to my other 1322 and 1377 builds and i have questions i need to answer regarding what benefit i got from going FTP. pinning the valve on this new build will help me either answer that question, or at least check it off the list. either way, the benefit of pinning it from a safety standpoint makes sense. ;)
-
Our own Mr. Gary/Wyoman does it.
I emulated his method and had mine drilled and tapped (2 tiny stainless 6-32 set screws) with the valve installed inside the tube.
Do it top and bottom so that the set screws stay hidden when the breech and trigger assembly are installed.
It is a very solid mod.
https://www.crosman-air-pistol-owners-forum.com/board/index.php/topic,16685.15.html (https://www.crosman-air-pistol-owners-forum.com/board/index.php/topic,16685.15.html)
-
Our own Mr. Gary/Wyoman does it.
I emulated his method and had mine drilled and tapped (2 tiny stainless 6-32 set screws) with the valve installed inside the tube.
Do it top and bottom so that the set screws stay hidden when the breech and trigger assembly are installed.
It is a very solid mod.
https://www.crosman-air-pistol-owners-forum.com/board/index.php/topic,16685.15.html (https://www.crosman-air-pistol-owners-forum.com/board/index.php/topic,16685.15.html)
thanks Rick... "registration is currently disabled". ill try again later today. ;)
-
(https://i.imgur.com/atBV2VZ.jpg)
(https://i.imgur.com/OaafOrN.jpg)
(https://i.imgur.com/sZCBK5h.jpg)
The set screws are hidden by the breech and trigger assemblies, so it looks clean.
Also had the machinist make me a valve screw with a wider head.
22xx Don Cothran tubes do come with screws that are very tight, so your valve has no movement at all.
-
thanks for the pictures Rick. looks nice and clean. 8)
i have the 1377 tore down now and the location for the pin on top marked. im only going to do one on top like Gary shows in his pics. im not looking to push this thing to crazy power thresholds. its a 1377 and i have to be realistic. above 600 FPS, preferably in the 650 range, but i will take what i can get over 600 and call it a day. ;)
it will probably be a week or two yet before the FTP arrives. it gives me time to do some detail work like smoothing edges and deburring, polish the hammer, little things i didnt do before. ;)
-
Yes, a drill press would be a good investment.
I always seem to forget to buy a Harbor Freight one, but I will get one when I am in the area.
I would also like to imitate Mr. Gary's/Wyoman's 13xx barrel band reinforcement.
Crosman tubes are pretty soft for drilling, you know.
Just look for the thickest part of the 13xx valve and drill it.
If the valve cap, like the 22xx's, is thicker than the valve body, then that is where I would hit it.
The top and bottom reinforcement looks much cleaner than the Disco's L/R method.
-
Yes, a drill press would be a good investment.
I always seem to forget to buy a Harbor Freight one, but I will get one when I am in the area.
I would also like to imitate Mr. Gary's/Wyoman's 13xx barrel band reinforcement.
Crosman tubes are pretty soft for drilling, you know.
Just look for the thickest part of the 13xx valve and drill it.
If the valve cap, like the 22xx's, is thicker than the valve body, then that is where I would hit it.
The top and bottom reinforcement looks much cleaner than the Disco's L/R method.
ya know... i never even gave harbor freight a thought for a small/inexpensive drill press. i will check them out and see what i can get. I know my dad has one in his barn and that is probably where i am going when i do this. my friend at work would do it, but i hate always asking him for favors.
definitely... going to set it under the breach just like Gary shows, opposite of the front trigger frame screw. ;D
-
well, i ordered a drill press from harbor freight. nothing fancy, nothing special, really cheap. the reviews were decent and the video shows it seems to work well. it isnt a big one but i dont need anything huge or fancy for the things i will use it for. ;)
https://www.harborfreight.com/8-in-5-speed-bench-drill-press-60238.html?_br_psugg_q=drill+press (https://www.harborfreight.com/8-in-5-speed-bench-drill-press-60238.html?_br_psugg_q=drill+press)
should have it in a week. works out just about right timewise with the parts coming.
