On 14 Feb 2009 20:36:48 GMT, "DoN. Nichols"
wrote:
snip
But if you don't have the collets, take a cylinder of brass or
mild steel (hot rolled, not cold to avoid the stresses in the material),
drill and bore to be a sliding fit on the allthread, then use the mill
and a slitting saw to cut a radial slit from the OD to the ID. Put this
in the chuck (with the slit facing away from the #1 jaw, if you want
repeatability) and when you clamp the jaws on the cylinder, it will
close on the allthread and grip it strongly.
snip
If the TIR required is not too close or you can spend some time
shimming, it is possible to use two nuts that fit the Allthread.
Hacksaw a slot though through the middle of a flat on each nut.
File the burrs out of the slot with a triangle file [simply file
straight down below the root of the thread], and as required
clean out with a tap to a easy running fit on the Allthread. To
use, thread on the rod so that one nut is to the front of the
chuck jaws and one nut to the back, and position the nuts so the
slots are between two jaws. When you tighten the chuck the nuts
will squeeze down and grip the rod. As before watch out for whip
of any material extending out the back of the headstock.


Unka' George [George McDuffee]
-------------------------------------------
He that will not apply new remedies,
must expect new evils:
for Time is the greatest innovator: and
if Time, of course, alter things to the worse,
and wisdom and counsel shall not alter them to the better,
what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman.
Essays, "Of Innovations" (1597-1625).