JIS B 1180 (AT2.1):2004 Small Hex Head Bolt features a reduced head profile, making it suitable for metric joints with compact installation space, dense surrounding components, or restricted tool access.
It retains the standard tightening method of a hex head while offering lighter weight and reduced interference from the smaller head. Typical applications include Japanese-standard equipment, precision machinery, instrument brackets, electrical cabinets, and compact mechanical structures.
Selection should consider assembly clearance, torque requirements, and wrench size. Different materials, strength classes, and finishes can be supplied to support mass production, spare-part programs, and general corrosion resistance needs.

Dimensions unit: mm
| Thread size d | M8 | M10 | M12 | (M14) | M16 | (M18) | M20 | (M22) | M24 | (M27) | M30 | (M33) | M36 | (M39) | ||||
| P | Pitch | Coarse teeth | 1.25 | 1.5 | 1.75 | 2 | 2 | 2.5 | 2.5 | 2.5 | 3 | 3 | 3.5 | 3.5 | 4 | 4 | ||
| Fine Teeth | 1 | 1.25 | 1.25 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | 2 | 2 | 2 | 2 | 3 | 3 | ||||
| ds | Max. | 8 | 10 | 12 | 14 | 16 | 18 | 20 | 22 | 24 | 27 | 30 | 33 | 36 | 39 | |||
| Min. | 7.85 | 9.85 | 11.8 | 13.8 | 15.8 | 17.8 | 19.8 | 21.8 | 23.8 | 26.8 | 29.8 | 32.75 | 35.75 | 38.75 | ||||
| k | Nominal | 5.5 | 7 | 8 | 9 | 10 | 12 | 13 | 14 | 15 | 17 | 19 | 21 | 23 | 25 | |||
| Max. | 5.65 | 7.15 | 8.2 | 9.2 | 10.2 | 12.2 | 13.2 | 14.2 | 15.2 | 17.2 | 19.25 | 21.25 | 23.25 | 25.25 | ||||
| Min. | 5.35 | 6.85 | 7.8 | 8.8 | 9.8 | 11.8 | 12.8 | 13.8 | 14.8 | 16.8 | 18.75 | 20.75 | 22.75 | 24.75 | ||||
| s | Max. | 12 | 14 | 17 | 19 | 22 | 24 | 27 | 30 | 32 | 36 | 41 | 46 | 50 | 55 | |||
| Min. | 11.75 | 13.75 | 16.75 | 18.65 | 21.65 | 23.65 | 26.65 | 29.65 | 31.6 | 35.6 | 40.6 | 45.6 | 49.6 | 54.55 | ||||
| e | ≈ | 13.9 | 16.2 | 19.6 | 21.9 | 25.4 | 27.7 | 31.2 | 34.6 | 37 | 41.6 | 47.3 | 53.1 | 57.7 | 63.5 | |||
| D | ≈ | 11.5 | 13.5 | 16.5 | 18 | 21 | 23 | 26 | 29 | 31 | 34 | 39 | 44 | 48 | 53 | |||
| r | Min. | 0.4 | 0.4 | 0.6 | 0.6 | 0.6 | 0.6 | 0.8 | 0.8 | 0.8 | 1 | 1 | 1 | 1 | 1 | |||
| da | Max. | 9.2 | 11.2 | 13.7 | 15.7 | 17.7 | 20.2 | 22.4 | 24.4 | 26.4 | 30.4 | 33.4 | 36.4 | 39.4 | 42.4 | |||
| z | ≈ | 1.2 | 1.5 | 2 | 2 | 2 | 2.5 | 2.5 | 2.5 | 3 | 3 | 3.5 | 3.5 | 4 | 4 | |||
| c | ≈ | 0.4 | 0.4 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | / | / | / | / | / | |||
| Thread length b | - | - | - | - | - | - | - | - | - | - | - | - | - | - | ||||
ABOUT US
Better Fastener is a professional fastener enterprise specializing in the manufacturing of steel washers, stainless steel washers, spring washers and sealingwashers. Founded in 2001 as a washer factory, the company expanded into a comprehensive enterprise integrating washers, nuts, bolts, spring nuts and other fastener products in 2010.
The company positions itself as a provider of comprehensive one-stop services for customers, relying on technological R&D, industrial investment and trade distribution.
With an experienced professional team and a sound sales network, Better Fastener has achieved excellent sales performance in both domestic and foreign markets,and has grown into one of the competitive manufacturers and suppliers in China's industrial fastener industry.
Better Fastener is committed to becoming a trusted fastener supplier for customers with reliable product quality, reasonable prices and on-time delivery
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