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1340 Lathe Rebuild

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  • 1340 Lathe Rebuild

    So, I finished rebuilding a MSC 1340 lathe. I'm trying to ascertain just how tight the compound, cross slide and carriage should be. The cross slide has some back lash, and I've adjusted it so its a bit stiff, but, movable. The compound is rather tight, takes thumb and forefinger on the 2 handles to turn it half a turn. The carriage is a bit tight too, it's a bit of a work out moving it back and forth a few times. I.E. you can't just move it with a light touch.

    Thanks, Billy

  • #2
    I like my carriage to move fairly freely with cranking the wheel. And in fact I can pull on the carriage for my 12x36 and pull it along with the handwheel spinning merrily. There are anti lift keepers on the rear side for sure and maybe the front as well. These should be very close to the running surfaces of the bed but not touching. You might need to shim to achieve that setting... Maybe .003 to .005? If you can get easy no bind movement with less than .003 then go for it.

    On the cross slide I like the gib snug enough that I can move it without the lead screw with firm hand pressure. So not a LOT of drag but certainly not just floating on an oil film easy. I'd say aim for something like 8 to 10 lbs of pressure to move it.

    The compound I set up a touch tighter. The dovetail is a smaller area so for directly pushing on it I like the same 8 to 10 lbs to make it move. For the little 2" diameter hand wheel it has this translates to something like your two fingers on the opposing handles. But not enough that it'll leave a pressure mark on my fingers. In fact it's tough but I can "just" spin it with my hand on just one of the little post handles.

    My own machine uses a tapered gib. Yours clearly shares the same Asian beginnings as mine. So setting the gibs for these two slides seems like a good way to avoid any play or flex that can be avoided. At least without having any proper locking screws to press the gib tighter into position and lock the travels.
    Chilliwack BC, Canada


    • #3
      Another thing to verify is whether the gib strips are assembled with the machined surface on the correct side. Don't ask me how I know!!



      • #4
        The gib strip is in correctly.. However, on the cross slide, it's harder to move in one direction than the other. I'm sure that's the gib strip, but, the screws are tight on both ends and the gib strip isn't slipping from what I can tell (I.E. wedging in when moving one way). It's a bit strange. I've never seen that before. I'll check the hold downs on the carriage. They weren't shimmed before I performed the tear down. You would think it would be looser now than before seeing as it should be worn in...


        • #5
          Tapered strip? Both screws tight? I had that happen on one of my strips and it turned out that the strip was going in too far on one end and sticking out the other. Seems that the "tightening" screw was bottoming out before the wedge was fully adjusted. So the gib was floating back and forth a little. On our setups you can reach in and set a pin of some sort against the end of the gib and should be able to quickly tell if it's floating back and forth a little. And it sure doesn't take much floating to get that same tight one way and loose the other feel.

          It's been a while and I can't recall if I made a new screw with a bit of a protruding nose, cut down the threads on the old screw or just stuck a bit of a loose thread ID sized washer in there to act as a spacer. But I do recall that I had the same issue. Even had to trim about 3/16 off the small end of the gib because it was going in so far that I could not get the other small end locking screw to start by more than about one or two turns. Had to cut the gib down a touch to let me get the head of the locking screw down flush with the face. The fit and drag was consistent in both directions after that.
          Chilliwack BC, Canada


          • #6
            I believe I recall a similar issue with my import 12x24 as well or maybe my Chinese mill on some of the gibs. If you got both screws tight it almost creates sort of a bind compared to getting them perfectly "not tight but not loose". I've definitely had the case BC describes as well in both directions where the screw or gib needed a little mod to bring the adjustment into range.