madmandotcom Posted May 10, 2011 Posted May 10, 2011 no prime, the type of time fuse used in the cross matching and passfires tutorial, hairspray, no wadding, several tests-approximately 5
killforfood Posted May 10, 2011 Posted May 10, 2011 You guys can hate on me if you like but combustion type spud guns make me wanna punch babies. I hated the unreliable ignition, nasty hair spray and having to unscrew the end cap over and over again. I switched over to CO2 and diaphragm valves. My spud guns fire with 100% reliability and recharge automatically after each shot. I don't worry about them blowing up in my face because I control the pressure with regulators. There is a down side though… I have to drag around hoses and a big CO2 bottle. I do have a small man portable 2.5lb bottle but it needs frequent refills. My favorite is my golf ball gun. It can launch a ball almost further than I can see. Around 8 or 9 seconds hang time is normal. The random spikey pressures generated by combustion cannons are just not safe in my opinion.
FrankRizzo Posted May 10, 2011 Posted May 10, 2011 (edited) You guys can hate on me if you like but combustion type spud guns make me wanna punch babies. I hated the unreliable ignition, nasty hair spray and having to unscrew the end cap over and over again. I switched over to CO2 and diaphragm valves. My spud guns fire with 100% reliability and recharge automatically after each shot. I don't worry about them blowing up in my face because I control the pressure with regulators. There is a down side though… I have to drag around hoses and a big CO2 bottle. I do have a small man portable 2.5lb bottle but it needs frequent refills. My favorite is my golf ball gun. It can launch a ball almost further than I can see. Around 8 or 9 seconds hang time is normal. The random spikey pressures generated by combustion cannons are just not safe in my opinion. While more reliable, and more powerful, I've found pneumatic cannons to be much more dangerous than simple (metered propane, not hybrid) combustion cannons. About 10yrs ago when my friends and I were really into spud guns, we made quite a few pneumatic guns (ball valve, sprinkler solenoid, improved "supah"-type). One of my buddy's dad owns a plumbing company, and when he heard of our experimentation, took the pressure chamber from one of our guns to work to be x-rayed. This particular chamber was 4" SCH-40 (not cell-core), and had been used routinely @ 100PSI and not higher than 115PSI (the limit of the air compressor we were using). What he found was that the entire pipe was spiderwebed with hairline fractures! That pipe is not meant to be pressurized and depressurized with the ferocity that happens when the valve dumps all the air quickly. He surmised that we maybe would've gotten a couple dozen more cycles before the chamber would have come apart explosively. So, that put us off pneumatic cannons made of PVC. We later switched to pneumatic cannons that utilized empty 20lb propane tanks for the pressure vessel. With stungun ignition and metered propane though, sticky hairspray and misfires are a thing of the past. I still enjoy my combustion cannon for its portability, and it enables me to shoot things like burning 000 steel wool attached to a spud. Edited May 10, 2011 by FrankRizzo
killforfood Posted May 10, 2011 Posted May 10, 2011 Frank, I use sched 80 CPVC for the pressure chambers and usually only need to run 60psi-70psi pressure. My golf ball gun probably has a thousand cycles on it. I also rig them with quick dis-connects so that I can run around with a charged cannon. They work great for water fights. At close range using a big long 2" barrel full of water; you can darn near put a kid on his butt. The recoil is very intense though. Rue the day you come at me with a garden hose. I don't know what a "Supah" valve is. I just used ball valves and modified sprinkler valves. I was going to move up to propane tanks but lost interest and haven't built a new one in quite a while. Stun Gun ignition sounds cool.
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