McMaster-Carr

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	System of Measurement System of Measurement

Metric

	Thread Size Thread Size	Show

M12

	Thread Size Thread Size	Hide

	Thread Pitch Thread Pitch

1.25 mm

1.5 mm

1.75 mm

	Thread Type Thread Type

Metric

	Installed Length Installed Length

10 mm to 19.9 mm

20 mm to 24.9 mm

25 mm or greater

	Thread Spacing Thread Spacing

Coarse

Fine

Extra Fine

	Material Material

Stainless Steel

	For Minimum Material Thickness For Minimum Material Thickness

10 mm to 19.9 mm

20 mm to 24.9 mm

25 mm or greater

	Drill Bit Size Drill Bit Size

31/64"

12.5 mm

	For Maximum Hole Diameter For Maximum Hole Diameter

0.25" to 0.499"

10 mm or greater

	Helical Insert Style Helical Insert Style

With Prong

	Thread Direction Thread Direction

	Right Hand

	Tensile Strength Tensile Strength

200,000 psi

	Passivation Passivation

Not Passivated

	Specifications Met Specifications Met

DIN

	For Tap Type For Tap Type

Helical

	Number of Inserts Included Number of Inserts Included

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31 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.

Inserts that meet DIN 8140 adhere to international standards for dimensions.

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

Metric

Inserts										Through-Hole Taps		Closed-End Hole Taps		Installation Tools		Prong Break-Off Tools
Thread Size	Thread Pitch, mm	Thread Spacing	Installed Lg., mm	Drill Bit Size	For Max. Hole Dia.	Specifications Met	Pkg. Qty.		Pkg.		Each		Each		Each		Each
18-8 Stainless Steel—Right-Hand Threaded
M12	1.75	Coarse	12	12.5 mm	12.5mm	DIN 8140, MA-3279-114	10	000000000	00000	000000000	000000	000000000	000000	000000000	0000000	000000000	0000000
M12	1.75	Coarse	18	12.5 mm	12.5mm	DIN 8140, MA-3279-164	5	000000000	0000	000000000	00000	000000000	00000	000000000	000000	000000000	000000
M12	1.75	Coarse	24	12.5 mm	12.5mm	DIN 8140, MA-3279-214	5	000000000	0000	000000000	00000	000000000	00000	000000000	000000	000000000	000000
M12	1.75	Coarse	30	12.5 mm	12.5mm	DIN 8140, MA-3279-264	5	000000000	00000	000000000	00000	000000000	00000	000000000	000000	000000000	000000
M12	1.5	Fine	18	12.5 mm	12.5mm	DIN 8140, MA-3279-163	5	000000000	0000	000000000	00000	000000000	00000	000000000	000000	000000000	000000
M12	1.25	Extra Fine	12	31/64"	31/64"	DIN 8140, MA-3279-112	10	000000000	0000	000000000	00000	000000000	00000	000000000	000000	000000000	000000
M12	1.25	Extra Fine	18	31/64"	31/64"	DIN 8140, MA-3279-162	5	000000000	0000	000000000	00000	000000000	00000	000000000	000000	000000000	000000
M12	1.25	Extra Fine	24	31/64"	31/64"	DIN 8140, MA-3279-212	10	000000000	00000	000000000	00000	000000000	00000	000000000	000000	000000000	000000

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 that meet DIN 8140 adhere to international standards for dimensions.

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

Metric

Inserts										Through-Hole Taps		Closed-End Hole Taps		Installation Tools		Prong Break-Off Tools
Thread Size	Thread Pitch, mm	Thread Spacing	Installed Lg., mm	Drill Bit Size	For Max. Hole Dia.	Specifications Met	Pkg. Qty.		Pkg.		Each		Each		Each		Each
18-8 Stainless Steel
M12	1.75	Coarse	12	12.5 mm	12.5mm	DIN 8140, MA-3329-114	5	000000000	00000	000000000	000000	000000000	000000	000000000	0000000	000000000	0000000
M12	1.75	Coarse	18	12.5 mm	12.5mm	DIN 8140, MA-3329-164	5	000000000	0000	000000000	00000	000000000	00000	000000000	000000	000000000	000000
M12	1.75	Coarse	24	12.5 mm	12.5mm	DIN 8140, MA-3329-214	1	000000000	0000	000000000	00000	000000000	00000	000000000	000000	000000000	000000
M12	1.75	Coarse	30	12.5 mm	12.5mm	DIN 8140, MA-3329-264	1	000000000	00000	000000000	00000	000000000	00000	000000000	000000	000000000	000000
M12	1.5	Fine	18	12.5 mm	12.5mm	DIN 8140, MA-3329-162	1	000000000	0000	000000000	00000	000000000	00000	000000000	000000	000000000	000000
M12	1.25	Extra Fine	12	31/64"	31/64"	MA-3329-112	5	000000000	0000	000000000	00000	000000000	00000	000000000	000000	000000000	000000
M12	1.25	Extra Fine	18	31/64"	31/64"	DIN 8140, MA-3329-163	1	000000000	0000	000000000	00000	000000000	00000	000000000	000000	000000000	000000
M12	1.25	Extra Fine	24	31/64"	31/64"	MA-3329-212	1	000000000	0000	000000000	00000	000000000	00000	000000000	000000	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.

Metric

18-8 Stainless Steel—Right-Hand Threaded
Thread Size	Thread Pitch, mm	Thread Spacing	Installed Lg., mm	Drill Bit Size	For Max. Hole Dia.	No. of Inserts Included	Includes		Each
M12	1.75	Coarse	18	31/64"	31/64"	5	Drill Bit, Through-Hole Tap, Installation Tool	000000000	000000
M12	1.5	Fine	18	31/64"	31/64"	5	Drill Bit, Through-Hole Tap, Installation Tool	000000000	00000
M12	1.25	Extra Fine	18	31/64"	31/64"	5	Drill Bit, Through-Hole Tap, Installation Tool	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.

Metric
Includes	No. of Inserts Included	Thread Spacing	Drill Bit Size	For Max. Hole Dia.		Each
18-8 Stainless Steel
M12×1.25 mm Thread × 12 mm Installed Lg. (6 Each) M12×1.25 mm Thread × 18 mm Installed Lg. (6 Each) M12×1.25 mm Thread × 24 mm Installed Lg. (6 Each) Drill Bit Through-Hole Tap Installation Tool	18	Extra Fine	31/64"	31/64"	000000000	0000000
M12×1.75 mm Thread × 12 mm Installed Lg. (6 Each) M12×1.75 mm Thread × 18 mm Installed Lg. (6 Each) M12×1.75 mm Thread × 24 mm Installed Lg. (6 Each) Drill Bit Through-Hole Tap Installation Tool	18	Coarse	31/64"	31/64"	000000000	00000

Terms and Conditions and Privacy Policy

How to Install Helical Inserts

About Helical Insert Length

Stainless Steel Helical Inserts

Stainless Steel Screw-Locking Helical Inserts

Helical Inserts with Installation Tools

Helical Insert Assortments with Installation Tools