Re: ATM Hogging Out

["Ken Hunter" <kb7h@onemain.com>]

You CAN'T do that!

Everyone knows (especially Bob May) that gravity causes the
disk on the bottom to become convex while the one on top becomes
concave.

Are you trying to go against conventional wisdom?

Ken Hunter


----- Original Message -----
From: "Bill Kelley" <flex@commspeed.net>
To: <atm@shore.net>
Sent: Saturday, August 03, 2002 9:49 PM
Subject: ATM Hogging Out


>
>   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
>
>
>