MS51981/NASM51981


FED. SUP CLASS
5305

APPROVED 11 MAR 1964       REVISED (A)10 SEP 1969 (B) 31 MAR 1972 (C) 15 MAR 1979.

NOMINAL SIZE .086 .112 .138 .164 .190 .250 .3125 .375 .500
THREADS PER INCH (UNC_3A) 56 40 32 32 24 20 18 16 13
J SOCKET WIDTH
ACROSS FLATS
NOM .035 .050 .062 .078 .094 .125 .156 .188 .250
R POINT RADIUS MAX
MIN
.079
.064
.099
.084
.135
.104
.154
.123
.173
.142
.219
.185
.265
.234
.312
.281
.406
.375
L LENGTH TOL. DASH NUMBER
.125
.188
.250
.312

.375
.500
.625
+.010 1
2
8
9
10
16
17
18
19

20

26
27
28

29
30

36
37
38

39
40


46
47

48
49
50


58
59

60
61
62





70
71
72






80
81
82
.750
1.000
+.020 51
52
63
64
73
74
82
83
      NOTES:
    1. MATERIAL : ALLOY STEEL IN ACCORDANCE WITH PROCUREMENT SPECIFICATION, HAVING A ROCKWELL HARDNESS OF C45-53
    2. PROACTIVE COATING: CADMIUM PLATED IN ACCORDANCE WITH PROCUREMENT SPECIFICATION.
    3. THREADS:THE THREADS SHALLL BE IN ACCORDANCE WITH MIL-S-7742.
    4. DIMENTIONS:ALL DIMENTIONS ARE IN INCHES, UNLESS OTHERWISE SPECIFIED.
    5. PART NUMBER: THE PART NUMBER CONSISTS OF THE MS NUMBER, PLUS THE DASH NUMBER.
      EXAMPLE: MS51981_1. PLAIN SETSCREW OR MS51981-1L SELF-LOCKING SETSCREW.
    6. REFERENCED DOCUMENTS SHALL BE OF THE ISSUE IN EFFECT ON DATE OF INVITATIONS FOR BID.
    7. FOR DESIGN FEATURE PURPOSES, THIS STANDARD TAKES PRECEDENCE OVER PROCUREMENT DOCUMENTS REFERENCED HEREIN.
    8. SELF-LOCKING ELEMENT:

      (C)
      1.     The self-locking element shall be a patch type or longtudinal strip in accordance with MIL-F-18240.

      2.     Maximum ring gage diameter that loacking region of serscrew must pass thru freely or with finger pressure shall be the nominal size pluse 0.010.
      3.     Locating of effective locking area, design and usage limitation. (see MS15981).
    INTERCHANGEABILITY

    Screws covered by the dash numbers given in MS51049 and MS51051 are cancelled after 11 March 1964 and superseded by screws covered on MS51981 having same dash number. Cancelled screws may be used until existing stock are depleted. Use only the MS51981 screws for new design.


    Screws covered by the dash numbers given in MS51053 are cancelled/ inactivated after 10 September 1969. Cancelled screws may be used until existing stock are depleted. Use only the superseding screws for new design. Replacement shall be in accordance with Table II.
TABLE II
CANCELLED SUSPERSENDING CANCELLED SUSPERSENDING CANCELLED SUSPERSENDING CANCELLED SUSPERSENDING
MS51053 MS51981 MS51053 MS51981 MS51053 MS51981 MS51053 MS51981
DASH NUMBER DASH NUMBER DASH NUMBER DASH NUMBER
401
402
403
404
405
411
412
**
1
2
**
**
**
8
413
414
415
416
417
418
419
9
10
**
**
**
**
**
420
426
427
428
429
430
**
16
17
18
19
20
431
432
433
434
435
436
**
**
**
**
**
**
** No Replacement
P.A AR
Order Cust
AS
99
TITLE
SETSCREW - HEXAGON SOCKET, OVAL POINT,
ALLOY STEEL, CADMIUM PLATED, UNC - 3A
MILITARY STANDARD
MS 51981
PROCUREMENT SPECIFICATION
FF-S-200
SUPERSEDES MS51049, MS51051 and in part MS51053, BCTX2, BCTX2.1, BCTX2.10 and BCTX4.1 SHEET       1       of       1

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