ATM Un-turning an edge

["Bill Prewitt" <bprewitt@neo.rr.com>]

Last week, somebody mentioned using an icecube on the edge of a blank before
figuring to shrink the edge so it doesn't turn.

It's a little late for me, and I never did mask that last 1/4" of my 20.
It's noticeable as a little brighter ring outside focus in a star test on a calm
night..... but I was thinking:

The equivalent, on a finished mirror would be to heat the edge while you use it.

Has anybody ever tried to "tune" a turned edge by resistance-heating it around
the lip near the face ?

          Bill Prewitt


My webpage of telescope making and caving
http://home.neo.rr.com/imaging