ATM Hogging Out

["Bill Kelley" <flex@commspeed.net>]

  To all:

  It occurred to a young friend and I, as we were hogging out an 8 inch
mirror tonight, and starting with two 8 inch blanks, that perhaps the
chordal stroke that everyone seems to use for hogging out is not the fastest
way to dig a hole in the center of the mirror.  So we put the mirror on the
bottom, sprinkled 80 grit, and spread it around with the tool.  Then our
hogging stroke consisted of pressure on the edge of the tool sweeping back
and forth over the center of the mirror with about a 4 inch stroke and heavy
pressure on the edge of the tool.  As the edge of the tool was being driven
into the center of the mirror, we continued the usual rotation of the tool
and walk around the barrel.  This dug a hole very quickly; much faster than
the traditional chordal stroke mirror on top.  To bring the rough figure
back to a sphere; every third charge of grit, tool still on top and heavy
edge pressure, we started our strokes with the tool concentric on the
mirror, and the edge of the tool stroked just across the center of the
mirror.

    We didn't do a sharpie test, but with the mirror back on top and with
very wet worn out grinding slurry, the bubbles that formed distributed
uniformly, moved off the tool and left us with two congruent surfaces that
did not seem to stick.

    I may well be that there is nothing new about this, but when you don't
know about something and you try it and it works very well, it is very
rewarding.     : ^ )

Bill Kelley