5/8"-18 Helicoils | McMaster-Carr

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System of Measurement

Thread Direction

Helical Insert Type

Material

Installed Length

Profile

For Use In

Number of Inserts Included

Tensile Strength

200,000 psi

For Tap Type

Helical

Military Specification

NASM21209

Thread Type

UNF

For Use With

Helical Inserts

Screw-Locking Helical Inserts

Thread Spacing

Fine

For Insert Thread Size

5/8"-18

U.S.–Mexico–Canada Agreement (USMCA) Qualifying

Yes

Drill Bit Size

41/64"

Export Control Classification Number (ECCN)

REACH

RoHS

Sold As

DFARS Specialty Metals

Compliant

Exempt

Not Compliant

Insert Tool Thread Type

For Use On

Passivation

18 Products

Helical Threaded Insert Removal Tools

To remove installed helical inserts, place the tip of these tools into the insert and lightly strike the tool’s head. Then, turn the tool counterclockwise with pressure to extract the insert.

Narrow Profile—The tip of these tools has a narrower angle than standard removal tools to reduce the chance it will dig into your material’s surface when you strike the tool.

	Mfr.		Each
Standard Profile



	6-32, 6-40, 8-32, 8-36, 10-24, 10-32, 12-24, 1/4"-20, 1/4"-28, 5/16"-18, 5/16"-24, 3/8"-16, 3/8"-24, 7/16"-14, 7/16"-20, 1/2"-13, 1/2"-20, 9/16"-12, 9/16"-18, 5/8"-11, 5/8"-18, 3/4"-10, 3/4"-16, 7/8"-9, 7/8"-14, 1"-8, 1"-12, 1"-14, M4, M5, M6, M7, M8, M9, M10, M12, M13, M14, M15, M16, M18, M20, M22, M24	—	90254A113	000000


	Narrow Profile



			7/16"-14, 7/16"-20, 1/2"-13, 1/2"-20, 1/2"-28, 9/16"-12, 9/16"-18, 5/8"-11, 5/8"-18, 5/8"-24, 3/4"-10, 3/4"-16, 3/4"-20, 7/8"-9, 7/8"-14, 7/8"-20, 1"-8, 1"-12, 1"-14, M12, M14, M16, M18, M20, M22, M24	Heli-Coil	90254A330	00000

Helical Threaded Inserts

Pronged

Restore, reinforce, or create threads in metal. The tough coils on these inserts expand once installed to anchor in a tapped hole. Also known as Heli-Coil inserts, they're often used in engine heads and machinery housings where strong connections are critical. Unlike threadlocking inserts, you can remove and reuse them without them losing their strength.

Installation requires a drill bit, a helical insert tap, and an installation tool.

Pronged—The prong attaches to an installation tool for precise control as you drive inserts in. Remove the prong with a punch or break-off tool before inserting a screw.

18-8 Stainless Steel—The choice for wet and outdoor environments, these inserts resist rust and mild chemicals.

	Inserts								Through-Hole Taps		Closed-End Hole Taps		Installation Tools		Inserts with Installation Tools
	Thread Size	Installed Lg.	Drill Bit Size	For Max. Hole Dia.	Specs. Met	Pkg. Qty.		Pkg.		Each		Each		Each	No. of Inserts Included		Each
Pronged







				18-8 Stainless Steel

				5/8"-18	0.625"	41/64"	0.641"	MS124662	1	91732A541	00000	91709A158	000000	91709A476	0000000	90261A182	0000000	10	98356A151	0000000


				5/8"-18	0.938"	41/64"	0.641"	MS124702	1	91732A238	0000	91709A158	00000	91709A476	000000	90261A182	000000	6	91732A038	000000

Extraction Tools

Remove installed helical inserts.

For Pronged Helical Inserts—Place the tip into pronged inserts and lightly strike the tool’s head. Then, turn the tool counterclockwise with pressure to extract the insert.

		Each
For Pronged Helical Inserts



	7/16"-14, 7/16"-20, 1/2"-13, 1/2"-20, 1/2"-28, 9/16"-12, 9/16"-18, 5/8"-11, 5/8"-18, 5/8"-24, 3/4"-10, 3/4"-16, 3/4"-20, 7/8"-9, 7/8"-14, 7/8"-20, 1"-8, 1"-12, 1"-14, M12, M14, M16, M18, M20, M22, M24	90254A330	000000

Helical Threaded Inserts with Installation Tools

Drill Bit, Installation Tool

and Through-Hole Tap

Quickly restore stripped threads—these inserts come with through-hole taps and installation tools. The tough coils on these inserts expand once installed to anchor in a tapped hole.