-
well, i ordered a drill press from harbor freight. nothing fancy, nothing special, really cheap. the reviews were decent and the video shows it seems to work well. it isnt a big one but i dont need anything huge or fancy for the things i will use it for. ;)
https://www.harborfreight.com/8-in-5-speed-bench-drill-press-60238.html?_br_psugg_q=drill+press (https://www.harborfreight.com/8-in-5-speed-bench-drill-press-60238.html?_br_psugg_q=drill+press)
should have it in a week. works out just about right timewise with the parts coming.
My HF has them actually.
I might swing by to get one today, but it is out of the way though.
-
well, i ordered a drill press from harbor freight. nothing fancy, nothing special, really cheap. the reviews were decent and the video shows it seems to work well. it isnt a big one but i dont need anything huge or fancy for the things i will use it for. ;)
https://www.harborfreight.com/8-in-5-speed-bench-drill-press-60238.html?_br_psugg_q=drill+press (https://www.harborfreight.com/8-in-5-speed-bench-drill-press-60238.html?_br_psugg_q=drill+press)
should have it in a week. works out just about right timewise with the parts coming.
My HF has them actually.
I might swing by to get one today, but it is out of the way though.
I picked up a vice clamp for it too. It amazes me that the shipping cost for these was only $6.99??? You know the thing has got to have some weight to it. That is some cheap shipping costs. 8)
-
That drill press was only $50 something when they went on sale a month or 2 ago (?).
-
That drill press was only $50 something when they went on sale a month or 2 ago (?).
Its been a loooong time since I visited their website, lol. ;)
-
Got mine pinned using Gary's diy. The valve gets chewed after a while even if i keep the trigger screw tight and decided to add an opposing set screw as per Wyoman. Stayed in place ever since.
-
It's a cheap drill press and not very rigid, but miles ahead of trying to use a hand drill.
Bought one years ago for drilling 35mm hinge pockets in cabinet doors I was making. Think it was about $120 back then...and came with
(http://i.imgur.com/tbDbKTvt.jpg) (https://imgur.com/tbDbKTv)
Sure wish we had Horror Freight up here.... https://www.canadiantire.ca/en/pdp/mastercraft-drill-press-with-led-0555530p.html#srp (https://www.canadiantire.ca/en/pdp/mastercraft-drill-press-with-led-0555530p.html#srp)
Al
-
Aluminum has it's place in a gun but not the best choice for a valve.
Arguably, one of the best low cost upgrades for a 13xx might be a brass valve.
They show up on eBay regularly for around $10.
Some are 70 years old and look like new after a little cleanup.
Stripped screws and migrating valves are a thing of the past.
-
A cross slide vise is the best accessory I got for my press. I wonder how I got along without it now. It has interchangeable jaws for different shapes. They are not cheap though but worth it. (http://)
-
You want to see a cheap drill press how about this. Got it at a yard sale for $10 on half price day and as you say "miles ahead of a hand drill" for some jobs. I keep it in the garage so I don't have to go to the shop every time I need to drill. It's even a variable speed model cheaply made but strong and accurate. (http://)
-
You want to see a cheap drill press how about this. Got it at a yard sale for $10 on half price day and as you say "miles ahead of a hand drill" for some jobs. I keep it in the garage so I don't have to go to the shop every time I need to drill. It's even a variable speed model cheaply made but strong and accurate. (http://)
that one is actually a little fancier than the one i ordered. yours has dial speed control 8). the one i got you have to loosen up the pully drive and physically change the belt location to a different groove set to change speed. but you know... for no more than i paid, it's a good one to start with and it will do what i need it to do. i got their $25 dollar cross side vise. figured it would be a good idea considering what i am trying to do. ;)
Aluminum has it's place in a gun but not the best choice for a valve.
Arguably, one of the best low cost upgrades for a 13xx might be a brass valve.
They show up on eBay regularly for around $10.
Some are 70 years old and look like new after a little cleanup.
Stripped screws and migrating valves are a thing of the past.
doesnt make sense to use aluminum there to me either. even the Mellon Valves are aluminum. it was Charles Mellon that recommended me doing this and why i started this thread looking for information. what Charles (psipumper) did with his adding a steel ring on the end for reinforcement... i thought that was a really good idea. 8)
Got mine pinned using Gary's diy. The valve gets chewed after a while even if i keep the trigger screw tight and decided to add an opposing set screw as per Wyoman. Stayed in place ever since.
if i manage to do this without messing something up on this new one... i will do it to the other two. ;)
-
got a new 1/8" drill bit, 8-32 tap, and a few 8-32 x 1/4" long set screws. we didnt have the set screws in stainless so had to settle for black oxide. those will have to do the job. ;)
-
Robert, you'll probably need to finish with a bottom tap or grind a bit off the (1/4" long) screw, or both. Otherwise the screw may not go deep enough to sit flush with the tube.
