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Re: [ATM] Sphereometer accuracy
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> 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.
Exactly my point for years now. If someone REALLY needs such
precision, then maybe measuring the actual ROC with reflected
light source using a micrometer attached to a piece of paper at
ROC would be more appropriate. There are very few of us that
really need the ROC to be this exact using a spherometer.
More to the point from my observations, some newbies
get depth easily within useful specs (goal is F/5.0, and
they get F/5.0 +/- negligible error), but are not getting
spheres right from the early stages of grinding.
Dominic-Luc Webb
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