How to Install Helical Inserts
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About Helical Insert Length
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How to Install Key-Locking Inserts
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Black-Phosphate Steel Easy-to-Install Thread-Locking Inserts
A black-phosphate finish provides mild corrosion resistance. Also known as E-Z Lok, these inserts use Loctite® adhesive to keep them in place. The adhesive reaches full strength after 72 hours. Installation requires a drill bit and a standard tap. Then set the insert with a bolt and two nuts, or use an installation bit.
Choose inserts with a thick wall for greater strength than thin-wall inserts, or to fill a large hole.
To drive slotted inserts, you can use a slotted screwdriver instead of using an installation bit or a bolt and two nuts.
For technical drawings and 3-D models, click on a part number.
Stainless Steel Helical Inserts

Also known as Heli-Coil inserts, these inserts have coils that expand once installed to securely anchor the insert. All have a prong for ease of installation. An installation tool grips the prong and reduces the coil diameter, enabling the insert to fit in tapped holes. Remove the prong to insert the screw. Installation requires a drill bit, a helical insert tap, an installation tool, and a prong break-off tool.
For technical drawings and 3-D models, click on a part number.
Inserts | Through-Hole Taps | Closed-End Hole Taps | Installation Tools | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Thread Size | Installed Lg. | Drill Bit Size | For Max. Hole Dia. | Specifications Met | Pkg. Qty. | Pkg. | Each | Each | Each | ||||
18-8 Stainless Steel—Right-Hand Threaded | |||||||||||||
9/16"-12 | 0.562" | 19/32" | 19/32" | MS122-086 | 5 | 000000000 | 000000 | 000000000 | 000000 | 000000000 | 0000000 | 000000000 | 000000 |
9/16"-12 | 0.844" | 19/32" | 19/32" | MS122-126 | 5 | 000000000 | 00000 | 000000000 | 00000 | 000000000 | 000000 | 000000000 | 00000 |
Stainless Steel Screw-Locking Helical Inserts

A distorted thread grips the screw to resist loosening. Also known as Heli-Coil inserts, these inserts have coils that expand once installed to securely anchor the insert. All have a prong for ease of installation. An installation tool grips the prong and reduces the coil diameter, enabling the insert to fit in tapped holes. Remove the prong to insert the screw. Installation requires a drill bit, a helical insert tap, an installation tool, and a prong break-off tool.
For technical drawings and 3-D models, click on a part number.
Inserts | Through-Hole Taps | Closed-End Hole Taps | Installation Tools | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Thread Size | Installed Lg. | Drill Bit Size | For Max. Hole Dia. | Specifications Met | Pkg. Qty. | Pkg. | Each | Each | Each | ||||
18-8 Stainless Steel | |||||||||||||
9/16"-12 | 0.562" | 19/32" | 19/32" | MS21209C9-10, NASM21209 | 1 | 000000000 | 00000 | 000000000 | 000000 | 000000000 | 0000000 | 000000000 | 000000 |
9/16"-12 | 0.844" | 19/32" | 19/32" | MS21209C9-15, NASM21209 | 1 | 000000000 | 0000 | 000000000 | 00000 | 000000000 | 000000 | 000000000 | 00000 |
Helical Inserts with Installation Tools

Inserts come with a through-hole tap and installation tool. Also known as Heli-Coil inserts, they have coils that expand once installed to securely anchor the insert. All have a prong for ease of installation. An installation tool grips the prong and reduces the coil diameter, enabling the insert to fit in tapped holes. Remove the prong to insert the screw.
Thread Size | Installed Lg. | Drill Bit Size | For Max. Hole Dia. | No. of Inserts Included | Includes | Each | |
18-8 Stainless Steel—Right-Hand Threaded | |||||||
---|---|---|---|---|---|---|---|
9/16"-12 | 0.844" | 19/32" | 19/32" | 6 | Drill Bit, Through-Hole Tap, Installation Tool | 000000000 | 0000000 |
18-8 Stainless Steel Key-Locking Inserts

Made of stainless steel, these inserts have good corrosion resistance. 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.
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.
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 Thick Wall | ||||||||||
9/16"-12 | 13/16"-16 | 13/16" | 49/64" | 0.771" | 4 | MS51831-107 | 000000000 | 000000 | 000000000 | 000000 |
18-8 Stainless Steel with Extra Thick Wall | ||||||||||
9/16"-12 | 7/8"-14 | 13/16" | 53/64" | 0.833" | 4 | MS51832-107 | 000000000 | 00000 | 000000000 | 00000 |
Black-Phosphate Steel Key-Locking Inserts

A black-phosphate finish provides mild corrosion resistance. 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. They’re comparable to Keensert® inserts. Installation requires a drill bit, a standard tap, an installation tool, and a hammer.
Choose inserts with a thick wall for greater strength than thin-wall inserts, or to fill a large hole with stripped threads.
Inserts with an extra thick wall are stronger than thick- and thin-wall inserts. Use them to reduce the size of tapped holes.
For technical drawings and 3-D models, click on a part number.
Inserts | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|
Each | Installation Tools | |||||||||
Thread Size | For Tap Thread Size | Installed Lg. | Drill Bit Size | For Max. Hole Dia. | No. of Locking Keys | 1-9 | 10-Up | Each | ||
Black-Phosphate Steel with Thick Wall | ||||||||||
9/16"-12 | 3/4"-16 | 13/16" | 45/64" | 45/64" | 4 | 000000000 | 00000 | 00000 | 000000000 | 000000 |
Black-Phosphate Steel with Extra Thick Wall | ||||||||||
9/16"-12 | 7/8"-14 | 13/16" | 53/64" | 53/64" | 4 | 000000000 | 00000 | 00000 | 000000000 | 00000 |
Key-Locking Insert Assortments with Installation Tool