You can make a bottom tap by grinding the tip and chamfer off a regular tap.
Keep in mind that you're using a small tap, in a blind hole, with 100% thread, in metal... use caution - reverse the tap often to break the chips, use some light oil for cutting fluid and have your compressed air ready to blow out the chips... hth-
Wyo
-
Robert, you'll probably need to finish with a bottom tap or grind a bit off the (1/4" long) screw, or both. Otherwise the screw may not go deep enough to sit flush with the tube.
You can make a bottom tap by grinding the tip and chamfer off a regular tap.
Keep in mind that you're using a small tap, in a blind hole, with 100% thread, in metal... use caution - reverse the tap often to break the chips, use some light oil for cutting fluid and have your compressed air ready to blow out the chips... hth-
Wyo
Thanks Gary,
I got two taps just in case. i will take one to work and take off the taper chamfer. i wondered how the screw would sit flat being the same length as the hole? thanks for answering that ;D. i have a bottle of cutting/tapping fluid so i am good there. i wont try this on the actual tube/valve until i have practiced it on something else and am confident i can do it without damaging the gun. never done this before, so i'm a little nervous.
-
Robert, you'll probably need to finish with a bottom tap or grind a bit off the (1/4" long) screw, or both. Otherwise the screw may not go deep enough to sit flush with the tube.
You can make a bottom tap by grinding the tip and chamfer off a regular tap.
Keep in mind that you're using a small tap, in a blind hole, with 100% thread, in metal... use caution - reverse the tap often to break the chips, use some light oil for cutting fluid and have your compressed air ready to blow out the chips... hth-
Wyo
Thanks Gary,
I got two taps just in case. i will take one to work and take off the taper chamfer. i wondered how the screw would sit flat being the same length as the hole? thanks for answering that ;D. i have a bottle of cutting/tapping fluid so i am good there. i wont try this on the actual tube/valve until i have practiced it on something else and am confident i can do it without damaging the gun. never done this before, so i'm a little nervous.
Wear your NIKE garb for inspiration ;D
-
Robert, you'll probably need to finish with a bottom tap or grind a bit off the (1/4" long) screw, or both. Otherwise the screw may not go deep enough to sit flush with the tube.
You can make a bottom tap by grinding the tip and chamfer off a regular tap.
Keep in mind that you're using a small tap, in a blind hole, with 100% thread, in metal... use caution - reverse the tap often to break the chips, use some light oil for cutting fluid and have your compressed air ready to blow out the chips... hth-
Wyo
Thanks Gary,
I got two taps just in case. i will take one to work and take off the taper chamfer. i wondered how the screw would sit flat being the same length as the hole? thanks for answering that ;D. i have a bottle of cutting/tapping fluid so i am good there. i wont try this on the actual tube/valve until i have practiced it on something else and am confident i can do it without damaging the gun. never done this before, so i'm a little nervous.
Wear your NIKE garb for inspiration ;D
yup, hahahaha! ;D
Hey Gary... can you post a pic of how much of this tap i need to grind back to make it a bottom tap? i dont want to grind it back so far as to cause it to chew up the threads as it makes them. thanks! ;D
-
You need to start the threads with a "plug" tap (a "tapered" tap has too much taper for such a shallow hole).... and then finish them with a "bottoming" tap.... You can grind almost all of the taper off to make a pseudo bottoming tap.... Look at some pics of them online to get the idea....
(https://static.grainger.com/rp/s/is/image/Grainger/41EP38_AS01?$zmmain$)
They are often sold in sets of three, one of each type.... Do not try and start the threads with a bottoming tap, you will almost certainly get them started crooked, or just strip the hole....
Bob
-
You need to start the threads with a "plug" tap (a "tapered" tap has too much taper for such a shallow hole).... and then finish them with a "bottoming" tap.... You can grind almost all of the taper off to make a pseudo bottoming tap.... Look at some pics of them online to get the idea....
