M2.5 Flat Point Set Screw (Flat Point Grub Screw), ISO 4026

With no head, the M2.5 flat point set screw (ISO 4026) sits flush or below the surface, turned with a 1.3 mm hex key. It comes in 8 lengths from 2.5 to 12 mm, each as simplified and threaded STEP.

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

• Also searched as: M2.5 set screw, M2.5 x 2.5 to M2.5 x 12 set screws
• Model id: iso4026-m2-5
• Standard: ISO 4026:2003 · thread M2.5 × 0.45, ISO metric coarse, right hand

Lengths

Length (mm)	Part key	Simplified	Threaded
2.5	iso4026-m2-5x2-5	STEP	STEP
3	iso4026-m2-5x3	STEP	STEP
4	iso4026-m2-5x4	STEP	STEP
5	iso4026-m2-5x5	STEP	STEP
6	iso4026-m2-5x6	STEP	STEP
8	iso4026-m2-5x8	STEP	STEP
10	iso4026-m2-5x10	STEP	STEP
12	iso4026-m2-5x12	STEP	STEP

Dimensions

Symbol	Name	min	nom	max	Modeled	Rule	Level
P	Thread pitch		0.45		0.45	nominal	L1
s	Socket width across flats	1.275	1.3	1.3	1.2875	midpoint of min–max	L1
e	Socket width across corners	1.454			1.454	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	1.25		1.5	1.375	midpoint of min–max	L1
dt	Truncation diameter, cone point			0.65	0.65	single limit (max), modeled at the limit	L1
dz	Cup diameter, cup point	0.95		1.2	1.075	midpoint of min–max	L1
z_short	Dog length, short dog point	0.63		0.88	0.755	midpoint of min–max	L1
z_long	Dog length, long dog point	1.25		1.5	1.375	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		0.45		0.45	nominal	L1
tap_drill	Tap drill diameter		2.05		2.05	nominal	L1
d1	Basic minor diameter		2.0128606		2.0128606	nominal	L1
ch_angle	Chamfered end angle			50	50	single limit (max), modeled at the limit	L2
dh_fine	Clearance hole, fine series		2.7		2.7	nominal	L1
dh_medium	Clearance hole, medium series		2.9		2.9	nominal	L1
dh_coarse	Clearance hole, coarse series		3.1		3.1	nominal	L1

Thread and holes

• Tap drill: 2.05 mm (method: d − P), L1, sources amesweb-tap-drill, rule-tap-drill.
• Clearance hole (ISO 273): close 2.7, normal 2.9, loose 3.1 mm (L1: fine, medium and coarse series (albany-clearance, wikipedia-de-clearance)).

Drawing

As a PDF: CC-ISO4026-SZ-M2.5.pdf.

Goes with the M2.5 flat point set screw

• Hex key: 1.3 mm, the socket's nominal width across flats (s) in the table above.

The M2.5 flat point set screw beside the M2 and the M3

The M2.5 is number 2, counting from the smallest, of the 7 ISO 4026 flat point set screws published here, from M2 to M8.

• Thread pitch (P): 0.45 mm on the M2.5 flat point set screw, against 0.4 mm on the M2 and 0.5 mm on the M3.
• Socket width across flats (s): 1.3 mm on the M2.5 flat point set screw, against 0.9 mm on the M2 and 1.5 mm on the M3.
• Socket width across corners (e): at least 1.454 mm on the M2.5 flat point set screw, against at least 1.011 mm on the M2 and at least 1.733 mm on the M3.
• Socket depth, short screws (t_short): at least 1.2 mm on the M2.5 flat point set screw, against at least 0.8 mm on the M2 and at least 1.2 mm on the M3.
• Socket depth, long screws (t_long): at least 2 mm on the M2.5 flat point set screw, against at least 1.7 mm on the M2 and at least 2 mm on the M3.
• Point diameter, flat and dog point (dp): 1.25 to 1.5 mm on the M2.5 flat point set screw, against 0.75 to 1 mm on the M2 and 1.75 to 2 mm on the M3.
• Truncation diameter, cone point (dt): up to 0.65 mm on the M2.5 flat point set screw, against up to 0.5 mm on the M2 and up to 0.75 mm on the M3.
• Cup diameter, cup point (dz): 0.95 to 1.2 mm on the M2.5 flat point set screw, against 0.75 to 1 mm on the M2 and 1.15 to 1.4 mm on the M3.

Other sizes

• One size smaller: M2 Flat Point Set Screw (Flat Point Grub Screw), ISO 4026, 0.9 mm hex key.
• One size larger: M3 Flat Point Set Screw (Flat Point Grub Screw), ISO 4026, 1.5 mm hex key.

Documents

• CC-ISO4026-DS-M2.5.pdf: M2.5 datasheet: values with levels, lengths, sources
• CC-ISO4026-SZ-M2.5.pdf: M2.5 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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