On Tue, 27 Jul 2004 14:11:07 -0500, Don Foreman
wrote:

I have a T-shaped parting tool in an Aloris BXA7 holder that won't cut
straight. It drifts to one side or the other as the cut progresses.
The bit is .063" at the bottom, .094 at the top, .686 high. As far
as I can tell the cutting edge is ground square (parallel to the
lathe axis), the bit is vertical in the holder to within a thou or
two, and the bit was square with the workpiece at center height.

I have a thinner tapered parting bit that does cut straight. It's
.0625 at the top, .043 at the bottom, .687 high.

The lathe is a 15x50 gearhead, no problem with stiffness or rigidity.

I'm not exactly a newbie with a lathe, but this one has me puzzled.

Any suggestions about what's going on here, please?

Thanks!

Don Foreman
Don,
Sometimes, when this happens to me, the parting blade will be dull on
the side(s) just back from the cutting edge. So, instead of having two
sharp corners there will be a slight radius along one edge. This is
the edge where the top meets the side. Then, grinding the tool back
fixes the problem.
ERS