(https://static.grainger.com/rp/s/is/image/Grainger/41EP38_AS01?$zmmain$)
They are often sold in sets of three, one of each type.... Do not try and start the threads with a bottoming tap, you will almost certainly get them started crooked, or just strip the hole....
Bob
Yes, makes perfect sense, Mr. Bob.
I am doing mine, too, but with two 6-32 screws ;D
-
You need to start the threads with a "plug" tap (a "tapered" tap has too much taper for such a shallow hole).... and then finish them with a "bottoming" tap.... You can grind almost all of the taper off to make a pseudo bottoming tap.... Look at some pics of them online to get the idea....
(https://static.grainger.com/rp/s/is/image/Grainger/41EP38_AS01?$zmmain$)
They are often sold in sets of three, one of each type.... Do not try and start the threads with a bottoming tap, you will almost certainly get them started crooked, or just strip the hole....
Bob
Thank you kindly Bob... I now have one of each. 8)
-
My drill press came today... "some assembly required". I had some trouble getting the chuck on the spindle. The instructions were a bit vague as to how far to press it on, and I'm still not sure even after calling harbor freight for help. I press it until I heard it it make a pop... I guess that's it? For the money... it is a decent tool. 8)
My FTP shipped, so that is on its way. Just waiting for the drill press vice, about a week yet for that, and I will be ready to do this. ;)
-
my FTP came from Mellon yesterday 8). this one has a white derlin piston. i like it! makes it easier to see the o-ring ;). just a couple more things and i will be ready to do the valve pinning and re-assemble the gun. ;D
-
my FTP came from Mellon yesterday 8). this one has a white derlin piston. i like it! makes it easier to see the o-ring ;). just a couple more things and i will be ready to do the valve pinning and re-assemble the gun. ;D
Would you like to do mine too?
;D
-
my FTP came from Mellon yesterday 8). this one has a white derlin piston. i like it! makes it easier to see the o-ring ;). just a couple more things and i will be ready to do the valve pinning and re-assemble the gun. ;D
Would you like to do mine too?
;D
Lol Rick ;D. No, I think I'm nervous enough about this, besides... your builds are just awesome! ;D
-
You'll do fine, Robert. Just don't get in a hurry, and if you get frustrated, put it away for a bit.
Looking back on my notes, which were not very good back then, I believe the pivot was reinforced at the same time the valve was pinned.
I was not very good at doing just one mod at a time...
Pivot Reinforcing:
(https://i.imgur.com/ZkGhrTT.jpg)
Barrel band is in the operating location
(https://i.imgur.com/WZGG6vh.jpg)
Drilled thru the tube into the barrel band insert with 1/8" drill
(https://i.imgur.com/50wHp10.jpg)
Tapped 8-32
(https://i.imgur.com/In5gE3N.jpg)
One side secured, repeat for the other side.... hth
Wyo
-
You'll do fine, Robert. Just don't get in a hurry, and if you get frustrated, put it away for a bit.
Looking back on my notes, which were not very good back then, I believe the pivot was reinforced at the same time the valve was pinned.
I was not very good at doing just one mod at a time...
Wyo
thanks Gary... I wont try this until my drill press vice comes in, then i will practice on something else a time or two. the independant youtube reviewer for the drill press said the side scale adjustment was very accurate, i will make sure it does no more than 1/4", otherwise mark the drill like you did ;).
my barrel band is the OEM plastic one, but that is a good idea as well. 8)
yeah, same here... one mod never seems to be enough, lol. ;D
-
Sadly, I have to delay my build a little bit. I installed the FTP into the pump tube and set the trigger screw to hold it in place for pinning. the hole for the transfer port sits offset causing the TP itself not to sit flat :(. I emailed Mr. Mellon with a picture and requested a replacement. all I can do is wait for his response and wait for the replacement. :(
I was able to take an allen wrench that fit inside the TP port of the Valve and shift it a little to center it. can i do this without fear of the seal leaking?
-
If the alignment is just slightly off then it's normal, just back it off a little.
Should be fine unless you plan on really pushing it past 2K psi.
You can use a 90 duro seal between the valve halves and or Teflon tape the threads.
Pro tip: Scribe a line on the valve after the valve halves are aligned to the tube.
