Enlighten me on copper

[GunsOfNavarone]

I have always looked forward to working with copper, I expected it to be smooth, easy and beautiful finish. Nope. Being that I really only work with stainless and 1018, this is a completely different horse.
I really only use carbide, perhaps this is a bulk of the problem. I tried tighter nose radius and then larger radius. I started at high RPM (450) and settled at about half that. Started at about .04 mm DOC and settled at more like .025 mm.tried WD40 and ended preferring a sulfur based fluid.
Never really thrilled with outcome...I’m doing an LED pill/heat sink.
Any input would be appreciated.

 

[Aukai]

I can understand a quest for perfection, or close to it, but that is far from terrible

 

[Liljoebrshooter]

I watched a u tube video about a guy machining copper hammer heads on his CNC. He had a lot of issues. I think I read on practical machinist that the old timers used whole milk for a cutting fluid.
Your results look good.

Joe

 

[Reddinr]

That doesn't look half bad to me. When I was working with copper a couple of years ago, I found this: Copper.org
You probably know this but don't forget to use a high quality thermal paste between your LED(s) and the copper, else you waste the benefit of the copper. Maybe silver works easier? Only a buck a gram from the mint.

 

[GunsOfNavarone]

Thanks guys, but that was a lot of experimentation and under closer exam, it’s not that great. Threads particularly bit great. The whole milk maybe some solid advice, but just like lard...no food on the lathe! I’m assuming carbide is the culprit, but I don’t KNOW that. Falling @ss backwards into an ok finish just makes me uncomfortable!

 

[Technical Ted]

It's been a long time since I machined any copper, but one thing to watch is drilling it! It can suck the drill right out of your chuck! Grinding or honing a small flat on the cutting edges will help.

Ted

 

[benmychree]

Copper is a b itch to machine, best done with very sharp HSS tools.

 

[jbobb1]

It's all about super sharp. Some quality un-coated carbide inserts might work, but HSS is the choice.
Or, you could drop 100.00+ for a Polycrystalline Diamond insert.

 

[markba633csi]

Copper and brass are known as "tenacious" metals and tend to be very grabby and hard to machine, copper especially. John is right on about using very sharp HSS tools, and I would use less positive rake
Never tried the milk but it probably works
-Mark

 

[NCjeeper]

Copper is a b itch to machine, best done with very sharp HSS tools.

I second that.