weight and mirror polishing

I have just aquired a polishing machine on loan. Small problem though. I have a light hydrostone tool and a comparatively light mirror, it is only 3/4" plate glass. Anyway I intend to polish Mirror on top. If I place a 7" diameter 10lb. weight in the center of the 12" mirror will this cause problems? The way the arm was design I can't get anything larger diameter o the mirror. Any other suggestions?

Sam D

Samuel,

Why are you going to spend the time and effort to try and convert a piece of 3/4" plate glass, 12" dia, into a telescope mirror? I am not questioning that it is possible to be successful with this endevor, but the extra difficulty hardly seems worth any saving in money. Why not purchase a somewhat thicker pyrex blank and avoid the problems of fabricating such a thin mirror?

Just curious,

Russ Schnitzer