C If you find a TDE, what changes in your stroke should you make to C correct it? I performed this check on my 10" at the 20 micron stage, C and am about to start 9micron grit - the center did appear to wear C faster than the edge. Should this be corrected before going to 9 micron, C or during 9 micron as suggested?
I think that all this gets a bit confusing. Your center will ALWAYS wear a bit faster than the edge, simply because it is 100% of time in contact with the tool, while edges are not ground 50% of time (when tool overhangs to one side). If you are at micron powders stage, the best indicator of sphericity of your mirror/tool is smoothness. If your tool/mirror flows evenly during the stroke, you can safely proceed to the next (9 micron) grit, providing that you are happy with residual pitting. If it sticks, runs away from the center, or goes jerky during the stroke, you've got the problem. But if you use normal 1/4 to 1/3 dia even, steady strokes and no pressure, you'll automatically get there, no matter what you do. It's quite safe and foolproof technique !
Bratislav