3-48 Inserts | McMaster-Carr

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Number of Inserts Included

288

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Less than 0.25"

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

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100,000 psi or greater

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19 Products

Helical Threaded Insert Assortments with Installation Tools

Repair damaged threads or create new ones. These convenient assortments include helical inserts, an installation tool for each thread size, a drill bit, and a tap. The inserts are 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.

	Drill Bit Size	For Max. Hole Dia.		Each
Pronged







	18-8 Stainless Steel

	288	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 Installation Tools Through-Hole Taps	Coarse	5/64" 3/32" 36 Ga. 31 Ga. 26 Ga. 17 Ga.	0.078" 0.094" 0.107" 0.120" 0.147" 0.173"	000000000	0000000

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



	2-56, 3-48, 3-56, 4-40, 4-48, 5-40, 6-32, 6-40, 8-32, 8-36, M2, M2.2, M2.5, M3, M3.5, M4	—	000000000	000000


	Narrow Profile



			3-48, 3-56, 4-40, 4-48, 5-40, 5-44, 6-32, 6-40, 8-32, 8-36, 8-40, M2.5, M3, M3.5, M4	Heli-Coil	000000000	00000

Helical Threaded Inserts

Pronged

Restore, reinforce, or create metal threads. 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. Easy-start installation tools compress the diameter of your insert so it fits easily into a tapped hole. These tools are the best choice for preventing misaligned or damaged threads—just make sure you have space to turn the crank.

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		Prong Break-Off Tools
	Thread Size	Installed Lg.	Drill Bit Size	For Max. Hole Dia.	Specs. Met	Pkg. Qty.		Pkg.		Each		Each		Each		Each
Pronged







				18-8 Stainless Steel

				3-48	0.099"	7/64"	0.109"	MS122115	10	000000000	00000	000000000	000000	000000000	000000	000000000	0000000	000000000	0000000


				3-48	0.148"	7/64"	0.109"	MS122155	10	000000000	0000	000000000	00000	000000000	00000	000000000	000000	000000000	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



	3-48, 3-56, 4-40, 4-48, 5-40, 5-44, 6-32, 6-40, 8-32, 8-36, 8-40, M2.5, M3, M3.5, M4	000000000	000000

Spring-Loaded Helical Threaded Insert Prong Break-Off Tools

Cleanly snap prongs off installed helical inserts with just one hand. Because they work faster than standard prong break-off tools, these are a good choice when you have many prongs to remove. Press your tool into an insert to trigger the spring-loaded punch and snap off the prong.

For Standard-Length Inserts—Use these tools for inserts that are 1 to 2 times as long as the diameter.

For Long Inserts—Use these tools for inserts that are 2 _1/2 to 3 times as long as the diameter.

	Mfr.		Each
For Standard-Length Inserts



	2-56, 3-48, 3-56	Heli-Coil	000000000	0000000


	2-56, 3-48, 3-56, M2, M2.2	—	000000000	00000


	For Long Inserts



			3-48, 3-56, M2.5	—	000000000	00000

Press-Fit Nuts for Sheet Metal

Add permanent threads to thin panels in seconds. The knurls on these clinch-style nuts deform and grip sheet metal to create a permanent hold. Push them into a drilled or punched hole with an arbor press around your workpiece to install—no messy welding required.

Zinc-Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.

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

				Head
Thread Size	Drill Bit Size	For Min. Panel Thk.	For Maximum Panel Hardness	OD	Ht.	PEM® Part No.	Head Shape	Pkg. Qty.		Pkg.







			Zinc-Plated Steel

			3-48	19 Ga.	0.04"	Brinell 150, Rockwell B80	0.25"	0.07"	—	Round	25	000000000	000000




					18-8 Stainless Steel

					3-48	19 Ga.	0.03"	Brinell 125, Rockwell B70	0.25"	0.07"	CLS-348-0	Round	10	000000000	0000


					3-48	19 Ga.	0.04"	Brinell 125, Rockwell B70	0.25"	0.07"	CLS-348-1	Round	10	000000000	0000
					3-48	19 Ga.	0.056"	Brinell 125, Rockwell B70	0.25"	0.07"	CLS-348-2	Round	10	000000000	0000

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

				3-48	5/8"	1 15/16"	UNC	3	7/64"	0.1094"	Square	000000000	000000	000000000	000000

Helical Threaded Insert Installation Tools

Straight 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.

	Handle Style	For Use With		Each
Standard (UN) Thread



	3-48	Straight	Helical Inserts, Screw-Locking Helical Inserts	000000000	0000000

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 automobile parts and other machinery that shakes and rattles. 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.

	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.	Specs. Met	Pkg. Qty.		Pkg.		Each		Each		Each		Each
Pronged







				18-8 Stainless Steel

				3-48	0.099"	7/64"	0.109"	NASM21209, MS21209C0310	5	000000000	00000	000000000	000000	000000000	000000	000000000	0000000	000000000	0000000


				3-48	0.148"	7/64"	0.109"	NASM21209, MS21209C0315	10	000000000	0000	000000000	00000	000000000	00000	000000000	000000	000000000	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


Crank Handle	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.

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.

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



	3-48	Crank	Threaded	Helical Inserts, Screw-Locking Helical Inserts	0000000	000000

Punch-Style Helical Threaded Insert Prong Break-Off Tools

Break the prong off of installed helical inserts. Place these tools inside the insert and hit the back with a hammer. Once removed, thread in your fastener.

For Thread Size	Handle Style	For Use With		Each
2-56, 3-48, M2, M2.5	Straight	Helical Inserts, Screw-Locking Helical Inserts	0000000	00000