On 2011-08-05, Ignoramus32707 wrote:
http://igor.chudov.com/misc/ebay/tmp/tmp-8848.jpg

This is a very strange collet. It looks a lot like 5C and the same
approximate size, but it is left hand threaded and the thread is very
coarse.

Looks as though it is designed to lock tighter if it starts to
spin. Is there an index pin in the chuck? And perhaps a four start
thread (or is it three starts), so it will tighten much more quickly
(the usual problem with this style of collet chuck.

Have you measured it to see how close it is to a 5C in
dimensions, other than the thread?

It was in that chuck.

Would anyone have any idea what are those called???

How about "weird". :-) (And hard to find. :-)

Is there a brand on the collet chuck? That is what I would
usually start by searching on.

You may be stuck with a collet chuck with a single collet to fit
it. What is the shank of the chuck? Perhaps a Morse taper No. 3? Or
is it a straight shank? (It sort of looks tapered, but with the angle
of the photo, that could be an artifact of the framing.

If I were forced to use a collet chuck, and could get a full set
of matching collets at a reasonable price, I would be tempted by that.
But since I have a lever drawbar 5C collet closer in my Clausing, I
don't really need that. (Hmm ... if it were a MT No. 2 shank, and no
larger than 5" diameter, I might be tempted to use it in my
Compact-5/CNC lathe -- given the availability and affordability of the
collets. :-)

Stumped in Illinois

Color me "ditto". :-)

Good Luck,
DoN.

--
Remove oil spill source from e-mail
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---