Adding Ping Pong Balls Part 3

Remove the ball from the tube.
Set the ball down on the cut hole. The hole will keep it from rolling away on a flat surface.

Set your tube on the top of the ball, center the tube between the tick marks you made in the last step. Draw another line around the tube with a sharp pencil.

Score, remove the center and smooth sand as before.

The ball on the left is the one I just cut, going over a BT-50.

The ball to the right is being used as an adapter between the BT-50 and the upper BT-20 tubes.
There are two 2050 centering rings inside. Take a little time to plan the fit and it works well.