Thread: 260 fitted with precision bearing

I seem to remember, years ago when you could buy a new 260, you could choose between a standard model and a precision model, otherwise they looked identical. Could that explain the higher grade bearing?

Jordan

The standard 260 came with ordinary ABEC 3 bearings, the same precision class as used on car wheels and the like. In my 260 it's Timken brand.

For $350 extra, option 05HAN was available, described as follows in the 1988 price list: "05HAN - Extra Charge, Lathe supplied to precision limited: high precision spindle bearings, half error alignment and accurate"

I think this would have included ABEC 7 spindle bearings. Last year I had a check how much a set of such ABEC 7 taper roller bearings would cost. One of the two bearings is a fairly common size, but the other has to be ordered from the US (the Hercus uses imperial size bearings). Cost was well over AU$1,000. Far too much for me.

ABEC 7 bearings have less bearing noise, meaning the spindle rotates "rounder" in a less wavy motion. This improves the roundness of the parts you turn, and aslo improves surface finish. In practice, this only matters if you are turning hig precision parts like bearing seats, parts that in industry would be invariably ground and not finish turned. ABEC 7 bearings have matched inner and outer races and cage, engraved with a unique individual serial number and must not be mixed.

Chris

Timken inch based tapered rollers do not use the ABEC nomenclature for bearings...ABEC only applies to ball and non-tapered roller bearings..

For precision bearings they use three classes... 3, 0 and 00. These classes are different from the standard tapered roller, the type you fit to the likes of wheels and gearboxes...

From page 19 of this http://www.timken.com/en-us/products...8_09-09-29.pdf


Precision Tapered Roller Bearings (Class C/S/3, B/P/0 and A/00)
The more demanding the precision objective, the more accurate
the bearing must be. Timken provides three tapered roller bearing
classes, in both metric and inch systems, that cover the full range of
precision application requirements. In ascending order of accuracy,
they are identifi ed in the metric system as Class C/S, B/P, and A,
while in the inch system as Class 3, 0, and 00.

Timken still use their own inhouse precision classes (after all Henry Timken invented the taper roller bearing in 1898).

But I think all other taper roller bearing makers choose to use ABEC precision class for imperial bearings and ISO P class for metric bearings. I am no bearing expert though.

Timken class 3 is approximately like ABEC 5, or ISO P5
Timken class 0 is approximately like ABEC 7 or ISO P4 to P5
Timken class 00 is approximately like ABEC 9 or ISO P2

Chris