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For a mechanical design, I would need a small/light axle, having high precision (as less loose as possible and reduced drag). With precision, there is not a very strict definition, however, I target ~0.2º of radial rotation (axial movement is not that an issue).

The length of the axle is around 24mm, on which I would attach a few elements (~50g).

The first idea is to use a bearing on each side of the axle, but I am not sure what is the good practice for attaching the bearing.

Following is my current sketch:

enter image description here

The closest example of what I am doing is the axle in the actuator of a Hard-Disk, however, the bearing there is internally tapped for fixation. Most of the bearing I found on the market are not tapped. My feeling is that tapping the bearing is not a good idea.

enter image description here

My question is:

What are the commonly use pieces, practices, terms and fixations for this type of problem?

I understand is a quite broad question, but either I miss terminologies and in any case I did not found answers online. Also, I do not need a deep answer, but some indications of where to look further.

Others possible tags: axle, matched-set

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  • $\begingroup$ Do you mean "axle" ? Further, what is the actual problem you are trying to solve? $\endgroup$
    – Carl Witthoft
    May 25, 2017 at 13:30
  • $\begingroup$ What is wrong, in your opinion, with tapping the bearing? It is tapped early in its manufacturing process before being assembled and even, before hardening. $\endgroup$
    – Solar Mike
    May 25, 2017 at 13:46
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    $\begingroup$ You can thread the axle and use a nut and locking washer, you can put a groove in the axle and use a circlip - just two possibilities. $\endgroup$
    – Solar Mike
    May 25, 2017 at 14:24
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    $\begingroup$ Take a floppy drive or a CD ROM drive apart; the bar upon which the head slides is very precise, hard, and should be what you need. As for affixing the bearings, the usual approach is a minuscule amount of super-glue. $\endgroup$
    – SF.
    May 25, 2017 at 15:14
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    $\begingroup$ Press fits are quite common, so is Loctite on a less precise fit. $\endgroup$
    – user_1818839
    May 25, 2017 at 21:33

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Axle type rod is available under different names on-line. Try searching for "8mm linear shaft", "linear rail shaft", "ground polished shaft" just to start.

Bearings that fit snug don't require much of a fastener to keep them from walking off of the shaft. You could machine a hole through the end, or a groove around the end, and use an R-clip or c-clip snapped onto the end. It would probably be overkill, but you could drill and tap a hole straight into the center of each end for a screw and washer.

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