New to me Jacobs 91 chuck

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whateg0
Posts: 1114
Joined: Sat Mar 28, 2009 3:54 pm
Location: Wichita, KS

New to me Jacobs 91 chuck

Post by whateg0 »

I just picked up a chuck and a full set of collets. So far I like the performance of this chuck, despite there being some who find it to be a waste of money. Much of what I do is an odd size, so ER collets have been my go-to, but needing a wrench to loosen and tighten when making a batch of parts is a drag. So, this should serve me well.

This one has a problem, though. The key that clocks the collet nose is shorter than it should be. That is, it does not extend to the front as it appears it should. I have included a couple of pictures of chucks I have found on the web as well as a screenshot of an assembly diagram, showing the key. Mine doesn't do that. It looks like the not-to-scale CAD drawing here. Notice that the keyseat does not extend all the way to the front, which seems odd to me since the key must be just hovering for the last 1/2" or so. I can see not wanting to weaken the tapered part of the body, but this doesn't make sense to me.

Has anybody had one apart far enough to know what they key should look like?
existing key.jpg
key diagram.jpg
s-l1600 (2)cr.jpg
s-l1600 (1)cr.jpg
s-l1600cr.jpg
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