A brass dome nut is a hexagonal cap nut with a closed, rounded top. It is also known as a brass acorn nut or brass cap nut. The internal thread engages a matching male thread, while the closed dome covers the exposed end of the bolt.
We are a custom brass dome nut manufacturer and supply brass dome nuts to OEMs, distributors, and industrial buyers in the United States, Asia, and across European markets, including Germany, France, Spain, the Czech Republic, the Netherlands, the UK, and Italy.
All our custom brass domed nuts will be manufactured according to the customer's drawing and sample. Custom thread sizes, dimensions, thread systems, and designs according to customer requirements. Custom brass grades are supported according to customer requirements, along with both metric and imperial thread configurations.
We support medium- to high-volume production requirements. Samples and a small batch are also supported for quality and testing.
Request a Quote for Custom Brass Cap NutThe closed dome covers the exposed end of a bolt after installation. This helps protect the thread end from contact and reduces exposed sharp thread edges around the assembly.
The dome conceals the exposed thread end and gives the fastening point a smooth, finished appearance. This makes useful for visible hardware where the fastener remains exposed after assembly.
Brass is conductive and essentially non-magnetic, so brass dome nuts can suit selected electrical and electronic assemblies.
A brass dome nut works by engaging its internal thread with the matching external thread on a bolt, screw, and stud. The nut is rotated onto the male thread until the mating parts are clamped together.
The hexagonal body provides the driving surface used to tighten the dome nut with a suitable wrench. As the nut advances along the bolt thread, the mating components are clamped together.
Because the top of a Cap nut is closed, the bolt projection must fit within the nut’s available internal depth. The assembly also needs sufficient thread engagement. A bolt that extends too far into the dome can prevent the nut from seating fully against the joint.
A standard brass Acorn nut covers the exposed thread end but does not automatically create a pressure-tight seal. Applications requiring sealing need a cap-nut design with an appropriate sealing feature.
| Item | Specification |
|---|---|
| Brass Grade | Brass, including C36000, CW614N / CuZn39Pb3, IS 319 Grade I, and customer-specified brass grades |
| Custom Dome Nut Types | Custom brass dome nuts manufactured according to customer drawings |
| Thread System | Metric, UNC, UNF, BSW, BSF, BA, customer-specified thread systems |
| Surface Finish | Natural brass, polished brass, tumbled finish, tin plating, nickel plating, and customer-specified finishes |
| Tolerance | General tolerance ±0.10 mm, tighter tolerances according to drawing requirements |
| Inspection | Dimensional and thread inspection according to drawing requirements, using calipers, micrometers, thread gauges, and other suitable measuring equipment |
| Material Certification | Available on request according to order requirements |
| Drawing Formats | STEP, PDF, DXF, DWG, and customer-specified formats |
| Packaging | Poly bags, boxes, master cartons, pallets, and custom packaging |
| MOQ | Based on dome nut geometry, material grade, tooling, quantity, and production requirements |
| Lead Time | According to quantity and production requirements |
| Tooling Ownership | All tooling are customer-owned. Tooling is never reused for other customers |
For more details, please visit our main brass nut page.
We manufacture custom dome nuts in metric and inch thread configurations according to customer drawings.
| Thread Size | Standard Pitch | Across Flats | Overall Height |
|---|---|---|---|
| M4 | 0.70 mm | 7 mm | 8 mm |
| M5 | 0.80 mm | 8 mm | 10 mm |
| M6 | 1.00 mm | 10 mm | 12 mm |
| M8 | 1.25 mm | 13 mm | 15 mm |
| M10 | 1.50 mm | 16 mm | 18 mm |
| M12 | 1.75 mm | 18 mm | 22 mm |
| M14 | 2.00 mm | 21 mm | 25 mm |
| M16 | 2.00 mm | 24 mm | 28 mm |
| M18 | 2.50 mm | 27 mm | 32 mm |
| M20 | 2.50 mm | 30 mm | 34 mm |
| M22 | 2.50 mm | 34 mm | 39 mm |
| M24 | 3.00 mm | 36 mm | 42 mm |
Note: Sizes and dimensions shown are reference values based on DIN 1587 for high-form metric dome nuts.
| Thread Size | TPI | Thread Series | Across Flats (Low Crown) | Overall Height (Low Crown) |
|---|---|---|---|---|
| #4-40 | 40 | UNC (commercial size) | 1/4 in. | 1/4 in. |
| #6-32 | 32 | UNC | 5/16 in. | 9/32 in. |
| #8-32 | 32 | UNC | 5/16 in. | 9/32 in. |
| #10-24 | 24 | UNC | 3/8 in. | 11/32 in. |
| #10-32 | 32 | UNF | 3/8 in. | 11/32 in. |
| #12-24 | 24 | UNC | 3/8 in. | 11/32 in. |
| 1/4-20 | 20 | UNC | 7/16 in. | 3/8 in. |
| 1/4-28 | 28 | UNF | 7/16 in. | 3/8 in. |
| 5/16-18 | 18 | UNC | 9/16 in. | 7/16 in. |
| 5/16-24 | 24 | UNF | 9/16 in. | 7/16 in. |
| 3/8-16 | 16 | UNC | 5/8 in. | 1/2 in. |
| 3/8-24 | 24 | UNF | 5/8 in. | 1/2 in. |
| 7/16-14 | 14 | UNC | 3/4 in. | 9/16 in. |
| 7/16-20 | 20 | UNF | 3/4 in. | 9/16 in. |
| 1/2-13 | 13 | UNC | 3/4 in. | 9/16 in. |
| 1/2-20 | 20 | UNF | 3/4 in. | 9/16 in. |
| 5/8-11 | 11 | UNC | 1 in. | 3/4 in. |
| 5/8-18 | 18 | UNF | 1 in. | 3/4 in. |
| 3/4-10 | 10 | UNC | 1-1/16 in. | 7/8 in. |
| 1-8 | 8 | UNC | 1-7/16 in. | 1-1/4 in. |
Note: Inch sizes shown are reference values from established acorn nut and brass cap-nut product data. Exact dimensions depend on the specified dome-nut design and applicable standard.
Brass dome nuts are used in applications such as lighting fixtures. Electrical and electronic equipment, Machinery hardware, and furniture.
Brass dome nuts are used in pendant lighting fixtures.
Brass Cap Nuts used as mechanical fasteners in electrical and electronic equipment.
Brass acorn nuts are used in some furniture and cabinet hardware applications to cover exposed threaded ends.
Brass dome nuts are used on decorative machinery covers.
Yes. The joint should be evaluated for galvanic corrosion when moisture is present. The risk depends on the metals, service environment, exposed area, and electrical isolation used in the joint.
A washer is not required for every installation. It can help distribute the bearing load and protect the surface under the nut. Washer selection depends on the joint design, bearing surface, and required clamping load.
A standard acorn nut does not have an inherent locking feature. Applications with significant vibration may require a locking dome-nut design that uses a suitable locking feature specified for the joint.
A brass cap nut can be reused when the product specification permits reuse and the threads, bearing surface, and dome remain undamaged. Inspect the nut before reuse and replace it when damage affects the fastening surfaces.
DIN 1587 specifies the high-form hexagon domed cap nut. DIN 917 specifies the low-form hexagon cap nut. The different profiles affect the available height and clearance around the threaded end.
Do not assume that a brass dome nut has the same load capacity as a structural hex nut. The required load should be checked against the brass grade, nut dimensions, thread engagement, applicable specification, and joint design.
To request a brass dome nut quotation, send your drawing and RFQ details.
Please include:
Send your RFQ and drawings to receive a quotation with pricing and indicative lead time.
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