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  • Another Jacobs chuck key thread.

    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?

  • #2
    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.
    Kansas City area

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    • #3
      Your chuck should take a K3 key which is the same key used by the 14N super chuck. Is this a new chuck?
      Mike
      Central Ohio, USA

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      • #4
        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.

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        • #5
          Originally posted by Toolguy View Post
          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

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          • #6
            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

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            • #7
              Originally posted by Blackfoot View Post
              ......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.

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              • #8
                Originally posted by andywander View Post
                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

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                • #9
                  Locktite would be an easy repair.
                  mark costello-Low speed steel

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                  • #10
                    What is the name of the company that makes Jacob's Chucks, and where is it located? I notice UK on the K3 key.



                    Is this a clue?

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                    • #11
                      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?

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                      • #12
                        Originally posted by oxford View Post
                        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.
                        Kansas City area

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                        • #13
                          Originally posted by oxford View Post
                          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.
                          Last edited by Blackfoot; 03-07-2015, 12:36 PM.

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                          • #14
                            Here you go....

                            http://www.jacobschuck.com/keyed-dri...k-repair-guide

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                            • #15
                              Thanks Toolguy and Blackfoot. I will take the chuck to work on Monday and give it a go in the press.

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