-
If the alignment is just slightly off then it's normal, just back it off a little.
Should be fine unless you plan on really pushing it past 2K psi.
You can use a 90 duro seal between the valve halves and or Teflon tape the threads.
Pro tip: Scribe a line on the valve when the valve halves are aligned.
it was probably about a 1/16th, of an inch, maybe a little more...
(https://i.imgur.com/4Ad0XQ2.jpg)
... i should be ok with this.
good tip, thank you... just scribed it. 8)
-
While you're at it consider replacing the stock grip frame screws with hex head screws.
The stock front screw only engages about 3 1/2 threads and strips out too easy.
A 1/2" long screw will grab 6 1/2 threads.
Another option is to use a long set screw and acorn or locknut.
This gun is drilled and tapped for a 10-32 screw.
-
While you're at it consider replacing the stock grip frame screws with hex head screws.
The stock front screw only engages about 3 1/2 threads and strips out too easy.
A 1/2" long screw will grab 6 1/2 threads.
Another option is to use a long set screw and acorn or locknut.
This gun is drilled and tapped for a 10-32 screw.
Thanks Ron... screws will be hex head. I got some 8-32 button head screws from work that are 1/2" ;). i never liked those square bit screws. Allens are so much easier to work with on the trigger frame and they look cleaner too. 8)
-
had to cancel the drill press vice part of my harbor freight order. they had no idea when it would be back in stock? ordered an x-y drill press vice from eBay. it cost a little more, but i will have it by Wednesday and finally be able to at least get this valve pinning over with and the bottom half assembled while waiting for the Max Flow TP from Alliance.
those of you replacing your OEM 1377 hammer springs for a stronger one, can you tell me which spring you are using for this?
i appreciate all the help everyone. i am learning more and using so many of the ideas shared here in this build. i am also realizing the mistakes i made on my previous 1377/1322 builds. ;)
-
had to cancel the drill press vice part of my harbor freight order. they had no idea when it would be back in stock? ordered an x-y drill press vice from eBay. it cost a little more, but i will have it by Wednesday and finally be able to at least get this valve pinning over with and the bottom half assembled while waiting for the Max Flow TP from Alliance.
those of you replacing your OEM 1377 hammer springs for a stronger one, can you tell me which spring you are using for this?
i appreciate all the help everyone. i am learning more and using so many of the ideas shared here in this build. i am also realizing the mistakes i made on my previous 1377/1322 builds. ;)
I use Magnum Air Power springs.
He has 3 tensions, but I always favor the .038" one even on my PCP builds.
-
I use Magnum Air Power springs.
He has 3 tensions, but I always favor the .038" one even on my PCP builds.
Thanks Rick... I will check them out. I have a Mellon hammer spring adjuster for this one. Can I use these with that, or are they just for the stock tube cap?
Disregard... found them... Looks like the .038 is the one to use with the adjuster. 8)
-
my mini x-y drill press vise came yesterday. while this is a really nice vise... too big for my drill press, lol. guess it wasnt "mini" enough :o. oh well... ordered a plain jane single direction mini vise. that one detailed measurements and i know it will fit.
i also whimped out on the piston / pump arm linkage shims. burned and scuffed fingers from sandpaper, some ducking here and there from trying to hold them on a belt and still no where close enough to fit one on each side... anyway... ordered shims from Mcmaster-Carr. ;)
-
ok, so today was the day to pin the valve. i have never been so nervous about anything in my entire life! the drill press works ok but the table flexes a little and it made drilling a bit hard with me holding the table and doing touch and go with the drill. that first layer (the barrel)... i though i would never get through it with the bits i got from work. i used plenty of cutting fluid but it still heated it to smoke a few times and i had to quickly back off and let it cool before trying further.
i followed all the directions given to the letter. i used the right drill, used the correct taps, took my time, checked and rechecked everything as i went.
i had my drill bit marked for 1/4" but i had to go at it a couple more times (after tapping sadly) to get it a little deeper. i finally gave up doing that out of fear that i might go too far, or damaged the tapped threads and just faced off the end of the set screw by the end nub and a couple end threads before it sit level and just below the surface of the barrel. it is in though, how well... i have no idea, but it is pinned.
i have some concerns and need advice...
i really need to remove the valve and check the o-ring. i also need to make sure i didnt go too far into the valve. can i do this without damaging it, or is this a done deal now?
im a nervous wreck, lol. im not sure i want to do this on the other two? if i do... i am going to drill a pilot hole in the barrel with the valve removed, then put the valve in and finish. i just need to calm down a little, lol. :o
-
I got it figured out and got the valve out. good thing too because there were tiny metal flakes in the TP area of the valve and it needed deburred. took the valve apart, cleaned it, replaced the outer o-ring, and thoroughly cleaned the pump tube.
