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ultra fast rotary gap?



I havn't been a subscriber for a bit what with graduation and all fast
approaching and the need to packup and move, so I hope this gets through.

A friend of mine and I were discussing very high speed motors specifically
those used in centrifuges used for blood work.  I've been told some units
can surpass 50,000 rpm and and are fully balanced to 100,000 rpm.  Used
units can be obtained from hospitals and medical supply houses.  The one I
was given sits in an all aluminum housing which is about 16" in diameter
and about 10" tall.  The actual rotor/armature arrangement is much smaller
though.  The motor runs off a standard 110/120 volt 50/60 hz.

I suggest that a balanced disc be mounted to the top in the 8 slots which
are designed to accodomate a standard test tube (for the blood specimens).
Another possiblity is to mount the disk inside the aluminum housing and use
the housing as a uv block.

Or, the following project can be attempted.

I have seen the motor removed from a unit similar to mine and placed in an
inverted configuration whereby the rotor is fixed and the armature now
turns.  The composite-material armature is supported by a point jewel
contact at both ends of the armature rod for front/aft support **and** uses
a magnetic bearing at both ends of the shaft to maintain armature alignment
around the rotor.  I've been told (though I've not seen it for myself),
that thus unit does in fact achieve > 50,000 rpm due to having only point
contact friction locations and not the usual oil/roller bearing
arrangement.  If true, that's about 833 revolutions per second.  Assuming 6
light weight copper bolts are used for the gaps, that gives about 5000
breaks/sec.  12 bolts would give 10k breaks/sec.

Love to hear if anyone has done this or might plan to.  As I said, I'm not
presently a subscriber, if you have questions, email me and I'll try to
reply.

Kyle