Re: [ATM] DC Motor for grinding machine question

["Don Clement" <don_clement@charter.net>]

> > The regular arraignment of the balls in a ball bearing race can add
> > a periodic component to the surface finish.  Even the artifacts
> > from the periodic arraignment of a ball bearing race can show up in
> > surface finish.
>
> You're contradicting your above statement.  I don't believe these
> artificts make their way onto the mirror's finish.  There is enough
> slop built into the typical machine arm, the pin and lap backer, and
> the compliant layer under the mirror to absorb any slight vibration
> coming from the bearings.


There is no contradiction. Using a FFT Dynamic Signal Analyzer (such as the
Agilent 35670A) and the proper sensors one can see the effects of rotating
equipment using ball bearing races. In fact, one can determine detailed
information on the ball bearing race parameters (such as number of balls,
etc) by examining the spectrum of rotating machinery. There is no doubt that
regular spaced balls in ball bearing races add some periodic component to a
rotating spindle of a polishing machine.  My polishing machine will use a
motor to drive the rotating spindle with single ball inverted bearing design
and two  independently driven voice coil actuators to the drive the tool.
The voice coil actuators will be driven by a PC  with D/A card which
includes an added random (white noise) component to the drive signals.



Don Clement

Running Springs, California

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