Pronged—The prong attaches to an installation tool for precise control as you drive inserts in. Remove the prong with a punch or break-off tool before inserting a screw.

18-8 Stainless Steel—The choice for wet and outdoor environments, these inserts resist rust and mild chemicals.

	For Max. Hole Dia.	No. of Inserts Included	Includes		Each
Pronged







	18-8 Stainless Steel

	5/8"-18	0.625"	41/64"	0.656"	10	Drill Bit Installation Tool Through-Hole Tap	98356A151	0000000


	5/8"-18	0.938"	41/64"	0.641"	6	Drill Bit Installation Tool Through-Hole Tap	91732A038	000000

Helical Insert Taps

Match the size of helical inserts so they fit tightly when installed in the hole.

High-Speed Steel—These taps resist heat and wear to stay sharp.

Plug Chamfer—Our go-to chamfer type. With a longer taper than a bottoming chamfer, they are easier to turn but won't thread as close the bottom of a hole.

Bottoming Chamfer—Cut all the way to the bottom of blind holes with taps that have the shortest taper. Since these require the most force to turn, they’re often used to finish holes started by taper- or plug-chamfer taps.

						Drill Bit			Plug Chamfer		Bottoming Chamfer
	For Insert Size	Thread Lg.	Overall Lg.	For Insert Thread Type	No. of Flutes	Size	Decimal Size Equiv.	Shank Type		Each		Each
High-Speed Steel







				Uncoated

				5/8"-18	1 13/16"	4 1/32"	UNF	4	41/64"	0.6406"	Square	91709A158	000000	91709A476	0000000

Easy-Start Helical Threaded Insert Installation Tools

These tools compress the diameter of your insert so it fits easily into a tapped hole. They’re the best choice for preventing misaligned or damaged threads—just make sure you have space to turn the crank. Screw or slide an insert onto your tool and drive it between a quarter-turn and half-turn below the surface. Also known as prewinders.

Threaded Insert Installation Tools with Depth Stop

T-Handle


Prong Slot Drive	Threaded Drive

Ensure consistent installation across multiple inserts. Set your desired installation depth, and the stop will prevent you from driving your insert any further.

Prong Slot Drive Helical Insert Tool—Install both left- and right-hand threaded inserts with any thread pitch. However, these tools don't align the threads like threaded-drive tools, so installation may be more difficult.

Threaded Drive Helical Insert Tool—These tools align each coil of your insert perfectly with the thread pitch of your tapped hole for easy installation.

	Mfr.	Handle Style	Helical Insert Tool Drive Type	For Use With		Each
Standard (UN) Thread



	5/8"-18	—	T-Handle	Prong Slot	Helical Inserts, Screw-Locking Helical Inserts	1338N38	0000000


	5/8"-18	Heli-Coil	T-Handle	Threaded	Helical Inserts, Screw-Locking Helical Inserts	90261A182	000000

Other Threaded Insert Installation Tools

T-Handle

Threaded Drive Helical Insert Tool—These tools align each coil of your insert perfectly with the thread pitch of your tapped hole for easy installation.

	Mfr.	Handle Style	Helical Insert Tool Drive Type	For Use With		Each
Standard (UN) Thread



	5/8"-18	Heli-Coil	T-Handle	Threaded	Helical Inserts	93060A051	000000

Screw-Locking Helical Threaded Inserts

Pronged

The irregularly shaped threads tightly grip screws to prevent them from loosening or backing out under vibration. Use these inserts to create or repair threads in pumps and other machinery that shakes and rattles. Also known as Heli-Coil inserts.

Installation requires a drill bit, a helical insert tap, and an installation tool.

Pronged—The prong attaches to an installation tool for precise control as you drive inserts in. Remove the prong with a punch or break-off tool before inserting a screw.

18-8 Stainless Steel—The choice for wet and outdoor environments, these inserts resist rust and mild chemicals.

	Inserts								Through-Hole Taps		Closed-End Hole Taps		Installation Tools
	Thread Size	Installed Lg.	Drill Bit Size	For Max. Hole Dia.	Specs. Met	Pkg. Qty.		Pkg.		Each		Each		Each
Pronged







				18-8 Stainless Steel

				5/8"-18	0.625"	41/64"	0.641"	MS21209F1010, NASM21209	1	90296A236	00000	91709A158	000000	91709A476	0000000	90261A182	0000000


				5/8"-18	0.938"	41/64"	0.641"	MS21209F1015, NASM21209	1	90296A237	0000	91709A158	00000	91709A476	000000	90261A182	000000

Left-Hand-Thread Helical Threaded Inserts

Fix threads in parts that rotate counterclockwise. Pair these inserts with left-hand-thread screws and turn them to the left to tighten. Also known as Heli-Coil inserts.

