M24 Reducers | McMaster-Carr

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29 Products

About Threaded Inserts

Choose the right threaded insert for your application and learn how to install it securely.

Thread-Locking Threaded Insert Assortments

These assortments include various sizes of thread-locking inserts, which won’t back out or loosen from vibration. Also known as E-Z Lok, they come with Loctite® adhesive already applied, and the adhesive reaches full strength after 72 hours. After drilling and tapping your hole, install inserts with a wrench or use an installation bit (not included). To use a wrench, thread an insert and two hex nuts onto a bolt. Then, grip and turn the top nut to drive into the hole.

Standard Wall—Stronger than thin-wall inserts, these are your go-to choice for threading most holes.

Black Phosphate-Coated Steel—These inserts resist occasional moisture.

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

				For Tap
	No. of Inserts Included	Includes	Thread Spacing	Thread Size	Thread Pitch	Drill Bit Size	For Maximum Hole Diameter	Drive Style		Each
Standard Wall







				Black Phosphate-Coated Steel

				33	M8×1.25 mm Thread × 12.5 mm Installed Lg. (10 Each) M10×1.5 mm Thread × 17 mm Installed Lg. (10 Each) M12×1.75 mm Thread × 17 mm Installed Lg. (8 Each) M16×2 mm Thread × 20 mm Installed Lg. (5 Each)	Coarse	M12 M16 M16 M24	1.75 mm 2 mm 2 mm 3 mm	10.4 mm 14 mm 14 mm 21 mm	10.4 mm 14 mm 14 mm 21 mm	Slotted	97084A290	0000000




						18-8 Stainless Steel

						33	M8×1.25 mm Thread × 12.5 mm Installed Lg. (10 Each) M10×1.5 mm Thread × 17 mm Installed Lg. (10 Each) M12×1.75 mm Thread × 17 mm Installed Lg. (8 Each) M16×2 mm Thread × 20 mm Installed Lg. (5 Each)	Coarse	M12 M16 M16 M24	1.75 mm 2 mm 2 mm 3 mm	10.4 mm 14 mm 14 mm 21 mm	10.4 mm 14 mm 14 mm 21 mm	Slotted	97120A035	000000

Thread-Locking Threaded Inserts

With Loctite® adhesive already on the threads, these inserts won’t back out or vibrate loose. The adhesive reaches full strength after 72 hours. Unlike helical inserts, you can install them with a standard drill and tap. However, thread-locking inserts are difficult to remove and reuse.

After drilling and tapping your hole, install inserts with a wrench or an installation bit. To use a wrench, thread an insert and two hex nuts onto a bolt. Then, grip and turn the top nut to drive into the hole. For slotted inserts, you can drive with a slotted screwdriver instead.

Standard Wall—Stronger than thin-wall inserts, these are your go-to choice for threading most holes.

Black Phosphate-Coated Steel—These inserts resist occasional moisture.

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

	Inserts									Installation Tools
	Thread Size	For Tap Thread Size	Installed Lg., mm	Drill Bit Size, mm	For Max. Hole Dia., mm	Drive Style	Pkg. Qty.		Pkg.		Each
Standard Wall







				Black Phosphate-Coated Steel

				M16 x 2 mm	M24 x 3 mm	20	21	21	Slotted	1	97084A270	00000	94110A190	000000


				M24 x 3 mm	M36 x 4 mm	30	33	33	Slotted	1	97084A317	00000	94110A250	00000




						18-8 Stainless Steel

						M16 x 2 mm	M24 x 3 mm	20	21	21	Slotted	1	97120A270	0000	94110A190	00000

Key-Locking Threaded Inserts for Soft Metal

Add strong threads in soft metal, such as aluminum. The keys on these inserts drive into holes to hold more securely than thread-locking or helical inserts. They prevent slipping and rotating, so they’re stable enough for use in vehicle or aerospace parts that experience heavy vibration. These inserts are comparable to Keensert inserts.

To install, drill and tap a hole in your material. Then, thread the insert onto the installation tool and screw it into the hole. Place the tool over the keys and hit it with a hammer to drive them in.

Standard Wall—Stronger than thin-wall inserts, these are your go-to choice for threading most holes.

Black Phosphate-Coated Steel—These inserts resist occasional moisture.

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

	Inserts									Installation Tools		Inserts with Installation Tools
								Each
	Thread Size	For Tap Thread Size	Installed Lg., mm	Drill Bit Size, mm	For Max. Hole Dia., mm	No. of Locking Keys		1-9	10-Up		Each	No. of Inserts Included		Each
Standard Wall







				Black Phosphate-Coated Steel

				M18 x 1.5 mm	M24 x 1.5 mm	24	22.5	22.5	4	90245A197	000000	000000	94010A350	000000	2	90245A321	000000


				M24 x 2 mm	M33 x 2 mm	33	31	31	4	90245A217	00000	00000	94010A365	00000	—	———	0
				M24 x 3 mm	M33 x 2 mm	33	31	31	4	90245A213	00000	00000	94010A365	00000	2	90245A341	000000




