SpudFiles

ok im building a cannon with a 3 inch chamber and a marble barrel...what size are marbles by the way? and i recently read that bell reducers are bad so i was wondering if i could get a 3 inch to 1 inch adapter....i would like the 1 inch part to be threaded...it could be male or female either one is fine...the 1 inch part will be going to a modded 1 inch orbit sprinkler valve

1.Marbles are all sorts of different sizes.
2. Bell reducers are fine, as long as they're rated for the pressure and fluid you'll be using. In this case, I'm guessing the fluid is air or some other inert gas, which rules out any PVC parts right off the bat.
3.You can get malleable iron threaded bell reducers or bushings for 3" to 1", as well as some that are socket weld on one side, and threaded on the other. Unfortunately, if you want a rating higher than 150 psi, you'll likely either have to go 3" to 2" to 1" (requiring two bushings) or make your own fitting.

Good luck. You'll learn a lot about plumbing from looking around the McMaster-Carr site.

hmm ill have a look around the site...also im going to go to lowes to see if i can put something together