In article ,
says...
Here are some collets I'm trying to ID. 2 5/8" LOA, 15/16" wide around the
machined area at the base. No threads. I have a whole board of these, in all
different round and hex sizes, plus a few odd ones like rectangular holes.

http://members.aol.com/gto69ra4/photos/collets.jpg


Probably fits the spindle of a turret lathe or automatic
screw machine. You may be able to ID them from one of the
docs he

http://www.hardingeworkholding.com/w1collets.html

I just quickly scanned the Hardinge workholding catalog and
the first match I see is for a Hardinge no. MP1287 which
fits a Pratt & Whitney #2 turret lathe.

Ned Simmons