I make these pistons by cutting 2" circular holes with a holesaw in a cutting board and then heat them up and press them together. Then turn them down on a drill press. I guess when I heated and pressed them together, I didnt do it good enough.


:D :D I'll do my best not to turn up like this guy ...

You need to get it up to about 375-425 degrees F to do this...

They will squish together with lots of pressure, but they won't become a solid mass simply by putting a bunch in a jar. I used clamps to laminate the piston.

Ok , so when you melted this stuff with your custom thermostatically ...

Oxbreath wrote: I have been considering it.

Same. There is a wide range on eBay, but they charge alot to post to NZ. I'm also looking for a quite a large piece (2.5").

Another idea I had was to buy a cheap plastic chopping board then use tech's technique to get your designated size.

Technician1002 wrote:It was HDPE.

The same stuff milk jugs are made of.
I wonder if anyone has tried molding a milk jug to make a block of HDPE?

Hey tech, on a external website you discussed in a build log how to merge two or more pieces of plastic together, for construction of a piston.
Since i can't find the link again can i ask what kind of plastic this was?
Also do you have any idea if UHMWPE or Nylon is able to be melted and molded in ...

I don't know about Auckland, but down south a workshop in town wanted about $50NZ to thread a 2" stainless steel pipe. This would probably be more than you would like to pay.

From what I read they have the same thread as a paintball tank, so finding a reg shouldnt be too hard.


I highly doubt that the thread would be the same. Otherwise everyone would be using them as a cheaper version of a paintball tank.
Having said that there is probably a adapter, which can be ...

I must say that is a nice compressor setup you got there. jealous

I put in a fair bit of oil to make sure its oiled...

Can someone confirm that it is fine to put small amounts oil in the air intake from time to time. (obviously not high viscosity motor oil) Or would this probably not help ...

For me it wasn't that i wasn't enthusiastic about this contest.
Its just that I don't have access to decent equipment for filming.
Sure there are members who lack interest in it, but i sense there must be others like me who wish they could enter.

Thanks hubb, but its not working for me. It says an error occurred then it trys to debug it.

Also does anyone know of a decent range calculator, that isn't the crude ggdt range calculator.

saefroch wrote:Any idea what the diameter of the head on that pump is?

This Link will help

It looks to be around 20mm.

MrCrowley wrote: Just a 1.5" barrel nipple epoxied in to the back of a 2"x1.5" bushing.

That's what I was after.
Do you mind me asking how much (approx) this cost you to build? I would presume those 2" fittings cost a bomb.

I'm still gawking at those pictures, even though I saw them on chat the other day.
Anyway, what exactly does the piston seat on? I can't quite tell from the pictures.

Chances of that happening are small but I think staying off the radar is the best plan for now. Then the only way they can search my garage is with probable cause or a warrant.

I agree, staying off the radar sounds like the best plan.


Funnily enough, I think misuse of a firearm and unlawful ...

I know some countries if you have a firearm permit the police can search your house without a warrant.

They can search search your land/building if the commissioned officer (i think this is a second lieutenant or above) suspect that you have a firearm or airgun that breeches the arms act.

So in ...