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Novel way to center work in a 4jaw chuck.

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  • Novel way to center work in a 4jaw chuck.

    About 50 years ago I had a friend, a retired Navy engine man. Who would center work in a 4 jaw chuck, using a 1" round of steel drilled and tapped to screw on to a 3MT arbor mounted in the tail stock. He would then run the tail stock into the 4 jaw chuck, very lightly snug the jaws on the round. He would then back the tail stock, and round out, and insert the part he wanted to turn.He had a collection of maybe a dozen different size rounds, for the sizes he might need. He said it was as fast as using the three jaw, and a lot more accurate. The final centering was done in seconds as he snugged the jaws on the work piece, and of course he was using a dial indicator.

  • #2
    Interesting approach but I doubt it was as fast as a 3 jaw. More accurate yes, but not as fast.

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    • #3
      Thanks for the tip. Always handy to have these ideas in ones cranial toolbox. Never know when one, or a variation of one will come in handy.

      Another quick way is to move the tool to the dia of your part (helpful it you have a dro set) and then rotate the chuck by hand setting each jaw flush with the tool. Goes very quick and get you in the ballpark right away.

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      • #4
        Not trying to be snarky, but it sounds like more trouble than it's worth. Each to his own.
        Sarge41
        Edit: I'm referring to the O.P.

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        • #5
          I think the 2 key method is faster. I’m thinking even faster than his final step.

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          • #6
            I never tried his method myself, mostly because I never wanted to take the time to set up the arbor and a round to do a job. But at one time my friend had several jobs that called for him to make a large quantity of parts made from 3/4", 1", and 1.125" round bar, and devised this method to save time. It was amazing how fast he could center round bar using this method.

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            • #7
              It seems like something of a special case. That is, square stock that you want to center. Anything rectangular is out. Any irregular part where you're dialing in a feature is out.
              .
              "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

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              • #8
                Honestly in those sizes listed in large quantities, he would have made out better with a collet setup.

                At least he made due with what he had on speeding up the 4 jaw.

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                • #9
                  The idea is sound, I would make a conical version with thin rings at measured diameters to fit in the tailstock. So many people seem to be too impatient to use an independant four jaw chuck.

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                  • #10
                    I generally measure the jaws with a ruler based on the rings cut into the chuck face. If the "round" stock is not particularly round this is as close as it gets.
                    Plasma cut from plate.

                    Some times the stock looks like so. Flame cut from 4" plate

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                    • #11
                      I like Old Marts idea, Much cleaner set up to have maybe 6 different sizes on one conical piece. I know that if I had to keep track oh a dozen individual rounds I would not be able to find the one I needed. The next time I feel the desire to make chips and don't have a project ready to go, I will give it a try.

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                      • #12
                        The style of expanding collets, with the steps, but without the slots could get the jaws close to the right size would work. The length of each step would have to be greater than any chamfer on the end of the jaws, and the angle of 45 degrees so the steps would be square. You can get MT's with a soft arbor such as MT2 with a 1" x 1" end. Put a step in the end and press on a stepped end to suit your chuck, as the ammount the jaws stick out from the face of the chuck is a factor.

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                        • #13
                          OR......

                          Just practice and become proficient at setting up a 4 jaw chuck.

                          -Doozer

                          DZER

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                          • #14
                            I agree with Bented. Been machining jet engine parts for 30 years in 4 jaw chucks. With enough practice you can do it pretty fast. Mark

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                            • #15
                              I just use a 4 jaw "Tru-Adjust" chuck. Loosen four bolts on back plate, they are kept snug with Belview washers. Tap chuck with a small lead hammer using a dial indicator on the work piece......done!

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