screws › machine screws
HT271A4-8
Screw
Description
Fastener Length: 63/64", Thread: 1/4-28, Thread Length: 1/2"
Specifications
| Countersink Angle | 99.5 degrees minimum and 100.5 degrees maximum |
|---|---|
| Fastener Length | 0.952 inches minimum and 0.999 inches maximum |
| Grip Diameter | 0.2490 inches minimum and 0.2495 inches maximum |
| Grip Length | 0.490 inches minimum and 0.510 inches maximum |
| Head Diameter | 0.502 inches minimum and 0.507 inches maximum |
| Head Height | 0.071 inches minimum and 0.073 inches maximum |
| Head Style | Flat countersunk undercut |
| Internal Drive Style | High-torque |
| Length | 63/64 |
| Material | Titanium |
| Material Specification | Nas621 comp 6al-4v assn std single material response or ams4928 assn std single material response |
| Special Features | Furnished with one o-ring seal |
| Surface Finish | 32.0 microinches grip, 32.0 microinches threads |
| Thread Class | 3a |
| Thread Diameter | 0.250 |
| Thread Direction | Right-hand |
| Thread Length | 0.442 inches minimum and 0.509 inches maximum |
| Thread Qty | 28 |
| Thread Qty Per Inch (tpi) | 28 |
| Thread Series Designator | UNJF |
| 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.
- 3M925C4-8A Commercial 1/4-28 · 31/32 in · Flat countersunk undercut · Steel
- ST3M430V4-8AS Other 1/4-28 · 31/32 in · Flat countersunk undercut · Titanium
- ST3M652C4-8A Other 1/4-28 · 31/32 in · Flat countersunk undercut · Steel
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Catalog data updated 2026-07-05. Report a data error