it should be fine to use steel pipe as an onboard air tank. you might want to look at the sch.80 steel pipe on McMaster, as it will provide a safe rating for 400 psi, along with the use of corresponding fittings. (on mcmaster, when you go to the fittings page for steel, you can select sch. 80 when y...

yes, the pressure produced from combustion inside the cannon will be at high levels for milli seconds, the pipe fittings can also withstand more than they are rated for, and the rating is based on a constant pressure at specific temperatures. You'll be fine.

Thanks for the comments and tips guys. I was originally going to use a 1" valve for the cannon, but i already had a 3/4" one layin around and I had all the fittings too, so I didn't want to go out of the way to pay for the appropriate 1" fittings, money is tight, since I have to drive over 70 miles ...

wow, thanks for the tip Lockednloaded, ill have to try that, and yes it is pipe over pipe. thanks for the comments guys! And yea, damage pics will be here either tomorrow or the next day.

New cannon i just made. I used a 3/4" rainbird sprinkler valve, the chamber is 3" PW PVC. The thing i did different from a lot of other over/under pvc cannons, is that the "u" bend from the chamber to the valve is made from stainless steel pipe fittings and nipples. I found that last time i used pvc...

you could put o-rings under the terminals, and use heat shrink wire wrap (radioshack) around the bare parts of the wires/terminals. They should not leak, as long as you use the proper tools, such as a tap and tap wrench, to thread the holes for the screws (if you're using screws). Thats the same thi...

oh, and something to add to inonicknames' post, if you weld aluminum, you may "activate" the aluminum using the heat and electric current, and this will affect the oxide.

yea they make those kiddy 4 wheelers with like 50cc engines. But don't bother welding aluminum or stainless steel, unless you have TIG welding experience or can oxy-fuel weld. However, don't be discouraged about using aluminum, it is strong stuff, just think, they use it on aircraft frames/bodies. P...

hyezzz! pumpkin chunker! great idea for the season! Oh, by the way tech, UHMW is some gooood stuff and I love machining it

oh, i must add that bursting pressure varies inversely with pipe size. and the warmer it is, the lower the pressure rating, since PVC is in fact a thermoplastic.

Wellll, actually, the max op. pressure for sch. 40 pvc is about 350. BUT, that is where ASTM rates it for safe use, if you wanted to risk it, you could refer to the bursting pressure which is appx. 1700-1800 psi. sch. 80 is obviously higher. But please don't interpret this the wrong way, im simply p...

Plans are on the drawing table for a 3 inch and 4 inch valved cannon.

Verrrry Nice! how big are you going to make the chamber? any design details e.g. paint job? I have been using 1" diy piston valves and sprinkler valves, I gotta move on up.

Depleted Uranium!! haha just kidding, i wish tho. The most destructive i have ever really used was a 3/4" ball bearing, with a hole bored thru the middle and had a nail like rcmans' inserted thru and welded in. if i can find it in the woods i will put a pic up but last time i shot it, it went thru a...

nice gun man, love the combo of brass and silvery look. how does your pushbutton release the pilot air? is there like a hole in the back?

hahaha thats awsome. a combination of creativity and boredom im assuming?