I finally got the time to draw up some preliminary CAD models of the Piston Seal Mold I mentioned in my last post.
They are not to the right dimensions but I just wanted you to see what I had in mind. I'll have to dig out one of the old factory Piston Seals I have in my storage room to get all the right dimensions..
I plan on first testing my 3D printed Piston Seal mold with plain silicone caulking. Then if it pans out I'll move to some Urethane caulking. The urethane caulking cures to a hardness level a bit softer than the factory piston seals so I'm thinking that if I apply some "Mold-Release" agent to the cavities of my mold and then dust the surface of the mold with some powdered graphite it will serve two purposes.
The powdered graphite should impregnate all of the contact surfaces and act as a dry lubricant while at the same time harden the outer surfaces of the molded Piston Seal just a bit more. If I remember correctly the "Duro-Meter" hardness level of the factory seals is something like 85-95. I contacted the customer service department of the manufacturer of the Urethane caulking sold at my local Home Depot store and they told me that the Duro-Meter hardness level of their cured Urethane is about 65. I'm thinking and hoping that by adding the powdered Graphite to the surface of my home made piston seals it will bring my hardness level up to the 80-85 level. I think that level of hardness should work in a pinch.
Some of you my remember some of my previous post where I tried turning my own Piston Seal replacements on my lathe with limited success. They worked but the material I made them out of was a bit to soft. That softness level cause my velocities to drop by a good 65-70 FPS. I've also mentioned at one point or another that I'd spent close to a combined hundred-buck on replacement piston seals over the years.
If I can get this to work It should save me some money. I hope. Wish me luck. (these Seals should work on all the clone Umarex Octane air rifles as well)