You may consider perforating a newtonian blank
yourself, take a sheet of cardboard and a compass
,make a circle which matches your blanks diameter
,and another circle inside of this which matches
the cass central perforation and cut out and save
this cardboard disc,center the cardboard disc(the
larger one that matches blanks diameter)then glue
the central cardboard disc to center of blank.
then remove large one,you then have a center
"guide" in which to use an improvised sort of biscuit cutter surrounded by a wax ring to hold in
the abrasive slurry,the cutting tool can be attached to a large drill press,or a trepanning
settup on a grinding machine,i would recommend doing this to larger mirror(16" or so)it might not
be worth the trouble for a 10"
if you dont want grind your mirror, find an amateur tm ,you will save $$$ and end up with
a better mirror. cass blanks and finished mirrors
cost alot. if you want more info email me.
stevec@ultrasw.com