Page 1 of 2

What material make a best piston?

Posted: Fri Feb 11, 2011 11:17 pm
by AnotherSnappedLine
I've read about Bondo, epoxy, and hot glue to make a piston; which is the best substance?

Posted: Fri Feb 11, 2011 11:21 pm
by chinnerz
what pressures are you planning on using it at??

Posted: Fri Feb 11, 2011 11:37 pm
by clemsonguy1125
I personally like rubber stoppers with epoxy cat around them for my small boar cannons and for large cannons steel washers with a coupler in between with a sealing gave bolted on.

Posted: Sat Feb 12, 2011 12:11 am
by jackssmirkingrevenge
Epoxy FTW!

For small projects likethis I usually cut the piston out of thick rubber sheet.
clemsonguy1125 wrote:my small boar cannons
Sorry, couldn't resist!

Posted: Sat Feb 12, 2011 12:41 am
by Gaderelguitarist
Epoxy will last the longest out of those choices.

Several people turn their pistons on lathes or drill presses from plastic stock. HDPE, UHMWPE, Polyamide, PVC, Nylon, etc etc.

I've made a wooden piston (big surprise) for a small wild boar cannon.

JSR, I don't know if I'm laughing more at the edit, or at that hunched over kid's facial expression.

Posted: Sat Feb 12, 2011 10:48 am
by Gun Freak
jackssmirkingrevenge wrote:Sorry, couldn't resist!
That just made my day lol!!! :D :lol:

@Gaderelguitarist- It's quite the jizz face huh? :lol:

Posted: Sat Feb 12, 2011 11:17 am
by clemsonguy1125
Lol. my ipod changed it.

Posted: Sat Feb 12, 2011 12:02 pm
by Gaderelguitarist
It's quite the jizz face huh?
It's as if Igor threw the main switch and doctor frankenstein lost control all over his hump.

And thats about as off topic as this should get :lol:

Posted: Sat Feb 12, 2011 12:53 pm
by jackssmirkingrevenge
What if I told you that was me 20 years ago?

lol no seriously, that was a random pic lifted from here, hope the poor child doesn't suffer the same fate as scumbag steve :D

Posted: Sat Feb 12, 2011 1:43 pm
by Labtecpower
...or the angry german kid!

[youtube][/youtube]

I'm sure most of you know him :D

I made the piston for my copper gun out of nylon, as the previous one broke down every few shots.

The cannon i'm building now uses a PVC piston.

Both are made on a lathe.

Posted: Sat Feb 12, 2011 3:42 pm
by saefroch
UHMWPE can be machined using a drill press, and if you round off one end, you can slowly force it into the part you want it to seal to and melt it with the friction while it's still spinning for a perfect fit, and probably a seal.

Posted: Sat Feb 12, 2011 4:17 pm
by Labtecpower
Just turn it down to the right diameter. I got a 0,01 mm fit on a lthe :D

I had to make it even smaller, because it didn't slide smooth. just keep 0,05 mm of space.

0,01 mm is 0,000393700787 inch by the way. google FTW!

Posted: Sat Feb 12, 2011 5:28 pm
by Gaderelguitarist
...or the angry german kid!
Is that a 2 girls one cup video reaction???

I'm a little concerned that the author of the post hasn't responded to any of these suggestions.

Posted: Sat Feb 12, 2011 6:19 pm
by AnotherSnappedLine
No, Im here...just had an all day wrestling tourney so Im finally getting on the computer. Im pretty confident on using epoxy.

Thanks for the feedback!

Posted: Sat Feb 12, 2011 6:58 pm
by mark.f
I guess the most pertinent question would be: what size of piston are you making?

Epoxy or bits of metal hardware with some sheet rubber are great for smaller pistons. For larger (1-1/2"+) pistons, I usually make them out of PVC (just use a sufficient bumper).