ASME/ANSI B18.9:2007 Square Countersunk Head Bolt combines a square head form with a countersunk profile. It is intended for inch-series joints requiring a special seat, low exposed surface, and dependable anti-rotation behavior.
The square countersunk head can lock into a matching recess and provide clear angular positioning, reducing head movement during tightening. It is suitable for wood structures, rail accessories, heavy plates, equipment bases, and custom mechanical joints.
The countersunk seat form, head size, thread specification, and grip thickness should be matched carefully. For custom projects, the hole geometry should be confirmed together with the drawing to ensure a flush surface and reliable load transfer.

Unit: mm
|
公称直径 |
s |
ds |
||
|
min |
max |
max |
min |
|
|
5/16 |
0.516 |
0.531 |
0.312 |
0.299 |
|
3/8 |
0.641 |
0.656 |
0.375 |
0.36 |
|
7/16 |
0.703 |
0.718 |
0.438 |
0.421 |
|
1/2 |
0.766 |
0.781 |
0.5 |
0.438 |
|
9/16 |
0.891 |
0.922 |
0.592 |
0.544 |
|
5/8 |
0.953 |
0.984 |
0.657 |
0.606 |
|
3/4 |
1.078 |
1.109 |
0.782 |
0.729 |
|
7/8 |
1.266 |
1.297 |
0.938 |
0.853 |
|
1 |
1.453 |
1.484 |
1.062 |
0.976 |
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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.
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