bolts › close tolerance bolts
NAS1581F4H4
Bolt
Description
Fastener Length: 21/32", Thread: 1/4-28, Thread Length: 27/64"
Specifications
| Countersink Angle | 99.0 degrees minimum and 101.0 degrees maximum |
|---|---|
| Fastener Length | 0.638 inches minimum and 0.668 inches maximum |
| Grip Diameter | 0.2485 inches minimum and 0.2495 inches maximum |
| Grip Length | 0.240 inches minimum and 0.260 inches maximum |
| Hardness Rating | 36.0 rockwell c minimum and 40.0 rockwell c maximum |
| Head Diameter | 0.3504 inches minimum and 0.3988 inches maximum |
| Head Style | Flat countersunk |
| Internal Drive Style | High-torque |
| Length | 21/32 |
| Material | Steel |
| Min. Tensile Strength (psi) | 160000 pounds per square inch |
| Specification Data | 80205-nas1581 professional/industrial association standard |
| Surface Finish | 32.0 microinches grip, 32.0 microinches threads |
| Surface Treatment | Cadmium and chromate |
| Surface Treatment Specification | Qq-p-416 type 2 cl 2 fed spec single treatment response |
| Thread Class | 3a |
| Thread Diameter | 0.250 |
| Thread Direction | Right-hand |
| Thread Length | 0.378 inches minimum and 0.428 inches maximum |
| Thread Qty | 28 |
| Thread Qty Per Inch (tpi) | 28 |
| Thread Series Designator | UNJF |
| Thread Size | 1/4 |
Other sizes
Parts that share this base number, ordered by size. Always verify the full specification before substituting.
- NAS1581F4H4
- NAS1581F4H5
- NAS1581F4H6
- NAS1581F4H9
- NAS1581F4H10
- NAS1581F4H15
Cross-reference
Similar parts
Parts with matching key dimensions — often from a different standards family. Candidates for comparison only; verify the full specification before substituting.
- NAS1581C4H4 NAS 1/4-28 · 21/32 in · Flat countersunk · Iron
- NAS1581K4R4 NAS 1/4-28 · 21/32 in · Flat countersunk · Titanium
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Catalog data updated 2026-07-05. Report a data error