How to Install Helical Inserts
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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.
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 |
| 1/4"-28 | 7/16"-14 | 3/8" | X | 0.401" | 2 | MS51831-202, NAS1395C4 | 000000000 | 0000 | 000000000 | 00000 |
| 5/16"-24 | 1/2"-13 | 7/16" | 29/64" | 0.457" | 4 | MS51831-203, NAS1395C5 | 000000000 | 0000 | 000000000 | 00000 |
| 3/8"-24 | 9/16"-12 | 1/2" | 33/64" | 0.521" | 4 | MS51831-204, NAS1395C6 | 000000000 | 0000 | 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 |
| 9/16"-18 | 13/16"-16 | 13/16" | 49/64" | 0.771" | 4 | MS51831-207, NAS1395C9 | 000000000 | 00000 | 000000000 | 00000 |
| 5/8"-18 | 7/8"-14 | 7/8" | 53/64" | 0.833" | 4 | MS51831-208, NAS1395C10 | 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 | 000000 | 00 |
| 1"-12 | 1 3/8"-12 | 1 3/8" | 1 5/16" | 1.317" | 4 | MS51831-211 | 000000000 | 00000 | 000000000 | 000000 |
18-8 Stainless Steel with Extra Thick Wall | ||||||||||
| 10-32 | 7/16"-14 | 5/16" | X | 0.401" | 2 | MS51832-201 | 000000000 | 00000 | 000000000 | 00000 |
| 1/4"-28 | 1/2"-13 | 3/8" | 29/64" | 0.457" | 4 | MS51832-202 | 000000000 | 00000 | 000000000 | 00000 |
| 5/16"-24 | 9/16"-12 | 7/16" | 33/64" | 0.521" | 4 | MS51832-203 | 000000000 | 00000 | 000000000 | 00000 |
| 3/8"-24 | 5/8"-11 | 1/2" | 37/64" | 0.583" | 4 | MS51832-204 | 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 | 7/8"-14 | 13/16" | 53/64" | 0.833" | 4 | MS51832-207 | 000000000 | 00000 | 000000000 | 00000 |
| 5/8"-18 | 1"-12 | 7/8" | 15/16" | 0.942" | 4 | MS51832-208 | 000000000 | 00000 | 000000000 | 00000 |
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.
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" | I | 0.272" | 2 | MS51830A201, NAS1394-3 | 000000000 | 00000 | 000000000 | 000000 |
| 1/4"-28 | 3/8"-16 | 3/8" | Q | 0.332" | 2 | MS51830A202, NAS1394-4 | 000000000 | 0000 | 000000000 | 00000 |
| 5/16"-24 | 7/16"-14 | 7/16" | X | 0.397" | 4 | MS51830A203, NAS1394-5 | 000000000 | 0000 | 000000000 | 00000 |
| 3/8"-24 | 1/2"-13 | 1/2" | 29/64" | 29/64" | 4 | MS51830A204, NAS1394-6 | 000000000 | 0000 | 000000000 | 00000 |
| 7/16"-20 | 9/16"-12 | 9/16" | 33/64" | 33/64" | 4 | MS51830A205, NAS1394-7 | 000000000 | 0000 | 000000000 | 00000 |
| 1/2"-20 | 5/8"-11 | 5/8" | 37/64" | 37/64" | 4 | MS51830A206, NAS1394-8 | 000000000 | 0000 | 000000000 | 00000 |
Cadmium-Plated Alloy Steel with Thick Wall | ||||||||||
| 10-32 | 3/8"-16 | 5/16" | Q | 0.332" | 2 | MS51831A201, NAS1395-3 | 000000000 | 00000 | 000000000 | 00000 |
| 1/4"-28 | 7/16"-14 | 3/8" | X | 0.397" | 2 | MS51831A202, NAS1395-4 | 000000000 | 0000 | 000000000 | 00000 |
| 5/16"-24 | 1/2"-13 | 7/16" | 29/64" | 29/64" | 4 | MS51831A203 | 000000000 | 0000 | 000000000 | 00000 |
| 3/8"-24 | 9/16"-12 | 1/2" | 33/64" | 33/64" | 4 | MS51831A204 | 000000000 | 0000 | 000000000 | 00000 |
| 7/16"-20 | 5/8"-11 | 5/8" | 37/64" | 37/64" | 4 | MS51831A205, NAS1395-7 | 000000000 | 0000 | 000000000 | 00000 |
| 1/2"-20 | 11/16"-11 | 11/16" | 41/64" | 41/64" | 4 | MS51831A206, NAS1395-8 | 000000000 | 0000 | 000000000 | 00000 |
| 9/16"-18 | 13/16"-16 | 13/16" | 49/64" | 49/64" | 4 | MS51831A207, NAS1395-9 | 000000000 | 00000 | 000000000 | 00000 |
| 5/8"-18 | 7/8"-14 | 7/8" | 53/64" | 53/64" | 4 | MS51831A208 | 000000000 | 00000 | 000000000 | 00000 |
| 3/4"-16 | 1 1/8"-12 | 1 1/8" | 1 1/16" | 1.062" | 4 | MS51831A209 | 000000000 | 00000 | 000000000 | 000000 |
High-Strength A286 Stainless Steel Key-Locking Inserts
The strongest and most corrosion-resistant stainless steel key-locking inserts we offer. Made of A286 stainless steel, these inserts stand up to salt water, harsh chemicals, and even high temperatures. Since you drive the keys into the surrounding material, these inserts also give you a more secure hold than thread-locking inserts. Use them to repair or add new, reusable threads to aluminum and other soft metal. They’re comparable to Keensert® inserts. Those that meet stringent military specifications or National Aerospace Standards have high-precision threads and tight tolerances.
Install them using 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 large holes. They’re often used when you need to drill out damaged threads.
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 | ||
A286 Stainless Steel with Thin Wall | ||||||||||
| 1/4"-28 | 3/8"-16 | 3/8" | Q | 0.332" | 2 | MS51830CA202 | 000000000 | 000000 | 000000000 | 000000 |
| 5/16"-24 | 7/16"-14 | 7/16" | X | 0.397" | 4 | MS51830CA203 | 000000000 | 00000 | 000000000 | 00000 |
| 3/8"-24 | 1/2"-13 | 1/2" | 29/64" | 0.453" | 4 | MS51830CA204 | 000000000 | 00000 | 000000000 | 00000 |
| 1/2"-20 | 5/8"-11 | 5/8" | 37/64" | 0.578" | 4 | MS51830CA206 | 000000000 | 00000 | 000000000 | 00000 |
A286 Stainless Steel with Thick Wall | ||||||||||
| 10-32 | 3/8"-16 | 5/16" | Q | 0.332" | 2 | MS51831CA201 | 000000000 | 00000 | 000000000 | 00000 |
| 1/4"-28 | 7/16"-14 | 3/8" | X | 0.397" | 2 | MS51831CA202 | 000000000 | 00000 | 000000000 | 00000 |
| 5/16"-24 | 1/2"-13 | 7/16" | 29/64" | 0.453" | 4 | MS51831CA203 | 000000000 | 00000 | 000000000 | 00000 |
| 3/8"-24 | 9/16"-12 | 1/2" | 33/64" | 0.516" | 4 | MS51831CA204 | 000000000 | 00000 | 000000000 | 00000 |
| 5/8"-18 | 7/8"-14 | 7/8" | 53/64" | 0.828" | 4 | MS51831CA208 | 000000000 | 00000 | 000000000 | 00000 |