Guide 13 · Fastener Reference Guide

Metal Threads & Self Tappers

Machine screw and self-tapping screw dimensions and gauges.

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Metric, Slotted Drive AS/NZS 1427

Diameter	Pitch mm	a mm (Min)	a mm (Max)	k mm (Min)	k mm (Max)
M2.5	0.45	4.40	4.70	1.30	1.50
M3	0.50	5.20	5.50	1.43	1.65
M3.5	0.60	6.90	7.30	1.69	2.35
M4	0.70	8.00	8.40	1.94	2.70
M5	0.80	8.90	9.30	2.20	2.70
M6	1.00	10.90	11.30	2.66	3.30
M8	1.25	15.40	15.80	3.58	4.65
M10	1.50	17.80	18.30	4.50	5.00

Metric, Slotted Drive AS/NZS 1427

Diameter	Pitch mm	a mm (Min)	a mm (Max)	k mm (Min)	k mm (Max)
M2.5	0.45	4.70	5.0	1.36	1.5
M3	0.50	5.30	5.6	1.66	1.8
M3.5	0.60	6.64	7.0	1.96	2.1
M4	0.70	7.64	8.0	2.26	2.4
M5	0.80	9.14	9.5	2.86	3.0
M6	1.00	11.57	12.0	3.30	3.6
M8	1.25	15.57	16.0	4.50	4.8
M10	1.50	19.48	20.0	5.70	6.0

Metric, Cross Recess Drive AS/NZS 1427

Diameter	Pitch mm	a mm (Min)	a mm (Max)	k mm (Min)	k mm (Max)
M2.5	0.45	4.7	5.0	1.96	2.10
M3	0.50	5.3	5.6	2.26	2.40
M3.5	0.60	6.6	7.0	2.46	2.60
M4	0.70	7.6	8.0	2.92	3.10
M5	0.80	9.1	9.5	3.52	3.70
M6	1.00	11.6	12.0	4.30	4.60
M8	1.25	15.6	16.0	5.70	6.00
M10	1.50	19.5	20.0	7.14	7.50

Metal Threads & Self Tappers AS/NZS 1427

Diameter	Pitch mm	a mm (Min)	a mm (Max)	k mm (Min)	k mm (Max)
M3	0.50	6.5	6.9	1.7	1.9
M4	0.70	8.9	9.4	2.3	2.5
M5	0.80	11.2	11.8	2.9	3.1
M6	1.00	13.2	13.9	3.4	3.6
M8	1.25	17.0	17.9	4.1	4.7

Pan Head ASME B18.6.3

Diameter Gauge No.	Pitch TPI	a3 (Min)	a3 (Max)	b (Min)	b (Max)
2	32	0.155	0.167	0.053	0.062
3	28	0.180	0.193	0.062	0.071
4	24	0.205	0.219	0.070	0.080
5	20	0.231	0.245	0.079	0.089
6	20	0.256	0.270	0.087	0.097
7	19	0.281	0.296	0.096	0.106
8	18	0.306	0.322	0.105	0.115
10	16	0.357	0.373	0.122	0.133
12	14	0.407	0.425	0.139	0.151
1/4	14	0.473	0.492	0.162	0.175
5/16	12	0.594	0.615	0.203	0.218
3/8	12	0.716	0.740	0.244	0.261

ASME B18.6.3

Diameter Gauge No.	Pitch TPI	a2 (Min)	a2 (Max)	e (Ref)
2	32	0.144	0.162	0.051
3	28	0.167	0.187	0.059
4	24	0.191	0.212	0.067
5	20	0.215	0.237	0.075
6	20	0.238	0.262	0.083
7	19	0.262	0.287	0.091
8	18	0.285	0.312	0.100
10	16	0.333	0.362	0.116
12	14	0.380	0.412	0.132
1/4	14	0.442	0.477	0.153
5/16	12	0.556	0.597	0.191
3/8	12	0.670	0.717	0.230

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