Machining Copper, without oil smoke or pain.

I had to machine a recess in an 8" copper disk for a part I manufacture.

The copper I use is "ETP" copper, or "Electrolytic Tough Pitch", but often people who machine it call it "Electrolytic Tough Bitch".

I found out why.

The first time I tried it, it took many hours, using carbide inserts. I had to use oil, and it was a disagreeable job. Traces of the cutting oil interfered with bonding later in manufacture.

But a properly ground and polished tool actually makes turning this material FUN..and FAST! Look at these chips, and the surface finish of the machined recess!

Polish the tool to a sharpness where you are afraid to get your hand near it, and it will reward you!

There was good advice given on rec.crafts.metalworking, including using milk as a cutting fluid. It works, but using my lathe to make yogurt caused problems on warm days.

I am fortunate to work at a company that has a big machine shop (40,000 square feet of mostly CNC's, and probably 20 or 30 lathes,) so I had a good chance to talk to some of the old hands there. One of the best machinists is an "English as a second language" guy and told me to "Grinda the HOOK" on the tool, and showed me one he uses for copper.

"Just Use High Speed, Fuck Carbide".

OK. I used a 1/2" tool blank.

I used a Foredom hand grinder to grind the "hook", and polished it with a Cratex wheel.

Then after grinding the tool to shape, I polished the surfaces on a #600 diamond lap followed by 4 micron aluminum oxide metallurgical film.

NO OIL was needed!! I just finished ten pieces in less than an hour on my South Bend Model A, set for a crossfeed of .112 per rev, at the large headstock spindle with the rear motor drive pulley in the faster position.