M8 Square Nut (Chamfered Square Nut), DIN 557

For M8 × 1.25 threads: an M8 square nut to DIN 557, 13 mm across the flats and 6.5 mm high. Download it as simplified and threaded STEP files.

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

• Also searched as: M8 square nut
• Model id: din557-m8
• Standard: DIN 557:1994 · thread M8 × 1.25, ISO metric coarse, right hand

Files

Part key	Simplified	Threaded
din557-m8	STEP	STEP

Dimensions

Symbol	Name	min	nom	max	Modeled	Rule	Level
P	Thread pitch		1.25		1.25	nominal	L1
s	Width across flats	12.57	13	13	12.785	midpoint of min–max	L1
m	Nut height	5.92	6.5	6.5	6.21	midpoint of min–max	L1
e	Width across corners	16.34		18.4	17.37	midpoint of min–max	L1
dw	Bearing face diameter	11.5			11.5	single limit (min), modeled at the limit	L1
mw	Height at the corners	4.1			4.1	single limit (min), modeled at the limit	L1
beta	Chamfer angle	15		30	22.5	midpoint of min–max	L0 (min, max: one source)
P	Coarse thread pitch		1.25		1.25	nominal	L1
tap_drill	Tap drill diameter		6.75		6.75	nominal	L1
d1	Basic minor diameter		6.646835		6.646835	nominal	L1
ch_angle	Chamfered end angle			50	50	single limit (max), modeled at the limit	L2
dh_fine	Clearance hole, fine series		8.4		8.4	nominal	L1
dh_medium	Clearance hole, medium series		9		9	nominal	L1
dh_coarse	Clearance hole, coarse series		10		10	nominal	L1

Thread and holes

• Tap drill: 6.75 mm (method: d − P), L1, sources amesweb-tap-drill, rule-tap-drill.
• Clearance hole (ISO 273): close 8.4, normal 9, loose 10 mm (L1: fine, medium and coarse series (albany-clearance, wikipedia-de-clearance)).

Drawing

As a PDF: CC-DIN557-SZ-M8.pdf.

Goes with the M8 square nut

• Spanner: 13 mm, the hexagon's nominal width across flats (s) in the table above.
• ISO 4762 socket head cap screw in 14 lengths from 12 to 80 mm, the same size as this M8 square nut: M8 Socket Head Cap Screw (Allen Bolt), ISO 4762 / DIN 912
• ISO 4017 hex head screw in 13 lengths from 16 to 80 mm, the same size as this M8 square nut: M8 Hex Head Screw (Hex Bolt), ISO 4017
• ISO 7089 flat washer, the same size as this M8 square nut: M8 Flat Washer (Plain Washer), ISO 7089

The M8 square nut beside the M6

The M8 is the largest of the 3 DIN 557 square nuts published here, from M5 to M8.

• Thread pitch (P): 1.25 mm on the M8 square nut, against 1 mm on the M6.
• Width across flats (s): 13 mm on the M8 square nut, against 10 mm on the M6.
• Nut height (m): 6.5 mm on the M8 square nut, against 5 mm on the M6.
• Width across corners (e): 16.34 to 18.4 mm on the M8 square nut, against 12.53 to 14.1 mm on the M6.
• Bearing face diameter (dw): at least 11.5 mm on the M8 square nut, against at least 8.7 mm on the M6.
• Height at the corners (mw): at least 4.1 mm on the M8 square nut, against at least 3.2 mm on the M6.
• Chamfer angle (beta): 15 to 30° on the M8 square nut, the same on the M6.
• Tap drill diameter (tap_drill): 6.75 mm on the M8 square nut, against 5 mm on the M6.

Other sizes

• One size smaller: M6 Square Nut (Chamfered Square Nut), DIN 557, 10 mm across flats.

Documents

• CC-DIN557-DS-M8.pdf: M8 datasheet: values with levels, sources
• CC-DIN557-SZ-M8.pdf: M8 drawing: this size's values on the views
• parts.json: the part record of this size (the platform contract)

Sources

albany-clearance, amesweb-tap-drill, fasten-it-din557, fasteners-eu-din557, fasteners-eu-din557-drawing, iso4753-2011-sample, krepcom-din557, 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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