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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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.
Inserts | Through-Hole Taps | Closed-End Hole Taps | Installation Tools | Prong Break-Off Tools | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Thread Size | Installed Lg. | Drill Bit Size | For Max. Hole Dia. | Specifications Met | Pkg. Qty. | Pkg. | Each | Each | Each | Each | |||||
18-8 Stainless Steel—Right-Hand Threaded | |||||||||||||||
6-40 | 0.138" | No. 25 | 0.1495" | MS124-653 | 10 | 000000000 | 00000 | 000000000 | 000000 | 000000000 | 000000 | 000000000 | 0000000 | 000000000 | 000000 |
6-40 | 0.207" | No. 25 | 0.1495" | MS124-693 | 10 | 000000000 | 0000 | 000000000 | 00000 | 000000000 | 00000 | 000000000 | 000000 | 000000000 | 00000 |
6-40 | 0.276" | No. 25 | 0.1495" | MS124-733 | 10 | 000000000 | 00000 | 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.
Inserts | Through-Hole Taps | Closed-End Hole Taps | Installation Tools | Prong Break-Off Tools | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Thread Size | Installed Lg. | Drill Bit Size | For Max. Hole Dia. | Specifications Met | Pkg. Qty. | Pkg. | Each | Each | Each | Each | |||||
18-8 Stainless Steel | |||||||||||||||
6-40 | 0.138" | No. 25 | 0.1495" | MS21209F0610, NASM21209 | 10 | 000000000 | 00000 | 000000000 | 000000 | 000000000 | 000000 | 000000000 | 0000000 | 000000000 | 000000 |
6-40 | 0.207" | No. 25 | 0.1495" | MS21209F0615, NASM21209 | 5 | 000000000 | 0000 | 000000000 | 00000 | 000000000 | 00000 | 000000000 | 000000 | 000000000 | 00000 |
6-40 | 0.276" | No. 25 | 0.1495" | MS21209F0620, NASM21209 | 5 | 000000000 | 0000 | 000000000 | 00000 | 000000000 | 00000 | 000000000 | 000000 | 000000000 | 00000 |
Helical Insert Assortments with Installation Tools

Assortments include various sizes of helical inserts and a tap, a drill bit, and an installation tool for each thread size. Also known as Heli-Coil inserts, the 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.
Includes | No. of Inserts Included | Thread Spacing | Drill Bit Size | For Max. Hole Dia. | Each | |
Inch | ||||||
---|---|---|---|---|---|---|
18-8 Stainless Steel | ||||||
Prong Break-Off Tool 6-40 Thread × 0.138" Installed Lg. (12 Each) 6-40 Thread × 0.207" Installed Lg. (12 Each) 6-40 Thread × 0.276" Installed Lg. (12 Each) Drill Bit Through-Hole Tap Installation Tool | 36 | Fine | No. 25 | 0.1495" | 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.
Inserts with a thin wall are often used in small holes or near the edge of a workpiece.
Screw-Locking Key-Locking Inserts

Forming the strongest hold of any of our threaded inserts, these inserts have a distorted internal thread to lock screws into place and keys that drive into surrounding material to prevent slipping and rotating. This creates a mechanical lock, which is stronger than the chemical lock from adhesive on thread-locking inserts. Because they’re made of a solid piece of metal, these inserts are also stronger than helical inserts, which are made of coiled wire. They're often used in molds, tools and dies, and suspension systems in vehicles to create completely new threads, add strong threads in soft metal, or replace existing threads that are damaged or need to be resized.
A dry-film lubricant makes it easy to install them and screw fasteners in. To install, use a tap to create the threads in your material and an installation tool to drive the keys into the material. All are made to tight tolerances with strictly controlled materials. Many inch sizes also meet military or aerospace standards for dimensions and material.
These inserts resist corrosion in wet environments. Inserts with thin walls are best for small holes or near the edge of a workpiece. They’re often used in electronics that require small fasteners.
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.
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.