Procedure for checking headstock shims on Atlas 10F Lathe

 from a Practical-Machinist post by wa5cab

One thing that hasn't been mentioned are the spindle bearing shims. Under both sides of the bearing cap when it left the factory should have been a 0.010" (originally) shim. Each shim is made of five 0.002" shims glued together. To evaluate the two bearing/spindle conditions requires a dial indication good for at least +/- 0.001" that can be attached to the bed or headstock and measure/indicate spindle vertical and horizontal movement near the bearing caps. First confirm that the four bearing cap screws are properly tightened. Atlas apparently never specified a torque figure but something in the range of 25 to 35 lb-ft seems appropriate. move the end of the spindle that is being indicted vertically and horizontally. Presuming that no chuck is on the spindle, insert something like a piece of 3/4" diameter round bar at least a foot long into the spindle bore. Pull up and push down on the end of the bar to determine the vertical clearance. Push and pull in the horizontal plane to determine the horizontal clearance. Do this at both ends of the spindle. If the vertical movement is greater than about 0.0015", remove one shim wafer from either whichever shim is the thickest or from the front shim if they are both the same. Reinstall the shims and bearing cap and repeat. If still too loose, remove one shim from the thicker shim pack. Continue until the vertical movement with the cap screws fully tightened is under 0.002 at both ends and the spindle still spins freely with little resistance.