M3 Dog Point Set Screw (Dog Point Grub Screw), ISO 4028

A headless M3 × 0.5 dog point set screw (ISO 4028), turned with a 1.5 mm hex key. Available as 7 lengths from 4 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 set screw, M3 x 4 to M3 x 16 set screws
• Model id: iso4028-m3
• Standard: ISO 4028:2003 · thread M3 × 0.5, ISO metric coarse, right hand

Lengths

Length (mm)	Part key	Simplified	Threaded
4	iso4028-m3x4	STEP	STEP
5	iso4028-m3x5	STEP	STEP
6	iso4028-m3x6	STEP	STEP
8	iso4028-m3x8	STEP	STEP
10	iso4028-m3x10	STEP	STEP
12	iso4028-m3x12	STEP	STEP
16	iso4028-m3x16	STEP	STEP

Dimensions

Symbol	Name	min	nom	max	Modeled	Rule	Level
P	Thread pitch		0.5		0.5	nominal	L1
s	Socket width across flats	1.52	1.5	1.58	1.55	midpoint of min–max	L1
e	Socket width across corners	1.733			1.733	single limit (min), modeled at the limit	L1
t_short	Socket depth, short screws	1.2			1.2	single limit (min), modeled at the limit	L1
t_long	Socket depth, long screws	2			2	single limit (min), modeled at the limit	L1
dp	Point diameter, flat and dog point	1.75		2	1.875	midpoint of min–max	L1
dt	Truncation diameter, cone point			0.75	0.75	single limit (max), modeled at the limit	L1
dz	Cup diameter, cup point	1.15		1.4	1.275	midpoint of min–max	L1
z_short	Dog length, short dog point	0.75		1	0.875	midpoint of min–max	L1
z_long	Dog length, long dog point	1.5		1.75	1.625	midpoint of min–max	L1
fl_angle	Flat point chamfer angle			50	50	single limit (max), modeled at the limit	L2
cone_angle	Cone point included angle, long lengths		90		90	nominal	L2
cone_angle_short	Cone point included angle, short lengths		120		120	nominal	L1
dog_angle	Dog point chamfer angle			50	50	single limit (max), modeled at the limit	L2
cp_angle	Cup point outer chamfer angle			50	50	single limit (max), modeled at the limit	L2
cup_angle	Cup recess included angle		120 ref		120	reference value	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-ISO4028-SZ-M3.pdf.

Goes with the M3 dog point set screw

• Hex key: 1.5 mm, the socket's nominal width across flats (s) in the table above.

The M3 dog point set screw beside the M2.5 and the M4

The M3 is number 3, counting from the smallest, of the 7 ISO 4028 dog point set screws published here, from M2 to M8.

• Thread pitch (P): 0.5 mm on the M3 dog point set screw, against 0.45 mm on the M2.5 and 0.7 mm on the M4.
• Socket width across flats (s): 1.5 mm on the M3 dog point set screw, against 1.3 mm on the M2.5 and 2 mm on the M4.
• Socket width across corners (e): at least 1.733 mm on the M3 dog point set screw, against at least 1.454 mm on the M2.5 and at least 2.303 mm on the M4.
• Socket depth, short screws (t_short): at least 1.2 mm on the M3 dog point set screw, against at least 1.2 mm on the M2.5 and at least 1.5 mm on the M4.
• Socket depth, long screws (t_long): at least 2 mm on the M3 dog point set screw, against at least 2 mm on the M2.5 and at least 2.5 mm on the M4.
• Point diameter, flat and dog point (dp): 1.75 to 2 mm on the M3 dog point set screw, against 1.25 to 1.5 mm on the M2.5 and 2.25 to 2.5 mm on the M4.
• Truncation diameter, cone point (dt): up to 0.75 mm on the M3 dog point set screw, against up to 0.65 mm on the M2.5 and up to 1 mm on the M4.
• Cup diameter, cup point (dz): 1.15 to 1.4 mm on the M3 dog point set screw, against 0.95 to 1.2 mm on the M2.5 and 1.75 to 2 mm on the M4.

Other sizes

• One size smaller: M2.5 Dog Point Set Screw (Dog Point Grub Screw), ISO 4028, 1.3 mm hex key.
• One size larger: M4 Dog Point Set Screw (Dog Point Grub Screw), ISO 4028, 2 mm hex key.

Documents

• CC-ISO4028-DS-M3.pdf: M3 datasheet: values with levels, lengths, sources
• CC-ISO4028-SZ-M3.pdf: M3 drawing: this size's values on the views
• parts.json: the part record of every length (the platform contract)

Sources

accu-iso4027, albany-clearance, amesweb-iso4026-4029, amesweb-tap-drill, fasten-it-iso4026, fasten-it-iso4027, fasten-it-iso4028, fasten-it-iso4029, fuller-iso4026, fuller-iso4027, fuller-iso4028, fuller-iso4029, iso4753-2011-sample, iso4753-2011-sample-text, 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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