ATM Funny blank to fix

[Andrew Melville <a.melville@mailbox.gu.edu.au>]

Hi

  I posted a few days ago about a funny 200mm (8") blank I have with raised 3mm concentric rings. The rings are, I think, from the mould. I have decided to grind them off, but there is a lot of glass there to remove. These rings are on the back of both the blank and tool and they catch when I gently tried to rub both sides that have the rings on, so I cant use the back of the tool the grind the back of the blank. I have hogged out nearly 1mm from the blank so I dont want to use the flat side of the tool to grind the ringed side of the blank (I wont bother cleaning up the back of the tool). Any ideas about a grinding surface to use? I am using 80 grit to hog out, is it worth going to 60 or even rougher grit for this job?

mtia

 Andrew J. Melville

 Time flies like an arrow,
fruit flies like a banana.