Cutting copper with woodworking saws

Question

I'm working on a project which includes a copper bushing (made of 3/8" OD copper tubing--the walls of which are somewhere around 1/16"), and am considering how to batch out these parts. The approach I'd like to take is to create a wider blank, with the bushing installed--then to resaw the blank into several individual pieces.

I'd prefer to do this on my bandsaw, which currently has a ~6tpi blade. Would cutting the copper tubing be likely to damage the blade, or destroy the workpiece (excessive tearout, etc)? I've cut aluminum on my circular wood blades before, but never the bandsaw--and understand pure aluminum is softer than copper.

PS) For a little more context, I'm making keychains. Here's a prototype--it's approximately 3" long and 1/2" thick. If you have other ideas about how to produce these please add a comment!

Answer 1

Would cutting the copper tubing be likely to damage the blade

I doubt it since copper is one of the softest metals going, and bandsaw blades of spring-temper steel are already regularly used to saw metals, including aluminium alloys that are much harder than straight aluminium.

Obviously you'll want to test this once or twice and gauge how the cut goes with your blade, but the above should at least indicate that it's not a crazy notion and that excessive wear to the steel shouldn't be a particular worry — in fact some woods would be far more wearing due to their silica content, silica being significantly harder than copper (7 on the mohs scale versus ~3).

That said, I'd prefer to do this with a blade with much smaller teeth than on a 6TPI but it should still be possible.

• First off, make sure your bandsaw is well adjusted before you start (good guide to this from Stumpy Nubs).
• Bring the table up so there's minimal blade exposure (to increase support and reduce vibration).
• Run the saw faster rather than slower.
• Feed slowly for the same reason as the above — so that as many teeth as possible are involved in the cut.
• If you're batching out a large number don't do too many cuts sequentially in case this might overheat the blade.

If you want to take an extra precaution and ensure the pipe is as soft as it could be you can quite easily anneal it¹ but you'll have to abrade it inside and out to restore the bright finish. This is very quick work with modern abrasives, but dusty.

Pipe cutter?
You could of course use a pipe cutter to cut your little pipe segments, but they're not made to produce visually neat cut ends..... they only have to be good enough to work inside a pipe fitting of some kind where they're hidden from sight forever :-)

If you try to batch out correctly sized copper inserts with a pipe cutter you'll hate yourself, trust me². If you do end up choosing to make yours this way I would deliberately cut them overlong, planning to sand off the excess from both faces once glued in and the glue has fully cured.

---

Deburring
Do make sure to factor in the time this will take into your calculations. Regardless of the method used to cut the pipe you'll have to deburr at least the inside of the tubing; there may not be much to choose between methods in this respect, especially with post-cut sanding added into the mix.

---

¹ Heat to a dull red, then cool any way you like — there's no quench-hardening in copper, so you can plunge it directly into cold pickling solution if you want to proceed quickly. This has the advantage of flaking off quite a bit of the oxide skin that forms, saving you having to remove it in the next step.

² I have to make a few copper ferrules infrequently but regularly for tool handles and even with that relatively small number doing this with a pipe cutter is the only part of the whole job that I dread. Even the tedious and sometimes tricky drilling out of the centre of the handle is less onerous.

Answer 2

The carbide tipped blade on my Skilsaw slices through ten penny nails like they were butter. I would consider using a radial arm or chop saw with such a blade.

Answer 3

Cutting metal with bandsaw blade and blade speed designed for cutting wood will ruin the blade very quickly (unless you've got a carbide resaw blade, but even then, I wouldn't do it - those are expensive blades, and there is no doubt you'd be degrading the wood cutting edge of the blade cutting hardened, unannealed copper). That said, there are obviously blades made for bandsaws that are hardened and designed to cut metal. You could use such a blade - it'll cut the plywood just fine, although you might have trouble with the blades becoming overloaded with fine chips, leading to poor cutting and burning, particularly since your wood bandsaw will be running the metal cutting blade significantly over its design speed.

But what I would do if I were building your design, is to cut the bushed end of the piece in a vice with a hacksaw, then flip the piece over and make the rest of the cut on the bandsaw. Unless you're making hundreds of these, that'd be easier and faster than setting up the bandsaw with a different blade. A sharp, 12tpi hacksaw will cut through the bush end quickly and accurately.

Answer 4

While it would be more convenient to cut the tubing and wood all in one go, there are a couple of issues:

1. It may be difficult to get the tube through all the blanks in one shot, especially if it's a very snug fit. Getting a 1/2" in piece in is one thing. Getting a 12" piece in is a whole 'nuther matter.
2. 6 TPI will make a nasty cut in the metal.
   • Just like cutting wood, the more teeth, the smoother the cut will be. Any metal cutting tool you see will have a lot of teeth (except for a demolition blade for a Sawzall™-type saw, because it doesn't matter).
   • The more teeth, the slower the cut in wood will be.
3. The comments well address the damage you'll likely end up doing to a blade designed for wood, and a metal-cutting band saw blade will probably not do a very good job of cutting wood.

I'd suggest a standard plumber's pipe cutter to cut the tubing:

^{image courtesy of lowes.com. No endorsement intended or implied}

It should give you a nice clean cut with very little roughness to clean up before installing the pieces into the wood. It doesn't take long at all to cut through copper plumbing pipe by hand (I've done a fair bit of it, it does go quickly), then a couple of swipes with some emery cloth (or even just sandpaper) to smooth off any burrs and ensure it's smooth enough for hands and pants pockets and you're ready to go.

I've never had one dimple or otherwise damage the pipe, so there should be no need to put anything into the pipe to support it. Don't forget, plumbers use these for cutting pipe all day long all around the world - they don't back the pipe with anything, and even a slight dimple would leave them with leaking joints, so it shouldn't be a problem.