From: Mark Holm 
To: sberfield{at}xbox.com, atm{at}shore.net
Reply-To: Mark Holm 


That's a turned edge all right!  But, both inside the point where it turns over,
and outside, the mirror looks nice and smooth.  So you are doing several
things right.

Time to start a figuring log!  You need to keep track of the effects of
each modification of technique that you make in order to learn what does
what. There
are guidelines of course, but each person's idiosyncrasies make the guidelines a
  bit unpredictable.  I have had some luck with a TOT chordal stroke, trying to
concentrate the wear at the crest of the curve,  problem with this idea is
that it is easy to overdo and end up making the edge worse (ask me how I
know!).  to go the direction you want, the chordal strokes have to be kept
very short.  For chordal strokes, a subdiameter tool may be safer.

I know a lot of the list members work with the Ronchi test almost
exclusively, and some use it up till the last stages.  My own penchant
would be to start quantitative Foucault testing in at least 5 zones.  I
think when coming back from a turned edge (or just about any other figure
abnormality), it is hard to see the progress with a qualitative test.  This
is especially true when the progress may be slow, and on a fairly severe
turned edge, progress may well be slow at first.  I'd rather have data and
a plot on paper.  Now, of course you have images saved that you can use for
comparison.  That will make comparison of
the Ronchi results from session to session easier.

Mark Holm
mdholm{at}telerama.com

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