"Jon Elson" wrote in message
rvers.com...
snip---

Without having to buy $60 Ski-Carb end mills, I generally use small
4-flute end mills in aluminum, as you get twice as many cutting edges
per revolution.

But at the cost of less chip clearance. You generally can't run the table
feed fast enough to load the cutter well with two flutes, so 4 really serve
no purpose, and the minimal clearance you spoke of make using them a real
PITA. Lots of flute loading if you run at respectable speeds, and smearing
at the cutting edge. Avoid using 4 flute end mills in aluminum when
possible.

Today, practically all 4-flute cutters are center-cutting, too. Also,
don't forget the 3-flute cutters. They are a nice compromise. You can
even get 1-flute cutters!

Jon

But if you're serious about machining aluminum specify aluminum cutters, as
Jon already advised. The clearances are way different so they perform heads
and shoulders better. Aluminum cutting end mills are often so marked on
the shank. Don't use them for steel. They'll cut, but the slender edges
can't cool very fast and quickly burn.

Harold