Cap Nuts

Cap nuts are named such because they literally provide a cap over the exposed nut, which provides a clean and finished appearance and protection for the internal threads. This design aspect is crucial in applications where exposed threads could cause injury or snag wires. There are several different types of cap nuts that differ based on the internal and external base shape, material, and primary function (some provide connection support while others are purely decorative), but two of the most popular types are the acorn cap nut and the round cap nut.

The acorn and the round cap nut both feature a domed head over the base, but the shape is slightly different. Round nuts feature a perfectly round half-circle dome over the base; its main advantage is the lower profile that reduces the risk of interference with other components. Acorn nuts have a taller, more pointed cap that resembles an acorn; these work well when the mating threaded fastener needs more room to thread through the nut. Either option provides a clean-looking connection.

These nuts can be reused in applications where they are not subjected to extreme conditions that could cause wear or deformation. However, it's always recommended to inspect them for damage or wear and tear before attempting to reuse them.

While each specific type of cap nut provides a different benefit, the general purpose of the fastener is to provide protection for the mating threads and passing people or items. The threads are covered, which shields them from corrosive or damaging factors, while people and objects are also protected from the threads catching on items.