4th Axis design-> tapered roller bearings: Is bigger better? How big is too big?

G'day guys,

I managed to get my hands on a pair of CSF-32-50-SP harmonic bearings and so have started designing a 4th axis for my cnc.

I have been looking into tapered roller bearings for the spindle and balancing up availability, size and cost. My original design had 60x85x17 size bearings but I just found some 65x100x23 SKF units for a reasonable price.

These are quite a bit larger and heavier so I was wondering if anyone has experienced a scenario where bigger wasn't better? I don't believe their inertia will be an issue due to the stepper I am looking to use. But wasn't sure if getting the right amount of preload would become difficult or anything else.

I plan on mounting a 100mm 3-jaw chuck or a PAF-H54 style vice and also a NEMA34, 4.5Nm stepper with a belt drive.
Cheers!


This is a companion discussion topic for the original entry at https://www.cnczone.com/forums/linear-and-rotary-motion/471054-4th-axis-design-gt-tapered-roller-bearings-new-post.html