Inputting Round thumb measurement How to inputting a round thumb information How to input a round thumb information. To enter the information for a round thumb hole, click " Round" Button on thumb info section located on Spec Sheet. Example: When the size of the thumb is determined , click on "Size" button. When the window opens, click on the down arrow and choose the size of the bit that corresponds to the measured size.  Example: The Taper is the next step to complete for the round thumb. When the Taper is determined, click on "Taper Size" and when the box opens up, click on the down arrow and choose the taper size. Example: Your round thumb is set to drill .