CNC Machine (Page 2 of 2)

Use a carbide end mill, I assume you have the 1/8" collet? Get a good cutting oil and start cutting slowly, with very light passes. I would recommend starting out at a safe speed & feed until you find a comfortable rate. Your spindle may be weaker than mine was, or stronger for that matter. I'd say, start out by jogging down to the aluminum, feeding in 1mm after a shot of cutting oil & try 10mm/min with a shot of cutting oil a few mm in. Check the chips produced, is it a fine chip, like sand? If so, you should be fine with using cutting oil at that speed.
In a large VMC, or lathe, or what have you, you want large chips with good heat xfer, but trying to chew large chips with the tiny spindle on my CNC 3020 would have shattered my end mill or stopped the spindle.
Forgive me if I sound scatter brained, been a long day. The moral is, go SLOW, the little machines just don't have the power for high speed stock removal.