SpudFiles

My progression of skills in epoxy casting... First two from left are cheap Loctite 5min epoxy, which is great for certain applications - just not for pistons. First try yielded a piston which was permanently fused to the brass coupler, 8$ down the drain lol. I think it(the coupler) had a tiny ridge in the center which for some reason, I didn't think it would be an issue. Second version did not work from the start, too loose tolerances. I then coated it in spray laquer several times which yeilded occasional firings. I then ground a groove for an o-ring, which was too thick and had to be sanded. This yielded a few hundred shots until it began leaking into the barrel when pressurized. The final one is my pride and joy. Bit the bullet and bought the 22$ bottle of West Systems 205 hardener to go with the 105 resin I already had. Pours beautifully, cures to a jewel like clear amber. Perfect fit with no sanding at all! I actually went about making this piston in a different way which turned out well for my application. First I cast an epoxy piston, with no screws, rubber sealing surfaces or anything. This gave me an epoxy plug the full length of my brass housing. After curing I drilled a small hole in the best side of the plug, poured some 5 min epoxy in the hole, then lined up the sealing surface followed by washer and finally a small screw with epoxy already in the threads. Works great! JSR would be proud. Maybe...hehe

I was think of doing something like this on my gun as the part is quiet large and aluminium is expensive for it,
Only concern for me is does it go hard all the way through as it will need to be drilled?

It is quite hard as a surface, but drilling through it it so easy that you'd think it has no strength at all. I think using epoxy as a part would all be based on how it sees forces. I think its great for compression, but very poorly handles friction or torsion? What are you thinking of casting?

On a dsr 1 its the hand grip at the front.
was think of molding a block then drilling milling and sanding it to shape

JSR would be even more proud of you if you'd put something light in the core of the piston to safe weight, without added dead space

Other than that, absolutely great work!

It would probably work as long as it doesnt experience any clamping distortion from mounting or anything. I'm out of my league on complex designs such as yours, but you might consider using fiberglass instead. I've had decent results in kayak building, using forms made out of cardboard which was glued together, then coated in several layers of fiberglass,basically encapsulating the cardboard, pretty economical and very strong structurally.

Think I will have a play about with it seams a smart way to form parts.

Thanks Labtech! I have a ton of foamboard, but I can't really find a definitive answer on whether or not epoxy would dissolve it. I know crazy glue eats through it, and also Super 77 adhesive spray.

I'm sure epoxy doesn't dissolve foam maybe wrong, I know polyester resin melts everything lol just test a piece.

Epoxy doesn't eat styrofoam, doesn't have solvents in it

Foamboard is great to help you casting epoxy in tubes, you just plug the tube with it, and cast epoxy on top.

Labtecpower wrote:JSR would be even more proud of you if you'd put something light in the core of the piston to safe weight, without added dead space

JSR sees that his work here is done