I know there is a Guage to determine Roated Dies...but is there any sort of guage to determine off-centering?
Ihave never seen one, except for the 'estimates' that always seem to be exact, however, have you ever noticed that they are always in round figures? Like: 5%, 20% etc. Never 12%.
I believe you take the known diameter of a normal coin, along with the measurement of where the error coin's design begins to the edge of the blank portion, and use a mathematical equation to come up with a percentage. I'm terrible at math, but an easy example would be a 22mm coin, who's off-center design started 11mm away from the edge of the unstruck portion. That would obviously be 50% off-center.
