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National Stock Number:
5305-01-348-2686
Federal Supply Class:
5305
National Item Identification Number:
013482686
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:
| AN178C20A | 88044 | AERONAUTICAL STANDARDS GROUP DEPT OF NAVY AND AIR FORCE |
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Techincal Specification:
| FASTENER LENGTH | 2.078 INCHES MINIMUM AND 2.124 INCHES MAXIMUM | | GRIP DIAMETER | 0.4986 INCHES MINIMUM AND 0.4991 INCHES MAXIMUM | | GRIP LENGTH | 1.952 INCHES MINIMUM AND 1.982 INCHES MAXIMUM | | HARDNESS RATING | 26.0 ROCKWELL C MINIMUM AND 32.0 ROCKWELL C MAXIMUM OVERALL | | HEAD HEIGHT | 0.265 INCHES MINIMUM AND 0.297 INCHES MAXIMUM | | HEAD STYLE | HEXAGON | | INTERNAL DRIVE STYLE | CROSS RECESS TYPE 1 | | MATERIAL DOCUMENT AND CLASSIFICATION | MIL-S-18732 MIL SPEC SINGLE MATERIAL RESPONSE OVERALL | | MATERIAL | STEEL COMP 431 OVERALL | | MINIMUM TENSILE STRENGTH | 125000 POUNDS PER SQUARE INCH | | NOMINAL THREAD DIAMETER | 0.500 INCHES | | WIDTH BETWEEN FLATS | 0.740 INCHES MINIMUM AND 0.752 INCHES MAXIMUM | | SURFACE FINISH | 32.0 MICROINCHES BEARING SURFACE OF HEAD32.0 MICROINCHES GRIP | | SURFACE TREATMENT | PASSIVATE OVERALL | | THREAD CLASS | 3A | | THREAD DIRECTION | RIGHT-HAND | | THREAD LENGTH | 0.781 INCHES NOMINAL | | THREAD SERIES DESIGNATOR | UNF | | THREAD QUANTITY PER INCH | 20 |
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