bolts › close tolerance bolts
NAS1581F4T21
Bolt
Description
Fastener Length: 1-23/32", Thread: 1/4-28, Thread Length: 27/64"
Specifications
| Countersink Angle | 99.0 degrees minimum and 101.0 degrees maximum |
|---|---|
| Fastener Length | 1.700 inches minimum and 1.730 inches maximum |
| Grip Diameter | 0.2485 inches minimum and 0.2495 inches maximum |
| Grip Length | 1.302 inches minimum and 1.322 inches maximum |
| Hardness Rating | 36.0 rockwell c minimum and 40.0 rockwell c 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 23/32 |
| Material | Steel |
| Material Specification | Mil-s-5626 mil spec 1st material response or mil-s-5000 mil spec 2nd material response or mil-s-6049 mil spec 3rd material response |
| 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, 63.0 microinches bearing surface of head |
| Surface Treatment | Cadmium and chromate |
| Surface Treatment Specification | Qq-p-416 ty2 cl2 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.
Cross-reference
No interchangeable or dimensionally similar parts are on record for NAS1581F4T21. Try the cross-reference lookup to search by a different part number.
Catalog data updated 2026-07-05. Report a data error