SpudFiles

me and my friends built a pneumatic cannon today and about 5 hours after we glued it all up part of the cannon burst off right before the ball valve with only about 10-15 psi in it. my neighbor came over and told us that we did it all wrong and were going to kill ourselves and blah blah blah i only say blah blah blah because hes one of those people who seem to know everything about everything even when they dont is it possible that it could blow up? we figured that the reason the part that burst off only came off because we were being impatient and didnt wait long enough and that i didnt put enough glue on there its my 2nd pneumatic cannon and my friends first and it went pretty smoothly besides trying to get the valve through the end cap really appreciate it jack tthe cannon 3" to 2" to 1" to 1" ball valve to 1" to 2" to 3" i cant post picture unfortunatley

Well from my perspective it seems the pvc was wet or dirty. If not was it snug?

You need to let it sit for more than 24 hours for a complete welled joint so yeah that was most probably your problem.

1. Parts not clean enough (use cleaner or primer on both parts).
2. Not enough glue (both pieces should be completely coated).
3. Joint not fully seated (the male part needs to be fully inserted into the female part, all the way down to the stop).
4. 24 Hours to dry, longer if the inside of the cannon is poorly ventilated.

#3 can be tricky. I generally measure the depth of the the socket then mark that distance on the pipe using tape (a marker won't work since the cleaner or primer you are using will erase the mark). When assembling the joint you need to get the pipe all the way up to the tape mark. You then need to hold the assembly for a minute or two (or more) since often a joint will push itself back apart.

we just tried to shoot it we didnt have access to a air compressor so we had to use a bike pump we probably pumped it over 400 times into our 4 foot 7 inch 3 inch pvc air tank and it just kinda dinkly falls out how can we open the ball valve faster?

Do you know how much psi your putting in?

no there was no guage on pump

The tank seems large, so you probably just didnt have enough pressure or the valve is opening too slow. Im still learning myself so maybe someone can confirm..

Also does adding a longer barrel add distance right now we have a 10 inch barrel and were thinking of adding a 3 foot one for distance. Will it help?

CPVC cement is specifically made for CPVC. Don't use ANYTHING besides PVC primer, and PVC glue on PVC. The only other thing that you can cement with PVC glue is ABS pipe, and fittings.

Evan... there is special glue for ABS. You don't use PVC glue.

Gun Freak wrote:Evan... there is special glue for ABS. You don't use PVC glue.

It's okay to use it for combustion cannons only.

By that logic, it's perfectly fine to hot glue the chamber together!

i know your not supposed to, but ive used differnt glues on differnt pipes and had no problems, but everything was clean and primed