"Jon Anderson" wrote in message ...

On 19/04/2017 6:10 AM, Bob La Londe wrote:

Here is what I am asking. When I am spiral milling to drill holes I
noticed at more than about 0.40 inches it starts making some noise that
annoys my primordial hind brain. Since I work with a lot of 1/2" bar
stock that leaves me finishing on the drill press among my other
secondary operations. What causes that eerie noise, and what can I do
about it?

I suspect end mill deflection, which though slight, becomes ever more
pronounced as depth increases, causing a sort of chatter due to the
rubbing contact of the flutes. Might try stub end mills,

*** Unless you are using long reach end mills 1/8 inch shank anything pretty
much is a stub end mill.

and relieve the
shank a bit behind the flutes.

*** That is not at all a bad idea. I may have to look into that. Even a
couple thousandths would probably do if deflection from rubbing is the
issue.

Jon

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