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National Stock Number:
5305-01-625-0392
Federal Supply Class:
5305
National Item Identification Number:
016250392
Description:
SCREW,CLOSE TOLERANCE
Detail:
A SCREW, MACHINE or SCREW, CAP, SOCKET HEAD whose unthreaded portion is of specified grip length, plated or unplated, and is machined to a tolerance of one thousandth (0.001 IN.) (0.025 mm) or less of a specific diameter for items (1.000 IN.) (25 mm) or less in diameter. Items over (1.000 IN.) (25 mm) in diameter shall have a tolerance of fifteen ten thousandths (0.0015 IN.) (0.038 mm) or less. The nominal major diameter of the threads shall be at least one thousandth (0.001 IN.) (0.025 mm) below the minimum shank diameter, but not below the minimum major diameter for applicable class of fit, as shown in the Screw Thread Standards, FED STD H28 and/or other nationally recognized standards. The head is designed to be held or driven with an inserted driver. It is not designed for rotation by the thumb and fingers. A locking feature may be incorporated in the design of the head or threads.
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Manufacturer Information:
| ST3M557-4-3M | 76301 | THE BOEING COMPANY |
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Techincal Specification:
| COUNTERSINK ANGLE | 99.0 DEGREES MINIMUM AND 101.0 DEGREES MAXIMUM | | FASTENER LENGTH | 0.6565 INCHES NOMINAL | | FEATURES PROVIDED | DRY FILM LUBRICANT | | GRIP LENGTH | 0.1875 INCHES NOMINAL | | GRIP DIAMETER | 0.2490 INCHES MINIMUM AND 0.2495 INCHES MAXIMUM | | HEAD HEIGHT | 0.015 INCHES MAXIMUM | | HEAD DIAMETER | 0.3898 INCHES MINIMUM AND 0.3948 INCHES MAXIMUM | | HEAD STYLE | FILLISTER COUNTERSUNK | | INTERNAL DRIVE STYLE | HIGH-TORQUE | | MATERIAL | NICKEL ALLOY 718 OVERALL | | MINIMUM TENSILE STRENGTH | 125000 POUNDS PER SQUARE INCH | | NOMINAL THREAD DIAMETER | 0.2500 INCHES | | SURFACE TREATMENT | PASSIVATE OVERALL | | THREAD CLASS | 3A | | THREAD DIRECTION | RIGHT-HAND | | THREAD LENGTH | 0.469 INCHES NOMINAL | | THREAD SERIES DESIGNATOR | UNIFIED NATIONAL JOINT FINE (UNJF) | | THREAD QUANTITY PER INCH | 28 |
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