2-56 Helicoils | McMaster-Carr

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System of Measurement

Helical Insert Style

Material

Installed Length

Specifications Met

Military Specification

Thread Type

Thread Direction

For Tap Type

Drill Bit Size

Passivation

Finish

Number of Inserts Included

288

Tensile Strength

200,000 psi

Not Rated

DFARS Specialty Metals

REACH

RoHS

Compliant with Exemptions

Not Compliant

Export Control Classification Number (ECCN)

EAR99

Thread Spacing

Coarse

Certificate Type

Accuracy Certificate Traceable to NIST

Calibration Certificate Traceable to NIST

Gauge Measurement Type

No-Go

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48 Products

How to Install Helical Inserts

About Helical Insert Length

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.

Inch

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
2-56	0.086"	No. 41	0.096"	MS122-095	10	000000000	00000	000000000	000000	000000000	000000	000000000	000000	000000000	0000000
2-56	0.129"	No. 41	0.096"	MS122-135	10	000000000	0000	000000000	00000	000000000	00000	000000000	00000	000000000	000000
2-56	0.172"	No. 41	0.096"	MS122-175	10	000000000	0000	000000000	00000	000000000	00000	000000000	00000	000000000	000000
2-56	0.215"	No. 41	0.096"	MS122-215	10	000000000	0000	000000000	00000	000000000	00000	000000000	00000	000000000	000000

Stainless Steel Helical Inserts for Particle-Free Environments

Made of Nitronic 60 stainless steel, these inserts prevent the screw from binding or sticking without any coating or lubricant that could contaminate particle-free environments. 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. 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.

Inch

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.	Pkg. Qty.		Pkg.		Each		Each		Each		Each
Nitronic 60 Stainless Steel
2-56	0.086"	No. 41	0.096"	5	000000000	00000	000000000	000000	000000000	000000	000000000	000000	000000000	0000000
2-56	0.129"	No. 41	0.096"	5	000000000	0000	000000000	00000	000000000	00000	000000000	00000	000000000	000000

Lubricated Stainless Steel Helical Inserts

A dry film keeps the screw from sticking or binding in these inserts during installation. 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. 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.

Inch

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
2-56	0.086"	No. 41	0.096"	MIL-I-8846, MS122-095	1	000000000	00000	000000000	000000	000000000	000000	000000000	000000	000000000	0000000
2-56	0.129"	No. 41	0.096"	MIL-I-8846, MS122-135	1	000000000	0000	000000000	00000	000000000	00000	000000000	00000	000000000	000000
2-56	0.172"	No. 41	0.096"	MIL-I-8846, MS122-175	1	000000000	0000	000000000	00000	000000000	00000	000000000	00000	000000000	000000

Lubricated Stainless Steel Helical Inserts for Dissimilar Metals

Eliminating the need for primer, these inserts are coated to resist corrosion when installed in different materials. They also prevent the screw from sticking or binding in the insert during installation. 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. 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.

Inch

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.	Pkg. Qty.		Pkg.		Each		Each		Each		Each
18-8 Stainless Steel
2-56	0.086"	No. 41	0.096"	1	000000000	00000	000000000	000000	000000000	000000	000000000	000000	000000000	0000000
2-56	0.172"	No. 41	0.096"	1	000000000	0000	000000000	00000	000000000	00000	000000000	00000	000000000	000000

Nickel Alloy Helical Inserts

Made of nickel alloy, these inserts are more resistant to acids and salt water than stainless steel inserts. 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. 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.

Inch

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.	Pkg. Qty.		Pkg.		Each		Each		Each		Each
Nickel Alloy
2-56	0.129"	No. 41	0.096"	1	000000000	00000	000000000	000000	000000000	000000	000000000	000000	000000000	0000000

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.

Inch

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
2-56	0.086"	No. 41	0.096"	MS21209C0210, NASM21209	10	000000000	00000	000000000	000000	000000000	000000	000000000	000000	000000000	0000000
2-56	0.129"	No. 41	0.096"	MS21209C0215, NASM21209	10	000000000	0000	000000000	00000	000000000	00000	000000000	00000	000000000	000000
2-56	0.172"	No. 41	0.096"	MS21209C0220, NASM21209	10	000000000	0000	000000000	00000	000000000	00000	000000000	00000	000000000	000000
2-56	0.215"	No. 41	0.096"	MS21209C0225, NASM21209	1	000000000	0000	000000000	00000	000000000	00000	000000000	00000	000000000	000000

Lubricated Stainless Steel Screw-Locking Helical Inserts

A dry film keeps the screw from sticking or binding in these inserts during installation, yet a distorted thread grips the screw to resist loosening. 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. 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.

