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breech loading/hopup
Posted: Sun Jul 02, 2006 9:43 pm
by djt
for my new marble cannon (all done except for getting the sprinkler valve) i want to make it breech loaded with a half inch barrel. the reason for this is so i can put a sort of stopper, kind of like a hop up system in an airsoft gun, to keep the marble from rolling down the barrel when pointed down. any ideas on how to do breech loading on half inch pvc? i want it to be some sort of sliding thing. i know the concept but i dont know how to make it airtight. plus i dont really want to mess with o rings.
Posted: Sun Jul 02, 2006 10:10 pm
by huse_spud
you don't need a stopper, just use a little wadding from a napkin or small peice of cloth. it'll make a tighter fit and fire harder for better performance. and it'll keep the marble from rolling down.
forget breech loading, all that'll do is make the barrel not air tight if you don't do it correctly with o-rings.
remember, less sophistication means less worry.
Posted: Mon Jul 03, 2006 11:14 pm
by noname
It's easy to do a breech loader. First off, put male and female threads on your barrel near the valve. If you use threaded valves, forget this step. Then get a piece of 1/2" PVC and put male and female threads on that. Make it so the whole piece is ~4" long. Drill a hole big enough to drop a marble in. Get a 6" long piece of pipe that fits inside the male threaded piece (male threads have a smaller ID than the pipe here) but doesn't allow a marble to fit in. So the marble can go in the PVC but not the metal pipe. Cut a groove with a notch in the PVC starting at the hole for the marble. The notch should be close to the hole. Put the metal pipe inside the PVC and put it so that when you slide it under the hole, it covers the whole thing (You can't see PVC other than on top). Drill a hole in the metal pipe That a screw or bolt can fit in. Drill the hole in the notch that you made when the metal pipe is inside the PVC. Put the bolt or screw in the hole you just drilled. You should be able to push it out of the notch, slide it down the groove, and have a place to put the marble. Then put the marble in and slide the bolt back up and put it in the notch. Fire and repeat.