Smithy Bearings Again

I posted this question before into a hurricane (as it were) of posts
about the gov'ment and New Orleans; normally I wouldn't be so rude as to
re-post it but I think it got lost in the flood.
So: I have this Smithy 1/3 in 1 machine, and the milling section has
problems with the bearings. They're tapered roller bearings much like
those in RWD car's front end, with a funky nut for adjustment, etc. The
bearings are TIGHT on the spindle, to the point that tightening the nut
won't pull the bearings together. I have no idea of the machine was
this way from the factory or if it got that way (there was an episode of
hot bearings judging from the bluing on the spindle).
In your valued opinion should I:
1. Sand or stone down the spindle diameter until I get a fit that'll
allow me to adjust the bearing with the nut? This would be a hand or
semi-hand operation, so there'd be some loss of precision but (a) it's a
Smithy and (b) it's the top bearing that I'm contemplating messing with.
2. Buy new bearings and see how they fit before I mess with the spindle.
2a. Buy new bearings from someone _other_ than Smithy.
3. See if I can get a new spindle out of Smithy.
Reply to
Tim Wescott
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Now this is stupid. One bearing has to be tight (OK, not necessarily with tapered) and the other one has to have a interference fit. Best, if you just can move it with the hand.
So, I would buy new bearings, see how they fit and hone one seat to make a snug fit. Shrink (heat and freezer) the other bearing on. I've done that on my lathe. There were only some 1/1000mm to be removed. I did it with sanding strips (the ones you get on coils, about 15mm wide) and oil. 10 strokes, rotate, 10 strokes, rotate, ...
Note, that you get bearings in different tolerance classes. P7 (or P6?) is for precision machines. But it might be wasted money for your's :-))
Nick
Reply to
Nick Müller
Carefully mike the spindle, accurate to .0001 or so if you can. Compare your measurement to this chart:
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If the spindle is in tolerance, buy new bearings. If it's oversize, new bearings won't help; you'll have to hone the spindle a bit.
Reply to
Don Foreman
Which you might well do in the lathe.
BTW, I suspect a lube problem. My Smithy is now over ten years old with no bearing problems.
Ted
Reply to
Ted Edwards
Smithy has an owners forum- try posting here
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Reply to
EdFielder
Certainly some sort of defect. Given the fact that I only use it occasionally and that there was bluing I think the bearings were installed way wrong.
Now I just need access to a mike that'll span over an inch and is good to a few tenths.
Or I just buy new bearings and fit them up...
Reply to
Tim Wescott

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