On my machine (JET 20" swing mill drill) I have tapered roller bearings on one end of each original 19mm acme lead screws. The bearings are #30203 with dimensions of 40mm outside, 17mm inside and 13.25mm wide. Are tapered roller bearings what other brand machines have or are do they originally come with ball bearings with the Acme lead screws?
The CNC conversions I am seeing on this site use angular contact ball bearings. I have a few questions:
1. Is there a reason to change to angular contact bearing when I go to ball screws?
2. Can't you zero the backlash with the tapered roller bearings? I can't see a need for endplay in the cold state as there shouldn't be a lot of heat build up due to the low speeds it will turn.
3. When I machine the .631 ball screws, the ends seem to want to get small in diameter. My motors will have 640 oz-in and a .500" shaft. I will be going direct drive. How small are the shafts you guys use on your conversions?
Thanks for your help - Dave