screws › close tolerance screws
NAS1581A4T4
Close Tolerance Screw
Description
Fastener Length: 21/32", Thread: 1/4-28, Thread Length: 27/64", NAS1581 series screw
Specifications
| Countersink Angle | 100.0 degrees |
|---|---|
| Fastener Length | Between 0.638 inches and 0.668 inches |
| Grip Diameter | Between 0.2485 inches and 0.2495 inches |
| Grip Length | Between 0.240 inches and 0.260 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 |
| 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 | Class 2 federal specification single treatment response type 2 qq-p-416 |
| 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 |
Other sizes
Parts that share this base number, ordered by size. Always verify the full specification before substituting.
- NAS1581A4T4
- NAS1581A4T5
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.
- NAS1581C4T4 NAS 1/4-28 · 21/32 in · Flat countersunk · Iron
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Catalog data updated 2026-07-05. Report a data error