This section contains reduced rivet space anchor nuts which are good for tight or confined spaces, but have more risk of cracks forming between rivet holes and screw holes. It is not recommended to use these anchor nuts in high stress areas.
MS21069, MK1000 self-locking 2 lug low height fixed anchor nut reduced rivet spacing.
NOTE: reduced fatigue life because of the reduced rivet spacing.
MK1000 is Alcoa fastening systems (Kaynar) number for similar anchor nut.
Options: ‘L’ – Dry film lubricated (most common)
‘-’ – Non lubricated
‘K’ – dimpled/countersunk holes for rivets
Current spec: NASM 21069 (still uses MS21069 for part number)
Common sizes
Dash number |
Thread |
Rivet spacing |
Height |
Rivet size |
06 |
6-32 (.138) |
.437 |
.171 |
3/32 |
08 |
8-32 (.164) |
.468 |
.250 |
3/32 |
3 |
10-32 (.190) |
.500 |
.250 |
3/32 |
4 |
¼-28 (.250) |
.562 |
.281 |
3/32 |
5 |
5/16-24 (.3125) |
.718 |
.328 |
1/8 |
6 |
3/8-24 (.250) |
.828 |
.344 |
1/8 |
Examples: MS21069L3 is a 10-32 anchor nut lubricated
MS21069-3 is a 10-32 anchor nut not-lubricated
MS21069L3K is a 10-32 anchor nut lubricated dimpled rivet holes
MS21071, MK2000 self-locking 1 lug low height fixed anchor nut reduced rivet spacing.
NOTE: reduced fatigue life because of the reduced rivet spacing.
MK2000 is Alcoa fastening systems (Kaynar) number for similar anchor nut.
Options: ‘L’ – Dry film lubricated (most common)
‘-’ – Non lubricated
‘K’ – dimpled/countersunk holes for rivets
Current spec: NASM 21071 (still uses MS21071 for part number)
Common sizes
Dash number |
Thread |
Rivet spacing |
Height |
Rivet size |
06 |
6-32 (.138) |
.219 |
.171 |
3/32 |
08 |
8-32 (.164) |
.219 |
.250 |
3/32 |
3 |
10-32 (.190) |
.219 |
.250 |
3/32 |
4 |
¼-28 (.250) |
.219 |
.281 |
3/32 |
5 |
5/16-24 (.3125) |
.269 |
.328 |
1/8 |
6 |
3/8-24 (.250) |
.269 |
.344 |
1/8 |
Examples: MS21051L3 is a 10-32 anchor nut lubricated
MS21051-3 is a 10-32 anchor nut not-lubricated
MS21051L3K is a 10-32 anchor nut lubricated dimpled rivet holes
MS21073, MK3000 self-locking corner low height fixed anchor nut reduced rivet spacing.
NOTE: reduced fatigue life because of the reduced rivet spacing.
MK3000 is Alcoa fastening systems (Kaynar) number for similar anchor nut.
Options: ‘L’ – Dry film lubricated (most common)
‘-’ – Non lubricated
‘K’ – dimpled/countersunk holes for rivets
Current spec: NASM 21073 (still uses MS21073 for part number)
Common sizes
Dash number |
Thread |
Rivet spacing |
Height |
Rivet size |
06 |
6-32 (.138) |
.308 |
.171 |
3/32 |
08 |
8-32 (.164) |
.331 |
.250 |
3/32 |
3 |
10-32 (.190) |
.354 |
.250 |
3/32 |
4 |
¼-28 (.250) |
.398 |
.281 |
3/32 |
5 |
5/16-24 (.3125) |
.508 |
.328 |
1/8 |
6 |
3/8-24 (.250) |
.585 |
.344 |
1/8 |
Examples: MS21073L3 is a 10-32 anchor nut lubricated
MS21073-3 is a 10-32 anchor nut not-lubricated
MS21073L3K is a 10-32 anchor nut lubricated dimpled rivet holes
MS21075, MF5000 self-locking 2 lug low height floating anchor nut reduced rivet spacing.
NOTE: reduced fatigue life because of the reduced rivet spacing.
MF5000 is Alcoa fastening systems (Kaynar) number for similar anchor nut.
Options: ‘L’ – Dry film lubricated (most common)
‘-’ – Non lubricated
‘K’ – dimpled/countersunk holes for rivets
Current spec: NASM 21075 (still uses MS21075 for part number)
All available sizes
Dash number |
Thread |
Rivet spacing |
Height |
Rivet size |
06 |
6-32 (.138) |
.437 |
.203 |
3/32 |
08 |
8-32 (.164) |
.468 |
.250 |
3/32 |
3 |
10-32 (.190) |
.500 |
.250 |
3/32 |
4 |
¼-28 (.250) |
.562 |
.281 |
3/32 |
5 |
5/16-24 (.3125) |
.718 |
.328 |
1/8 |
Examples: MS21075L3 is a 10-32 anchor nut lubricated
MS21075-3 is a 10-32 anchor nut not-lubricated
MS21075L3K is a 10-32 anchor nut lubricated dimpled rivet holes
