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Thread: Old Jacobs Chuck
10-21-2011, 01:24 AM #1
Old Jacobs Chuck
I have a very sturdy old Champion 1600 drill press ($50 at the metal recycler) that is missing the chuck key. Chuck says
"Jacobs Chuck 34B Cap. 0-1/2 THD 3/4-16" on it.
Can't find a chuck key anywhere to fit it. Any help out there?
10-21-2011, 03:42 AM #2
10-21-2011, 10:37 AM #3
Jacobs Chuck Specifications
the only 3/4" threaded mount chuck is a 36B and takes a K4 key. My chuck isn't listed (specs don't match) though, and neither the K3 nor K4 keys fit it.
10-21-2011, 10:50 AM #4
Well, what doesn't 'fit'?
If the teeth don't fit, that's kind of a deal breaker.
If the pin is too large, reduce its diameter.
If the pin is too small, install a bushing.
If you can remove the chuck, shop it around at a few well-stocked supply houses, see if anyone comes up with a fit.
Or just buy another chuck.
Did you try a K3C?
You might want to specify the details of the chuck key, perhaps somebody has one sitting in a drawer.
Next time you visit, tell us of your failures, and we won't repeat them.
I suspect Michigan Pnuematic has somebody at its parts desk that could help.
10-21-2011, 11:50 AM #5
I found the chuck listed in the 1974 Jacobs catalog.
VintageMachinery.org - Jacobs Manufacturing Co. - Publication Reprints - Jacobs Chucks
It takes a 1974 K3 key I guess. The current K3 key pilot inserts completely and snugly, but the teeth only mesh slightly. They will quickly strip. If I grind 1/16" of the narrow end of the taper down to the diameter of the pilot, and shorten that if needed, they will mesh nicely.
Plastic, help thyself.
10-21-2011, 12:12 PM #6
I have an old jacobs chuck that the bottoms of the holes were packed with epoxy, as well as the valleys on the teeth. I picked it all out and now the standard key fits fine. I have also had to bush out the holes because of overtightening/wear.
10-21-2011, 01:25 PM #7
Welcome to the forum. We're not always this testy, but sometimes we're even worse.
If neither the K3 nor K4 keys fit, and suggested K3C doesn't fit either, then it may indeed be time to "chuck the chuck" !
My own understanding, based only on looking at the Jacobs table on the Michigan Pneumatic site, is that the K3C key is intended for the 34-33Cm which is a model 34 that fits a #33 Jacobs Taper with a locking collar I've never seen such an arrangement.
As your chuck is not listed on the Jacobs site, it may be an obsolete model or more likely it is a "special". Have you tried calling Jacobs?
10-21-2011, 06:17 PM #8
10-25-2011, 06:33 AM #9
I've seen others with locking Jacobs backs - but in the days when a drillpress was expected to make holes in more than just particle board and acrylics.