Least Material Condition

Of particular note in the MS21042 series of nuts is the nuts wall thickness. The drawings below illustrate the wall thickness of the MS21042 series as compared to nuts of similar sizes, such as the 42FLW lock-nut series, MS21043 series, and MS21044N series of lock-nuts.

Thread Diameter MS21042 lock-nuts NAS1804 lock-nuts MS21043 lock-nuts MS21044N lock-nuts
.086" MS21042-02 MS21043-02 MS21044N02
MS21042-02 MS21043-02 MS21044N02
.1120" MS21042-04 MS21043-04 MS21044N04
MS21042-04 MS21043-04 MS21044N04
.1380" MS21042-06 MS21043-06 MS21044N06
MS21042-06 MS21043-06 MS21044N06
.1640" MS21042-08 MS21043-08 MS21044N08
MS21042-08 MS21043-08 MS21044N08
.1900" MS21042-3 NAS1804-3 MS21043-3 MS21044N3
MS21042-3 NAS1804-3 MS21043-3 MS21044N3
.2500" MS21042-4 NAS1804-4 MS21043-4 MS21044N4
MS21042-4 NAS1804-4 MS21043-4 MS21044N4
.3125" MS21042-5 NAS1804-5 MS21043-5 MS21044N5
MS21042-5 NAS1804-5 MS21043-5 MS21044N5
.3750" MS21042-6 NAS1804-6 MS21043-6 MS21044N6
MS21042-6 NAS1804-6 MS21043-6 MS21044N6

Below are downloadable PDFs of all of the LMC drawings above:

MS21042 Series | Cadmium Plated Steel-Alloy Lock-Nut

MS21042L Series | 'L' - Dry Film Lubricated

MS21043 Series | Dimensionally the same as MS21042, only made of stainless

MS21044N Series | A hexagonal self-locking nut with nylon insert

NAS1804 Series | 12 point lock-nut, which is dimensionally similar to the MS21042 series. Made of alloy steel and cadmium plated

NAS1805 Series | Dimensionally the same as the NAS1804, only made of A286. May be cadmium or silver plated, and with or without lubricant.

The NAS1291 series are dimensionally the same as the MS21042 series, with the addition of larger thread diameters up to .6250" . NAS1291-02 thru -6 are inactive for design, and have been superseded by NASM21042. NAS1291C04 thru C6 were superseded by NASM21043:

NAS1291X | Cadmium Plated without Lubricant

NAS1291 | Cadmium Plated, Dry File Lubricated

NAS1291C | Stainless A286, Silver Plated, without Lubricant

Past Revisions

Past revisions of the military standard of MS21042 series lock-nuts can be found on everyspec.com, such as the print below:

MS21042 Drawing Revision M, 1993



The prints found here within are not to be used for the manufacturer, procurement, or use of MS21042 hardware. They are for educational proposes only. The most current revision can be found on IHS Global , and are the property of the AIA.