Acorn / Cap Nuts

Acorn Nuts

Acorn nuts are a simple way to cover exposed threads and give an assembly a safer, cleaner finish. Also called a cap nut, this dome-style nut threads onto an external male thread and leaves a smooth, finished appearance instead of sharp, exposed threads. The domed end encloses the fastener tip, which helps in areas where hands, clothing, or wiring may brush past the hardware.

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Browse All Acorn Nut Styles

Fastener SuperStore stocks multiple acorn nuts for sale to match appearance, corrosion needs, and fit. Choose from steel and stainless steel options, several protective finishes, and open-end styles when you need a capped look but extra clearance. Metric sizes are also available.

Standard Low Crown / Steel / Nickel

Standard low crown acorn nuts in steel with a nickel finish cap exposed threads for a safer, cleaner-looking fastener. The low-profile dome fits tighter clearances than higher crown styles, while nickel plating adds extra corrosion resistance and a bright, polished appearance for light-duty and decorative applications.

Standard Low Crown / Steel / Black Oxide

Black oxide acorn nuts offer a subdued finish for indoor equipment, displays, and fixtures where you want less shine. The dome nut design covers external threads to reduce snags and give hardware a more intentional look, while the low crown keeps the profile tidy.

Standard Low Crown / Steel / Black Zinc

Black zinc options add a darker protective finish while keeping the familiar low crown shape. These acorn cap nuts are often selected for visible fasteners on racks, brackets, and assemblies where you want covered exposed threads and a consistent, uniform appearance across the build.

Standard Low Crown / 18-8 Stainless Steel

18-8 stainless steel acorn nuts are a solid pick for damp areas, outdoor exposure, and general corrosion resistance needs. The blind nut design caps the external male thread so you get a clean finished appearance while also reducing contact with sharp thread ends.

Washer-Based / Diecast Zinc Alloy

Washer-based acorn nuts use an integrated washer surface to spread load and improve seating on softer materials. The diecast zinc alloy construction is often used for light-duty assemblies where appearance matters and you want covered external threads without separate washer hardware.

Low Crown / Open End / Steel / Nickel

Open-end acorn nuts have a domed look but allow more thread length to pass through, which helps when you need adjustment or extra engagement. This nickel-finish style still reduces snag points and improves appearance, while the open end provides clearance for longer exposed threads.

Metric Acorn Nuts

Metric acorn nuts are used on metric external threads when you need the same capped finish as inch sizes. They’re common in equipment, imported assemblies, and mixed-spec builds. Match the thread pitch and crown height so the acorn nut cap fully seats and covers the end of the thread.

Benefits of Using Acorn Nuts in Safety & Decorative Applications

Acorn cap nuts are used for two reasons: they improve safety and they clean up the look of exposed hardware. By covering external threads and the tip of an external male thread, the domed end encloses the sharp end that can snag hands, clothing, cords, or packaging. That makes them useful on racks, handrails, furniture, displays, and assemblies that get handled often. They also help protect the threads from minor impact and keep dirt from collecting on the thread tip in certain environments. From a visual standpoint, a domed cap nut gives a consistent, finished appearance across a project, especially when hardware is visible from the front side. Whether you call it a crown hex nut, dome nut, or cap nut, the purpose is the same: a cleaner finish with less exposure and fewer sharp edges.

Frequently Asked Questions:

What are acorn nuts?

Acorn nuts are cap-style nuts with a domed top that covers the end of a bolt or stud. They thread onto external threads like a standard nut, but the dome creates a finished appearance and reduces direct contact with exposed threads at the end.

When should I use acorn nuts?

Use them when the end of the fastener will be visible or where people may brush against it. They’re common on furniture, handrails, racks, and fixtures because the domed cap nut shape helps reduce snags while also improving the look of the hardware.

What are open-end acorn nuts?

Open-end acorn cap nuts have a domed exterior but an opening inside that allows a longer bolt to pass through. They’re used when you want the capped look but need extra thread engagement or adjustment beyond what a fully closed cap will allow.

Are stainless steel acorn nuts rust-resistant?

Stainless steel options offer strong corrosion resistance for many outdoor and damp environments, which makes them a common choice for visible hardware. They won’t rust like plain steel in normal conditions, but grade selection and exposure still matter for long-term performance.

Do you offer acorn nuts in bulk quantities?

Yes. Our acorn cap nuts are available in bulk packaging for shops, production builds, and contractors. Bulk ordering helps standardize finishes and sizes across assemblies, reduces restocking delays, and keeps your hardware consistent when you’re repeating the same build over and over.