TM 5-2420-230-24-2
Tap-Drill Chart - U.S. Customary and Metric
B3.9 and B5.9 Series Engines
Page V-76
Section V - Specifications
Tap-Drill Chart - U.S. Customary and Metric
NOTE ON SELECTING TAP-DRILL SIZES: The tap drill sizes shown on this card give the theoretical tap drill size for
approximately 60% and 75% of full thread depth. Generally, it is recommended that drill sizes be selected in the 60%
range as these sizes will provide about 90% of the potential holding power. Drill sizes in the 75% range are recom-
mended for shallow hole tapping (less than 1 1/2 times the hole diameter) in soft metals and mild steel.
g-02 (tap)
L-1440