M3 Button Head Screw (Button Head Allen Bolt), ISO 7380-1

An M3 button head screw (ISO 7380-1) has a head 5.4 to 5.7 mm across and 1.4 to 1.65 mm tall, driven with a 2 mm hex key. This page has 5 lengths from 6 to 16 mm, each as simplified and threaded STEP.

How these parts are made, and what the levels mean: read the method

• Also searched as: M3 bolt, M3 x 6 to M3 x 16 bolts
• Model id: iso7380-m3
• Standard: ISO 7380-1:2011 · thread M3 × 0.5, ISO metric coarse, right hand

Lengths

Length (mm)	Part key	Simplified	Threaded
6	iso7380-m3x6	STEP	STEP
8	iso7380-m3x8	STEP	STEP
10	iso7380-m3x10	STEP	STEP
12	iso7380-m3x12	STEP	STEP
16	iso7380-m3x16	STEP	STEP

Dimensions

Symbol	Name	min	nom	max	Modeled	Rule	Level
P	Thread pitch		0.5		0.5	nominal	L2
b	Thread length		18 ref		18	reference value	L2
da	Transition diameter			3.6	3.6	single limit (max), modeled at the limit	L2
dk	Head diameter	5.4		5.7	5.55	midpoint of min–max	L2
dL	Head top diameter		2.6 ref		2.6	reference value	L2
ds	Shank diameter	2.86		3	2.93	midpoint of min–max	L2
dw	Bearing face diameter	5			5	single limit (min), modeled at the limit	L2
e	Socket width across corners	2.303			2.303	single limit (min), modeled at the limit	L2
k	Head height	1.4		1.65	1.525	midpoint of min–max	L2
rf	Head dome radius	3.3		3.7	3.5	midpoint of min–max	L2
rs	Underhead fillet radius, plain shank	0.1			0.1	single limit (min), modeled at the limit	L2
rt	Underhead fillet radius, fully threaded	0.3			0.3	single limit (min), modeled at the limit	L2
s	Socket width across flats	2.02	2	2.08	2.05	midpoint of min–max	L2
t	Socket depth	1.04			1.04	single limit (min), modeled at the limit	L2
w	Wall thickness	0.2			0.2	single limit (min), modeled at the limit	L2
P	Coarse thread pitch		0.5		0.5	nominal	L1
tap_drill	Tap drill diameter		2.5		2.5	nominal	L1
d1	Basic minor diameter		2.458734		2.458734	nominal	L1
ch_angle	Chamfered end angle			50	50	single limit (max), modeled at the limit	L2
dh_fine	Clearance hole, fine series		3.2		3.2	nominal	L1
dh_medium	Clearance hole, medium series		3.4		3.4	nominal	L1
dh_coarse	Clearance hole, coarse series		3.6		3.6	nominal	L1

Thread and holes

• Tap drill: 2.5 mm (method: d − P), L1, sources amesweb-tap-drill, rule-tap-drill.
• Clearance hole (ISO 273): close 3.2, normal 3.4, loose 3.6 mm (L1: fine, medium and coarse series (albany-clearance, wikipedia-de-clearance)).

Drawing

As a PDF: CC-ISO7380-SZ-M3.pdf.

Goes with the M3 button head screw

• Hex key: 2 mm, the socket's nominal width across flats (s) in the table above.
• ISO 4032 hex nut, the same size as this M3 button head screw: M3 Hex Nut (Hexagon Nut), ISO 4032 / DIN 934
• ISO 7089 flat washer, the same size as this M3 button head screw: M3 Flat Washer (Plain Washer), ISO 7089

The M3 button head screw beside the M4

The M3 is the smallest of the 5 ISO 7380-1 button head screws published here, from M3 to M8.

• Thread pitch (P): 0.5 mm on the M3 button head screw, against 0.7 mm on the M4.
• Thread length (b): 18 mm (reference) on the M3 button head screw, against 20 mm (reference) on the M4.
• Transition diameter (da): up to 3.6 mm on the M3 button head screw, against up to 4.7 mm on the M4.
• Head diameter (dk): 5.4 to 5.7 mm on the M3 button head screw, against 7.24 to 7.6 mm on the M4.
• Head top diameter (dL): 2.6 mm (reference) on the M3 button head screw, against 3.8 mm (reference) on the M4.
• Shank diameter (ds): 2.86 to 3 mm on the M3 button head screw, against 3.82 to 4 mm on the M4.
• Bearing face diameter (dw): at least 5 mm on the M3 button head screw, against at least 6.84 mm on the M4.
• Socket width across corners (e): at least 2.303 mm on the M3 button head screw, against at least 2.873 mm on the M4.

Other sizes

• One size larger: M4 Button Head Screw (Button Head Allen Bolt), ISO 7380-1, 7.24 to 7.6 mm head, 2.5 mm hex key.

Documents

• CC-ISO7380-DS-M3.pdf: M3 datasheet: values with levels, lengths, sources
• CC-ISO7380-SZ-M3.pdf: M3 drawing: this size's values on the views
• parts.json: the part record of every length (the platform contract)

Sources

albany-clearance, amesweb-iso7380-1, amesweb-iso7380-1-lengths, amesweb-tap-drill, bossard-bn19-lengths, fasten-it-iso7380-1, fasteners-eu-iso7380-1, iso4753-2011-sample, iso7380-1-2011-sample, iso7380-1-2011-sample-lengths, rule-basic-minor, rule-tap-drill, wikipedia-de-clearance, wikipedia-iso261. Full citations: the method page and this size's datasheet.

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