I'm having a hard time finding this marine epoxy you speak of. The link you gave seems to be to an expired ebay bid. Do you have a link to a store inventory, or maybe a description of what im looking for? I found some stuff that is meant for repairing fiberglass, but i dont know how to tell if its ...

You sir, are a godsend. Me and my brother have been trying to find an easy source of airtight rubber sheeting, and mouse pads never crossed my mind.

couple questions though...

1. whats the purpose of the bolt/washer in this design? is it hard to keep the neoprene in place while the epoxy sets ...

Last weekend I made my first barrel sealing piston cannon with whatever I could find at home depot that seemed like it would work.

The piston I ended up using is a core cut from a 2x4 with a 3 1/4" hole saw, then sanded down to fit the inside of a 3" chamber. The hole saw has a pilot drill in the ...

I have ggdt and i have been playing around with it the past day or two. What I've found actually, is that I can have a ridiculously long barrel, like 1500 inches, and it doesn't mind so long as I have a really large chamber as well.

I don't think I understand what would cause that. The only concept I am familiar with which would cause that is pressure loss due to friction between the air and the inside of the barrel. Are you saying there's a point where you cant really overcome that with a larger chamber, or higher initial ...

Is there a reason to try for SOS? Is this for a project for something or just a personal quest?

Well, I've heard speed of light is a bit harder to pull off so I figured I'd start here :D

Seriously though, purely personal quest. I built my first spudgun probably 10 years ago with my brother and ...

Ok, maybe that doesn't sound like the smartest title, but it properly expresses my enthusiasm.

My goal is to build a spudgun that is capable of throwing something at the speed of sound. I am curious if someone experienced can tell me roughly what is required to make that happen. That is, can it ...