Correct Bearing Preload for Clausing 5914 QC Gear Box?

[Rata222]

I replaced the bearings in my Clausing 5914 Quick Change gear box. Four 6202 ball bearings are recessed into counter bores from the outside of the gearbox housing. The two gear cluster shafts run through the bearings with nuts holding the shafts in. The alignment of the gears as well as the bearing preload would be accomplished by adjusting the nuts on the ends of the gear shafts (located on the outside of the gear box housing.) I adjusted the position and set the preload by tightening the nuts.

Installing the first shaft in the housing I adjusted the nuts till I could just detect some light drag while spinning the gear shaft.

While installing the second gear cluster shaft, which engages with first – it was harder to detect small drag as I tightened the nuts, so I utilized an indicator. Lightly pushing on the ends of the shaft gives me about .002” total axial movement in the shaft- (.001” each direction). The indicator returns to zero on release.

The gears and shafts should not see any axial load during operation. Would this be enough preload? I have no idea on correct procedure – it was just what felt right. Should this be OK? Any better method to use in this scenario?
Thanks Jim

EDIT: After posting this I thought that I should measure end play in the first shaft - where I could feel when bearings started to lightly drag. It has .001 total shaft movement. So I will match this in the second shaft. Does this sound correct? Too loose? Too tight?

 

[Ulma Doctor]

roller bearings are made for axial loads.
thrust loads will destroy the small bearing at an accelerated rate.
you would best be served to go for zero clearance - .001" should be sufficient if you don't feel any binding

 

[Rata222]

roller bearings are made for axial loads.
thrust loads will destroy the small bearing at an accelerated rate.
you would best be served to go for zero clearance - .001" should be sufficient if you don't feel any binding

There will be no thrust load on this setup. I read that if the bearing ball to race clearance was too large the balls will skip in the races, but wasn't sure how to tell the preload since I couldn't feel the drag due to contact of the remaining gears.
.001 is a go then.!
Thank you for the advice.
Jim

 

[machPete99]

The shaft one that drives the leadscrew will likely see some thrust pressure when doing any threading work. I would try to minimize the play there.