GTA
All Springer/NP/PCP Air Gun Discussion General => Air Gun Gate => Topic started by: Methuselah on January 13, 2016, 12:40:56 AM
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I'll post a pic or two when I finish building it, but was wanting to know if 2" of travel in releasing spring (or ram) travel will be enough, and if not, will it be enough to handle the rest of the travel by hand? If it matters the three are Hatsan 125, Remington Express, and D34. All three need work...
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Two inches of travel should be adequate for most guns. If you install a new spring which hasn't been set you will probably be looking at four inches of travel. The cure for that - set the spring before attempting to install it. This is only a problem with new springs.
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"set the spring"
What does that mean?
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Setting the spring (also known as scragging) has to do with changing the spring length, which would happen over time in the airgun. A brand new spring may be difficult to install as it will be too long. If you compress the spring to the point of being coil bound and leave it for about four hours before removing the pressure it will assume its working length.
Read the article for more information:
https://www.pyramydair.com/blog/2012/03/resizing-a-mainspring/ (https://www.pyramydair.com/blog/2012/03/resizing-a-mainspring/)
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Thank you.
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Two inches is not nearly enough!!! Consider that the end block is set in a couple of inches, and I've worked on guns with about 3-4 inches of spring pre-load. Trying to "handle the rest of the travel by hand" would be a real pain, and potentially dangerous (slip with a heavily loaded spring!). I would go with at least six inches of travel (I have about 7" on mine).
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I truly believe you need more travel to work safely, especially on the 125. I would change the design so the pressing feature is adjustable and has a longer throw.
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Two inches is not nearly enough!!! Consider that the end block is set in a couple of inches, and I've worked on guns with about 3-4 inches of spring pre-load. Trying to "handle the rest of the travel by hand" would be a real pain, and potentially dangerous (slip with a heavily loaded spring!). I would go with at least six inches of travel (I have about 7" on mine).
Well, I don't have to use it for the ones that need more than I will have, but a picture is worth a thousand words, so after the controlled release of 2" I'll be able to "slip" the yoke holding the breach end another inch or two and after that if it isn't possible to handle the load by hand with brute force then I'll know the contraption I've built can't handle the reassembly --- in that case I'd have to call it a design failure or if the ending pressure is not too bad, fix it to slip more. Got most of it built, some supplies still missing but available locally, so will post the pic when it's finished.
Thanks all for the input!
BTW, 4" preload, does that apply to the three airguns I listed? Hatsan 125, Remington Express, Diana (RWS) 34? I know I've seen comments the D34 can be done without a compressor, but the Hatsan gets done first, before the warranty runs out I need to find out why FPE went from 28 to 24'#. Great comments on setting the spring first too ;D Didn't think about that one! Surely the two with springs aren't going to hold up forever...
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Definitely the Hatsan 125 will need the 4" its a monster of a spring . gas springs when blown have no or little resistance but the new ones do put up a fight too. so yes re-design your project. I used a cheap 8" C clamp to build a quickie version to replace gas ram in a Crosman MTR this spring. <~ pun not intended
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I know I've seen comments the D34 can be done without a compressor.
SAFETY FIRST. The D34 does need a spring compressor. Yes I have seen it done without a compressor, but safety first. I even had a friend who would use a spring compressor on a TX200 because it makes things easier and less chance to scratch a customer's rifle.
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Two inches of travel is suitable for a gas strut powered gun but that's about it. They typically have less than a half inch of preload.
Two inches is MARGINAL for a Diana 34. It can be made to work but you have to work at it. There are two pins holding it together. I can tighten the clamp and remove both pins then start backing off the pressure. When it is far enough back to put pin number two into hole number one I secure the action and readjust my stops. Then I can resume pressure, remove the pin and back it off. Reassembly is the reverse - a two step process. I really need to rebuild my compressor.
I have no idea how much spring is in a Hatsan 125. Due to the power the gun produces I suspect it's a very strong spring. The Diana 34 or a TX 200 CAN be done without a spring compressor, though reassembly can be a real problem - compressing the spring and attempting to align everything at the same time.
