I think I just learned something.

I am trying to bore a 5 inch diameter hole in 6 inch diameter
aluminum bar stock about 5 inches deep.

I was getting tool chatter.  At first I thought I needed a stiffer
boring bar. My boring bar is about .75 inch in diameter.

I discovered if you speed up the carriage feed the chatter goes away
more or less.

Some of you guys on here are expert machinist.

Have you heard of this before ?

Paul Lamar

Paul,
The spindle speed formula    RPM= Surface Feet per Minute x 4/ tool Diameter
SFM for aluminum is 400 & R is .002/.009
And the feed rate formula     Feed (rate per minute)= RPM x T (number of teeth) x R (chip load)

Ray Hellstrom

Thanks Ray,

Interesting.

Paul Lamar

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