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Stuck 14N Jacobs Chuck disassembly?

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  • Stuck 14N Jacobs Chuck disassembly?

    I have a stuck 14N Ball Bearing chuck--the jaws are stuck all the way open. The instructions for disassembly say to close the jaws so they don't get damaged when you press the outer ring off. I can only move the jaws a little bit (they don't even clear the end of the chuck before they jam up.)

    What is typically damaged when the jaws are in the wrong position? I don't really have a choice but to force it off, unless you have any better ideas?

    Thanks--Mike.

  • #2
    Can you see if anything is jammed in one of the jaws that might be wedging the jaws open.
    The shortest distance between two points is a circle of infinite diameter.

    Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

    Southwestern Ontario. Canada

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    • #3
      JMO, but there has to be something, a chip or speck of something caught behind one of the jaws.
      (Unless this chuck is worn out, and one of the jaws has cocked slightly jamming it?)

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      • #4
        I am wondering if I try to skim a light lathe cut across the opening that the jaws are supposed to protrude from. They look like they might be catching on the edge of the opening?

        I slipped a pipe over the chuck key and even with lots of force it won't open.

        What will I break if I press the outer ring off the chuck to free the jaws?

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        • #5
          it sounds like yours is jammed pretty good, but i'm assuming you did lubricate the living daylights out of it first, didn't you? i've bought a few jacobs super chucks that have been incredibly dry and had chips and filings jamming them up. in all of mine, a very liberal spraying of wd-40 from every angle, followed by a few minutes to soak in, and all it took was a strong jiggle of the handle to get it moving afterwards.

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          • #6
            I just "repaired" a Jacob's chuck. Someone had drilled through a part and rubbed the end of the chuck on the part. a few strokes with a diamond stone and I could close the chuck. While involved I took it completly apart after a real good soaking with Kroil. A little extra polishing in the jaw grooves where they exit the chuck and it runs like new.

            Pete

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            • #7
              Originally posted by mikem View Post
              I have a stuck 14N Ball Bearing chuck--the jaws are stuck all the way open. The instructions for disassembly say to close the jaws so they don't get damaged when you press the outer ring off. I can only move the jaws a little bit (they don't even clear the end of the chuck before they jam up.)

              What is typically damaged when the jaws are in the wrong position? I don't really have a choice but to force it off, unless you have any better ideas?

              Thanks--Mike.
              The last one or two teeth on the back side of the jaws may interfere with the ring and be broken on disassembly. I have done it on a smaller Jacobs chuck. After trying the above suggestions, go for it. New jaws are not expensive on eBay. The teeth clear about half way open, which is where I set them before disassembly. It is more stable that way while pressing the ring off.

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              • #8
                I did oil it well, but to no avail!

                The nose of it seems really soft and looks like maybe someone beat on it and mushroomed the end onto the path of the jaws?

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                • #9
                  If the "nose" is soft, take a clean and sharp single cut file and dress it until all edvidence of the "beating" is removed. Then debur the inside edges with a stone or a fine chainsaw file. The "beating" was probably done while trying to mount it to a taper. Sometimes the bigger hammer treatment does more harm than good.

                  I like to put the taper in the freezer for a bit and heat the chuck until it is almost too hot to hold. If both the internal and external taper are clean and burr free, there is nothing more than a tap with a dead blow hammer to seat the chuck.

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                  • #10
                    From an internet search it appears these are the parts that come with a repair kit. So.... these are the parts that one can basically destroy in the attempt to free up the chuck.




                    http://www.use-enco.com/1/1/68181-30...uck-parts.html

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                    • #11
                      I got the jaws to protrude slightly by cleaning up the peening on the nose but the chuck is still jams after a few turns. Tomorrow maybe I'll try to press it apart. Buying the parts kit for $140 is more than what is sensible for me to spend since I have other chucks. It is just a shame that this one screwed up!

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                      • #12
                        Parts are $45 on eBay if I ruin it!

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                        • #13
                          The jaws have to be at mid range open to press the chuck appart. Example chuck range 1/8-1/2 the jaws have to be set at 5/16 open or you will damage the chuck. Just soak it in 50% automatic transmission fluid and 50% aceton and hopefully you will be able to move the jaws

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                          • #14
                            I will try the soaking......what have I to lose? It is so crazy that it turns freely for a few revolutions and then solidly jams. There May be an imbedded chip in the gear teeth?

                            I tried a tube slipped over the chuck key for more leverage and could feel the handle of the key flex from the force. More force than that will probably break or permanently deflect something.

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                            • #15
                              Open it all the way and work on the inside of the nose. Maybe even file off a bit more from the face of the nose. It only takes a "frogs hair" to cause them to stick. Soak it with Kroil or ATF and let it sit for a day or two.

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