The 91-A6 or 91-F6 came with a 4" flange mount that was designed for special
applications or threaded spindles. Apparently the user was expected to
fabricate his/her own adapter. The A6 was recommended for lathes with
2-1/16" or larger threaded spindles; the F1 for 2" or less.

There was another Jacobs chuck (Model 50?) that might have been designed for
threaded spindles. At least the ones I've seen on Ebay all seemed to be
designed for lathes with threaded spindles. They featured a slightly
different collet design that had a lower maximum capacity - might have been
1", compared to 1-3/8" for the 91 series.

Mike

"rhncue" wrote in message
...
I've been seeing a lot of Jacob's collet chucks on e-bay lately and
I've noticed most are LOO or LO or other mounts for particular lathes.
What I'm wondering is did they make a chuck that can be mounted to a
threaded backing plate or if these other specialty chucks can be adapted
to using a threaded backing plate. I've got a 5C collet closer mounted now
but I certainly like the idea of being able to use the much larger
collets. As I have never seen one of these chucks up close and I don't
want to buy one just to appease my curiosity I thought maybe some one on
this group would be knowledgeable on them.
Dick


--
Richard H. Neighbors
Building fine pool cues for real pool players at affordable prices.
Over 35 years experience in cue repair.
318 Linden st.
Cinti. OH 45216
ph# 513 233-7499
web site: http://www.dickiecues.com