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  • Newbie Lathe Questions

    How do you adjust the carriage to eliminate slop?

    I found this when checking the spindle and tailstock alignment. I have a round bar about 12" long in the chuck and supported on the other end with a dead center in the tailstock.

    I put a mag base on the cross slide and set the dial indicator against the OD of the bar near the chuck and then moved the carriage with the hand wheel toward the tailstock. When I got to the tailstock and started to travel back toward the chuck I noticed that the dial indicator moved .003" before the carriage moved. The same thing happens at the end of the bar near the chuck. I can work the hand wheel back and forth just enough to take out the slack and that's when the indicator moves.

    I'm guessing that there is some slop between the carriage and the ways. The cross slide and the compound have gibs, but I'm not seeing how the carriage is adjusted.

    Troy

  • #2
    Depends on the lathe. Flat or V ways? Commonly - look on the back of the carriage up underneath the back edge. Mine has a length of steel that runs on the underside of the V way back and is adjustable. My Emco had a teflon strip.

    Gravity and tool force (downwards) have a lot to do with carriage tracking.
    Last edited by lakeside53; 12-27-2011, 11:47 PM.

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    • #3
      If youre referring to backlash from moving in the Z, most lathe carriages have a rack and spur gear providing movement, and little if any adjustment for backlash. Its the reason that many (if not most) lathes dont have a dial on the carriage handwheel.

      If youre saying that your carriage is lifting off of the ways, there are quite a few ways in which that can be resolved depending upon the machine.
      "I am, and ever will be, a white-socks, pocket-protector, nerdy engineer -- born under the second law of thermodynamics, steeped in the steam tables, in love with free-body diagrams, transformed by Laplace, and propelled by compressible flow."

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      • #4
        ha... good point. I may have misunderstood the OP by not reading the post fully!

        Backlash is a fact of life for both leadscrews and the typical rack/pinion drive of a carriage.

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        • #5
          Originally posted by justanengineer
          If youre referring to backlash from moving in the Z, most lathe carriages have a rack and spur gear providing movement, and little if any adjustment for backlash. Its the reason that many (if not most) lathes dont have a dial on the carriage handwheel.

          If youre saying that your carriage is lifting off of the ways, there are quite a few ways in which that can be resolved depending upon the machine.
          My lathe has a carriage handwheel dial, but its only like 0.02" per graduation! And even then you still have only move in on direction to take the backlash up for it to be of any use, as there is I believe around 0.02" or so backlash. (12x36 chinese lathe)
          Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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          • #6
            I think Lakeside had it right the first time. The OP should look at the far side of the carriage for the gibs and make sure they are in adjustment.

            He says he's getting a difference on the indicator before the carriage even moves.

            Also, make sure the tailstock is locked down.

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            • #7
              Originally posted by TxBandit
              I put a mag base on the cross slide and set the dial indicator against the OD of the bar.
              The side of the bar, the top?? Are you measuring vertical movement or horizontal? Makes a big difference. Also what brand of lathe, i.e. what type of bed?

              Ed P

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              • #8
                Dial indicators are notorious for changing readings, when direction is changed. Thats why it is important to only read a DI when it moves one way, and not read it the other----if you are using it for reference to a starting position.
                Flat ways will give you a horizontal move (slop) of the carraige when the gibs are loose.
                Dovetail Ways will give both horizontal and vertical if the carraige is worn.
                This is also known as boat-tailing
                The gib on a Dovetail way carriage has far less impact, as the weight centers on the dovetail.

                I suspect you have both, some slop , and some indicator wobble

                Suggestion
                Run the indicator all the way in, until it is almost out of travel and recheck the reading. You will see less wobble as the internal spring pressure tighens up the movement. Or better yet, use a Last Word indicator

                Rich
                Green Bay, WI

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                • #9
                  I have came upon some with a bolted machined plate directly under the way at
                  the operator tough to get at, and then I have one that has nothing at all
                  (trying to say) it depends on the weight of the thing. As far as backlash,
                  thats as to winshield wipers its the nature. When everything gets under load
                  by by backlash. So this so called saddle really doesnt need gibs cause it is
                  loaded vertically downward. Atleast thats what I see In my machines. sam

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