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Lathe Spindle Bearing Adjustment Question

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  • Lathe Spindle Bearing Adjustment Question

    I am polling the group for suggestions on adjustment of spindle bearings. The easy answer is to look in the book. I have a copy around. Finding it is a challenge. :-(
    Here is a overall view. Its a Super 7 clone. After looking at the Myford manual it looks different in the details of the spindle. Or at least I am not following the manual. The Colt does not seem to have the two locking rings that the Myford manual shows. I guess I need to clean the grease off to see if the is a single locking ring. In the Myford you adjust the bearings with the two locking rings on bearings. Then move the bearing assembly to adjust the spindle as it rides into the bronze bushing on the spindle end. Not sure if this one has the bronze bushing.

    Reading the Myford Manual seems to suggest oil instead of grease. It came to me greased and I have been continuing the practice. Any comments?

    The spindle end

    Reason to inquire is I have some fairly major deflection happening when turning. About 0.010" over an inch. This is even after doing several light cuts.
    Any suggestions are appreciated. I will try here first then ask the Myford group as I am not sure if they will lynch me for talking about a knock off there. ;-)

  • #2
    I'm not familiar with that machine or it's spindle design. If you have .010 of runout in 1 inch I would start looking for loose or bad bearings, or play in the saddle and compound rest. I've never seen spindle bearings lubed with grease other than grinder spindles that were sealed. The wrong grease could cause premature wear. I would start by indicating the spindle.



    • #3
      I have an ML7 and it specifies ISO 27. I think the Super 7 calls for 32.

      Looking at the details in the photos I am wondering if it has tapered roller bearings. The reason I say this is because the 920 lathe I had before the Myford had tapered rollers and this Colt was made in Taiwan (I think). A lot easier to make and then assemble than the tapered front bushing on a S7.

      If it is indeed a bearing style spindle then a slight preload is needed (as I recall from the 920 mini-manual).



      • #4
        Thanks for the reply. I am going to have to figure out the oil vs grease thing soon. Just finished up reading on the yahoo group. The original owner was rather well informed on things related to lubes. He is not longer able to answer questions. :-(
        I guess I will have to research oil guns.
        Would a tapered bearing have only the one adjustment on the back, that being the nut with two holes in the last picture?
        Thanks Dave


        • #5
          Yes, that would be typical. There might also be a locking set screw (or other means). Adjustment is often by "feel". On my Emco, you tighten the nut, spin the chuck by hand (Gear box in neutral) and it should not rotate more than 1 revolution. Then run it for 20 minutes at say 1250 rpm and make sure the casting near the bearings "doesn't get get more than warm". Your process might be different, so be conservative.