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Creative workholding on the Lathe, Chapter 6 (or is it 7, 8??)

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  • Creative workholding on the Lathe, Chapter 6 (or is it 7, 8??)

    The latest installment in the continuing saga of hay harvest in the Green Bluff, Washington area.

    All hay harvesting machinery has some sort of overload protection, usually either a slip clutch or shear pin.

    Slip clutches have their own set of problems. If they are not exercised regularly, they can rust together and transfer any overload protection responsibilities to the next weakest component, often the driveline or associated universal joints.

    The advantage of the slip clutch is that as soon as the problem is resolved, it is just back to business as usual.

    With the shear pin style, the usual problem is the devious nature of the design engineer, in his/her attempts to prevent insertion of anything other than OEM approved devices.

    I say this somewhat tongue in cheek as I realize that there are very valid reasons for using the proper components as designed to protect the the rest of the machine. However it can be difficult to keep this thought in mind when faced with an hour and a half drive both ways to spend $25.00 each for what is essentially a 12 - 24 machine screw.

    So one of the local farmers wants something tougher than the 10 - 32 Allen capscrews that I had given him to get him going again. I have some larger 1/4 -20 capscrews I could use as raw stock, but being the lazy ba&%ard that I am, I am loathe to change to the collet chuck to turn .035" off of 3 pieces of a 2" long screw.

    Using 2 jaws of a 4 jaw chuck is not a new thing around here, see above about the lazy ______, but usually I do it with more than a 1/4" of material held in the jaws. However tenuous this looks, all 3 pieces were finished in 10 - 15 minutes without mishap.

  • #2
    Lazy bastard? How about crazy bastard. Though, I guess you can't argue with success. Well done.
    Location: Long Island, N.Y.


    • #3
      Yup, I done that. Works well but you get funny looks from people who never think outside the box.

      You'd think: what's keeping the work from slipping sideways? Answer: the center serration acts like a V block on small diameter work. Not so good as the diameter increases but still workable. As you get larger still you get in the range where all four jaws grip so the problem of scale becomes moot.

      However the gripped portion does get bruised from from the serrations. so you wouldn't use this trick without protecting finished diameter with copper jaw pads. On the rare occasions I used a two jaw grip, the bruising didn't matter. I peened the raised metal flush and dressed the surface. Practically disappeared. I concede aesthetics do count a little in spite of my prior fulminations.
      Last edited by Forrest Addy; 07-28-2017, 10:54 AM.