SpudFiles

My friend and I are building a simple combustion spud gun, but the pipe we bought didn't fit together well. We could get the pipes to almost bottom out when joined, but when we applied the primer and cement and tried to get them together again, they could hardly go in halfway. We used a hammer and board and got them to compress together reasonably, but they definately didn't bottom, except for the last seal (coupler to clean-out adapter), which was within a centimeter of a full seal.

Will this affect the durability of the gun, and if we build another, how can we avoid this problem.

If it was glued and bonded properly, then you eally shouldn't have any problems unless you do some crazy stuff. As long as you use Right Guard or propane and stay away from Oxygen and Acetylene you'll be fine.

If you really think that it will affect the safety, go ahead and rebuild it by all means.

Odd, I'v always found that fittings apply easier to apply once the solvent has been applied.
Are you shure you solvent welded properly?

i've got the same question as BLB, it seems like you may have let the primer or cement dry partially before you put it all together, you gotta keep it all wet

It may have dried, I got the instructions from spudtech.com and it had me apply the primer and cement to all of the parts before assembling them. After I did it, I actually did think I might have been better off doing them one by one. Oh well.

And don't worry, I've read the horror stories about using acetylene as a propellant/incendiary device.

i usually prime both ends of a connection (fitting and pipe) and then cement and put them together quick, dont prime all of the pieces at once, you might knock one over and if it gets dirt in it its stuck there

Okay, we've finally got it completed and working. We kinda had to bootleg the spark assembly because the screws weren't nearly close enough, and no calibration would make them spark (excpet a hookup to a power line, hmm....), so we cut an appropriate length off of some spare screws and used a nut to join it to the screw already in the pipe. The second screw just didn't want to cooperate, so I wound up using duck tape! Hooray for duck tape! It doesn't look the best, it's got about an inch of purple primer sticking out from all of the joints and we insulated the electrodes on the outside with duck tape, and also the BBQ sparker is attached with duck tape. It's a lot easier (and safer) than drilling holes in it, to me at least.

I would post some pictures, but I don't have a digital camera. Go ahead. Laugh it up.

Sometimes cutting PVC will deform or burr the ends. I use a piece of fine sandpaper to chamfer the ID & OD (edge only) of the pipe. It makes assembly much easier if the pipe is squared using this method before assembly.

Yeah I sanded mine down and it was smooth as silk when I slid it in. As for DUCT, NOT DUCK tape, I'd be careful of those screws, they might fly out. I'd use caulk if I were you.

regre7 wrote:It may have dried, I got the instructions from spudtech.com and it had me apply the primer and cement to all of the parts before assembling them. After I did it, I actually did think I might have been better off doing them one by one. Oh well.

And don't worry, I've read the horror stories about using acetylene as a propellant/incendiary device.

By before do you mean you applied the cement to every part that needed it and then assembled it, or you cemented one at a time as needed? because that stuff dries pretty rapidly, and it would be kinda hard to put it together if it dried at all.