How to Install Key-Locking Inserts
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Mil. Spec. Stainless Steel Key-Locking Inserts
These inserts are made to stringent military specifications. Drive the keys into the surrounding material for a more secure hold than thread-locking inserts. Use them to repair or change threads in soft metals such as aluminum. Inserts may be mildly magnetic. They’re comparable to Keensert® inserts. Installation requires a drill bit, a standard tap, an installation tool, and a hammer.
Inserts with a thin wall are often used in small holes or near the edge of a workpiece.
Choose inserts with a thick wall for greater strength than thin-wall inserts, or to fill a large hole.
For technical drawings and 3-D models, click on a part number.
Inserts | Installation Tools | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Thread Size  | For Tap Thread Size | Installed Lg. | Drill Bit Size | For Max. Hole Dia. | No. of Locking Keys | Specifications Met | Each | Each | ||
18-8 Stainless Steel with Thin Wall | ||||||||||
| 4-40 | 12-24 | 1/4" | 14 | 0.183" | 2 | NAS1395C04 | 000000000 | 00000 | 000000000 | 000000 |
| 10-32 | 5/16"-18 | 5/16" | I | 0.276" | 2 | MS51830-201, NAS1394C3 | 000000000 | 0000 | 000000000 | 00000 |
| 1/4"-28 | 3/8"-16 | 3/8" | Q | 0.336" | 2 | MS51830-202, NAS1394C4 | 000000000 | 0000 | 000000000 | 00000 |
| 5/16"-24 | 7/16"-14 | 7/16" | X | 0.401" | 4 | MS51830-203, NAS1394C5 | 000000000 | 0000 | 000000000 | 00000 |
| 3/8"-24 | 1/2"-13 | 1/2" | 29/64" | 0.457" | 4 | MS51830-204, NAS1394C6 | 000000000 | 0000 | 000000000 | 00000 |
| 7/16"-20 | 9/16"-12 | 9/16" | 33/64" | 0.521" | 4 | MS51830-205, NAS1394C7 | 000000000 | 0000 | 000000000 | 00000 |
| 1/2"-20 | 5/8"-11 | 5/8" | 37/64" | 0.583" | 4 | MS51830-206, NAS1394C8 | 000000000 | 0000 | 000000000 | 00000 |
18-8 Stainless Steel with Thick Wall | ||||||||||
| 10-32 | 3/8"-16 | 5/16" | Q | 0.336" | 2 | MS51831-201, NAS1395C3 | 000000000 | 0000 | 000000000 | 00000 |
| 10-32 | 7/16"-14 | 5/16" | X | 0.401" | 2 | MS51832-201 | 000000000 | 00000 | 000000000 | 00000 |
| 1/4"-28 | 7/16"-14 | 3/8" | X | 0.401" | 2 | MS51831-202, NAS1395C4 | 000000000 | 0000 | 000000000 | 00000 |
| 1/4"-28 | 1/2"-13 | 3/8" | 29/64" | 0.457" | 4 | MS51832-202 | 000000000 | 00000 | 000000000 | 00000 |
| 5/16"-24 | 1/2"-13 | 7/16" | 29/64" | 0.457" | 4 | MS51831-203, NAS1395C5 | 000000000 | 0000 | 000000000 | 00000 |
| 5/16"-24 | 9/16"-12 | 7/16" | 33/64" | 0.521" | 4 | MS51832-203 | 000000000 | 00000 | 000000000 | 00000 |
| 3/8"-24 | 9/16"-12 | 1/2" | 33/64" | 0.521" | 4 | MS51831-204, NAS1395C6 | 000000000 | 0000 | 000000000 | 00000 |
| 3/8"-24 | 5/8"-11 | 1/2" | 37/64" | 0.583" | 4 | MS51832-204 | 000000000 | 00000 | 000000000 | 00000 |
| 7/16"-20 | 5/8"-11 | 5/8" | 37/64" | 0.583" | 4 | MS51831-205, NAS1395C7 | 000000000 | 0000 | 000000000 | 00000 |
| 1/2"-20 | 11/16"-11 | 11/16" | 41/64" | 0.646" | 4 | MS51831-206, NAS1395C8 | 000000000 | 00000 | 000000000 | 00000 |
| 1/2"-20 | 13/16"-16 | 11/16" | 49/64" | 0.771" | 4 | MS51832-206 | 000000000 | 00000 | 000000000 | 00000 |
| 9/16"-18 | 13/16"-16 | 13/16" | 49/64" | 0.771" | 4 | MS51831-207, NAS1395C9 | 000000000 | 00000 | 000000000 | 00000 |
| 9/16"-18 | 7/8"-14 | 13/16" | 53/64" | 0.833" | 4 | MS51832-207 | 000000000 | 00000 | 000000000 | 00000 |
| 5/8"-18 | 7/8"-14 | 7/8" | 53/64" | 0.833" | 4 | MS51831-208, NAS1395C10 | 000000000 | 00000 | 000000000 | 00000 |
| 5/8"-18 | 1"-12 | 7/8" | 15/16" | 0.942" | 4 | MS51832-208 | 000000000 | 00000 | 000000000 | 00000 |
| 3/4"-16 | 1 1/8"-12 | 1 1/8" | 1 1/16" | 1.067" | 4 | MS51831-209 | 000000000 | 00000 | 000000000 | 000000 |
| 7/8"-14 | 1 1/4"-12 | 1 1/4" | 1 3/16" | 1.192" | 4 | MS51831-210 | 000000000 | 00000 | 000000000 | 000000 |
Mil. Spec. Alloy Steel Key-Locking Inserts
The strongest key-locking inserts we offer, these inserts are made to stringent military specifications. Drive the keys into the surrounding material for a more secure hold than thread-locking inserts. Use them to repair or change threads in soft metals such as aluminum. Inserts may be mildly magnetic. They’re comparable to Keensert® inserts. Installation requires a drill bit, a standard tap, an installation tool, and a hammer.
