Join Date: Sep 2013
Location: South Central Connecticut
A couple of ideas come to mind... If the back side of the ball, directly behind those holes, will be covered then the holes could be cut by hand on a lathe. You would use a screw chuck to mount the ball to the lathe. There would be a hole for the screw on the back side of the ball.
Or, a standard twist drill bit could be used if you have a way to hold the ball while drilling. You'll get about a 60° taper, not conical, but a bit can be ground to a different profile or you can follow it with a rotary wood rasp to make the hole conical.
Dave in CT, USA
Last edited by Maylar; 07-14-2018 at 09:52 AM.