Re: [ATM] Pits and Pendulums

["Bob May" <rmay@nethere.com>]

Thee problem with the pendulum grinder is that first is needs to
be very rigid  in length.  If not then it will bounce about and
not make an even surface.  Second is that you can't do climb
cutting with it or it will run away from you unless you rigidly
control the movement of the wheel.  Lastly is that thee cut is
small and thus you need to do a lot of finish grinding to get to
where you can start fine grinding.
Doing the cutting with a cup  o type wheel allows for the cutting
wheel and the motor to be rigidly mo8unted with only the angle of
the cutter/motor head being set to a particular angle as part of
the setup and turning the glass underneath it is a lot more
inherently rigid and the surface, if you used a correct wheel,
can be fine ground from that point.  Peter Hjohn Smith used a
mill for his pictures because that is what he had readily at hand
and didn't need to make any tools to use it other than a holder
for the flat diamond disk which is arced to bring the edge out
from the center holding bolt.\Yes, you can use a pendulum but it
is a lot more risky than the cup wheel method and doesn't produce
as nice a surface.
Bob May
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