Seng Hardware

INDUSTRIAL SUPPLIES OF CUTTING TOOL, TREADING, TAPS & DIES, DRILLS

TAPPING DRILL SIZES

ALL SIZES ARE “SUGGESTED SIZES” ONLY AND MAY BE VARIED TO SUIT INDIVIDUAL REQUIREMENTS

ISO METRIC (Coarse)				METRIC (Fine)			UNC Unified National Coarse
Tap Size	Pitch	Tapping Drill mm		Tap Size	Pitch	Tapping Drill mm	Tap Size	Pitch	Tapping Drill mm
M2	0.4	1.6		M8	1.0	7.0	3(.099)	48	2.0
M2.5	0.45	2.05		M10	1.25	8.8	4(.112)	40	2.25
M3	0.5	2.5		M12	1.25	10.8	5(.125)	40	2.6
M3.5	0.6	2.9		M12	1.5	10.5	6(.138)	32	2.75
M4	0.7	3.3		M14	1.5	12.5	8(.164)	32	3.4
M4.5	0.75	3.7		M16*	1.5	14.5	10(.190)	24	3.8
M5	0.8	4.2		M18	1.5	16.5	12(.216)	24	4.4
M6	1.0	5.0		M20*	1.5	18.5	1/4	20	5.1
M7	1.0	6.0		M22	1.5	20.5	5/16	18	6.6
M8	1.25	6.8		M24	2.0	22.5	3/8	16	8.0
M9	1.25	7.8		M12	0.5	-	7/16	14	9.4
M10	1.5	8.5	*METRIC CONDUCT				1/2	13	10.8
M11	1.5	9.5					9/16	12	12.2
M12	1.75	10.2					5/8	11	13.5
M14	2.0	12.0		SPARK PLUG			3/4	10	16.5
M16	2.0	14.0		SPARK PLUG			7/8	9	19.5
M18	2.5	15.5		M10	1.0	9.0	1″	8	22.0
M20	2.5	17.5		M12	1.25	10.8	1-1/8	7	25.0
M22	2.5	19.5		M14	1.25	12.8	1-1/4	7	28.0
M24	3.0	21.0		M16	1.5	16.5	1-1/2	6	34.0
M27	3.0	24.0	Taper pipe threads of improved quality are obtained when taper is pre-formed
M30	3.5	26.5
M33	3.5	29.5
M36	4.0	32.0	Always wear eye protection when using cutting tools.				NPTF (Taper) DRYSEAL
M39	4.0	35.0					NPTF (Taper) DRYSEAL
M42	4.5	37.5					1/8	27	8.4
M45	4.5	40.5					1/4	18	11.0
M48	5.0	43.0					3/8	18	14.5
M52	5.0	47.0					1/2	14	17.5
“The tapping drill sizes indicated are recommended only and should give approximately 75% of thread depth”.							3/4	14	23.0
							1″	11-1/2	29.0
							1-1/4	11-1/2	37.5

UNF Unified National Fine				BSW Bristish Standard Whitworh			BSF British Standard Fine
Tap Size	T.P.I.	Tapping Drill mm		Tap Size	T.P.I.	Tapping Drill mm	Tap Size	T.P.I.	Tapping Drill mm
3(.099)	56	2.1		*3/32	48	1.9	3/16	32	4.0
4(.112)	48	2.35		1/8	40	2.55	1/4	26	5.4
5(.125)	44	2.65		*5/32	32	3.2	5/16	22	6.8
6(.138)	40	2.9		3/16	24	3.7	3/8	20	8.3
8(.164)	36	3.5		*7/32	24	4.5	7/16	18	9.8
1(.190)	32	4.1		1/4	20	5.1	1/2	16	11.0
1(.216)	28	4.6		5/16	18	6.5	9/16	16	12.7
*3/16	32	4.0		3/8	16	8.0	5/8	14	14.0
1/4	28	5.5		7/16	14	9.3	3/4	12	16.5
5/16	24	6.9		1/2	12	10.5	7/8	11	19.5
3/8	24	8.5		9/16	12	12.2	1″	10	22.5
7/16	20	9.8		5/8	11	13.5	1-1/8	9	25.5
1/2	20	11.5		3/4	10	16.5	1-1/4	9	29.0
9/16	18	12.8		7/8	9	19.5	1-1/2	8	34.5
5/8	18	14.5		1″	8	22.0	1-3/4	7	40.5
3/4	16	17.5		1-1/8	7	25.0
7/8	14	20.5		1-1/4	7	28.0
1″	12	23.5		1-1/2	6	34.0
*1″	14	24.0		1-3/4	5	39.0
1-1/8	12	26.5		2″	4-1/2	45.0	G SERIES (BSPF) ISO G Parallel Series
1-1/4	12	29.5		*WHIT. FORM			G SERIES (BSPF) ISO G Parallel Series
1-1/2	12	36.0					G1/8	28	8.8
*UNS				Rc SERIES (BSPT) ISO Rc Taper Series			G1/4	19	11.8
				Rc SERIES (BSPT) ISO Rc Taper Series			G3/8	19	15.0
				Rc1/8	28	8.2	G1/2	14	19.0
				Rc1/4	19	10.8	G5/8	14	21.0
				Rc3/8	19	14.5	G3/4	14	24.5
NPSF (Straight) DRYSEAL				Rc1/2	14	17.5	G7/8	14	28.0
NPSF (Straight) DRYSEAL				Rc3/4	14	23.0	G 1″	11	30.5
1/8	27	8.5		Rc 1″	11	29.5	G1-1/4	11	39.0
1/4	18	11.0		Rc1-1/4	11	38.0	G1-1/2	11	45.0
3/8	18	14.5		Rc1-1/2	11	43.5	G1-3/4	11	51.0
1/2	14	18.0		Rc 2″	11	55.0	G 2″	11	57.0