(https://i.imgur.com/8zJovWR.jpg)
(https://i.imgur.com/jRxr5Nq.jpg)
i touched up the pump tube where i filed the burr from drilling and have the lower half assembled now. it definitely has good compression. been waiting for a month for Alliance to send me my max flow TP. as soon as i get it i can wrap this up and do some chrony tests. ;)
i did some shim work to where the pump arm attaches to the piston. it ended up being .025" on each side. had to do the washers at work. laid them on a belt sander belt to keep the from moving, then used a stone to thin them down. used the spacer from the Mellon air pivot pin on the end. there is no slop in the pump arm at all now. 8)
-
Well done, Robert... It looks great!
Next mod a larger TP?...
If/when you install the larger diameter transfer port, you’ll need to enlarge the barrel port as well or it may not be very helpful. If you’ve already got this covered then disregard…
The stock valve port is .156” (5/32”) and is a pretty good starting point for a modified 1322. The stock transfer port and barrel port are both .140” (9/64”) and can strangle the air flow in a 1322 (shooting faster than 450 fps). So both would need enlarged, and again.. .156” is a good place to start…
Drilling the barrel port:
Get a .25” wooden dowel and profile the end so it matches the barrel leade-in taper. It should extend past the barrel port and have a really tight fit to the barrel i.d….
(https://i.imgur.com/CMp2lZS.jpg)
This will ease the break-thru of the drill and lessen the tear-out. You’ll probably still have a burr but it’s easy enough to fix… roll up some 600 grit really tight that is just over the barrel i.d. Rotate it into the bore in the direction it was rolled. It should be hard to get in. Rotate and work in and out. When you feel that it stops cutting, reverse direction and repeat…
(https://i.imgur.com/zED53dV.jpg)
This will remove the burr and polish the leade. Flush with WD-40 (or similar), blow-out with air, and pull a couple of patches and it’s good to go… just one way to do it, hth-
Wyo
-
Well done, Robert... It looks great!
Next mod a larger TP?...
If/when you install the larger diameter transfer port, you’ll need to enlarge the barrel port as well or it may not be very helpful. If you’ve already got this covered then disregard…
The stock valve port is .156” (5/32”) and is a pretty good starting point for a modified 1322. The stock transfer port and barrel port are both .140” (9/64”) and can strangle the air flow in a 1322 (shooting faster than 450 fps). So both would need enlarged, and again.. .156” is a good place to start…
Drilling the barrel port:
Get a .25” wooden dowel and profile the end so it matches the barrel leade-in taper. It should extend past the barrel port and have a really tight fit to the barrel i.d….
(https://i.imgur.com/CMp2lZS.jpg)
This will ease the break-thru of the drill and lessen the tear-out. You’ll probably still have a burr but it’s easy enough to fix… roll up some 600 grit really tight that is just over the barrel i.d. Rotate it into the bore in the direction it was rolled. It should be hard to get in. Rotate and work in and out. When you feel that it stops cutting, reverse direction and repeat…
(https://i.imgur.com/zED53dV.jpg)
This will remove the burr and polish the leade. Flush with WD-40 (or similar), blow-out with air, and pull a couple of patches and it’s good to go… just one way to do it, hth-
Wyo
i am actually using Alliance hobby max flow TP's in both my previous builds and have one coming for this new 1377. it never occurred to me that changing the TP to a larger ID without changing the barrel port ID to match would make a difference, but you are right... it makes perfect sense. i have a couple stock Crosman 10" barrels i will never use and can take one and try this before attempting it on my LW barrel. im not sure this drill press can handle the barrel? it was stopping as it cut into the aluminum valve and i had to do tiny increments. with it already opened to .140... it might do this? so, a 5/32" drill bit is what you are saying to use for the barrel port, correct?
