it is not always easy or economical to find the correct size and thickness of shim washers.
Standard washers with the correct ID will have too large an OD and be way too thick in most cases. And I wasn't about to spend upwards of 5 or 6 bucks per washer to be special made and wait how many years ??? with the way things take months to get now days.
But I had a bin full of thin fender washers the correct OD and thickness the hole was just way too small.
No problem just bore them out. but I was not going to bore them 1 at a time.
I made holder to enable me to bore 12 at a time. The project requires 8 so if I do 2 runs of them I will have enough for 3 machines