Just did one. Set the handle up straight in a drill press. I put a piece of masking tape on the end of the knob, measured up 7/16" and back 1/2", and drew intersecting lines. Put a small punch mark, drilled a 3/16" hole thru to the 3/8" hole that is there for the handle to screw into. Got to drill straight... Followed that with a 21/64" drill that was 7/8" deep. Then tapped 1/4"x20 NC for set screw. Was able to find 1/4"x20 by 3/8"long set screws at Home Depot. I haven't been able to locate the 1/2" long 1/4"x20 NC set screw. Believe the original length was 1/2" long ....Dave