Inch

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
2-56	0.086"	No. 41	0.096"	MS21209C0210L, NASM21209	5	000000000	00000	000000000	000000	000000000	000000	000000000	000000	000000000	0000000
2-56	0.129"	No. 41	0.096"	MS21209C0215L, NASM21209	5	000000000	0000	000000000	00000	000000000	00000	000000000	00000	000000000	000000
2-56	0.172"	No. 41	0.096"	MS21209C0220L, NASM21209	5	000000000	0000	000000000	00000	000000000	00000	000000000	00000	000000000	000000

Stainless Steel Screw-Locking Helical Inserts for Particle-Free Environments

Made of Nitronic 60 stainless steel, these inserts prevent the screw from binding or sticking without any coating or lubricant that could contaminate particle-free environments. Once the screw is installed, a distorted thread grips the screw to resist loosening. 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. 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		Prong Break-Off Tools
Thread Size	Installed Lg.	Drill Bit Size	For Max. Hole Dia.	Pkg. Qty.		Pkg.		Each		Each		Each		Each
Nitronic 60 Stainless Steel
2-56	0.086"	No. 41	0.096"	5	000000000	000000	000000000	000000	000000000	000000	000000000	000000	000000000	0000000
2-56	0.129"	No. 41	0.096"	5	000000000	00000	000000000	00000	000000000	00000	000000000	00000	000000000	000000

Stainless Steel Helical Inserts without Prong

Without a prong to break off and retrieve, these inserts are often used where debris could cause damage. Also known as Heli-Coil inserts, they have coils that expand once installed to securely anchor the insert. Installation requires a drill bit, a helical insert tap, and an installation tool.

For technical drawings and 3-D models, click on a part number.

Inch

Inserts								Through-Hole Taps		Closed-End Hole Taps		Installation Tools		Extraction 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
2-56	0.086"	No. 41	0.096"	NAS1130-02-10	10	000000000	00000	000000000	000000	000000000	000000	000000000	0000000	000000000	0000000
2-56	0.129"	No. 41	0.096"	NAS1130-02-15	10	000000000	0000	000000000	00000	000000000	00000	000000000	000000	000000000	000000
2-56	0.172"	No. 41	0.096"	NAS1130-02-20	10	000000000	0000	000000000	00000	000000000	00000	000000000	000000	000000000	000000
2-56	0.215"	3/32"	0.0937"	NAS1130-02-25	10	000000000	0000	000000000	00000	000000000	00000	000000000	000000	000000000	000000
2-56	0.258"	3/32"	0.0937"	NAS1130-02-30	10	000000000	0000	000000000	00000	000000000	00000	000000000	000000	000000000	000000

Lubricated Stainless Steel Helical Inserts without Prong

A dry film keeps the screw from sticking or binding in these inserts during installation. Without a prong to break off and retrieve, they are often used where debris could cause damage. Also known as Heli-Coil inserts, they have coils that expand once installed to securely anchor the insert. Installation requires a drill bit, a helical insert tap, and an installation 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.	Pkg. Qty.		Pkg.		Each		Each		Each
18-8 Stainless Steel
2-56	0.086"	No. 41	0.096"	5	000000000	00000	000000000	000000	000000000	000000	000000000	0000000
2-56	0.129"	No. 41	0.096"	5	000000000	0000	000000000	00000	000000000	00000	000000000	000000
2-56	0.172"	No. 41	0.096"	5	000000000	0000	000000000	00000	000000000	00000	000000000	000000

Screw-Locking Helical Inserts without Prong

A distorted thread grips the screw to resist loosening. Without a prong to break off and retrieve, these inserts are often used where debris could cause damage. Also known as Heli-Coil inserts, they have coils that expand once installed to securely anchor the insert. Installation requires a drill bit, a helical insert tap, and an installation tool.

For technical drawings and 3-D models, click on a part number.

Inch

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
2-56	0.086"	No. 41	0.096"	NAS1130-02L-10	5	000000000	00000	000000000	000000	000000000	000000	000000000	0000000
2-56	0.129"	No. 41	0.096"	NAS1130-02L-15	5	000000000	0000	000000000	00000	000000000	00000	000000000	000000
2-56	0.172"	No. 41	0.096"	NAS1130-02L-20	5	000000000	0000	000000000	00000	000000000	00000	000000000	000000

Helical Inserts with Installation Tools

Shown with Five Inserts and Drill Bit

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.

