How do I remove this broken arbor from the Jacobs Chuck?
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  1. #1
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    Default How do I remove this broken arbor from the Jacobs Chuck?

    I was drilling a large hole with this in the tailstock when the bit grabbed and broke the tang. Does the hole go through the chuck or do I use a wedge on the small shoulder between the chuck and the arbor?



    Sent from my Nokia 7.1 using Tapatalk

  2. #2
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    I'm guessing here but that may be a shrink fit, at least if the "3 Taper" refers to the shank and not to JT3, which is an inside taper.

    What makes me suspect the former is that the shoulder looks too small for wedges to likely work unless you custom make your own for a close fit.

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    Just weld a new tang on it. I have done it several times. Easy peasy.

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    The shoulders on MT/JT arbors like the one in your picture usually aren't large or square enough to drive off with wedges, but you can file or grind a better shoulder to use with the wedges.

    You can also cut the bulk of the arbor off, tap it for something decent like 5/16 or 3/8, then use a slide hammer to pop it out.

    On many chucks of this type, you can drill a 1/4" hole, from the jaw end, through the end of the body into the recess where the JT taper attachs, and use a punch to drive the arbor out.

    A good soak in PB Blaster or your preferred penetrating lubricant should make it easier to get the arbor off, too.

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    You can drill through the back of the chuck and use a punch to press out the shank. Personally I would follow the suggestion to weld up the tang.

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    More on drilling. Some will be amazingly tight. On an 18N put together (I assume) by W&S (had their 1.500" hardened shank) , I drilled 21/32 and used a 5/8 pin to push with in press. Finally broke free with a sound like a cannon shot

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    Quote Originally Posted by moonlight machine View Post
    Just weld a new tang on it. I have done it several times. Easy peasy.
    I used work at a really big place that had lots of damaged tapers just like that one. We used to send them out to a company that specialised in repairing tangs. Broken ones and badly scored ones. They came back welded up as good as new.

    I have welded them myself if it was just the tang, as you say it's a pretty simple process.

    Regards Tyrone.

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    My favorite way to remove such an arbor, is to cut a piece of heavy walled pipe

    a little longer than the arbor, which will slip freely over the arbor and bear

    firmly against the back the chuck.

    Slam vertically on an anvil or similar surface. (watch out for pinched fingers)

    Inertia will pop many of these out.

    Immersing the arbor in liquid nitrogen also helps

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    Depends on how it was put in there. I had one once that was apparently installed with red locktite and a sledge hammer. We tried the "drill the chuck body and punch it out" trick. Also the "cross-drill the arbor for a dowel and then use wedges". Also heat combined with all of the above. Eventually cut it off with a saw, chucked it in the lathe, and bored it out until nothing was left of the arbor except a foil-thin shell. Even then it was stubborn, had to peel it out of the bore. I think it was glued in somehow (not sure how the glue survived the heat).

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    Thanks all.

    Sent from my Nokia 7.1 using Tapatalk


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