Quote Originally Posted by JAZZCNC View Post
Not always the best for Alu. It depends on the job and type of cut. If your profiling for instance and not slot cutting then more flutes are better. They allow faster feed rates with higher MRR and give better finish.
I find 3 flutes are best at roughing.? They are Stiffer and more ridged so can cut deeper. Feed rate and MRR is higher. They give a better finish if not roughers because More flutes.
The only thing is they need more attention to chip clearing and chip clearence. So not ideal for Slotting or small pockets and tight corners where tool cuts on two edges. When used with trochoidal tool paths they rock compared to 2 flute and can be run much faster with more DOC.
Agreed but generally this is good advice. I use 3 flute 8mm corn cob to rough. The rest are 2 flute.

Certainly anything higher than 3 in alu generally is a problem for most.