Shafts, bearings and circlips....

The diagram attached shows a mounting block with a protruding 17mm dia shaft. Part B (dark blue) rotates on this shaft on a 17x26x5 thin section bearing (shown in purple). Incidentally the shaft is bored through 11mm to allow another unrelated shaft to pass through.

Part B's dimensions are quite limitied so I need to use this bearing. Normally retaining the bearing on the shaft would be done with a circlip but a 17mm circlip would foul the outer race as shown. I could space the circlip off with a 19mm od, 17mm id washer, but that still leaves the issue of retaining the outer race in Part B with a cover, since there would be less than 0.2mm clearance between the circlip and the cover, the inner dia of which must be 24mm to properly retain the outer race.

So how to do it? The other option I can think of is a finely threaded collar but that means cutting an internal 17mm thread in a 19mm tube, not easy.

Attachment 10268

I take it the loading is such that relying on a press fit won't work?

What about a snap ring, which is held in place by a small spacer with a groove, that is held of the bearing by a wavy spring washer? Should use less diameter than a full circlip.

Internal threads aren't that hard to do with the right tools, so I wouldn't rule it out.

There are no axial forces and negligible loading so press fit on shaft and/or into part B could be ok. For ease of assembly/disassembly I'd prefer it to be press fit in part B, maybe with Loctite in which case I could probably dispense with the lip and make part B thinner, e.g. the width of the bearing. Would still need to retain on shaft to ensure registration against other parts in which case a spacer and circlip would would work ok. Relying on press fit isn't something I consider 'best practice' as a rule but here it might be ok.

Use a wire circlip

http://www.tracepartsonline.net/Part...09-071826L.gif

Thanks John, not come across those before and I thought I'd had some experience. Just shows you never stop learning! Presumably they can be used internally as well as externally?

What's your thoughts on using Loctite v a retaining lip and cover plate? I'm keen to minimise machining efforts.

Edit: of course I have seen those before - retaining gudgeon pin on pistons, I'm losing my marbles :(

What John posted is what I'd call a snap ring.

Another option could be a flat snap/retaining ring. Think a circlip with a continual rectangular profile, which usually just have a notch in either end to help springn them apart.

Quote:

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Originally Posted by m_c

What John posted is what I'd call a snap ring.

Another option could be a flat snap/retaining ring. Think a circlip with a continual rectangular profile, which usually just have a notch in either end to help spring them apart.

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The rectangular section ring works for me and is easier IMHO to machine the groove for.

Still wondering about use of Loctite to retain bearing outer race. If I go that route it can be 5mm mild steel plate with bearing pressed and glued in. If not it needs to be 8mm at least to make room for retaining lip and groove for snap ring. Plus two more accurate machining operations.

I'm trying to make this construct-able at low cost in the future.

How about make the plate 6mm thick, press fit the bearing, then peen/crimp the edges to ensure it remains secure?