						18-8 Stainless Steel

						M18 x 1.5 mm	M24 x 1.5 mm	24	22.5	22.5	4	93715A665	00000	00000	94010A350	00000	2	93715A475	000000


						M24 x 3 mm	M33 x 2 mm	33	31	31	4	93715A685	00000	00000	94010A365	00000	—	———	0

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., mm	Drill Bit Size	For Max. Hole Dia.	Specs. Met	Pkg. Qty.		Pkg.		Each		Each		Each
Pronged







				18-8 Stainless Steel

				M24 x 3 mm	36	31/32"	0.969"	DIN 8140, SAE MA3329-179	1	90296A431	000000	92450A325	0000000	91709A340	0000000	92450A189	000000

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., mm	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

				M24 x 3 mm	36	31/32"	0.969"	SAE MA3279-179	1	92450A125	00000	92450A325	0000000	91709A340	0000000	92450A189	000000	5	91732A969	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

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

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.

	Handle Style	Helical Insert Tool Drive Type	For Use With		Each
Metric Thread



	M24 × 3 mm	T-Handle	Prong Slot	Helical Inserts, Screw-Locking Helical Inserts	1338N74	0000000

Key-Locking Threaded Insert Installation Tools


Style A	Style D

Thread inserts and drive down their keys with a single tool. These tools are compatible with Keensert inserts.

Threaded Insert Installation Tools

Style A

	For Tap Thread Size	Style	Features		Each
For Thick-Wall Inserts



	M24	M33	A	Slotted End	6721N93	000000

Threaded Insert Installation Tools with Spring

Style D

The tradespersons’ choice for installing Mil. Spec. inserts. A spring holds the sleeve under tension, so wobbles and jostles don’t interfere with a clean, professional install.

	For Tap Thread Size	Style	Features		Each
For Thick-Wall Inserts



	M18	M24	D	Sleeve, Slotted End	93904A795	000000


	M24	M33	D	Sleeve, Slotted End	93904A798	00000

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.

For Pipe Size	Handle Style		Each



1"-8, 1"-12, 1"-14, M24 × 1.5 mm, M24 × 2 mm, M24 × 3 mm	1/2 BSPP, 5/8 BSPP	T-Handle	92450A189	000000

Helical Threaded Inserts with Installation Tools

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

	M24 x 3 mm	36	31/32"	0.969"	5	Installation Tool Through-Hole Tap	91732A969	0000000

Installation Bits for Slotted-Drive Threaded Inserts

For fast installation, use these installation bits with power drills and drill presses.

For Thread Size	Hex Shank Size		Each
M20, M24	3/8"	94110A250	000000

Key-Locking Threaded Insert Drivers

Place the tip of these tools into a key-locking insert after you've threaded it into a hole with your fingers. Then, strike these tools with a hammer to drive the keys into the material and secure the insert. They’re compatible with Keensert inserts.

Choose the tool that matches your insert’s thread size and tap thread size.

		Each
Metric Thread







	For Thick-Wall Inserts

	M18	M24	Straight	94010A350	000000


	M24	M33	Straight	94010A365	00000

Screw-Locking Seize-Resistant Key-Locking Threaded Inserts for Soft Metal

Create the tightest hold in aluminum and other soft metal without screws sticking. The lubricant on these inserts eases installation, and the irregularly shaped threads won’t let screws back out from vibration. Inserts have keys that drive into material to prevent them from slipping or rotating in the hole.

Standard Wall—Stronger than thin-wall inserts, these are your go-to choice for threading most holes.

Dry-Film-Lubricated Cadmium-Plated Steel—The plating creates a barrier against rust.

	Inserts								Installation Tools
	Thread Size	For Tap Thread Size	Installed Lg., mm	Drill Bit Size, mm	For Max. Hole Dia., mm	No. of Locking Keys		Each		Each
Standard Wall







				Dry-Film-Lubricated Cadmium-Plated Steel

				M24 x 3 mm	M33 x 2 mm	33	31	31	4	97255A338	0000000	93904A798	000000

Key-Locking Threaded Inserts with Installation Tools

Paired with the right tool for installation, these inserts create strong threads in soft metal, such as aluminum. They have keys that drive into material to prevent inserts from slipping and rotating in the hole.

Standard Wall—Stronger than thin-wall inserts, these are your go-to choice for threading most holes.

Black Phosphate-Coated Steel—These inserts resist occasional moisture.

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

	Drill Bit Size, mm	For Max. Hole Dia., mm	No. of Locking Keys	No. of Inserts Included		Each
Standard Wall







	Black Phosphate-Coated Steel

	M18 x 1.5 mm	M24 x 1.5 mm	24	22.5	22.5	4	2	90245A321	000000


	M24 x 3 mm	M33 x 2 mm	33	31	31	4	2	90245A341	000000




			18-8 Stainless Steel

			M18 x 1.5 mm	M24 x 1.5 mm	24	22.5	22.5	4	2	93715A475	000000