bolts › close tolerance bolts
NAS1578A4R20
Bolt
Description
Fastener Length: 1-21/32", Thread: 1/4-28, Thread Length: 27/64"
Specifications
| Fastener Length | 1.638 inches minimum and 1.668 inches maximum |
|---|---|
| Grip Diameter | 0.2485 inches minimum and 0.2495 inches maximum |
| Grip Length | 1.240 inches minimum and 1.260 inches maximum |
| Hardness Rating | 36.0 rockwell c minimum and 40.0 rockwell c maximum |
| Head Diameter | 0.477 inches minimum and 0.492 inches maximum |
| Head Height | 0.140 inches minimum and 0.150 inches maximum |
| Head Style | Pan no. 2 |
| Internal Drive Style | Torque-set ribbed |
| Length | 1 21/32 |
| 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-nas1578 professional/industrial association standard |
| Surface Finish | 32.0 microinches bearing surface of head, 32.0 microinches grip, 32.0 microinches threads |
| Surface Treatment | Cadmium and chromate |
| Surface Treatment Specification | Qq-p-416 ty 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.
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.
- NAS1578A4T20 NAS 1/4-28 · 0.073 in · Pan no. 2 · Steel
Looking for a specific part? Use the cross-reference lookup.
Catalog data updated 2026-07-05. Report a data error