screws › close tolerance screws
NAS1581F4T6
Close Tolerance Screw
Description
Flush Reduced Head Bolt
Specifications
| Countersink Angle | 100.0 degrees |
|---|---|
| Country of Origin | USA |
| Fastener Length | Between 0.763 inches and 0.793 inches |
| Grip Diameter | Between 0.2485 inches and 0.2495 inches |
| Grip Length | Between 0.365 inches and 0.385 inches |
| Hardness Rating | 36.0 rockwell c and 40.0 rockwell c |
| Head Diameter | Between 0.350 inches and 0.399 inches |
| Head Style | Flat countersunk |
| Internal Drive Style | Offset cruciform (torque set) |
| Material | Steel |
| Min. Tensile Strength (psi) | 160000 pounds per square inch |
| NIIN | 01-056-3204 |
| NSN | 5305-01-056-3204 |
| 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 ty2 cl2 federal specification single treatment response |
| Thread Class | 3a |
| Thread Diameter | 0.250 |
| Thread Direction | Right-hand |
| Thread Length | Between 0.378 inches and 0.428 inches |
| Thread Qty | 28 |
| Thread Qty Per Inch (tpi) | 28 |
| Thread Series | UNJF |
| Thread Series Designator | Unjf (fine thread with external controlled root radius) |
| Thread Size | 1/4 |
| Weight | 0.01 lb |
Other sizes
Parts that share this base number, ordered by size. Always verify the full specification before substituting.
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.
- NAS1581C4T6 NAS 1/4-28 · 25/32 in · Flat countersunk · Iron
Looking for a specific part? Use the cross-reference lookup.
Catalog data updated 2026-07-05. Report a data error