Diesel Engine Specifications
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Tap-Drill Chart - U.S. Customary and Metric
NOTE ON SELECTING TAP-DRILL SIZE: The tap drill size 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
recommended for shallow hole tapping (less than 1 1/2 times the hole diameter) in soft metals and mild steel.
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