We have created the below interactive Clearance Drill and Tap Drill Chart as an engineering & machining resource when working with American National Thread Machine Screws. The chart is simple to use. For reference, we have included the hole size equation for American Unified Thread form. This equation computes the recommended size of the tap drill hole for any chosen percentage of full thread depth. Please note that the Percent Full Thread parameter must be entered as a decimal. For example, a 50% full thread value would be entered as 0.50. Once the hole size is calculated, one chooses the tap drill size closest to and less than the calculated hole size.
Download Drill Chart
Clearance Drill & Tap Drill Chart for Machine Screws
with American National Thread Form