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Gunner
 
Posts: n/a
Default Lathe chatters and I can't get rid of it

On Tue, 03 Jan 2006 22:37:25 -0600, Jon Elson
wrote:

Ben Woodward wrote:
Can't measure any chuck movement with a prybar under the chuck on the
saddle.
Is this normal, or should I 86 this lathe?

Well, apparently from the previous message, it USED to work OK, right?

So, what changed? Did something break, wear out, or what?

If it absolutely won't cut, then either the tool profile is wrong
(not presenting a sharp edge to the workpiece) or the material is
hard as hades. Not being there, I can't tell. If the cutoff
tool is too high, it presents the front face to the work, instead
of the cutting edge.

If it tries to cut, but just grumbles and the work tries to climb
over the cutter, then the workpiece is at least very hard, and/or
the whole stackup from the bed, carriage to the tool is flexing,
somehow. Usually it is the compound rest and toolpost that are
the weak links.

Also, extending the compound rest so it has an "overhang" can
seriously alter the dynamics of the lathe. It makes the tool
point have a long lever arm to the compound swivel, and on some
lathes can dramatically increase the "springiness" of the whole
lathe.

Jon


The one place Ive seen that a "Lantern post" type tool holder is
great..is for cutting off.. assuming you stack enough spacers under
the cutoff tool and can get in close enough to the workpiece. All the
forces are directly over the compound, and the only leverage is front
to back, rather than front, back, and to the side.

When I had the old Logan 10, I ground down a chunk of 5/16 rectangular
bar stock so it had a .5 long cutting tool on the front of it, with a
1/8" width..and I stuck it in the lantern post tool holder with
spacers under it to get it to center height. That puppy would hog out
a groove really slick

Gunner

The aim of untold millions is to be free to do exactly as they choose
and for someone else to pay when things go wrong.

In the past few decades, a peculiar and distinctive psychology
has emerged in England. Gone are the civility, sturdy independence,
and admirable stoicism that carried the English through the war years
.. It has been replaced by a constant whine of excuses, complaints,
and special pleading. The collapse of the British character has been
as swift and complete as the collapse of British power.

Theodore Dalrymple,