ASME/ANSI B18.5 80°Slotted Countersunk Head Bolts
ASME/ANSI B18.5 80° Slotted Countersunk Head Bolts feature an 80° countersunk head and a traditional slotted drive for flush, low-profile fastening. The angled head seats into a matching countersunk hole, allowing the fastener head to remain close to or below the surrounding surface and reducing interference with adjacent components.
The slotted drive provides a simple, accessible driving interface, while the countersunk head helps create a clean fastening surface. This configuration is suitable for fixtures, fabricated assemblies, equipment panels, brackets, and other applications where a recessed fastener head is required. For selection, customers should consider the nominal diameter, bolt length, head dimensions, countersink angle, material, mechanical property requirements, and surface finish. Carbon steel, alloy steel, stainless steel, and nonferrous versions can be specified according to the applicable material and performance requirements.
Specification:
ASME/ANSI B18.5 specifies the dimensional requirements for inch-series round head bolts, including 80° Slotted Countersunk Head Bolts. The countersunk head geometry, nominal diameter, length, head dimensions, and thread characteristics determine how the bolt fits into the mating component. The 80° head angle should be matched with the corresponding countersunk hole to achieve the intended recessed installation.
Material and mechanical properties are specified separately according to the selected material and grade. Carbon steel versions may be supplied to ASTM A307 or SAE J429 requirements, while stainless steel and nonferrous versions can be specified to ASTM F593 and ASTM F468, respectively, where applicable.
| Item | Specification |
|---|---|
| Specification | ASME/ANSI B18.5 |
| Product Type | Slotted Countersunk Head Bolt |
| Head Angle | 80° |
| Drive Type | Slotted |
| Thread System | Inch |
| Thread Series | UNC/UNF |
| Size Range | 1/4”-1-1/2“ |
| Carbon Steel Standard | ASTM A307/SAE J429 |
| Stainless Steel | ASTM F593 |
| Nonferrous Alloy | ASTM F468 |
| Material | Carbon Steel, Stainless Steel, Brass |
| Surface Treatment | Zinc Plated,Black Oxidation,Dacromet, Bright Finish,Passivation |
- RELATED BOLT LISTS:
- ASME B 18.31.5 HRA Hook Bolts
- ASTM A394 HDG Tower Bolts
- ASTM A354 Hex Bolts
- ASME B 18.2.1 Square Head Bolts
- ASME/ANSI B 18.5 Round Head Square Neck Bolts
- ASME/ANSI B18.5 T- Head Bolts
- ASME/ANSI B18.2.1 Hex Head Flange Bolts
- ASME/ANSI B18.5 80°Slotted Countersunk Head Bolts
- ASME/ANSI B18.2.1 Hex Cap Bolts
- A307 Hex Head Bolts
Dimension Chart of ASME/ANSI B18.5 80°Slotted Countersunk Head Bolts:
The dimension chart provides the measurements needed to match the bolt with the countersunk hole and the available installation space. Nominal diameter and length determine the basic fastening capacity, while the 80° countersunk head dimensions determine how the bolt seats against the mating surface. For installation planning, the head diameter, head height, slot dimensions, and thread length should also be considered. The countersink in the mating component should be designed to accommodate the specified 80° head geometry for proper seating.
| Thread Diameter | 1/4 | 5/16 | 3/8 | 7/16 | 1/2 | 5/8 | 3/4 | 7/8 | 1 | 1-1/8 | 1-1/4 | 1-3/8 | 1-1/2 |
| P | 20|28|32 | 18|24|32 | 16|24|32 | 14|20|28 | 13|20|28 | 11|18|24 | 10|16|20 | 9|14|20 | 8|12|20 | 7|12|18 | 7|12|18 | 12|18 | 6|12|18 |
| ds max | 0.26 | 0.324 | 0.388 | 0.452 | 0.515 | 0.642 | 0.768 | 0.895 | 1.022 | 1.149 | 1.277 | 1.404 | 1.531 |
| ds min | 0.237 | 0.298 | 0.36 | 0.421 | 0.483 | 0.605 | 0.729 | 0.852 | 0.976 | 1.098 | 1.223 | 1.345 | 1.47 |
| dk max | 0.493 | 0.618 | 0.74 | 0.803 | 0.935 | 1.169 | 1.402 | 1.637 | 1.869 | 2.104 | 2.337 | 2.571 | 2.804 |
| dk min | 0.445 | 0.558 | 0.668 | 0.726 | 0.845 | 1.066 | 1.285 | 1.511 | 1.735 | 1.962 | 2.187 | 2.414 | 2.64 |
| k max | 0.15 | 0.189 | 0.225 | 0.226 | 0.269 | 0.336 | 0.403 | 0.47 | 0.537 | 0.604 | 0.671 | 0.738 | 0.805 |
| k min | 0.131 | 0.164 | 0.196 | 0.196 | 0.233 | 0.292 | 0.349 | 0.408 | 0.466 | 0.525 | 0.582 | 0.641 | 0.698 |
| n max | 0.075 | 0.084 | 0.094 | 0.094 | 0.106 | 0.133 | 0.149 | 0.167 | 0.188 | 0.196 | 0.211 | 0.226 | 0.258 |
| n min | 0.064 | 0.072 | 0.081 | 0.081 | 0.091 | 0.116 | 0.131 | 0.147 | 0.166 | 0.178 | 0.193 | 0.208 | 0.24 |
| t max | 0.068 | 0.086 | 0.103 | 0.103 | 0.103 | 0.137 | 0.171 | 0.206 | 0.24 | 0.257 | 0.291 | 0.326 | 0.36 |
| t min | 0.045 | 0.057 | 0.068 | 0.068 | 0.068 | 0.091 | 0.115 | 0.138 | 0.162 | 0.173 | 0.197 | 0.22 | 0.244 |
Application of ASME/ANSI B18.5 80°Slotted Countersunk Head Bolts:
Equipment Panels and Access Covers
80° Slotted Countersunk Head Bolts can be used for equipment covers, machine panels, access plates, and fabricated enclosures where the fastener head needs to sit within a prepared countersunk hole rather than protrude significantly from the surface.
Machinery and Fabricated Assemblies
They are suitable for machine frames, brackets, guards, mounting plates, and fabricated steel components where a traditional slotted drive is practical and the connection benefits from a recessed head profile.
Fixtures and General Mechanical Assembly
The 80° countersunk configuration can be used in jigs, fixtures, equipment supports, and mechanical assemblies where the mating component is prepared with a matching countersink. The slotted head provides a simple drive interface for assembly and maintenance.