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chuck question

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  • chuck question

    I came across a 7 1/2" 3 jaw chuck, they want $125.00 for it. It is in ok shape but has no back plate or wrench. It was used on a rotary table and has some holes in the face. It also only has threaded mounting holes in the back. My question is, would I be able to make a back plate (for threaded spindle) and use it as a smaller chuck for my lathe? I worry some about having cap screw heads on the back side of the chuck to catch things on (stringy chips etc.) I also was not sure if it would be up to the speed it may get, having been a table chuck.

    Thanks for any help

  • #2
    Originally posted by chip's
    ...I worry some about having cap screw heads on the back side of the chuck to catch things on (stringy chips etc.) ...
    That can be handled easily...countersink them!


    • #3
      In my opinion $125 is a little high for a used chuck that has been modified>

      Just my opinion


      • #4
        If you want, you can get countersink cap screws.

        You can also get button head cap screws which I like and have used for mounting chucks. They don't proturde as much and have a much more user friendly profile if you get your hand in the way. They also permit a loose fit for home brew true-adjust mounts. Again, I have done this.

        As for the speed thing, I doubt that any manufacturer made chucks specifically for table use and used a lesser alloy. I have never seen this kind of thing advertised. Table mounted chucks are just lathe chucks mounted differently. The holes drilled in it for table mounting should not weaken it significantly unless there are cracks around them. It will have a upper speed limit, but I doubt that you have to worry about it unless you have a particularly high speed machine.
        Paul A.

        Make it fit.
        You can't win and there is a penalty for trying!


        • #5
          Something to keep in mind - Buttonhead screws and Flathead screws have a smaller hex wrench size and depth than the equivilant thread Socket Head Cap Screw. If you want to sock some torque into the screws stick to a SHCS or Hex head.

          Also a flat head screw uses a countersink (angled hole). The screw centering will fight the pilot on the chuck; or if you don't have a chuck pilot you will never be able to center it as the screw countersinks will set the position.

          If you are still worried about the screws sticking out you can put them in counterbores.
          Last edited by gda; 05-24-2009, 05:56 AM.


          • #6
            Just me, if I was to use a chuck on a RT it would be my used chuck where I could dial it in. Just because it was on a RT doesn't mean it hasn't seen heavy or abusive use. Assuming you want it for a lathe, see if you can check it out on one first.

            Nothing worse than a sprung chuck, I use one.

            Cheers, Bob


            • #7
              Thanks all, I like the button head idea. I would have to use 1/2 - 3/4" plate or casting if I counterbore the heads. I was concerned about the speed too but sounds like it won't matter. I will check the chuck and advise. Thanks again for all the help.