#2-56 UNC tap drill size

#50 drill — 0.0700 in / 1.78 mm (69% thread)

Major Ø 0.0860 in · 56 threads per inch · coarse series. The chart pick targets 75% thread; nearby standard drills:

Drill	Decimal (in)	mm	Thread %
#49	0.0730	1.85	56%
#50	0.0700	1.78	69%
#51	0.0670	1.70	82%
#52	0.0635	1.61	97%

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, fine series: #2-64 UNF