First off, it is about three feet long with a 32.5" barrel. By using GGDT (made by D_Hall over at spudtech.com/forums), I was able to create some numbers. I will see how accurate my inputs were when I test it. It needs to set for three days and I finished it about two horus ago, so... Anyway, pics!
That is the chamber/valve body and barrel, suspended from a $300 lifetime warrantied vise so that the glue poured into the reducer bushing will set evenly. I poured a quarter to half inch of cement down there. I had to re-adhere the barrel after I had already cemented the whole deal to the chamber. Since it wasn't far enough in the first time, the bond had to be broken (did that within a minute) and redon. Wow, that muzzle break is really white. That's what I get for hand sanding it with 100 and 240 grit sandpaper.
That was my first attempt at doing the bushing on the barrel. The bushing needs to be a whole 'nother two inches closer to the muzzle (the hand in that photo, which isn't mine by the way. Looks the same...).
There's some random stuff with the chamber/valve body without barrel adapter and coupler attached. The coupler is behind it on the table.
That's the piston. It is made of 1 1/4" PVC fittings: a ground down bushing plug and a coupler.
There's the piston sealing face. It is made of 2.214mm thick reinforced rubber sheet, industrial super glue holds the sealing face to the piston, then it is held in securely by the ridge on the inside of the coupler. Yes, the bushing plug was put in upside down. There is a paint cross-section of the piston here.
That is the removeable pilot/fill valve. I plug it into a compressor when I need it filled, then unplug it and open the blowgun to fire it. Since the whole deal is removeable, I can breach load and/or remove the piston without having to break any joints.
Well, that's all for now. I'll edit this later with ranges and whatnot.
edit: There...I finally read all of the post again and fixed the errors and things which I messed up on the night before. Picking up the cannon today after school to let it dry at my house. Then I will charge it to 40 psi and try it out on Saturday. How many layers of cardboard would be necessary to simulate what would be ballistically safe for Nerf at a hundred or so feet? Three? Four? I'll just add more until the dart doesn't penatrate or something...
Edited by GeneralPrimevil, 30 March 2006 - 06:51 PM.