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Jacobs Chuck Key

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  • #16

    Dang, you hit the nail on the head. I didn't realize that you can could adjust the sleeve up and down like that. I thought it would be a fixed constant as such on this el cheapo chuck I have. I have it adjusted so that the key engages as much of the sleeve as possible without binding. What really threw me off was the information I got from the Jacobs tech support guy. Didn't even try to offer any suggestion as soon as he confirmed the Hartford origin of the chuck. Seems like you guys here understand more about the chuck then the tech guy did. As Woussko said.. a k4 is a k4.

    Thanks guys for all your assistance.


    • #17

      In that case you do need the 3/4" chuck that you have. Don't worry about driving-pushing the collar too far. Normally there is a bump stop. The more I look at your pictures, the more I think that another key and cleaning up the ring gear (Try an old toothbrush if you don't have a little fine wire brush around.) will slove your problems.

      Please try what Chic suggested regarding the collar-sleeve, but if you have a piece of of aluminum or brass sheet metal around try to make little covers for your vise jaws. This is just so you won't scratch up the chuck body. Don't worry too much about it. If you don't have a soft hammer, tapping it with a wood block may help. I really think this is more a case of either a bad key, dirt in the ring gear teeth or maybe both. If you need to run your drill in reverse, you'll need to drill out the center hole in the chuck body. Start from the jaws end of the chuck and I hope you have a drill press and also a good way to hold the chuck. The correct size twist drill would be size F which is just a bit over 1/4" and thus will allow the retaining screw to pass through but not be sloppy. If you only need the forward direction, then forget this.

      This is just a thought, but if you can find a short 5/8-16 hex head screw and a flat washer that fits it well (5/8 SAE or 9/16 regular) you might be able to grip the head in your bench vise, place a washer or two over the threaded end and screw on the chuck. Now you could try drilling out the screw hole using a hand held drill. I would go in steps like 3/16" first and then the final size. Again, this is only if you need to run the drill in reverse. When you want to get the big chuck off and go back to normal, please insert the short end of a 3/8" L shape hex key into the chuck jaws and tighten them. Now smack the long arm of the hex key (Allen Wrench) with a little wood block or a soft hammer and it should screw off. Please remember the chuck has right hand threads but the retaining screw has left hand threads. For some odd reason on big 3/4" drills the retaining screws normally (if there is one) have right hand threads.

      Please remember above all else to think SAFETY for yourself and anyone nearby. Tools and machines can be repaired or replaced, but it's totally different with people.


      • #18

        Blind old me didn't see your 4:28am posting where Chic had the answer, so I had to run my monster size mouth again. Anyway, I'm glad that worked for you and yes the industrial grade drill chucks come apart by pressing the body out of the outer sleeve. Please see my PDF files and have a good look. Normally you need an arbor press, correct size bushings and such to correctly take them apart and reassemble your chuck(s). Jacobs has rebuild kits for their true industrial chucks that you can buy through good industrial supply companies. For many of us the problem is finding someone with the equipment and that's willing to work on them at a reasonable price. Most good machine shops and factories get setup as they have lots of chucks to keep in top condition. Anyway good luck with your project and keep posting. Woussko must now take a vacation from this forum. Merry Christmas and Happy New Year to all.

        As for Tech Support, they are there to help, but also to help their company boost sales. It's all about the $$$ factor.
        Last edited by Woussko; 12-19-2006, 07:47 AM.