According to :
I have a 5C Chuckollet collet chuck made by the "Hancock Mfg Co of
Santa Clara, CA" I can't see how to stop the threaded protion of the
chuck spinning as I try to screw a collet into it. Is there anyone
have a collet chuck like this who could help with info on using it?

I'm not familiar with your particular chuck, but *usually* a 5C
collet holder has a pin back in the bore which engages the groove in the
collet to prevent the collet from rotating while you tighten the
threaded portion (be it a drawbar or a threaded plate or ring, or a
lever closer of some form) onto the back of the non-rotating collet.

It may have been sheared off (or removed by a previous owner) if
this is not a new device.

Good luck,
DoN.
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