cutting an aluminum scuba tank

Must be something in the air! I'm in the midst of this very same project, but I'm using old steel carbon dioxide cylinders.

My understanding is that aluminum is very bad for use with an abrasive chop saw. Apparently it can load up in the blade, cause it to overheat, and explode. There was a thread about it over on rec.crafts.metalworking not long ago, the consensus seemed to be that a power mitre saw (as in one used for wood work) is a better and safer tool to use. A web page I saw about the "cylinder-to-bell conversion" had the author using a reciprocating saw (i.e. a Sawzall) to cut the ends off; when I posted asking for suggestions, I was told everything ranging from plasma cutters to abrasive cutoff discs as a viable option.

You can often get old cylinders for free from welding supply stores, but it can take a bit of hunting around. Many are reluctant to give them to you because they aren't convinced you aren't going to do something bad with a bottle that has their name stamped on it. I think if you can convince them of your intentions, however, they're much more relaxed and willing.

If what I have read about the dangers of aluminum in an abrasive chop saw are correct, then I'd be scared to death to try cutting through a 1" wall thickness tank since that'd be a total material thickness of 2" at points, if not wider when cutting through curved sections. There's images posted of successful cuts done to that thickness using a hand held circular saw in the metalworking.com drop box, so I'm willing to bet the mitre saw trick would work. For my cylinders, I'm thinking about constructing a cylinder holder with wheels that allows the cylinder to be spun with a motor. Then I'd use a lathe parting tool fixed to the base of the "cylinder spinner" to cleanly slice the end of the cylinder off. A cheap single purpose lathe, essentially. Failing that, well, I've been trying to justify the purchase of a plasma cutter....

Use a standard skil saw with a 7 1/4 inch carbide tipped aluminum cutting blade. You can even cut it with a wood cutting blade as long as you have around thirty plus teeth. Lay out a line around the tank with a felt marker. Set your blade depth shallow around one inch maximum. Face shield and gloves are wise. Secure your tank so that it doesn't rotate. You should be able to cut at least a quarter around before having to reposition. Randy

I suspect that steel tanks will sound better.

...snipped

I wish I could find some for free. I want to melt the aluminum and cast with it. They can crush it, smash it, cut a hole it or anything else they want to do. Give me names and addresses. I'll pickup or pay to ship.

Al

"Cannot find server"

Try again, works for me.

Have you schmoozed your local welding supply shops yet? Although admittedly, you'll likely have no luck finding aluminum tanks from a welding shop. Just steel ones. Welding shops (at least the ones around here) have to pay to have the old cylinders hauled off, so many of them happily give them away for free because they save money that way. The smaller, independent shops are usually the most interested in that kind of savings. Just make sure to try to actually buy some stuff from them now and again... they're much more willing if they know you're a regular customer.

As for aluminum tanks, I'd think your best bet would be schmoozing the scuba shops, maybe even posting ads in them and leaving word with the shop owners that you'll pay people for tanks that have failed visual or hydro. I'd say check with paintball stores too, but those guys don't bother to safety check their gear and wouldn't retire a bottle unless it had a crack large enough to leak gas. Either way, pounding the pavement and making your face known is the best bet. Leaving a printed up ad at the store (most stores have a bulletin board for stuff like that) or better yet, getting the owner to leave your contact info next to the filling station, would eventually generate a few hits.

Also, what about posting a message now and again to a Usenet scuba group? Maybe to some web-based boards as well? If you're paying for the tank and for shipping, I bet you'd get plenty of interested people before too long.