Technical Information ·Oct 05, 2016

Pilot Hole Data

Pilot Hole and Shank Clearance Hole Boring Recommendations for Wood Screws

Screw Diameter	Bit or Drill Sizes						No of Auger Bit To Counterbore for striking head
	For Shank Clearance Holes		For Pilot Holes
	For Shank Clearance Holes		Hard Woods		Soft Woods
	Twist Bit Nearest Size in fractions of an inch	Drill Gauge No or letter to be used for maximum holding power	Twist Bit Nearest Size in fractions of an inch	Drill Gauge No to be used for maximum holding power	Twist Bit Nearest Size in fractions of an inch	Drill Gauge No to be used for maximum holding power
0	1/16	52	1/32	66	1/54	75	-
1	5/64	47	-	57	1/32	71	-
2	3/32	42	-	54	1/32	65	3
3	7/54	37	1/16	53	3/64	58	4
4	7/54	32	1/16	51	3/64	55	4
5	1/8	30	5/64	47	1/16	53	4
6	9/64	27	-	44	1/16	52	5
7	5/32	22	-	39	1/16	51	5
8	11/64	18	7/64	35	5/64	48	6
9	3/16	14	7/64	33	5/64	45	6
10	3/16	10	1/8	31	3/32	43	6
11	13/64	4	-	29	3/32	40	7
12	7/32	2	-	25	7/64	38	7
14	1/4	0	3/16	14	7/64	32	8
16	17/64	1	-	10	9/64	29	9
18	19/64	N	13/64	6	9/64	26	10
20	21/64	P	7/32	3	11/64	19	11
24	3/8	V	1/4	D	3/16	15	12

Self Tapping Screws - Hole Size Recommendations

Screw Diameter	Thickness of Metal		Pierced Hole	Drilled or clean Punched Hole		Screw Diameter	Thickness of metal		Pierced Hole	Drilled or clean Punched Hole
Screw Diameter	USS Gauge No	Equivalent	Hole Dia	Hole Dia	Drill Size	Screw Diameter	USS Gauge No	Equivalent	Hole Dia	Hole Dia	Drill Size
4 .112	28 26 24 22 20	.0156 .0188 .0250 .0313 .0375	.086 .086 .093 .098 .100	.0860 .0860 .0935 .0935 .0980	44 44 42 42 40	8 .165	26 24 22 20 18	.0188 .0250 .0313 .0375 .0500	.137 .137 .137 .137 -	.1130 .1130 .1160 .1200 .1280	33 33 32 31 30
6 .138	28 26 24 22 20	.0156 .0188 .0250 .0313 .0375	.111 .111 .111 .111 .111	.0995 .0995 .0995 .1015 .1065	39 39 39 38 36	10 .191	26 24 22 20 18	.0188 .0250 .0313 .0375 .0500	.158 .158 .158 .158 .158	.1285 .1285 .1285 .1360 .1495	30 30 30 29 25
7 .115	28 26 24 22 20 18	.0156 .0188 .0250 .0313 .0345 .0500	.121 .121 .121 .121 .121 -	.1040 .1040 .1100 .1130 .1160 .1200	37 37 35 33 32 31	12 .218	24 22 20 18	.0250 .0313 .0375 .0500	- .185 .185 .185	.1470 .1495 .1520 .1570	26 25 24 22
						14 .251	24 22 20 18	.0250 .0313 .0375 .0500	- .212 .212 .212	.1800 .1890 .1910 .1960	15 12 11 9