Re: [ATM] Edging a Blank

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

The thing here to remember is that roughness can be taken care of by
springing the grinding pad alone.  To get the glass round, a stop should be
included to get the glass round.  A short spring that has a high pressure
will pretty much do this as the grinding will stop when the spring is
relaxed but that will tend to be a bit iffy for an exact diameter.  Better
to use a stop to keep the pad from going all the way in.
The old timers generally used the glass spinning against a metal leaf with
grit to do the work and that tended to be the short stiff spring routine at
work.  The leaf would be moved toward the glass as necessary to get the
right diameter.
Using a spinning diamond disk is just another method of getting the excess
material off of the glass.  Holding it rigidly means that you do the work in
one pass or the glass will tend to move on the spindle.
Using a "brake shoe" type of grinding pad will tend to also make the surface
to a particular diameter but the ends of the pad will be ground down first
(larger diameter of the glass will make this so) until the diameter of the
glass is right at which point the center of the pad will then make contact
and any work past that point will continue to make the glass smaller in
diameter using the center of the pad primarily to grind.  At this point tho,
the glass will be round as this will be the condition that provides the
least grinding of the glass.
Bob May
http://nav.to/bobmay
bobmay@nethere.com
NEW! http://bobmay.astronomy.net


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