Made this water cooled transistor today. Cutting copper sucks, pretty messy but the idea was to create lots of ridges using a ball end mill to increase surface area and turbulence so not too worried about surface finish.
15000rpm, 3mm ball end mill, 400mm/min, 1.5mm doc, 2.5mm stepover.
Yeah, copper is nasty to work with because it’s so gummy. I’ve heard that if you lubricate the cut with lard or soft wax it’ll do better.
I guess you mean water cooled transistor heatsink, right? Are you cooling a huge Mosfet?
No that is the back of a 2x tripple Darlington module (old version of an igbt) that normally would bolt up to a heat sink. 1000v, 150A 1000w per transistor. Something like, that free scrap from an old vsd.