Hello everyone!
I am new to this forum and new to creating airgun valves in general. My apologizes if this post is not in the right place.
After giving a few attempts at my own design I was hoping that someone with more experience would be able to help me out.
To give some background, I am trying to create what I believe is called a poppet valve that is used with standard 800 psi CO2 cartages. I have limited capabilities in my shop and I want the design to have some forgiveness to lose tolerances and to use as many of the shelf parts as possible. My current version of the valve (depicted below) has only lasted a few cartridges before it starts to leak. All the parts of the valve are not included, but it should get the point across. I believe that the material used for my piston seal (part 3) and/or the adhesive that I'm using to attach it to part 2 may be the problem.
I have been using 1/32" thick, shore A 60 hardness, EDPM rubber for part 3. I am adhering it to part 2 with permabond 105 which is great for "difficult" rubbers like EDPM. I originally chose EDPM because I thought was that it needed to withstand cold temps when rapid firing. But after some testing, I believe the the seal is becoming damaged after only a few uses. After some more research I have been seeing that shore A 80 polyurethane may be used here instead due to its ability to withstand many compression/decompression cycles? But this is my main question... what is typically used here? Also, is there a better design that would allow me to remove the adhesive all together? Or is using adhesive fine? I have seen designs where the piston (part 4) is made out of derlin and there is no seal or adhesive, but I am trying to use a common part there instead of something custom. It is currently is an off the shelf threaded standoff... McMaster-Carr part "91125A339".
I have used two materials for part (2). The first was steel. I later tried nylon which i found to have ample strength and better adhesion to the seal (part 3) when using the permabond 105. It is also much easier to drill.
My next material choice for part 3 would be shore A 80 polyurethane, 1/16" thick and I plan to use permabond 105 again. Any insight on these choices would be greatly appreciated. I am also open to design changes that remove the adhesive altogether, but I'd like to keep the same form factor and not make any more custom parts. Currently only parts 2 and 3 are custom and they are very easy to make.
Thanks in advance for any help!
I am new to this forum and new to creating airgun valves in general. My apologizes if this post is not in the right place.
After giving a few attempts at my own design I was hoping that someone with more experience would be able to help me out.
To give some background, I am trying to create what I believe is called a poppet valve that is used with standard 800 psi CO2 cartages. I have limited capabilities in my shop and I want the design to have some forgiveness to lose tolerances and to use as many of the shelf parts as possible. My current version of the valve (depicted below) has only lasted a few cartridges before it starts to leak. All the parts of the valve are not included, but it should get the point across. I believe that the material used for my piston seal (part 3) and/or the adhesive that I'm using to attach it to part 2 may be the problem.
I have been using 1/32" thick, shore A 60 hardness, EDPM rubber for part 3. I am adhering it to part 2 with permabond 105 which is great for "difficult" rubbers like EDPM. I originally chose EDPM because I thought was that it needed to withstand cold temps when rapid firing. But after some testing, I believe the the seal is becoming damaged after only a few uses. After some more research I have been seeing that shore A 80 polyurethane may be used here instead due to its ability to withstand many compression/decompression cycles? But this is my main question... what is typically used here? Also, is there a better design that would allow me to remove the adhesive all together? Or is using adhesive fine? I have seen designs where the piston (part 4) is made out of derlin and there is no seal or adhesive, but I am trying to use a common part there instead of something custom. It is currently is an off the shelf threaded standoff... McMaster-Carr part "91125A339".
I have used two materials for part (2). The first was steel. I later tried nylon which i found to have ample strength and better adhesion to the seal (part 3) when using the permabond 105. It is also much easier to drill.
My next material choice for part 3 would be shore A 80 polyurethane, 1/16" thick and I plan to use permabond 105 again. Any insight on these choices would be greatly appreciated. I am also open to design changes that remove the adhesive altogether, but I'd like to keep the same form factor and not make any more custom parts. Currently only parts 2 and 3 are custom and they are very easy to make.
Thanks in advance for any help!
