screws › close tolerance screws
NAS1581C4T18
Close Tolerance Screw
Description
Flush Reduced Head Bolt
Specifications
| Countersink Angle | 99.0 degrees minimum and 101.0 degrees maximum |
|---|---|
| Country of Origin | USA |
| Fastener Length | 1.513 inches minimum and 1.543 inches maximum |
| Grip Diameter | 0.2485 inches minimum and 0.2495 inches maximum |
| Grip Length | 1.115 inches minimum and 1.135 inches maximum |
| Head Diameter | 0.350 inches minimum and 0.399 inches maximum |
| Head Style | Flat countersunk |
| Internal Drive Style | Offset cruciform (torque set) |
| Length | 1 17/32 |
| Material | Iron |
| Material Specification | Ams5731 assn std single material response or ams5732 assn std single material response or ams5737 assn std single material response |
| Min. Tensile Strength (psi) | 160000 pounds per square inch |
| NIIN | 01-443-8385 |
| NSN | 5305-01-443-8385 |
| Specification Data | 80205-nas1581 professional/industrial association standard |
| Surface Finish | 32.0 microinches grip, 32.0 microinches threads |
| Surface Treatment | Passivate |
| Thread Class | 3a |
| Thread Diameter | 0.250 |
| Thread Direction | Right-hand |
| Thread Length | 0.403 |
| Thread Qty | 28 |
| Thread Qty Per Inch (tpi) | 28 |
| Thread Series Designator | UNJF |
| Thread Size | 1/4 |
| Weight | 0.02 lb |
Other sizes
Parts that share this base number, ordered by size. Always verify the full specification before substituting.
Cross-reference
No interchangeable or dimensionally similar parts are on record for NAS1581C4T18. Try the cross-reference lookup to search by a different part number.
Catalog data updated 2026-07-05. Report a data error