"joel" wrote in message
...
trying to figure out where I'm going wrong...


1 3/8" brass hex stock chucked up nicely in the lathe, need to bore a
7/8" x 3" deep hole. i center drill then progressively drill up to 1/2"
and slightly shallow on the depth so i can finish later. everything good
so far. i switch over to a small boring bar to open it up another 1/8"
so i can switch to the 1/2" bar for the finish. The small bar leaves
some ripples which i attribute to tool flex, but i figure the bigger bar
will be stiffer and there shouldn't be a problem. However, with the
bigger bar, the problem is remaining the same. i have lots of ripples,
some as big as 3-4thou down the length of the bore. all combinations of
fast/slow feed rate, fast/slow RPM, large/small cut seem to make no
difference. the larger boring bar is a 1/2 kennametal with clean, sharp
insert. Turning the outside diameter down results in clean, smooth
finish.

I'm ripping my hair out on this. aluminum, steel, etc. seems to have the
same effect.

help?

--Joel

Hi- raise the bar above the center line of the lathe by 1/8 "or more. This
will prevent the part of the tool below the side cutting edge from rubbing.
Jim.