Re: ATM where can I purchase a 12.5" f/20 mirror

[mdholm@telerama.com]

Bob May wrote:

>I'll bet a dozen wets at 320 grit will get you most of that depth.

Unless the blank and tool are both quite flat to start, it will take more than 
this to get the surface waviness and defects out, and bring the blank and tool 
into good contact.  Depending on the roughness and fit, it may be wisest to 
start at 120.  For this small a sagitta (depth of curve), anything larger is 
probably overkill.

Mark Holm
mdholm@telerama.com