How to Turn 101 Copper?

[ACHiPo]

I just ordered an 8" x 1/2" slug of forged 101 copper. I want to turn it down to a 7.875" x 0.480" cylinder.

I've heard horror stories about how hard (soft) copper is to machine. This is largely a decorative piece, so dimensions aren't critical, but I'd like a decent finish on it.

First question--how do I chuck it? I've got a Logan 816 (10" swing) with 3-jaw and 4-jaw chucks, but I'm thinking taping it or screwing it to a faceplate would be my best bet? I do have forming taps so can screw into the copper from the back.

Next question--what tool should I use to face it and turn down the diameter?

Last question (for now)--what speed and feed?

 

[aliva]

I've turned some copper, the problem being its very soft. I tried carbide CCMT inserts with a so so result. I then tried HSS with a very small nose radius and,sharp , results were very good, so I would recommend HSS. Don't take too big of a cut as the copper will heat up and may want to fold over at the cut line and pieces will stick. Keep the feed rate between 5 and 8 thou/rev The speed should be 300 to 600 rpm. Pick which very gives you the finish your looking for, you can alway clean things up with emery and scotch bright. As far as chucking, go with the 3 jaw if you can afford to loose a little length in the chuck. Try and keep the stick out to minimum. If you need the entire length turn between centers using a lathe dog. Hope this helps.

 

[ACHiPo]

Thanks. Definitely gives me a starting point.

 

[jlsmithseven]

Thanks. Definitely gives me a starting point.

So does a spot drill. LOL. Sorry I had to.

 

[darkzero]

For carbide, I use CCGT alumn specific inserts to turn copper. These inserts have a high positive geometry & are very sharp. Any other common molded insert won't leave a good finish. And use lube as the copper tends to smear. But HSS would be a better choice, key is to have a very sharp edge for a good surface finish.

 

[Wreck™Wreck]

I just ordered an 8" x 1/2" slug of forged 101 copper. I want to turn it down to a 7.875" x 0.480" cylinder.

I've heard horror stories about how hard (soft) copper is to machine. This is largely a decorative piece, so dimensions aren't critical, but I'd like a decent finish on it.

First question--how do I chuck it? I've got a Logan 816 (10" swing) with 3-jaw and 4-jaw chucks, but I'm thinking taping it or screwing it to a faceplate would be my best bet? I do have forming taps so can screw into the copper from the back.

Next question--what tool should I use to face it and turn down the diameter?

Last question (for now)--what speed and feed?

Do you require a 7.875" OD X .480 ID "cylinder of unknown length?
Or a 7.875" OD cylinder .480" long of unknown ID?

 

[kwoodhands]

I just ordered an 8" x 1/2" slug of forged 101 copper. I want to turn it down to a 7.875" x 0.480" cylinder.

I've heard horror stories about how hard (soft) copper is to machine. This is largely a decorative piece, so dimensions aren't critical, but I'd like a decent finish on it.

First question--how do I chuck it? I've got a Logan 816 (10" swing) with 3-jaw and 4-jaw chucks, but I'm thinking taping it or screwing it to a faceplate would be my best bet? I do have forming taps so can screw into the copper from the back.

Next question--what tool should I use to face it and turn down the diameter?

Last question (for now)--what speed and feed?

I have seen turpentine or milk used as a lubricant. One of my cousins is a machinist and he uses turpentine, HSS and compressed air to cool the work while turning. I have only turned and faced copper twice, both miserable experiences.

 

[ACHiPo]

For carbide, I use CCGT alumn specific inserts to turn copper. These inserts have a high positive geometry & are very sharp. Any other common molded insert won't leave a good finish. And use lube as the copper tends to smear. But HSS would be a better choice, key is to have a very sharp edge for a good surface finish.

I think I have some CCGT inserts. I also have a bunch of HSS tools which I can learn/practice sharpening. Given that the slug is over $100, I may try to find some smaller pieces to practice on first.

 

[ACHiPo]

Do you require a 7.875" OD X .480 ID "cylinder of unknown length?
Or a 7.875" OD cylinder .480" long of unknown ID?

I need a right cylinder ~7.875" OD and ~0.480" long. There is no ID. It's a disc.

 

[ACHiPo]

I have seen turpentine or milk used as a lubricant. One of my cousins is a machinist and he uses turpentine, HSS and compressed air to cool the work while turning. I have only turned and faced copper twice, both miserable experiences.

Milk sounds, um, icky? I've got mineral spirits, WD40, and oils of various viscosities.