Re: ATM Tool for rough grinding?

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

I tend to make the guys do a circular stroke which spends most of the time
in the middle (where the glass really needs to be ground out) and lesser
times out to the edge.  After they get about 1/2 way in, I'll pull out the
cheap 3 point spherometer and check the surface quickly for maintaining the
curve.  The closer you get to the real surface, the faster the tile tool
gets ground in.
If you make a lot of glass surfaces, you really do need to make a
spherometer and, when you can get a thousandth reading dial indicator for $9
or so, the cost of making one is really cheap, especially since the one
critical thing on them is getting the radius of the circle measured
correctly and a friend with the a good caliper can do that for you if you
don't have one.  If you have access to a lathe, everything becomes real easy
for making either a ring or a 3 point spherometer.
Bob May
http://nav.to/bobmay
bobmay@nethere.com