1-1/2-6 UNC tap drill size

1-11/32 drill — 1.3438 in / 34.13 mm (72% thread)

Major Ø 1.5000 in · 6 threads per inch · coarse series. The chart pick targets 75% thread; nearby standard drills:

Drill	Decimal (in)	mm	Thread %
1-23/64	1.3594	34.53	65%
1-11/32	1.3438	34.13	72%
1-21/64	1.3281	33.73	79%
1-5/16	1.3125	33.34	87%

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: 1-1/2-12 UNF