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Use of Spherical Joint

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stevea41

Computer
Jul 19, 2015
2
Thank you for considering my issue.

I am aware that a spherical joint can be used as a snap joint in plastic enclosures. Taking this concept further, I wish to use the spherical joint to allow three axes of movement - with memory of position - of a suspended enclosure that weighs around three ounces.

In theory, can a spherical joint be used in this manner?

If so, can the position of the suspended enclosure be afforded position memory by a correctly designed spherical joint? I also have a concern that over time, position memory may be degraded by wear between the ball and socket.

If so, should the ball and socket be of the same material?

If so, what should be the diameter tolerancing of the external ball and of the internal socket?

 
 http://files.engineering.com/getfile.aspx?folder=bb687f77-5df3-4d3f-beb2-17d725231cc0&file=Spherical_Joint.jpg
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It can probably be done, provided that you castellate the socket.
That way, the socket becomes a polar array of cantilever beams, which you can design to have an arbitrary preload, or to post-load, e.g. by means of a garter spring or an o-ring stretched around the array.

In general, you want two very different materials in any sliding joint for reasonable service life; joints made of the same material tend to fail by adhesion/ welding/ galling/ whatever you want to call it.



Mike Halloran
Pembroke Pines, FL, USA
 
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