Chester's CQ2365/ 920

Hi James

I'd be surprised if you need to get a new spindle made or change the lathe to solve your problem. If the headstock bearings are the same as the 920 then they are tapered rollers. The fact that giving the spindle a smack with a small hammer has caused movement suggests to me that something in the bearing system is not seated correctly. If the bearing outer ring is not located correctly that should give you an axis misalignment and if it can move variable run out. If the inner ring is not seated on the spindle shaft then that could give rise to variable run out under changes of loading - giving it a smack with a hammer. I think you need to strip the spindle and head stock bearings down and start from first principles. Are the bearing seats clean and undamaged - there might be burrs. Are the bearing rings seating correctly when you enter them ie are they fully home and correctly aligned? Is the spindle itself straight? Are the bearings correctly adjusted - taper rollers (opposed) should give a very "rigid" bearing system (I don't mean tight to turn) - thats what is often used in car wheeel bearing systems, about the same diameter bearings and those have to put up with large shock loads and "overturning" loads from steering. Trying to diagnose the problem from "outside" by swapping bits around and tapping with a hammer won't do it unless you are VERY lucky. Basically if you can affect things with a half pound hammer something ain't right - your cutting loads will cause everything to shift.

Keith

Hi JSK

You have a message.

Keith

Edited By Bogstandard on 14/09/2010 11:17:08