Installation requires a drill bit, a helical insert tap, and an installation tool.

Pronged—The prong attaches to an installation tool for precise control as you drive inserts in. Remove the prong with a punch or break-off tool before inserting a screw.

18-8 Stainless Steel—The choice for wet and outdoor environments, these inserts resist rust and mild chemicals.

	Inserts							Through-Hole Taps		Installation Tools		Inserts with Installation Tools
	Thread Size	Installed Lg.	Drill Bit Size	For Max. Hole Dia.	Pkg. Qty.		Pkg.		Each		Each	No. of Inserts Included		Each
Pronged







				18-8 Stainless Steel

				5/8"-18	0.938"	41/64"	0.641"	1	92090A155	00000	92090A355	000000	92090A555	000000	2	92090A659	0000000

Extraction Tools

Remove installed helical inserts.

For Pronged Helical Inserts—Place the tip into pronged inserts and lightly strike the tool’s head. Then, turn the tool counterclockwise with pressure to extract the insert.

		Each
For Pronged Helical Inserts



	7/16"-14, 7/16"-20, 1/2"-13, 1/2"-20, 1/2"-28, 9/16"-12, 9/16"-18, 5/8"-11, 5/8"-18, 5/8"-24, 3/4"-10, 3/4"-16, 3/4"-20, 7/8"-9, 7/8"-14, 7/8"-20, 1"-8, 1"-12, 1"-14, M12, M14, M16, M18, M20, M22, M24	90254A330	000000

Left-Hand Thread Helical Threaded Inserts with Installation Tools

Save time when repairing threads in parts that rotate counterclockwise—these inserts come with installation tools. Pair them with left-hand-thread screws, and turn them the left to tighten. Also known as Heli-Coil inserts.

Pronged—The prong attaches to an installation tool for precise control as you drive inserts in. Remove the prong with a punch or break-off tool before inserting a screw.

18-8 Stainless Steel—The choice for wet and outdoor environments, these inserts resist rust and mild chemicals.

	For Max. Hole Dia.	No. of Inserts Included	Includes		Each
Pronged







	18-8 Stainless Steel

	5/8"-18	0.938"	41/64"	0.641"	2	Installation Tool Through-Hole Tap	92090A659	0000000

Helical Threaded Insert Installation and Prong Break-Off Tools

T-Handle

Install helical inserts and break off prongs with one tool and a hammer strike. These tools have a slot that grips your insert’s prong for turning both left- and right-hand threads. Slide an insert onto these tools and drive them a quarter-turn to half-turn below the material’s surface. Then, strike the end of the tool with a hammer to break off the prong. These tools work with pronged helical inserts.

	Handle Style		Each
Standard (UN) Thread



	5/8"-18	T-Handle	92090A555	000000

Left-Hand Thread Helical Insert Taps

Size holes for installing helical inserts that anchor left-hand bolts and rods. Helical inserts reinforce the connection between holes and fasteners that secure counter-clockwise rotating parts. Left-hand threads keep components such as flywheels and propellers from loosening and spinning off.

High-Speed Steel—These taps resist heat and wear to stay sharp.

Plug Chamfer—Our go-to chamfer type. With a longer taper than a bottoming chamfer, they are easier to turn but won't thread as close the bottom of a hole.

						Drill Bit			Plug Chamfer
	For Insert Size	Thread Lg.	Overall Lg.	For Insert Thread Type	No. of Flutes	Size	Decimal Size Equiv.	Shank Type		Each
High-Speed Steel







				Uncoated

				5/8"-18	1 13/16"	4 1/32"	UNF	4	41/64"	0.6406"	Square	92090A355	000000

Helical Threaded Insert Installation Tools

No Handle

Install your pronged helical inserts into tapped holes. Screw an insert onto these tools and drive them a quarter to half-turn below the material’s surface.

Square Shank—These tools don’t have a handle. Attach them to a tap wrench to turn.

	Shank Type	For Use With		Each
Standard (UN) Thread



	5/8"-18	Square	Helical Inserts, Screw-Locking Helical Inserts	93060A089	000000