The simple cure would be to use a properly designed spring compressor with threads adequate to go at least four inches and six inches would probably be better.
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125 Spring is a beast. My compressor has lots of travel and that spring still puckers certain parts of my anatomy!
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This was fairly easy and cheap. There will be many many designs on GTA that work well and won't break the bank.
http://www.gatewaytoairguns.org/GTA/index.php?action=dlattach;topic=89592.0;attach=116182;image (http://www.gatewaytoairguns.org/GTA/index.php?action=dlattach;topic=89592.0;attach=116182;image)
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I use an old scissor jack from a small car.
Gives me more then enuff travel for any springer!
Plus you can find them all over the place!
I've got 5 or 6 of them I've found.
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This was fairly easy and cheap. There will be many many designs on GTA that work well and won't break the bank.
http://www.gatewaytoairguns.org/GTA/index.php?action=dlattach;topic=89592.0;attach=116182;image (http://www.gatewaytoairguns.org/GTA/index.php?action=dlattach;topic=89592.0;attach=116182;image)
The Hatan's a gas ram. I did have a c-clamp I could have cut up but didn't want to have to hack-saw it and then drill mounting holes, so instead I bought this push-pull clamp:
http://www.gatewaytoairguns.org/GTA/index.php?topic=101808.msg961208#msg961208 (http://www.gatewaytoairguns.org/GTA/index.php?topic=101808.msg961208#msg961208)
The clamp is rated 500#, hope that's enough. I think fill pressure on the Hatsan ram is 1900 psi. The end bracket is 1/8" thick steel. Anyway, almost finished then will post some pictures (before I try to use it!)
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Sorry --- down and dirty after losing 30 minues to error ...
gun disassembled bad seal blahblahblah
6 pics ... now 1. Back needs to be changed to "loose your post"... sigh
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error: empty body...
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not empty
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Hatsan 125 had about 1/2" to 1" of preload on the ram.
More later, getting stink-eye from daughter to get off puter...
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I would build it for more than 2". It's better to have more than you need than not enough and have to build it again. You never know what guns you may want to use it on in the future.
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I would build it for more than 2". It's better to have more than you need than not enough and have to build it again. You never know what guns you may want to use it on in the future.
Yup. Agreed Bill. It was designed around that push-pull thing. 2" ram travel + 1/2" more if I turn the screw. But the fixture end can be slipped - perhaps I'll change the bottom bracket to one tall end and use something like an anchor bolt to add more travel?
Pic below, L goes in hole, threaded end through bottom bracket. So far only other guns are the two listed --- maybe 2 1/2" will at least handle those if I don't have to set a new spring?
The Hatsan 125 I took down with it has a less than perfectly tight barrel lock pin fit. Other than that nothing I saw worried me that I can't get her shooting accurately (yet)... . More on that, but probably in the Turkish gate ;D
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For a heavier spring I would add another block to fit the receiver.
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I took ideas from several other creations in an earlier thread:
(http://i912.photobucket.com/albums/ac325/Oldgringo/DSCN0449.jpg) (http://s912.photobucket.com/user/Oldgringo/media/DSCN0449.jpg.html)
Except for the $3 worth on bolts, nuts and washers, this was made from scraps laying around my shop. There is a 4" C-clamp and plenty of length adjustment, bungees for hold down and wood shims for final centering adjustments. Hope this helps?
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I took ideas from several other creations in an earlier thread:
(http://i912.photobucket.com/albums/ac325/Oldgringo/DSCN0449.jpg) (http://s912.photobucket.com/user/Oldgringo/media/DSCN0449.jpg.html)
Except for the $3 worth on bolts, nuts and washers, this was made from scraps laying around my shop. There is a 4" C-clamp and plenty of length adjustment, bungees for hold down and wood shims for final centering adjustments. Hope this helps?
Bungees are a good idea, thanks ;D
I ended up spending $10 on the push-pull clamp, rest is junk lying around. I think I like your design better, but I was too lazy to cut up and drill a c-clamp. In hindsight, should have.
