Nuts

Hex nuts, lock nuts, wing nuts, and specialty fasteners.

Hex Nut

The most common nut type with six flat sides for wrench engagement. Used with hex bolts for general fastening.

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Lock Nut (Nylon Insert)

Hex nuts with a nylon ring insert that grips bolt threads to prevent loosening from vibration.

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Wing Nut

Nuts with two projecting wings for hand tightening without tools. Used where frequent adjustment is needed.

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Acorn Nut

Decorative cap nuts with domed tops that cover exposed bolt threads. Provides finished appearance and protection.

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Castle Nut

Slotted hex nuts designed for use with cotter pins. Prevents loosening in critical safety applications.

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Coupling Nut

Long hex nuts used to join two threaded rods end-to-end. Extends length of threaded assemblies.

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Flange Nut

Hex nuts with integrated circular flange that acts as a built-in washer. Often serrated for vibration resistance.

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Jam Nut

Thin hex nuts used in pairs to lock against each other or under standard nuts. Half the height of regular nuts.

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Square Nut

Four-sided nuts that fit in square holes or slots. Used with carriage bolts and in T-slot applications.

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T-Nut

Flanged nuts with prongs that embed in wood for through-bolting. Install from back side of panel.

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Prevailing Torque Nut

All-metal lock nuts with distorted threads that create friction. Work at high temperatures where nylon fails.

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Knurled Nut

Nuts with textured grip surfaces for hand tightening. Common in electronics and precision instruments.

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Barrel Nut

Cylindrical cross-dowel nuts that mount perpendicular to the bolt. Used in knockdown furniture assembly.

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Rivet Nut

Threaded inserts installed from one side that create permanent threads in thin materials.

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Weld Nut

Nuts designed for resistance welding to sheet metal. Provide permanent threaded attachment points.

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Cage Nut

Square nuts held in spring-steel cages that snap into square holes. Used in server rack mounting.

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Frequently Asked Questions

What is the difference between a lock nut and a regular hex nut?
A regular hex nut relies solely on thread friction and clamping force to stay in place. Lock nuts have an additional locking mechanism — either a nylon insert (nyloc) that grips the bolt threads, or a prevailing torque design with a deformed top section. Lock nuts resist loosening from vibration and are used in automotive, machinery, and structural applications.
Can I reuse nylon lock nuts?
Nylon lock nuts (nyloc) lose locking effectiveness after repeated installation and removal. The nylon insert deforms to grip the bolt threads, and this deformation reduces with each use. Most manufacturers recommend single-use for critical applications. For non-critical applications, they may be reused 2-3 times if the nylon insert still provides noticeable resistance during threading.
What is a castle nut used for?
Castle nuts (also called castellated nuts) have slots cut into the top that align with a hole in the bolt. A cotter pin is inserted through the slot and bolt hole to positively lock the nut in place. They are used in safety-critical applications such as steering linkages, wheel bearings, and aircraft assemblies where the nut must never loosen.
When should I use a flange nut instead of a nut with a washer?
Flange nuts have a built-in washer (flange) at the base that distributes load and prevents the nut from pulling through soft materials. They eliminate the need for a separate washer, reducing parts count and assembly time. Serrated flange nuts also provide vibration resistance. Use them in automotive and assembly-line applications where speed and reliability matter.
What size wrench do I need for a given nut?
Wrench size corresponds to the width across flats (WAF) of the nut, not the thread size. For imperial nuts, common pairings: 1/4" bolt = 7/16" wrench, 5/16" bolt = 1/2" wrench, 3/8" bolt = 9/16" wrench, 1/2" bolt = 3/4" wrench. For metric: M6 = 10mm, M8 = 13mm, M10 = 17mm, M12 = 19mm. Always verify — some standards differ.