[ATM] Sphereometer accuracy

["The Alarm Co." <tac@i1.net>]

In reading the recent posts about sphereometers, it occured to me that when
using balls for feet, the actual spacing between the feet will vary with the
depth of the curve being measured; the spacing gets wider with concave
surfaces, and narrower with convex ones.  Also, if the tip of the indicator
is flat, it will measure concave surfaces slightly shallower than they
actually are.  This all may have been a moot point with older indicators,
but now we're talking about measuring one micron!  Are these factors  taken
into account in equations for converting the measurements to ROC?  Or, are
they so slight as to be insignificant even now?

 *  Best regards, Bob
*
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