screws › machine screws
NAS517-4-20
Close Tolerance Flat Head Screw - 100 Degree
Description
Fastener Length: 1-47/64", Thread: 1/4-28, Thread Length: 1/2", NAS517 series screw
Specifications
| Countersink Angle | Between 99.0 degrees and 101.0 degrees |
|---|---|
| Fastener Length | Between 1.704 inches and 1.749 inches |
| Finish | Cadmium per QQ-P-416 Type II Class 2 |
| Grip | 1.250 |
| Hardness Rating | Between 36.0 rockwell c and 40.0 rockwell c |
| Head Diameter | Between 0.452 inches and 0.510 inches |
| Head Style | Flat Head, Flat countersunk |
| Internal Drive Style | Cross recess type 1 |
| Length | 1.719 |
| Material | Steel |
| Min. Tensile Strength (psi) | 160000 pounds per square inch |
| Screw Material | Steel comp 8630 |
| Screw Material Specification | Mil-s-6050 military specification single material response or an-s-9 military standard single material response |
| Screw Surface Treatment | Cadmium and chromate |
| Screw Surface Treatment Specification | Qq-p-416 type 2 cl 3 federal specification single treatment response |
| Size | 1/4-28 |
| Thread Class | 3a |
| Thread Diameter | 0.250 |
| Thread Direction | Right-hand |
| Thread Length | Between 0.368 inches and 0.514 inches |
| Thread Qty | 28 |
| Thread Qty Per Inch (tpi) | 28 |
| Thread Series | UNF |
| Thread Series Designator | Unf (fine thread) |
| Thread Size | 1/4 |
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.
- NAS517-4-21 NAS 1/4-28 · 1-3/4 in · Flat Head, Flat countersunk · Steel
Looking for a specific part? Use the cross-reference lookup.
Catalog data updated 2026-07-05. Report a data error