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- Dec 20, 2012
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It depends on the sped you run your lathe at. If you rarely use higher speeds I doubt it would make much difference either way but after 20 minutes or so at max speed the bearings, and therefore the spindle can get rather hot. As the spindle heats it expands which increases the preload further increasing heat build up. My guess would be that the bigger the lathe the more of a problem this becomes - after all a longer spindle will expand more for a given temperature increase.
No, tapered roller bearings are preloaded when cold and the effect of that preload is assessed at running temps. You assess the adequacy of that setting by measuring bearing temp with the lathe hot and by measuring spindle end play and run out as RJ corrected above. Preload is intended to optimize internal bearing clearances and to make sure the bearings run against the race they are intended to contact under load. Setting preload when hot will result in excessive clearances until the lathe heats up and bearing damage can occur so yes, it makes a difference and is why I queried it. RJ knows his stuff and I suspected he just misspoke, which he just corrected.