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  • Jacobs super chuck question

    From bp@www.zefox.net@21:1/5 to All on Wed Mar 13 23:35:15 2024
    I have a knurled-sleeve Jacobs No. 1 Super Chuck which came
    to my hands among tooling for a lathe. The chuck has a small
    slotted screw in back end, near the outer perimeter, roughly
    parallel to the shank.

    Anybody have an idea what it's for? I don't think any Jacobs
    chucks used screws from the factory. First thought was maybe
    a rotation stop to prevent putting a wildly-wrong drill in
    a production setup, but the chuck adjusts full range.

    The question is mostly a matter of curiosity. The chuck looks
    rather beat up, though it's not seized and the jaw surfaces
    aren't obviously mangled. I'm not likely to use it soon....

    Thanks for reading, and any ideas.

    bob prohaska

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  • From bp@www.zefox.net@21:1/5 to Jim Wilkins on Fri Mar 15 23:43:57 2024
    Jim Wilkins <muratlanne@gmail.com> wrote:
    wrote in message news:ustd7j$16u57$2@dont-email.me...

    I have a knurled-sleeve Jacobs No. 1 Super Chuck ...

    ---------------------

    Does it have diamond knurling? I have a very old Jacobs that does, but no extra screw in the back. Perhaps it was added to attach a work stop for production?

    Yes, it's diamond knurling. I took the screw out and looked inside,
    the screw hole runs into the annular passage where the tails of the
    jaws reside. No moving parts visible at all. The screw is very neatly
    set so it doesn't alter the outline of the chuck significantly. Not
    at all a hack job.

    Could it have been to connect some kind of purge line, to keep debris
    from getting into the chuck?

    The whole chuck looks battered, as if it was used in an extremely
    rough environment like a mine or quarry, or maybe a heavy blacksmith
    shop. It moves freely when more than half open, closing it all the
    way takes a key and some effort but no other tools.

    The oddest artifact is three marks between the key pivot holes.
    It looks as if the chuck was placed in a larger three jaw chuck
    and squeezed until the larger jaws left impressions between the
    pivot holes. Must have taken considerable force..

    Thanks for writing,

    bob prohaska

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