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NAS517-4-21
Close Tolerance Flat Head Screw - 100 Degree
Description
Fastener Length: 1-51/64", Thread: 1/4-28, Thread Length: 1/2
Specifications
| Countersink Angle | Between 99.0 degrees and 101.0 degrees |
|---|---|
| Fastener Length | Between 1.766 inches and 1.811 inches |
| Finish | Cadmium per QQ-P-416 Type II Class 2 |
| Grip | 1.312 |
| 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 | 1.781 |
| 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 |
| 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.
- NAS517-4-20 NAS 1/4-28 · 1-3/4 in · Flat Head, Flat countersunk · Steel
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Catalog data updated 2026-07-05. Report a data error