Re: ATM How Does It Work

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

Assuming a random shape, you may want to make a slightly larger circle first
and then grind that to size.
A square for example will put the grinding tool way into the glass quickly
and, since you are not allowed to dig in more than a certain amount, the
corners will first be trimmed down and finally, the corners will be rounded
enough to join together and make a circle.
Unlimited digging into the glass will indeed make for problems with
circularity.
Bob May
http://nav.to/bobmay
bobmay@nethere.com
NEW! http://bobmay.astronomy.net