On Sat, 26 May 2018 08:26:31 -0700, "Bob La Londe"
wrote:

I often find myself cutting aluminum flat bar that extends beyond the jaws
of the vise. When that happens it can result in chatter or harmonics that
affect surface finish. Particularly in the actual first surfacing pass. I
can go with a really small WOC, but then the surfacing of the bar starts to
take up a significant amount of time.

Do you think jacks under the part are enough to reduce that or should I just
start working on setting up a second vise aligned with the first on those
machines?


The jacks won't help much unless they apply pressure against the work
or are somehow affixed to the work. With a typical cutter that has a
helix that pulls the work up a thin part will be pulled away from the
jack and you will still get chatter. If you can apply pressure to the
work, say with a finger or a wooden stick, to hold the work against
the jacks then the jacks will help. You can use double sided tape to
hold the part to the jack, I have done this more than once and it can
work very well. The jack of course must be fixed to the table for
this method to work. Have you thought about vacuum? You could make up
little vacuum jacks that would hold themselves to the work and the
table. I seem to recall you saying you have a vacuum pump. Maybe that
was someone else.
Eric