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
|
Nominal Diameter d |
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 |
FAQ
A: We take every inquiry seriously. On working days, we will respond within 12 hours after receiving your inquiry.
A: We focus on the production of fasteners made of carbon steel, stainless steel, and low-alloy steel. We are a direct manufacturer with independent production capacity. ASME/ANSI B18.9:2007 Square Countersunk Head Bolt Factory. We own several fastener manufacturing facilities and have an international sales department, providing full-process services from production to export.
A: Customized production is our core business. We can develop and manufacture products based on the drawings or samples you provide.
A: Yes. In addition to custom products, we also produce general construction machinery parts (GET parts) for equipment such as excavators, including bucket teeth, tooth holders, corner blades, pins, clips, bolts and nuts. ASME/ANSI B18.9:2007 Square Countersunk Head Bolt Wholesale.
A: We have 12 energy-efficient and environmentally friendly modern production lines (including one fully automatic shell molding line and four heat treatment lines), with an annual production capacity exceeding 20,000 tons, enabling us to steadily meet various order requirements.
A: Trade terms (such as FOB, CIF, etc.) are confirmed when quoting. For batch production, we typically require a 30% deposit, with the balance paid against the copy of the bill of lading. T/T is the main payment method accepted, and L/C can also be negotiated.
A: We are only 35 km away from Shanghai Port and Ningbo Port, so sea freight is the main mode of transportation, which is convenient and efficient. For urgent deliveries, we can also arrange air freight via Ningbo or Shanghai airports.
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. ASME/ANSI B18.9:2007 Square Countersunk Head Bolt Suppliers in China.
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 deliveryNEWS