Angular contact bearing end float in face-to-face config.

[Mark Davison 1Participant @markdavison1]

I have a pair of SKF angular contact bears that I am trying to use to secure the end of a ball screw. I've tried to replicate a BK15 fixed bearing block where the bearings are mounted face to face. Trouble is I seem to have a lot of end float. Almost 0.2mm. The outer races are clamped tight so im pretty sure the movement is between the inner and outer races. Should I expect to have to separate the inner races and then apply fixed preloaded on the outer races? I was expecting almost no end float. 15mm ID, 35mm OD, 11mm width bearings with a 20mm dia ball screw.

[Mark Davison 1Participant @markdavison1]

[Nick HulmeParticipant @nickhulme30114]

Use a shim disc between the inner races to provide the required pre-load.

[HOWARDTParticipant @howardt]

Angular contacts come in many variations. Bearings are selected to make particular set, the set can vary from a matched pair as back to back, or face to face and any number of build options. Each option will give a variation of load and stiffness in a particular direction. As offered by using spacers with slightly different thickness will give you what you want. But the difference will be guess work when working with stock unknown bearing tolerances.

[Pete RimmerParticipant @peterimmer30576]

Shimming is your only choice if you want to keep the bearings. I just had to do this to diagnose worn out bearings on my surface grinder.

Measure the end-float with a dial gauge then get some shim stock sandwiched between two pieces of scrap. Drill it through then turn the outside then you'll have the correct annular shim. You can do ID or OD depending on how you orientate the bearings.

[Mark Davison 1Participant @markdavison1]

Thanks folks. I've ordered some 0.1mm shims which will get me started. I may try and turn down some sheet shim stock that I have whilst I'm waiting.

[Pete RimmerParticipant @peterimmer30576]

Mark, I suppose you have checked the bearing orientation? The axial line of thrust must be opposing for each one, so they must be front to front or back to back.

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