In article ,
F. George McDuffee wrote:

On Tue, 06 Apr 2010 22:47:05 -0400, Joseph Gwinn
wrote:
snip
Instead of machining the face a
little flatter, the whole BXA tool post rotates on the compound, causing the
bit
on the BXA-16N to dig a bit deeper.
snip
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Old time machinists books advises (when possible) setting up a
tool for a lathe cut, that it should be arranged such that if
anything shifts the tool swings out of/away from the cut rather
than into the cut.

To the extent practical, for sure. But the setup is an Aloris BXA toolpost with
a BXA-16N toolholder held in the left dovetail (and thus perpendicular to the
bedway), cutting up close to the chuck, and the carriage can get only so close
without a collision. There is an irreducible torque arm here.

Another thing to note is that I didn't appear to have the problem when feeding
by hand. The power feed was slow, and so the carbide insert didn't cut when
presented the full face - the rise in force was too slow, so it just shoved the
toolpost gradually aside. If it had dug in and started cutting, the forces and
thus torque on the toolpost would have been lower.

It appears that the problem is common, as is the solution - a piece of paper
under the toolpost, which I will try.


Joe Gwinn