the truth is that im not entirely sold on the larger ID TP. i see you guys getting these awesome FPS in guns with little to no mods and i have these mods and struggling to reach stock OEM ratings. im tempted to put in the stock TP and run a few chrony tests before i decide. i will give it some thought for a day or two... i need to step away and take a break. ;)
thank you Wyo... all the tips and information are greatly appreciate. ;D
-
i gave opening up the barrel port in my 10" 1377 barrel this morning using a 5/32" drill. my drill press handled it just fine. i didnt have any kind of wooden dowels or anything that would fit so just had to do it as slowly/gently as possible. most of the burr flaked off then i finished with 400 grit followed by 800 grit. i pushed in a pellet then pushed it back out and inspected it. seems to go in smooth and removing it doesnt show any scratches or nicks from any burr. looks like i will be able to do this but i am going to have to research and invest in much better drill bits before i try this on my LW barrel. ;) 8)
-
Great reading and great advice. I will follow this thread since I may find some free time at some point. For now, I'm too new to even understand one tenth of the things you folks are talking about but I'm willing to learn. Keep 'em coming and @Spooner, great job and good luck with the rest.
-
Great reading and great advice. I will follow this thread since I may find some free time at some point. For now, I'm too new to even understand one tenth of the things you folks are talking about but I'm willing to learn. Keep 'em coming and @Spooner, great job and good luck with the rest.
Thanks Ted... im still learning too. ;)
-
i gave opening up the barrel port in my 10" 1377 barrel this morning using a 5/32" drill. my drill press handled it just fine. i didnt have any kind of wooden dowels or anything that would fit so just had to do it as slowly/gently as possible. most of the burr flaked off then i finished with 400 grit followed by 800 grit. i pushed in a pellet then pushed it back out and inspected it. seems to go in smooth and removing it doesnt show any scratches or nicks from any burr. looks like i will be able to do this but i am going to have to research and invest in much better drill bits before i try this on my LW barrel. ;) 8)
Another question with this barrel porting... do I need to do anything with the counterbore where the TP seals against it? It is reduced once the barrel is ported. I honestly can't see that small to tell if it needs cleaned up for burr, but I gently went around it with a small flat end diamond file. Can I add an o-ring or a TP seal here, or will it seal fine as it is? Thanks ;D
-
the bottom half of the new 1377 build is completed! ;D
i deburred every slot and hole surface i could reach, put flats on the side of the hammer and dry lubed, valve is pinned, shimmed the linkage between the pump arm linkage and the notch in the piston, shimmed the gap at the end of the pump arm, adjusted the piston so that the arm was 1/2" from closure and have excellent cam over, reinstalled the PA with a stronger hammer spring from AA.
i put 20 pumps into the gun and pulled the trigger. no retained air, and that was with the PA adjusted in just until i felt tension on it. i had a napkin folded twice over against the port where the TP goes and it blowed a hole all the way through it, lol. pieces went flying everywhere, hahaha ;D. truth is... doesnt look like i need the PA but will leave it on for now.
so far it looks very promising. hopefully, i can get the breech and barrel on this afternoon and get a few chrony readings in. ;D
@Wyoman... Thank you Gary for the links and porting chart and thank you for your kind guidance in PM. i used many of the ideas you suggested and they have made a huge difference to this point. i didnt do the MROD and lighter valve spring in this gun, it doesnt seem to need it. once i get a feel from the chrony readings with the stock TP and know where i stand FPS wise, i will apply these things to the 1322 and am going to do the MROD/Spring to it. the Crosman 14.6" crosman barrel i have will be ported as best i can. i will test the 1322 with it and the max flow TP, then test it with the LW barrel unported with the stock TP. if simply pinning the valve and cleaning up things will get it over 500 FPS with the LW barrel and stock TP... i'm good with that, and i am not far from it as it is :).
@Tachdriver10... you are right about the spring out, and my first build has way too much. after seeing this new one adjusted properly, its spring out is exactly where you said it would... about 30 degrees or a little less. Thank you very much for your help as well. ;D
-
Put a thin O-ring on top of your TP.
Also around behind the probe O-ring, as it will lock your cocking handle so much better and give you an improved seal.
-
Put a thin O-ring on top of your TP.
