Jack Nuts (Blind Threaded Inserts)

Description

Jack Nut Sizes, Grip Ranges & Specifications

The charts below list standard inch and metric jack nut sizes, grip ranges, overall lengths, mounting hole sizes and dimensional specifications. Select the required thread size and material thickness to request a production quote.

What Is a Jack Nut?

A jack nut is a light-duty blind threaded insert used to create a reusable female thread in thin, soft or brittle materials where conventional tapping, welding or backside access is impractical.

The jack nut has a slotted body that collapses into four legs during installation. These legs spread across the blind side of the material, creating a broad bearing area that helps distribute the clamping load and reduce damage to the panel.

Jack nuts are commonly used in thin sheet metal, plastic panels, fiberglass, composites and other materials that may deform or crack under the higher installation forces required by conventional rivet nuts.

They may also be searched as jack nut threaded inserts, blind jack nuts, expansion nuts, molly nuts, four-leg threaded inserts or blind threaded fasteners.

Available Thread Sizes & Grip Ranges

Jack nuts are available in standard UNC and metric thread sizes. Each thread size is offered in different body lengths and grip ranges for varying material thicknesses.

Inch Thread Sizes

• #6-32 × .669 Jack Nut — Grip Range: 0–.197 in.
• #6-32 × .866 Jack Nut — Grip Range: .197–.394 in.
• #10-24 × .709 Jack Nut — Grip Range: 0–.197 in.
• #10-24 × .906 Jack Nut — Grip Range: .197–.394 in.
• 1/4-20 × .709 Jack Nut — Grip Range: 0–.197 in.
• 1/4-20 × .906 Jack Nut — Grip Range: .197–.394 in.

Metric Thread Sizes

• M4 × 17 mm Jack Nut — Grip Range: 0–5 mm
• M4 × 22 mm Jack Nut — Grip Range: 5–10 mm
• M5 × 18 mm Jack Nut — Grip Range: 0–5 mm
• M5 × 23 mm Jack Nut — Grip Range: 5–10 mm
• M6 × 18 mm Jack Nut — Grip Range: 0–5 mm
• M6 × 23 mm Jack Nut — Grip Range: 5–10 mm

Refer to the specification chart above for exact mounting hole size, body diameter, head diameter, head height and overall length.

Why Use Jack Nuts?

Jack nuts are designed for applications where a conventional rivet nut may apply too much localized installation force or where the parent material is too thin, soft or brittle to support a tapped thread.

Key benefits include:

• Blind installation from one side
• Four expanding legs distribute load across a wider backside area
• Low installation force for delicate materials
• Wide grip range for varying panel thicknesses
• Reusable internal machine thread
• Economical design for production assembly
• No welding or thermal damage
• Suitable for thin, soft and brittle materials
• Available in inch and metric thread sizes

Jack Nuts vs. Standard Rivet Nuts

A jack nut uses four expanding legs to distribute load across a broad area behind the panel. It is generally selected for light-duty fastening in thin sheet metal, plastics, fiberglass and other delicate materials.

A standard rivet nut forms a compact blind-side bulge and typically provides greater thread strength, pull-out strength and torque resistance in metal panels.

A pre-bulbed plus nut also forms multiple backside legs but generally provides greater load capacity and a more robust threaded section than a jack nut.

Jack nuts should not be treated as structural fasteners. The correct product should be selected according to panel material, thickness, required clamp load, service torque and pull-out requirements.

Materials & Finishes

Jack nuts are available in carbon steel and stainless steel, depending on thread size and production requirements.

Available finish options may include:

• Clear or white zinc plating
• Yellow zinc plating
• Nickel plating
• Application-specific coatings

Zinc-plated steel provides economical performance and corrosion protection for general industrial applications. Stainless steel may be specified when greater corrosion resistance or material compatibility is required.

Material and finish availability varies by thread size, grip range, production quantity and application requirements.

How to Install Jack Nuts？

1. Insert the jack nut into the pre-drilled hole.
2. Thread the installation tool or screw into the jack nut.
3. Tighten the tool to collapse the legs behind the material.
4. The jack nut expands and creates a secure threaded insert.

Jack nuts are ideal for applications where access to the backside is limited, such as sheet metal, plastic, and fiberglass installations.

Watch how jack nuts are installed using a manual jack nut tool:

👉 View our Jack Nut Tool here.Jack Nut Tool | Installation Tool for M4–M6 & 6-32 to 1/4-20 | Factory Direct Supplier

Typical Jack Nut Applications

Jack nuts are commonly used for light-duty attachments in thin, soft or brittle materials.

Typical applications include:

• Electrical cabinets and enclosures
• Plastic access panels
• Fiberglass housings
• Automotive interior panels
• Recreational vehicles
• HVAC equipment
• Appliances
• Electronic equipment
• Display and signage assemblies
• Furniture and fixtures
• Inspection and identification plates
• Light-duty sheet metal assemblies
• Composite panels

Factory-Direct Supply & Custom Production

Imperial Rivets & Fasteners supplies factory-direct jack nuts and blind threaded inserts to OEMs, manufacturers, distributors and industrial assembly operations.

Standard inch sizes include #6-32, #10-24 and 1/4-20. Metric sizes include M4, M5 and M6, with multiple body lengths and grip ranges available for different panel thicknesses.

Carbon steel, stainless steel and custom finish options may be available depending on production requirements.

Select the required part from the specification chart above and add it to your RFQ. For production requirements, provide the thread size, material thickness, mounting hole size, parent material, finish and estimated annual quantity.

Jack Nut Installation Tools

Compatible manual and production jack nut installation tools are available for inch and metric sizes.

View Jack Nut Installation Tools

Questions or Custom Requirements?

Contact our sales team at sales@imperialrivet.com or (630) 964-0208.