I don't know about the 1 1/2" pads you have but the ones I have have a 1 1/8" cavity in them. The most you could grind off would be about 1/4". It appears that they used the same mold for the 1" pad and just extended it 1/2". Too bad, it would have been nice to be able to cut the pad to the thickness you need.

Jim

I learn something every day, and a lot of times it's that what I learned the day before was wrong