That wasn't what I was refering to.... there's more than one tolerance spec on a bearing
Its the race to ball tolerance that Irving is talking about, both the inner and outer diameters can to a tight fit(not always recomended) and there can still be axial and radial play if the accuracy is poor.

I'm just looking at the z axis and spindle design for mine and the design of spindles is very complex, It seems to boil down to tapered bearings for high load, low speed (10000rpm or less) and angular contact for every thing above.

There is the option of using deep groove bearings as they are capable of the highest speeds and stacking them in 4 or 5 deep to regain the load and ridigity, but the precision might not be there.

But I guess you knew that