I've got a problem. A friend of mine, a watchmaking student, is trying to turn what I believe to be electrical connector grade standard
copper bar on a nice Levin watchmaker's instrument lathe, and he's getting terrible finish.
I'm also a watchmaking student, but I was a beginner manual machinist and CNC programmer before I got into this. Hand grinding custom
HSS turning and form tools for the lathe is no problem for me, learned a long time back.
I am teaching my friend how to hand grind HSS blanks to custom cutters on simple bench grinders like I learned, without the rotary
diamond hones we use in school- but the problem is, I've never done copper before. It's gumming like crazy on him. Machinery's says the
grade I think he has has a machinability index of 10- ouch.
Oddly enough, I can't find anything on cutter forms for copper in the 28th or my old 7th edition of Machinerys. I know this stuff can be cut
to a mirror, I've seen it. I just didn't see what shape their tool was. I'm thinking negative rake, as it's soft, but can't find anything!
Can someone give some advice on HSS (yes, must be HSS!) cutter form for copper?
We do have access to rotary diamond hones, with marble wheels and diamantine for sharpening cutter blanks if a mirror finished cutter is part of this.