Any tips for deep slots/profiling in aluminium?

[EddyCurrent]

I don't know about aluminium but with wood an upspiral bit would help clear the chips, unlike wood the aluminium is not going to splinter on the top surface by using it. I would definitely use a larger cutter for the roughing cut as you say.

[JAZZCNC]

I don't know about aluminium but with wood an upspiral bit would help clear the chips, unlike wood the aluminium is not going to splinter on the top surface by using it. I would definitely use a larger cutter for the roughing cut as you say.

Eddy Milling cutters all tend to be spiral flute it's just the Helix angle that changes.