丝锥钻孔尺寸

Suggested Percentages of Full Thread in Tapped Holes

A common internal thread&#44 drilled so that it results in 50% of full thread will break the external thread&#44 before the internal thread will strip. A common internal thread drilled out so that it contains 100% of full thread is only 5% stronger than a 75% height of thread&#44 yet it requires 3 times the power to tap.