So Paul's ABEC 7's fitted in 1965 now have play, at what year did the unnoticed play exceed an ABEC1 specification?
Answers on a postcard please.
As a reference any named supplier of bearings like Nachi will not sell ABEC1 angular contact bearings as they know they have to do a far greater job as regards precision than a deep groove ball race.
ABEC1's are related to deep groove ball races that you buy for pence and fit to electric motors etc,
Quality suppliers like Nachi will only sell ABEC3 in angular contact series and whist what Forrest writes about bearings is correct you have to take into account what it's going in.
Today housing can be machines to less than tenths in climate controlled shops, advanced machine tools also built to fantastic standards ensure this.
Now rewind to 1960 and some dirty engineering shop on the wrong side of the tracks using WWII tooling to machine the next generation of machine tools. Were those housing really true and square, are all the spindles produced over a day from cold machine to hot machine exactly the same ?
Has the machine ever been abused, crashed, put away hot and sweaty with no oats in it's 50 years of life ?
The fitting of bearings is just as important as the quality, well fitted ABEC3's can be better than a set of ABEC 7's thrown in the hole.
John S.