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oxford
03-05-2015, 08:54 PM
I recently got a Jacobs 3a drill chuck but it was missing a key. I was already placing an order at McMaster for a few items so I ordered a key for it. It was McMaster part number 3169a15 and said it was for a 3a chuck, I got it and it was marked t6 on the end. The key did not fit the chuck, pilot was the right size but it was like the teeth were either not cut deep enough or maybe wide enough.

I gave McMaster an email and they said they it was the right key and they called the manufacture and there was no change. They did say that there was some reported issues with key not fitting some of the Jacobs chucks when they started making them in China. I don't know when they started making them over there but I think this chuck is not all that new.

I also found a factory Jacobs k3 key and that doesn't fit the chuck either, it fits the same as the one that I got from McMaster. Any ideas for this chuck? Maybe a made in China special?

Toolguy
03-05-2015, 09:22 PM
Sometimes when a key that should fit but doesn't, the sleeve on the chuck that has the teeth on it needs to be pressed up or down a little to make it match the chuck key. The sleeve is a press fit and they don't always get put on right or get changed during the life of the chuck. Sometimes tightening the chuck real tight with the key can force the sleeve up so the teeth don't have much engagement. If that is what's happening, it's a simple matter to press the sleeve back in place. If the teeth don't mesh together, that's a different issue.

Ohio Mike
03-05-2015, 09:31 PM
Your chuck should take a K3 key which is the same key used by the 14N super chuck. Is this a new chuck?

oxford
03-05-2015, 09:37 PM
Ohio Mike, it is a used chuck. A factory k3 key fit the same as the one from McMaster.

Toolguy, that is what is maybe going on with it but the sleeve would have come down towards the pilot hole for how the key is fitting. I will have to give it a look over.

Blackfoot
03-05-2015, 10:14 PM
Sometimes when a key that should fit but doesn't, the sleeve on the chuck that has the teeth on it needs to be pressed up or down a little to make it match the chuck key. The sleeve is a press fit and they don't always get put on right or get changed during the life of the chuck. Sometimes tightening the chuck real tight with the key can force the sleeve up so the teeth don't have much engagement. If that is what's happening, it's a simple matter to press the sleeve back in place. If the teeth don't mesh together, that's a different issue.

I have 4 Jacobs drill chucks. I bought them all new. 2 are 0.0" - 0.5" ball bearing chucks. They came with keys. The key pilots are getting worn and they can be less than nice to use. I tried getting a new key from a local supply house. The fit is worse than a worn out key. It is the correct replacement key (from China). NONE of the chuck keys that I have (including the key for a no-name 5/8" chuck) have pressed on gears. Where do they sell those? I would like to try one.

Roger

Blackfoot
03-05-2015, 10:26 PM
There is a lot of Jacobs chuck and key info here.

http://www.newmantools.com/jacobs/keys.htm#keys

No idea if theirs are any better than anybody else's

Roger

andywander
03-05-2015, 10:34 PM
......NONE of the chuck keys that I have (including the key for a no-name 5/8" chuck) have pressed on gears. Where do they sell those? I would like to try one.

Roger

It's the geared sleeve on the CHUCK that is pressed on, not the gear on the key.

Blackfoot
03-05-2015, 10:55 PM
It's the geared sleeve on the CHUCK that is pressed on, not the gear on the key.

Yup....you are right.....I've known that for at least 30 years. I just don't seem to read good sometimes.

I never thought to check that sleeve. I will tomorrow. I've been thinking about making a new pilot pin for the key from China. It has no value now.

I don't know how hard it is, but I think I can drill it out and make a new pin or grind it down and sleeve it. Gotta be a way to make a usable key.

Roger

Mcostello
03-06-2015, 10:13 PM
Locktite would be an easy repair.

Blackfoot
03-07-2015, 10:52 AM
What is the name of the company that makes Jacob's Chucks, and where is it located? I notice UK on the K3 key.

http://i1378.photobucket.com/albums/ah92/rmedendorp/K3-3_zpsteer4f2z.jpg

Is this a clue?

oxford
03-07-2015, 11:21 AM
Thanks for the replies. I have never taking a chuck apart before so before I muck something up I might as well ask. Is there a procedure for pressing the sleeve? I need the sleeve to go towards the back or MT side of the chuck. Can I just stand it up in the press and use a soft ring on the chuck teeth and press?

Toolguy
03-07-2015, 11:34 AM
Can I just stand it up in the press and use a soft ring on the chuck teeth and press?

Yes you can. I would use aluminum or soft steel for the ring. A short piece of pipe the right size will do nicely. Turn both ends on the lathe to make sure it's square.

Blackfoot
03-07-2015, 12:34 PM
Thanks for the replies. I have never taking a chuck apart before so before I muck something up I might as well ask. Is there a procedure for pressing the sleeve? I need the sleeve to go towards the back or MT side of the chuck. Can I just stand it up in the press and use a soft ring on the chuck teeth and press?

It's probably been 30 years since I've taken a Jacobs chuck apart. I'm pretty sure the sleeve comes off in the direction of the jaws. It goes back on against a dead stop so that the teeth are where they belong. Might even be 40 years ago, but I have taken several apart to rebuild. We had a drawer full of Jacobs chuck parts for rebuild/repair.

You also want to have the jaws closed when you press the sleeve off. If the jaws are not closed, or nearly closed, you will damage the chuck.

Blackfoot
03-07-2015, 01:44 PM
Here you go....

http://www.jacobschuck.com/keyed-drill-chuck-repair-guide

oxford
03-07-2015, 03:32 PM
Thanks Toolguy and Blackfoot. I will take the chuck to work on Monday and give it a go in the press.

Toolguy
03-07-2015, 03:36 PM
Do a little and check it with the chuck key, then a little more, etc. If you overdo, you can press it back the other way.

JoeLee
03-07-2015, 07:39 PM
Pictures of the chuck with the key inserted would help.
I had an 8 1/2N chuck that I had to press the sleeve down a little. With the play that the pilot hole has and the gap between the key gear and the sleeve gear the key would jump a few teeth when tightening, it got irritating so I cured the problem by moving the sleeve down. Follow toolguys advice and you'll be OK.

JL............

Blackfoot
03-07-2015, 08:46 PM
You can also buy repair kits for Jacobs chucks

http://www.jacobschuck.com/MagentoShare/media/documents/jacobs-catalog.pdf

oxford
03-11-2015, 04:10 PM
I got the chuck fixed up(hopefully). I put it in the press, gave a little tug, sleeve went down and the key fits in. I still need to get a drill bit into it and torque down on it and make sure I didn't go to far but I think everything is good on it. Thanks for all the advise.