Inserts with a thin wall are often used in small holes or near the edge of a workpiece.
Choose inserts with a thick wall for greater strength than thin-wall inserts, or to fill a large hole.
For technical drawings and 3-D models, click on a part number.
Inserts | Installation Tools | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Thread Size | For Tap Thread Size | Installed Lg. | Drill Bit Size | For Max. Hole Dia. | No. of Locking Keys | Specifications Met | Each | Each | ||
Cadmium-Plated Alloy Steel with Thin Wall | ||||||||||
| 10-32 | 5/16"-18 | 5/16" | 17/64" | 17/64" | 2 | MS51830-A201, NAS1394-3 | 000000000 | 00000 | 000000000 | 000000 |
| 1/4"-28 | 3/8"-16 | 3/8" | 21/64" | 21/64" | 2 | MS51830-A202, NAS1394-4 | 000000000 | 0000 | 000000000 | 00000 |
| 5/16"-24 | 7/16"-14 | 7/16" | 25/64" | 25/64" | 4 | MS51830-A203, NAS1394-5 | 000000000 | 0000 | 000000000 | 00000 |
| 3/8"-24 | 1/2"-13 | 1/2" | 29/64" | 29/64" | 4 | MS51830-A204, NAS1394-6 | 000000000 | 0000 | 000000000 | 00000 |
| 7/16"-20 | 9/16"-12 | 9/16" | 33/64" | 33/64" | 4 | MS51830-A205, NAS1394-7 | 000000000 | 0000 | 000000000 | 00000 |
| 1/2"-20 | 5/8"-11 | 5/8" | 37/64" | 37/64" | 4 | MS51830-A206, NAS1394-8 | 000000000 | 0000 | 000000000 | 00000 |
Cadmium-Plated Alloy Steel with Thick Wall | ||||||||||
| 10-32 | 3/8"-16 | 5/16" | 21/64" | 21/64" | 2 | MS51831-A201, NAS13953 | 000000000 | 00000 | 000000000 | 00000 |
| 1/4"-28 | 7/16"-14 | 3/8" | 25/64" | 25/64" | 2 | MS51831-A202, NAS1395-4 | 000000000 | 0000 | 000000000 | 00000 |
| 5/16"-24 | 1/2"-13 | 7/16" | 29/64" | 29/64" | 4 | MS51831-A203 | 000000000 | 0000 | 000000000 | 00000 |
| 3/8"-24 | 9/16"-12 | 1/2" | 33/64" | 33/64" | 4 | MS51831-A204 | 000000000 | 0000 | 000000000 | 00000 |
| 7/16"-20 | 5/8"-11 | 5/8" | 37/64" | 37/64" | 4 | MS51831-A205, NAS1395-7 | 000000000 | 0000 | 000000000 | 00000 |
| 1/2"-20 | 11/16"-11 | 11/16" | 41/64" | 41/64" | 4 | MS51831-A206, NAS1395-8 | 000000000 | 0000 | 000000000 | 00000 |
| 9/16"-18 | 13/16"-16 | 13/16" | 49/64" | 49/64" | 4 | MS51831-A207, NAS1395-9 | 000000000 | 00000 | 000000000 | 00000 |
| 5/8"-18 | 7/8"-14 | 7/8" | 53/64" | 53/64" | 4 | MS51831-A208 | 000000000 | 00000 | 000000000 | 00000 |
| 3/4"-16 | 1 1/8"-12 | 1 1/8" | 1 1/16" | 1 1/16" | 4 | MS51831-A209 | 000000000 | 00000 | 000000000 | 000000 |