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If (as a retired teacher of metalwork etc) I had to select metals for milling, copper would not be near the top of the list - even cnc milling the thin layer on printed circuit boards often tore the copper from the grp - a straight single flute engraving tool was about the only thing I'd let students use, with close supervision against the moment the tool got stuck and stalled the motor.
I'd be genuinely interested in the details if you get this to work!If I figure it out i'll definitely let you know.
My spindle is about as low powered as it gets and I am only cutting super slow and only nibbling the top 0.1mm with each pass. so whilst its really slow its actually cutting through fine. Its more the incredibly rough cut finish that is the problem. I'm using a 1.4mm corn cob end mill which I think might be the problem. I've read a few people saying the same as you...that 1 or 2 proper flutes with a straight end...so that is what i'll try next.
Stonehedge-
I was using a Roland PNC 2300 and tools similar to this:
https://www.prytec.com.au/product/160/Roland-Engraving-Cutters-for-Aluminium--Brass/
-all now very obsolete!
Attempts at manual control never gave a good outcome, and larger tools (more than 3mm diameter) generally tore the copper free regardless of machine or method of holding.For anything larger / structural / more decorative than a circuit board I would try to teach precision smacking with the correct hammer followed by various grades of abrasive, or advise students to use brass or aluminium as an alternative to copper.
Brass might work - IIRC a brief etch in warm ferric chloride will preferentially remove the zinc leaving a (thin) layer with a high proportion of copper and the appearance of a dull copper finish.
MrE
If (as a retired teacher of metalwork etc) I had to select metals for milling, copper would not be near the top of the list - even cnc milling the thin layer on printed circuit boards often tore the copper from the grp - a straight single flute engraving tool was about the only thing I'd let students use, with close supervision against the moment the tool got stuck and stalled the motor.
I'd be genuinely interested in the details if you get this to work!