These clocks use a 1 7/16" mini insert. You could also use the 1 7/16" picture frame insert as well. Use a 1 3/8" forstner bit to cut the hole for the insert.
I hope everyone is having a great weekend and spending time in the workshop. The weather here in Kentucky is spectacular. 70 degrees and clear. Not to mention my Kentucky Wildcat football team is giving the #1 LSU team all they want. If we win this game my heart might not be able to take it. I get a little excited.