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

Frequently, I have a perfect example.
Speeds, feeds, and tool shape are always a big factor. That and setting the tool tip location off or high of center are the other big ones, though those are basic. I always look up the suggested speeds and feeds in Machinery's Handbook. this completely saved me on one occasion where I had large interrupted cuts on a square steel part having a round shaft turned on it. (leaving about 1/2 of it square.) It was an odd steel alloy, and when I looked it up I was cutting it at 1/2 the speed and 1/4 the feed rate suggested. I was breaking tools about every 3rd part too. I was somewhat scared of what would happen when I cranked it up. But I decided to try it for 1 part. It cut perfectly and left a mirror finish too! I ran out the last 30 parts without breaking another tool! (inserts) It really does matter!
Bill Jepson




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