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3 jaw Buck Chuck

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  • 3 jaw Buck Chuck

    Hello All,
    As part of all of the tooling that came with my Powermatic-Logan 10" lathe, one of the chucks was a 3 Jaw Buck Chuck. It has allen screws on the side to allow some sort of adjustment. Can anyone fill me in on the "hows, wheres and whats" of this chuck.
    This "newbie" is very grateful for all of the great information and comaradarie that this board offers.
    Michael Quitt aka/qpens

  • #2
    That is a Buck Adjust-True chuck. It allows you to adjust it like a 4 jaw for fine tuning.
    No three jaw chuck is going to be repeatable throughout it's entire range. This feature lets you adjust for a particular size.
    To use it, chuck up a piece of stock in the range you are most likely to be working with, loosen the allen screws on the outer diameter of the chuck, leave the ones in the center tight. Now, you can adjust the chuck with the 4 allen screws on the side of the chuck as you would a 4 jaw chuck.
    Tighten everything back up, and the chuck will be very repeatable in that size range.
    This feature is especially useful with a threaded spindle, as they introduce more variables into the setup.
    Jim H.


    • #3
      I have a 21" buck and I would change the preceding to leave the center bolts snug.



      • #4
        Thanks for your answer to my question about the Buck Chuck. I repair vintage fountain pens and one of my problems has been how to accurately hold a pen cap that has a pocket clip attached without going to the trouble of removing the clip. Obviously, a collet won't work. Do you think that this chuck will help me solve that problem since the pocket clip can sit between the jaws of the chuck and the entire cap can then be "trued up" using the allen screws?
        BTW, I do have a threaded spindle. Does this allow me to do other things with this chuck?
        Thanks again,


        • #5

          Don't be so quick to rule out the use of collets. In my shop we use collets for all sorts of odd shapes. What you describe would not be a problem.

          Get a setup to use 5C collets in your lathe spindle. Buy some Hardinge emergency collets and bore to the appropriate diameter. Then mill a recess for clearance of the pocket clip. The collets are available in steel, brass or plastic.

          I have done something very similiar to your
          pen caps. We had extruded aluminum bars in the shape of a key hole which we handled in this manner.

          Collets are far superior to a three jaw chuck for holding delicate items like yours.