SpudFiles

I understand that epoxy is more expensive in the long run. But i do not plan to make a mass amount of cannons. The copper piston cannon i spoke of will probably be the last one i make for a good while. I dont want a bunch of random cannons, just things to play around with. I want to build the copper cannon because i am looking for more power than i currently have in my sprinkler valved PVC cannon.

iisthemuffin wrote:Wow thats actually quite surprising to me. Only problem i have now is not having the proper things to solder.

a gas stove top in a house works.

Huh?? So your saying as long as i have a hot enough flame to heat the pieces and melt the solder then i will be fine?

http://www.bernzomatic.com/bernzomatic/ ... Prod100026
Also would i find one of these at lowes? And what is the average price for one?

All you need is some solder, a regular propane torch, and some flux paste.

The first solder joint I ever made held phenomonally well, it's an extremely easy thing to do- it practically solders itself

There are a pelethora of DIY solder guides on Google, why use messy Epoxy when you can just solder?

Any hardware store that does not sell a propane tank+torch head should no longer be allowed to bear the title "hardware store".

How could you think that soldering was difficult.

Just:

Apply Flux
Heat Joint
Apply a bit more Flux
Apply Solder to the joint
Allow to cool NATURALLY! (Too many people put the joint under water to make it cool faster, this will screw the joint).

Biopyro wrote:Properly soldered copper will hold WELL over 200psi! I've taken mine to 300, and I reckon you'd be fine up to 1.5k.
I wouldn't be suprised if the pipe went before the soldered joints!

page 28 of the copper handbook
I agree that it will hold over 200 but it isn't a good idea since it isn't reliable anymore.

EDIT: maxus it's better to sand it a little before the flux

just wanted to toss in here that I have had my copper gun to 400psi so far and am planning on going higher for a safety factor soon. (As soon as I get my fridge compressor, my 3/4" pump tends to become a bit of a workout at 3-400 psi.) I have seen soldered joints hold while the pipe blows out from (ice) pressure next too the fitting. I think 200psi is WAY safer than a person needs to be with a properly soldered fitting IMHO.

Sniper, I agree about the sanding, but I don't just do it "a little", I like to sand the pipe end and the inside of the fitting until there is no remnants of the original surface left.

iisthemuffin, I think you should definitely go with solder. A propane torch is the most expensive part, but it will come in handy for many things. Also if you get a wild hair in the future you could make a combustion with it if you wanted to.
Also you were saying you had some good epoxy? Well then your piston will be easy to make. Just cut a section of the pipe that the piston will be sliding in and cut it squarely to the length that you would like your piston to be. then coat the inside with a lube or wax, and pour it full of your epoxy. Then once its hard, break it loose from the piece of pipe and carefully sand the out side until it slides nicely in the pipe. Then sand both ends nice and square using the piece of pipe as a guide, and glue a disc of rubber to the end. Wala... instant piston.

Good luck I think you will have fun with the project.

Lock

DYI, while you have given great advice and provided me with very good information i would just like to inform you that i have never built a piston cannon

Sorry about that, I'd just got back from working a 12 hour shift, and was answering a few different posts at a time. I guess I started reading things that weren't there...

Anyhow, I assumed that you already had the equipment necessary for soldering when I stated it was cheaper than epoxy, because I couldn't imagine any spudder not having a blowtorch, fuel, solder, and flux lying around somewhere.

page 28 of the copper handbook
I agree that it will hold over 200 but it isn't a good idea since it isn't reliable anymore.

You must be reading a different copper handbook than I am, because the hugely extensive one I'm reading says that with a 95/5 tin/antimony solder, the joints on copper tube under 1" are rated for 1090 psi. Quite far from being unreliable up to 200...

So is flux used like a primer? And i do have access to a torch as of last night. All i would need now is the flux and solder correct? how much do you think that will cost?

Flux is about £4 for 1lb in the uk, lead free solder is about £8 for 1lb. Flux is very much like a primer. It removes oxidation and impurities so that the solder will join properly

Alright. Well i think this is going to happen guys. Thank you for all of the advice you have given me. Im going in for an interview tomorrow so hopefully this cannon will happen soon. Im off to find a good copper soldering guide now.4444
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EDIT - Sorry about the stiff at the end. New kitten, she loves me.