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4 jaw screw chuck

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  • 4 jaw screw chuck

    The recent threads on chucks has me wondering if there are any 'screw' chucks- by that I don't mean screw-on as to the spindle, but multiple screw adjustable jaws instead of the scroll. Been thinking about this for a long time now. Seems it could have an outer ring toothed on the inside, driving a mating gear on each jaw screw. Too complex maybe- too prone to damage- is there any such thing anyone knows about?
    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

  • #2
    I've never seen a "screw chuck" that didn't have independent jaws. I can't imagine any drive system that would be significantly better than a scroll when you consider how long they last, how well they work, their low maintenance requirements, and their tolerance of abuse.
    Any products mentioned in my posts have been endorsed by their manufacturer.

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    • #3
      Using a circular rack is not a new idea

      This is from an 1875 catalogue



      Here's an independently adjustable three jaw from the same catalogue:
      http://vios1.rdg.ac.uk/olib/images/n...2_b645/059.jpg

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      • #4
        Interesting. One of the issues which would have to be addressed is the surface area where each geared screw would bear against as it puts pressure on the workpiece being held. One would think that given a decent bearing area here, the chuck would be very repeatable, and you should be able to remount a workpiece and have it stay within a thou quite easily.

        It would seem to me that if the jaws were ground properly, then any diameter being clamped would automatically center well. The problem with a scroll chuck, as I see it, would be that in order for the scroll to be able to turn, it has to have some play radially, hence the probability for the jaws to close in different positions any time it's closed on a workpiece. Using the master hole to tighten would minimize this of course, but it's not a cure-all. Being able to adjust the jaws with leadscrews which bear against non-movable surfaces seems like a better way.

        Everything has its pros and cons, and I'm not trying to knock the scroll chuck, just exploring other ways for their possible advantages.
        I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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