#2-64 UNF tap drill size

#50 drill — 0.0700 in / 1.78 mm (79% thread)

Major Ø 0.0860 in · 64 threads per inch · fine series. The chart pick targets 75% thread; nearby standard drills:

Drill	Decimal (in)	mm	Thread %
#48	0.0760	1.93	49%
#49	0.0730	1.85	64%
#50	0.0700	1.78	79%
#51	0.0670	1.70	94%

Cut taps only — roll-form taps need a larger hole. 65–75% suits general work; drop toward 55% in tough material. Verify before you cut.

Same size, coarse series: #2-56 UNC