Also around behind the probe O-ring, as it will lock your cocking handle so much better and give you an improved seal.
Thanks Rick... i got boxes full of assorted o-rings. im sure i have a size that will fit both. ;D
-
Very simple mods, but it works ;D
I used to collect disposable lighters just to salvage their O-rings.
Do be careful when hammering them, as they will explode.
I cover them with a thick towel when I gave them the crushing blow ;D
-
The O-rings for these aforesaid reinforcements are very thin (thread-like) and small.
-
Sounds like you have the situation well in hand.
Shouldn't be a problem to get a good amount over 500 FPS.
Keep in mind that without the barrel there is no resistance so you may need the power adjuster when the gun is complete.
-
The O-rings for these aforesaid reinforcements are very thin (thread-like) and small.
we have them at work. the ones i have have too thick of wall thickness. i wont add the scope until i am sure i have everything covered, so not a big deal to remove the breech and barrel again.
Sounds like you have the situation well in hand.
Shouldn't be a problem to get a good amount over 500 FPS.
Keep in mind that without the barrel there is no resistance so you may need the power adjuster when the gun is complete.
i hope so Ron... been working on this thing for what seems like forever. understood Sir ;D. even if it is the same or marginally better then the previous build... the previous one got 612 at 10 pumps and its a mess, lol. this new one... i know i did all i could to do it right. 8)
-
And the results are in...
... at 10 pumps using 7.4gr Crosman Super Points
1. 639 / 6.7
2. 637 / 6.7
3. 636 / 6.6
4. 629 / 6.5
5. 636 / 6.6
With the choked LW 14.5" barrel... I couldnt be happier with this! I have no doubt that it will hit 650 FPS or better at higher pumps. I tested the PA where it is with the breech and barrel (no pellet though) at 20 pumps... no air retention. I put a 6.5" LDC from TKO on this one. WOW is this thing quiet!!!
I am a very happy fella! ;D
-
Nice job, Robert. Those are excellent numbers. Sorry I didn't get back with you sooner on the spring question, but it looks like you have it sorted out!
Wyo
-
Nice job, Robert. Those are excellent numbers. Sorry I didn't get back with you sooner on the spring question, but it looks like you have it sorted out!
Wyo
Thanks Gary ;D. i will get the gun sighted in tomorrow then take a much needed break before i tear in to the 1322, lol. the MROD valve stems came in today and i already have the springs from McMaster carr. i have everything else and know now what i need to do to both the 1322 and my first 1377. this new build has been stressful, but a very positive build.
this new 1377 with those numbers factoring in about a 20 FPS loss for the choked barrel... i achieved the goal i was hoping for. 8)
-
I was able to get the new 1377 sighted in. it isnt as accurate as my first build, but not too bad. got decent groups around the target center of 3/4" to 1" with no off the wall strays at 30 yards where my first build gets 1/4" to 1/2" using the same 7.4gr super points. i may work a little more on its sighting, but honestly... im ok with it. 8)
-
im getting a little better at this valve pinning. 8)
got the valve pinned in my 1322 yesterday. i gotta find some better bits. these bits we have at work take sooooo long to get through the steel tube and i burn one up every time even with the cutting fluid. i do touch and go cleaning away chips as i go but either this is really hard steel, or the bits are just cheap?
anyway... 1322 is done and it looks good! ;D
(https://i.imgur.com/Q1lzISr.jpg?1)
-
I am wondering how far forward of the TP hole should the pinning hole be drilled? Center to center of course.
-
I am wondering how far forward of the TP hole should the pinning hole be drilled? Center to center of course.
if you do the front pinning, do it directly opposite of the front trigger frame screw. I learned this the hard way... if you go back further from that location, you risk punching through into the valve area. Some have said they set one in the rear area of the valve but I have never set one there, so not sure where in the rear it would go?
-
I use the bottom screw hole as a guide to drill the top hole in the tube then drill into valve from top and tap.
This also works on the new C362 to pin valve.
-
on crosmans , i drill the sides right alongside the tp.. yes they puncture into the throat area, but the screws take up that new space.. and since the poppet is forward of the drill location , i dont need to worry about breaking the seal but puncturing a sealed area. Many ways to skin a cat.
-
Awesome, just wanted to be positive before I make an attempt. Thanks for the replies folks!