These assortments include various sizes of key-locking inserts with thick and thin walls, and an installation tool. Drive the keys into the surrounding material for a more secure hold than thread-locking inserts. Use them to repair or convert threads in soft metals such as aluminum. They’re comparable to Keensert® inserts.
18-8 stainless steel inserts are more corrosion resistant than black-phosphate steel. They may be mildly magnetic.
Black-phosphate steel inserts are mildly corrosion resistant.
Choose assortments with thick-wall inserts 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.
For Tap | ||||||
---|---|---|---|---|---|---|
Includes | No. of Inserts Included | Thread Size | Drill Bit Size | For Max. Hole Dia. | Each | |
Inch | ||||||
18-8 Stainless Steel with Thick Wall | ||||||
1/4"-20 Thread × 3/8" Installed Lg. (20 Each) 5/16"-18 Thread × 0.438" Installed Lg. (15 Each) 3/8"-16 Thread × 1/2" Installed Lg. (10 Each) 7/16"-14 Thread × 5/8" Installed Lg. (10 Each) 1/2"-13 Thread × 5/8" Installed Lg. (6 Each) 9/16"-12 Thread × 0.813" Installed Lg. (5 Each) 5/8"-11 Thread × 7/8" Installed Lg. (3 Each) 3/4"-10 Thread × 1 1/8" Installed Lg. (3 Each) 7/8"-9 Thread × 1 1/4" Installed Lg. (3 Each) 1"-8 Thread × 1 3/8" Installed Lg. (2 Each) Installation Tool | 77 | 7/16"-14 1/2"-13 9/16"-12 5/8"-11 3/4"-16 7/8"-14 1 1/8"-12 1 1/4"-12 1 3/8"-12 | X 29/64" 33/64" 37/64" 45/64" 53/64" 1 1/16" 1 3/16" 1 5/16" | 0.397" 29/64" 33/64" 37/64" 45/64" 53/64" 1 1/16" 1 3/16" 1 5/16" | 000000000 | 0000000 |
Black-Phosphate Steel with Thick Wall | ||||||
1/4"-20 Thread × 3/8" Installed Lg. (20 Each) 5/16"-18 Thread × 0.438" Installed Lg. (15 Each) 3/8"-16 Thread × 1/2" Installed Lg. (10 Each) 7/16"-14 Thread × 5/8" Installed Lg. (10 Each) 1/2"-13 Thread × 5/8" Installed Lg. (6 Each) 9/16"-12 Thread × 0.813" Installed Lg. (5 Each) 5/8"-11 Thread × 7/8" Installed Lg. (3 Each) 3/4"-10 Thread × 1 1/8" Installed Lg. (3 Each) 7/8"-9 Thread × 1 1/4" Installed Lg. (3 Each) 1"-8 Thread × 1 3/8" Installed Lg. (2 Each) Installation Tool | 77 | 7/16"-14 1/2"-13 9/16"-12 5/8"-11 3/4"-16 7/8"-14 1 1/8"-12 1 1/4"-12 1 3/8"-12 | X 29/64" 33/64" 37/64" 45/64" 53/64" 1 1/16" 1 3/16" 1 5/16" | 0.397" 29/64" 33/64" 37/64" 45/64" 53/64" 1 1/16" 1 3/16" 1 5/16" | 000000000 | 000000 |
Key-Locking Inserts with Installation Tool

Drive the keys into the surrounding material for a more secure hold than thread-locking inserts. These inserts are used to repair or convert threads in soft metals such as aluminum. They’re comparable to Keensert® inserts.
18-8 stainless steel inserts are more corrosion resistant than black-phosphate steel. They may be mildly magnetic.
Black-phosphate steel inserts are mildly corrosion resistant.
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.
Alloy Steel Thin-Wall Swage-Locking Inserts



Add or repair threads near the edges and corners of soft metal surfaces—these inserts have thinner walls than any of our key-locking and thread-locking inserts. With knurls that press (swage) into the surrounding material, they won’t budge when you tighten a screw. Made of alloy steel, they’re stronger than our 17-4 PH stainless steel inserts. They absorb impact without fracturing and stand up to high-pressure applications. A cadmium plating keeps them from corroding in wet environments. On top of the plating is a dry film lubricant to help these inserts thread in without sticking. Meeting the strict standards for MIL-I-45932/1, these inserts have highly precise threads and tight tolerances.
To install these inserts, you need a drill bit, a counterbore, a standard-sized tap, an installation tool, and a hammer. Drill a hole, counterbore the top, then tap it. Place the insert into the installation tool and hand-tighten it into the tapped hole. Hammer the tool to secure the insert in place, driving the knurls into the surrounding material.
For technical drawings and 3-D models, click on a part number.
17-4 PH Stainless Steel Thin-Wall Swage-Locking Inserts



Position strong, corrosion-resistant threads close to the edges of soft metal surfaces. These inserts have thinner walls than our key-locking and thread-locking inserts, so they don’t need as much space around them. Even as you tighten or loosen a screw, these inserts won’t budge—their knurls press (swage) into the surrounding material to keep them in place. They’re made of 17-4 PH stainless steel, which has the strength of steel and the corrosion resistance of 18-8 stainless steel. Manufactured to tight tolerances, these inserts meet the strict standards of MIL-I-45932/1.
To install these inserts, you need a drill bit, a counterbore, a standard-sized tap, an installation tool, and a hammer. Drill a hole, counterbore the top, and tap it. Place the insert into the installation tool, then hand-tighten it into the tapped hole. Hammer away at the tool to secure the insert and drive the knurls into the surrounding material.
For technical drawings and 3-D models, click on a part number.