I have a CNC router that was built from a CNC adhesive dispenser. I have a Rotozip as the power which runs at 30,000rpm.
I am trying to cut shapes in .020" copper sheet. The shapes are 2D but have some relatively complex curves and interlocking pieces. I would really like to use a 1/16" bit because that's the size my cutout pattern was designed for. I had a couple of 1/8" mills and a couple of 1/32 mills, but I quickly broke the 1/32" mills. I am going to get a 1/16th to try it out, but can anyone give me some ideas on how to do this effectively. What feedrate should I run? Should I try to cut through the whole .020" at once or is that too much? I tried a high feed rate for Aluminum and it killed the bit pretty quickly.
If it matters, it seems to have much more trouble plunging through the workpiece than actually doing the cutout. I broke the 1/32" bits that way, they deflected upon moving down in Z into the sheet and just snapped.
I am mounting the copper with sticky tape to a block of dense form (rigid) and sticking that to the table with tape. There is no apparent movement in the sheet when it's being machined and the cut lines are nice and smooth WHEN it works.
I think (guessing) the problem is the copper is so soft it's gumming up on the bit. Do I need a MUCH lower speed to do this right? If so, what RPM should I look at? A few times I seem to have gotten magical feed rates which have produced great cuts, but 99% of the time I dont get that. Is there anything I can put on the piece to help prevent the problems, some sort of lube?
Thanks!