On Fri, 14 Jan 2005 23:56:37 GMT, machineman
wrote:

Jim Stewart wrote:

Is it considered acceptable to hold work
with a Jacobs style chuck. Specifically,
is it ok to put a piece of drill rod stock
in the chuck, mount the chuck in a rotary
table and then make cuts on the stock with
my mill?
Usually not a good idea. The taper does not take side loads well and
can come loose. I saw one if my bosses try to mill a part with and
endmill in a drill chuck once, got about 1/4" before it fell off :-) If
you have some other way to hold the chuck other than by the tapers, it
might work. If its a thread-on chuck you have to watch which direction
you are milling or you could wind the chuck off of the arbor.
There are some inexpensive collet chucks available for 5-c collets.
They work horizontally or vertically and are easilly attached to a
rotary table.

http://busybeetools.ca/cgi-bin/pictu...6&NTITEM=B1963

The only sort of work holding a Jacobs chuck is good for, it to hold
various socket head capscrews, set screws, rod stock and HSS lathe
tooling when using a grinder or belt sander for variously shortening
or grinding so you dont burn your fingers. I do this regularly with
an old chinese 5/8 drill chuck that has a buggered up taper. Keeps
from burning your fingers nicely

Gunner

"At the core of liberalism is the spoiled child -
miserable, as all spoiled children are, unsatisfied,
demanding, ill-disciplined, despotic and useless.
Liberalism is a philosphy of sniveling brats." -- P.J. O'Rourke