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Novel way to center work in a 4jaw chuck.

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  • #46


    It seems like a lathe big enough to hold a 36" bar at the head stock, and not need to support the end in the tail stock, would be much bigger than most home shop machinists would have. If you are holding the far end in the tail stock then it doesn't seem like such a big deal. I still find your fathers idea on adjusting a 4 jaw interesting.

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    • #47
      My thoughts exactly. Stock doesn't have to be centered to be faced.--Although with doing 2" square tube, the center bore of the spindle must be enormous if I am thinking correctly of your set-up.---Brian
      Brian Rupnow
      Design engineer
      Barrie, Ontario, Canada

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      • #48
        Just a 13x40 lathe. Used a steady rest on the tail stock end. When using stock in the steady rest if it is not running purty true the stock will work it's way out of the chuck

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        • #49
          Originally posted by BtoVin83 View Post
          Just a 13x40 lathe. Used a steady rest on the tail stock end. When using stock in the steady rest if it is not running purty true the stock will work it's way out of the chuck
          No it won't necessarily. You can have the stock running out as much as you want at the chuck while the other end is in a steady with zero consequence to the part coming out. The important bit is that the steady is set correctly on center or slightly above, and that the diameter the rest is running on is true to the axis of rotation - that can be accomplished by cutting a spot or running a spider.

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          • #50
            can you explain that a bit more? diameter true to z-axis?

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            • #51
              Originally posted by eKretz View Post

              No it won't necessarily. You can have the stock running out as much as you want at the chuck while the other end is in a steady with zero consequence to the part coming out. The important bit is that the steady is set correctly on center or slightly above, and that the diameter the rest is running on is true to the axis of rotation - that can be accomplished by cutting a spot or running a spider.
              are you there?

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              • #52
                Yes, sorry, didn't get the first notification. The diameter needs to be true in terms of cylindrical and not cone shaped (tapered) or turned (or spidered) such that it's running true at the steady location. For example if you had a perfectly straight test piece and placed it in the lathe, with the steady set so the rollers were on center for the diameter of the test piece and the chuck end was offset with a 4-jaw such that it was running eccentric by .250" and the tailstock center was in the other end, the part of the shaft aligned with the steady rollers would be way out of whack and would need to be either turned straight there or a spider would need to be placed on the shaft and set to run true.

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