M8 Coupling Nut (Long Nut), DIN 6334

The M8 coupling nut (DIN 6334) is 13 mm across the flats and 24 mm high. The thread is M8 × 1.25; the files are simplified and threaded STEP files.

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

• Also searched as: M8 coupling nut
• Model id: din6334-m8
• Standard: DIN 6334 · thread M8 × 1.25, ISO metric coarse, right hand

Files

Part key	Simplified	Threaded
din6334-m8	STEP	STEP

Dimensions

Symbol	Name	min	nom	max	Modeled	Rule	Level
m	Nut length		24		24	nominal	L1
s	Width across flats		13		13	nominal	L1
e	Width across corners	14.38			14.38	single limit (min), modeled at the limit	L1
beta	Chamfer angle	15		30	22.5	midpoint of min–max	L0 (min, max: one source)
theta	Countersink angle		120		120	nominal	L0 (nom: 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-DIN6334-SZ-M8.pdf.

Goes with the M8 coupling 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 coupling 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 coupling nut: M8 Hex Head Screw (Hex Bolt), ISO 4017
• ISO 7089 flat washer, the same size as this M8 coupling nut: M8 Flat Washer (Plain Washer), ISO 7089

The M8 coupling nut beside the M6

The M8 is the largest of the 2 DIN 6334 coupling nuts published here, from M6 to M8.

• Nut length (m): 24 mm on the M8 coupling nut, against 18 mm on the M6.
• Width across flats (s): 13 mm on the M8 coupling nut, against 10 mm on the M6.
• Width across corners (e): at least 14.38 mm on the M8 coupling nut, against at least 11.05 mm on the M6.
• Chamfer angle (beta): 15 to 30° on the M8 coupling nut, the same on the M6.
• Countersink angle (theta): 120° on the M8 coupling nut, the same on the M6.
• Coarse thread pitch (P): 1.25 mm on the M8 coupling nut, against 1 mm on the M6.
• Tap drill diameter (tap_drill): 6.75 mm on the M8 coupling nut, against 5 mm on the M6.
• Basic minor diameter (d1): 6.646835 mm on the M8 coupling nut, against 4.917468 mm on the M6.

Other sizes

• One size smaller: M6 Coupling Nut (Long Nut), DIN 6334, 10 mm across flats.

Documents

• CC-DIN6334-DS-M8.pdf: M8 datasheet: values with levels, sources
• CC-DIN6334-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-din6334, fasteners-eu-din6334, fasteners-eu-din6334-drawing, iso4753-2011-sample, 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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