Washer for an polisher

Ok, i have made yerstaday something wrong with polish washer. It has 12.8mm hole in center, but really was need 11.8. This was outer diameter of polisher shaft thread. So was need to redo something, I.e. make new washer. Now all is much better.

Old is as left side. New is at the shaft. Beat of the washer is much better. And seems polishing wheel is also beating less. Sure i make cut of its surface.