Inch

18-8 Stainless Steel—Right-Hand Threaded
Thread Size	Installed Lg.	Drill Bit Size	For Max. Hole Dia.	No. of Inserts Included	Includes		Each
2-56	0.086"	3/32"	3/32"	10	Drill Bit, Through-Hole Tap, Installation Tool	000000000	0000000
2-56	0.129"	3/32"	3/32"	10	Drill Bit, Through-Hole Tap, Installation Tool	000000000	000000
2-56	0.172"	3/32"	3/32"	10	Drill Bit, Through-Hole Tap, Installation Tool	000000000	000000
2-56	0.215"	3/32"	3/32"	10	Drill Bit, Through-Hole Tap, Installation Tool	000000000	000000

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.

Inch
Includes	No. of Inserts Included	Thread Spacing	Drill Bit Size	For Max. Hole Dia.		Each
18-8 Stainless Steel
1-64 Thread × 0.11" Installed Lg. (24 Inserts and 24 Screw-Locking Inserts) 2-56 Thread × 0.129" Installed Lg. (24 Inserts and 24 Screw-Locking Inserts) 3-48 Thread × 0.148" Installed Lg. (24 Inserts and 24 Screw-Locking Inserts) 4-40 Thread × 0.168" Installed Lg. (24 Inserts and 24 Screw-Locking Inserts) 6-32 Thread × 0.207" Installed Lg. (24 Inserts and 24 Screw-Locking Inserts) 8-32 Thread × 0.246" Installed Lg. (24 Inserts and 24 Screw-Locking Inserts) Drill Bits Through-Hole Taps Installation Tools	288	Coarse	5/64" 3/32" No. 36 No. 31 No. 26 No. 17	5/64" 3/32" 0.1065" 0.12" 0.147" 0.173"	000000000	0000000

Installation Tools for Helical Inserts

Screw an insert onto these tools and drive them a quarter to half-turn below the material’s surface. They’re compatible with helical inserts that have a prong.

For technical drawings and 3-D models, click on a part number.

Inch

For Right-Hand Thread
For Thread Size	Style		Each
2-56	B	000000000	000000

Prong Break-Off Tools for Helical Inserts

Place the tip of these tools into installed inserts and push down to trigger the spring-loaded punch to break off the prong.

For technical drawings and 3-D models, click on a part number.

Inch

For Thread Size		Each
2-56, 3-48, 3-56	000000000	0000000

Extraction Tools for Helical Inserts

Place the tip of these tools into an insert and strike a light blow to the tool’s head. Then turn the tools counterclockwise with pressure to extract the insert.

For Thread Size		Each
2-56, 2-64, M2.2	000000000	000000

Installation Tools for Helical Inserts without Prong

Screw an insert onto these tools and drive them a quarter to half-turn below the material’s surface.

Tools with a hollow handle store the tip.

Replacement tips (sold separately) include one installation tip, two pins, and two springs.

Inch

Installation Tools					Replacement Tips
For Thread Size	Style	Features		Each		Each
2-56	A	Hollow Handle	000000000	0000000	000000000	000000

Extraction Tools for Helical Inserts without Prong

Thread these tools into an insert and turn counterclockwise to extract.

Tools with a hollow handle store the tip.

Replacement tips (sold separately) come with one removal tip, two pins, and two springs.

Inch

Extraction Tools			Replacement Tips
For Thread Size		Each		Each
2-56	000000000	0000000	000000000	0000000

Go/No-Go Helical Insert Threaded Plug Gauges with Handle

Check that holes tapped for helical threads are within tolerance. You’ll sometimes hear these threads referred to as Screw Thread Insert (STI) threads. To speed up tests, these gauges have a go gauge on one end and a no-go gauge on the other. The double-ended taperlock handle makes them quick to thread and unthread. It also lets you swap in new plug gauges (not included) in place of worn ones.

The go gauge checks the minimum internal thread size, and the no-go gauge checks the maximum. A part is within tolerance if it’s easy to thread the go gauge but difficult to thread the no-go gauge more than two turns.

Gauges with a certificate of accuracy traceable to NIST include verification from the manufacturer that their thread sizes are within tolerance. The certificate is also known as a certificate of compliance or a short-form certification.

Gauges with a calibration certificate traceable to NIST were calibrated in a lab. The certificate, sometimes called a test report or long-form certificate, details the tested measurements.

For technical drawings and 3-D models, click on a part number.

Certificate of Accuracy Traceable to NIST
Thread Size	Thread Type	Pitch Dia. Tolerance	Hardness	Material	Features	For Thread Fit		Each
Class X
2-56	UNC	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Class 2B	0000000	0000000
Calibration Certificate Traceable to NIST
Class X
2-56	UNC	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Class 2B	0000000	000000