Originally Posted by dafydd
don't you reach a point of "weakest link" somewhere between here and there if the races are not machined to as tight of tolerances?
Correct. Tolerances are stacked so that any piece of equipments accuracy is only as good as its worse tolerance. High percision bearings such as ABEC Class 9 requires the shafting and housings to be machined to the same percision class. Putting Class 9 bearings onto shafts and housings machined to class 1 nets you an overall accuracy of class 1. Acutal bearing performance will initially be high, however in short order a degeradation of performance will occur as the bearings are asked to absorb the lower percision shafting and housings