SpudFiles

Hey guys,

I'm looking to go pro with my cannon building. I'd love to get into machining my own pistons but I have no real idea on what plastic to use. I saw Nylon, HDPE and a few more but I don't know where to look to find the stuff.

What are some recommendations to use?

Thank you,

Mitcho.

If I had to pick one, it would be HDPE. It has excellent characteristics basically all around.

Though, if you wanted to do an ultra-high performance gun teflon would be excellent due to it's ultra low friction.

That's a great idea. I just have no idea where to get HDPE in Brisbane or how much it is. Tomorrow I may have a fiddle with car body filler. I have heaps of it here. I think it may crack and crumble though... Hmm..

Mitchza89 wrote:That's a great idea. I just have no idea where to get HDPE in Brisbane or how much it is. Tomorrow I may have a fiddle with car body filler. I have heaps of it here. I think it may crack and crumble though... Hmm..

Bondo, as the Americans would call it. If it's the same type, it's extremely strong (usually a kind of fiberglass resin)

Try a plastic supplier, or one that makes signs or similar.

Yeah the stuff we have in Aus is like a resin. It's a white paste along with a separate red past. It's got talc powder in it so it can be sanded. I wonder if this is what you guys have..

My hardtech teacher always has teflon rod laying around, up to 40mm. If I ever needed it, i'd ask him to order me some haha. Just check on Google for some websites I guess, maybe even eBay?

Just as I looked just then, I saw some plastic mobs about 20-30 min from me. I'll be sure to have a good look around. Price is just a bit of a problem for me. An epoxy piston (probably Bondo) might be the best bet for now I think.

Cheers for the tips up Crowley.

What diameter are you looking for anyway?
For diameters about 40mm and up, check out these:
http://www.spudfiles.com/forums/get-you ... 18661.html

Went to a boat-store today and they have solid plastic rods about 4-6" long, so they're not all necessarily in the hour glass shape.

To fit inside a 1'' Brass nipple. I may duck to BCF (boating-camping-fishing) tomorrow. They may have some thick HDPE or nylon cutting boards for pretty cheap. I could just use the drill press to punch out pistons close to the size I need and just turn them down on my drill press. That may be my best option.

I am in aus mitch..so ya 'we' have the same stuff

Ohhhh that really helps. Sorry ino, I had no clue . I reckon I may go ahead with the car bog idea. My only problem could be it's viscosity and cure time. It's pretty pasty so it's not going to run easily into a mold. I may have to just scrape it in and pray for the best..

"DuPont Delrin® acetal polyoxymethylene (POM) resins are highly versatile engineering polymers that bridge the gap between metals and ordinary plastics."

I make pistons using Acetal or Delrin. It has a high natural lubricity and is hard enough to be machineable .....extremely strong stuff!

Velocity brings up a good point. Delrin (commonly engineering plastic for prototyping) would make an excellent piston. I have long rods of it. It has good properties, and machines excellently.

inonickname wrote: Delrin (commonly engineering plastic for prototyping)

It's hard enough that it makes great bearings too. HDPE can't do that!

UHMW all the way. It comes oil impregnated for self lubrication and is specifically designed for impact resistance and bearing usage.