Does anyone know where to find a new valve for an AP 16? We recently acquired a refurb Std. from PA and it quit after 20 shots. We took it apart and found the broken valve. We can machine a new piece but what is that plastic? Acetal (Delrin)? Nylon? Thank you!...... Jim B. Beaufort Naval Armorers
Ataman AP 16 Valve Broken
- Thread starter BNA
- Start date
Acetal / Delrin is the most common material across the industry but I do not know about Ataman specifically.
If you are interested in using a better material, try PEEK. However do note that because it is less compressible, it is very unforgiving of surface finish in terms of sealing 100%. Usually best to get it as good as you can on the lathe and then spend a few minutes lapping it to the valve seat with a light abrasive.
If you are interested in using a better material, try PEEK. However do note that because it is less compressible, it is very unforgiving of surface finish in terms of sealing 100%. Usually best to get it as good as you can on the lathe and then spend a few minutes lapping it to the valve seat with a light abrasive.
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By the way, here is a recent thread that covers some questions on making a replacement valve stem (aka poppet).
https://www.airgunnation.com/topic/question-for-those-who-have-made-peek-valve-poppets
https://www.airgunnation.com/topic/question-for-those-who-have-made-peek-valve-poppets
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Thank you for the information. We have acetal on hand and just ordered PEEK. The metal rod is only 1/16" which is surprising considering these Ataman AP 16's are Russian made. We assumed 1.5 MM at a glance. The acetal has a bit better impact strength according to McMasterCarr. We'll probably try acetal first but make one out of PEEK while we're at it.
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Thanks again for your knowledgeable assistance. We're glad to report that our first prototype acetal valve (poppet?) and rod worked fine. We're going to take your advice and use our same prototype print to make a complete new valve assembly using the PEEK material you suggested....... JB
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Great, glad to hear you got it fixed. FWIW either material should last indefinitely. The two main advantages of using a harder material like PEEK are:
1. Easier to knock the valve open. Allows using less hammer spring tension and/or a lightweight hammer. This arrangement is advantageous for better efficiency, quieter report, and a generally more pleasant shot cycle.
2. Better compressive strength allows a relatively small sealing margin. That is, you can go with a smaller diameter poppet which is advantageous to flow rate, whereas a "lesser" material would extrude and fail. In the link above I stepped through an example with calculations.
1. Easier to knock the valve open. Allows using less hammer spring tension and/or a lightweight hammer. This arrangement is advantageous for better efficiency, quieter report, and a generally more pleasant shot cycle.
2. Better compressive strength allows a relatively small sealing margin. That is, you can go with a smaller diameter poppet which is advantageous to flow rate, whereas a "lesser" material would extrude and fail. In the link above I stepped through an example with calculations.
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This is awesome good information and thanks again for your help. I've always been into firearms and part of the gun culture since I was six. Now I've found out that I love the air gun science. Our wholesaler Davidsons, carries Byrna, Diana and Umarex and a few others. That's (the less lethal items) what got us started. I got the PEEK material in today and would like to make a new valve, metal rod and Peek (poppet?). For the rod, what is a good material? If I didn.t know better, I'd use drill rod or chrome molly pre hardened. What do you suggest? Thanks again!
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No problem, I’m always happy to help a fellow enthusiast and I like your roll-up-the-sleeves attitude.
I know some people have successfully used drill rod in its annealed (soft) state but I always harden it. At least for the peace of mind that the end won’t mushroom from the repeated hammer strikes, and less likely to have a mishap and bend it while pressing it into the poppet with an interference fit. Given the scant 1/16” stem in this case, I’d say it’s particularly important.
I typically use W1 steel for this purpose because it’s easy to work with. The only tools needed are a handheld propane canister torch and a bucket of water. Heat the stem to glowing red and drop it into the water. Then retrieve it and reheat it to a straw color and set it aside to let it cool slowly back down to room temperature. The result is a very hard and bend resistant stem for a couple of minutes effort.
Or like you said, go with a pre-hardened material and just cut it to length with an abrasive wheel.
I know some people have successfully used drill rod in its annealed (soft) state but I always harden it. At least for the peace of mind that the end won’t mushroom from the repeated hammer strikes, and less likely to have a mishap and bend it while pressing it into the poppet with an interference fit. Given the scant 1/16” stem in this case, I’d say it’s particularly important.
I typically use W1 steel for this purpose because it’s easy to work with. The only tools needed are a handheld propane canister torch and a bucket of water. Heat the stem to glowing red and drop it into the water. Then retrieve it and reheat it to a straw color and set it aside to let it cool slowly back down to room temperature. The result is a very hard and bend resistant stem for a couple of minutes effort.
Or like you said, go with a pre-hardened material and just cut it to length with an abrasive wheel.
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