Clausing 100 mk3a Timken spindle bearings

The ANSI/ABMA grading system for tapered roller bearings (inch design) in order of increasing precision runs

CLASS 4, 2, 3, 0, 00.

There is now a class 000 but my table dates to 1994 and doesn't show it.

The parameter of most interest on a Clausing or Atlas lathe is probably the Assembled Bearing Radial Runout. In ten-thousandths of an inch (NOT THOUSANDTHS), for tapered roller bearings with cup outside diameters up to 12", the limits are:

20, 15. 3, 1.5, 0.75

How they get around the fact that the bearings may have cup and cone packaged separately isn't explained.. But your Class 0 cone when mated to a class 0 cup should supposedly have a radial runout less than or equal to 0.00015".

 
Unfortunately I do not have a class 0 cup, the class 0 bearing I purchased is a cup and cone combo, but the cup is a 14277 which is .100” wider than the original. Maybe it will work, but I may have to either mate it up to the new “standard” precision timken cup, and hope for the best, or just put it aside and wait for class 0 bearing assembly to pop up. Also, I noticed you said that you hadn’t heard if the 1940-1950s clausing 100’s had dated engraved original bearings, my 1946 100 does indeed have the exact same engravings that my atlas/craftsman of the same era has, engravings even look like they were done by the same person, maybe timken does the engraving, because at the time these machines were built, atlas and clausing were still separate companies.CDA17B96-5BD8-4ABB-AE79-92207DEE1084.jpeg
 
Thanks for the info on the dates. Their presence and the similarity to those on the equivalent Atlas parts suggests that it was Timken who did it.

And you're right about Atlas and Clausing still being separate companies when the practice started. The earliest dated bearings that have been reported in an Atlas built machine (a 12" as it happens) are 11/08/1939 and 11/09/1939. And Atlas did not buy Clausing until 1949/50.
 
Taper rollers are by far the most difficult bearing to get a precision outcome...........In my experience of refitting with standard tapers,there is always a runout that is driven by the caged rollers.....it generally repeats about every second revolution.......this is not possible to adjust out,and when a front 1/2 runout is combined with a rear 1/2 runout,things get confused......A single roller has a number of possible variables .....size ,diameter ,angle,and end thrust surface.......and all these are difficult to measure.......unlike a ball bearing.....the ball is a certain diameter ,and thats it .....the only variable.........There is no one reading this forum who could test a taper roller,or either taper race,whereas just about anyone could test a ball or plain roller ,and the races.,for size and runout..............There is a film of Gamet bearing assembly,and the precision taper rollers are sorted into about 20 different categories prior to assembly...............most of the Euro lathes use balls or plain rollers ,not tapers.
 
All that you say is true. However... The only reason that any manufacturer would put ball bearings on a lathe spindle is that cost is more important to them than long term performance. Ball bearings and straight roller bearings wear out relatively quickly. And there is really nothing that you can do about it but replace them. Tapered roller bearings that are properly adjusted and lubricated will outlast most humans. New owners of old lathes generally make two mistakes. First, they seem to universally insist upon removing the headstock from the bed "to paint it." Second, they routinely want to change the spindle bearings. If the lathe has sleeve or ball bearings, they should, because odds are that the spindle bearings are worn. If the lathe has Timken tapered roller bearings, they most likely don't need to unless the lathe hasn't been oiled since it left the factory.
 
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