View Full Version : old Jacobs No. 100 chuck needs repair

08-17-2005, 08:10 PM
when i got my old SB 11" lathe it came with an old Jacobs keyless chuck with the following writing:

Jacobs Chuck No. 100
Cap 1/4-3/4
Center Rest
Hartford Conn
United States of America

you tighten the jaws by hand, then tighten a lockring on the chuck nose to lock the jaws in place. there are no other numbers on the chuck (none on the nose and no additional model numbers). it has a Jacobs taper to mount it to the No. 2 Morse to mount in the lathe tailstock.

it has brass jaws that are in need of replacement. i have reviewed the info on how to disassemble the chuck, but i have not been able to find a source for parts (the jaws and threaded ring). i have found many modern keyless Jacobs Model 100 chucks, but they are nothing like the one i have.

any ideas for a source for parts? i hate to buy a "new" (used) chuck on fleabay, but if parts are not available i may have to. the action on this chuck is so smooth i hate to not get it working.

andy b.

08-17-2005, 08:26 PM
Andy, that chuck is not a drill chuck. It is a center rest chuck, they were also called armature chucks.

It is used in a similar fashion to a tailstock center to hold work in a lathe. They were commonly used to hold starter and alternator armatures when turning the commutators.

The brass jaws are adjusted to hold the OD of work that does not or cannot have a center driled in it, and locked in place.

They are a useful chuck, and come in handy at times.

Here is a supplier of replacement jaws, I have not used them, and have no affiliation.

08-17-2005, 10:12 PM

you nailed it!!! i was searching past auctions on fleabay just a minute ago and found this:

http://cgi.ebay.com/Jacobs-100-Commutator-Chuck-South-Bend-Lathe-Interest_W0QQitemZ7535683270QQcategoryZ25292QQrdZ1 QQcmdZViewItem

and that is in fact exactly what i have. i think i will pick up a "normal" drill chuck to use and keep the armature chuck in the toolbox for an occasion when i may need it.

it does pose an interesting question though. i wonder why an 11" lathe with a 5' bed needed an armature chuck? i don't know what type of armature would be 4' long (at least one that would fit a 3/4" chuck). that is the only chuck that came with it, and the guy i bought it from said that was the only one he saw at the auction with it when he bought it.

andy b.

08-17-2005, 11:07 PM
I got one in a batch of local auction stuff about a year ago. I didn't think I'd use it much then and stuck it in a drawer. Took me almost two days to find it again. I've put it to work at least 10 times in the last couple of weeks. Nice to have when you need it.

Make sure you put a drop of oil on the jaws.