On Fri, 21 Dec 2012 13:53:55 -0600, Jon Elson
wrote:

rangerssuck wrote:


I don't think I saw anybody suggest this: Lock the carriage down before
you part off. Also, you only want the minimum length of parting tool
unsupported - just enough to reach to the center of the part.
Important, but I'd like to expand on that. There are many ways to
mount the cutoff tool holder to the compound, and what you want is to
have the compound rest and swivel as close to under the tip of
the cutter as you can. It is not just the overhang of the tool
itself, it is the whole stack that matters. When the tool tip
is far in front of the swivel, it allows many lathes to suffer
a forward rocking of the compound assembly, that causes the tool
to bite into the work. This is bad for any turning operation, but
much worse on cutoff. If the compound swivel is as far forward
as possible, then this forward rocking should be reduced, at least
by shortening the lever arm. The best case is when the tool tip
is maybe less than 1 inch in front of the swivel center and also
centered left-right over the swivel.

Jon
===============

For the less massively constructed lathes, common in home
shops, a rear mounted upside down tool holder for the cutoff
blade that mounts directly to the cross slide rather than
the compound [top slide] can be helpful.

For a picture of one we designed and built as a class
project click on
http://mcduffee-associates.us/machining/rearcoth.htm.
As the Brits might say -- it worked a treat.

Casting kits are available
http://www.statecollegecentral.com/m...the/MLA-6.html