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Hatsan 125 had about 1/2" to 1" of preload on the ram.
More later, getting stink-eye from daughter to get off puter...
Rest:
Dimensions of the wood base. I THOUGHT it was a 2 X 8, but it measures out at 9" wide. A 2 X 10 should be 9 1/2" wide. Anyway, its left over scrap from when a contractor built our addition. So; Base: 9" wide, 2 3/4 foot long, customary 1 1/2" thick. The slot under the fixture end could have been made with a router, but it was done on a mill with several passes using an end mill.
Clamp: push-pull from Amazon.com, rated 500#. This one: Uxcell a11120200ux0396 32mm Plunger Stroke 500-Pound Push Pull Metal Toggle Clamp. Any will do, this one had a 1.25" stroke plus you can turn the screw to gain a little over 1.5" more travel. My guy here who does machine work said leave 4 or 5 threads in the clamp for 500# load.
Riser under the clamp: shaved thinner to set height to match the other bracket height (in a table saw)
Fixture to hold the breach at the forks, measured for .005" over the measurement of the breach block on the Hatsan 125 (30 FPE gun), the other two are slightly smaller but they are 14 FPE so less force to hold. Room cut out for the cocking arm underneath. It was chopped up scrap. For a 14 FPE gun probably could have been just an L bracket. So, Fixture: 1/8" steel, custom cut with band saw and finished with a file for .005" side clearance
Hardware: Feet, scrap brackets with glue on foot pads (only found 3, needed 4). Bolts: clamp, 1/4-20 with a junk plate under. Nuts are self-locking nylon inserts and there are lock washers too. Tightened several times over couple days to account for settling into the wood. Fixture, 1/2" hex bolt, nc thread, support under is > 1/8" thick steel bracket (band saw took off from larger piece). Large matching washer under head to give support from lateral loading.
Adapter block. Have a hobby mill at home (doesn't get used much) and some micro bits from Harbor Freight, slotted it some to try and match up to end of the spring block in the gun. Miserable failure but hey, it got the job done (No artistic ability).
I reckon all this was mostly self-explanatory from the pictures, but if I did anything terribly wrong this additional info may help someone point out my mistakes?
Greg: Like the idea of just the dead-end. Be it barrel end or forks you had it covered. Simple, eloquent --- oh well, I guess mine works too, until the bracket bends anyway...
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Here's one I threw together to work on an AG in a Motel.
;D
(http://i108.photobucket.com/albums/n12/privateer_2006/Air%20Rifles/100_1549.jpg)
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Here's one I threw together to work on an AG in a Motel.
;D
(http://i108.photobucket.com/albums/n12/privateer_2006/Air%20Rifles/100_1549.jpg)
Looks like a Hatsan 95? Looks safer AND better than mine.
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Yes. That's a Mod 95. I like the scissor jacks. I find the small ones all over the place!
It's rated to 1500+ pounds!
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Yes. That's a Mod 95. I like the scissor jacks. I find the small ones all over the place!
It's rated to 1500+ pounds!
Where do you just "find them"? Do you mean free or at a garage sale or something?
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Found this one here at the job site. Found 2 others near job sites usually in trash piles or near junk cars.
1st one I ever used was the jack in my Dodge Dakota. I don't use that one anymore.
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The sicissor jack thing is awesome. You could get one for a song at a salvage yard.
BUT!! Your aviatar is KILLING my ADD. Must.....try.......to.........focus.......
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The sicissor jack thing is awesome. You could get one for a song at a salvage yard.
BUT!! Your aviatar is KILLING my ADD. Must.....try.......to.........focus.......
Yeah, usually hold a hand over the ones that move - very annoying, but we still love you Jeff
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OK. I changed the thingy back to my old one.
;D
I do prefer the scissor jacks as they are able to lift a car.
I'd not trust a C-Clamp to even try doing that.
Granted an AG should never be that much pressure but they are free or easy to find/buy cheap.
And you have a lot more range with one so it's a multi purpose tool.
They make a good front rest for bench shooting also!
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Seen some good ones here. I think there is a section on them in the GTA library