Just musing on trying to use tiny tooling in my mill. Feel free to chip in and explain why I'm bonkers, won't worry me if nobody does

I want to play at making injection moulds in aluminium, I want a nice clean finishing pass with cutter diameters down to around the 1mm mark. Unfortunately, 200 ft/minute then requires 19404 rpm

I can wind my poor old mill up to 2000 rpm but I can't say it enjoys it. Ten times that is cloud cuckoo land. The best I can offer in my comfort zone for a long cut is 1200 rpm.

Too slow a feed rate invites chatter, I think the tool rounds out the cut entry, rubs for a few teeth then suddenly takes a biggy so vibration can set in. Too fast and the tool will bend leaving an unremoveable excess. Have to do some test pocketing.

Gut says rough it out to 0.25mm under with a 3mm cutter, then finish with the 1mm and a feed rate of 1 mm/second giving a cut depth of 25 microns per tooth. When it reaches a 3mm corner the tool will suddenly start removing 0.45 rather than 0.25, so probably best to get in a good supply of votive candles.

I will spiral down on the finishing pass so there are no plunges to leave marks.

There's a 2 degree draft angle. I can either use a 2 degree tool and let it rub, which could introduce chatter, or use a ball nose and accept a scallop. A 0.25mm descent per lap would leave a 12 micron scallop which is right on the tolerance of the machine and hopefully easy to polish out.