I am making some rack mounts out of (presumably 6063) 2x2x1/4 angle. My
results are not good. I am using a new, sharp, two flute 3/8" end mill
with WD-40 as cutting fluid. Spindle speed is about 2800; I started
slower and went up to get better results. I am cutting both sides of the
slot.
I am experiencing tearout, vibration and a lousy finish.

Motherly advice?

Kevin Gallimore