Tim Wescott wrote:
On Mon, 24 Mar 2014 19:47:31 +0000, Cydrome Leader wrote:

I keep running into an issue with spiral reamers that leave what appears
to be rifling in anything (aluminum) that I ream.

changing speed and feed rates doesn't seem to matter. Dry or with
cutting oil doesn't seem to matter either.

The straight reamers of the same size don't seem to have this problem.

What might be causing this, or how does one stop it?

Use straight reamers?

heh, yeah.

Is this "normal" behavior? I can't quite figure out how it leaves such
distinct marks that appear to match the shape of the cutting flutes,
unless it's somehow bouncing around backwards like when a shaft is in a
worn bearing and it makes that horrible chatter. I've been following the
drill 1/64th undersize tip.