Cap Nut Vs. Acorn Nut
All fasteners serve several purposes – some are very specific, while others are broad. A cap nut serves to create a smooth finish and cover exposed bolt ends. The taller profile of an acorn nut provides better protection for bolt threads.
When You Should Use A Cap Nut
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A cap nut serves to protect the bolt threads underneath, but also provides a cleaner appearance, and may improve safety on certain joints and applications.
When your application requires a smooth finish, or all rough-edged fasteners and exposed threads must be covered, cap nuts provide an excellent solution. Cap nuts also come in a variety of styles, such as one-piece, two-piece, low crown, and acorn nuts.
When You Should Use An Acorn Nut
An acorn nut serves a very specific purpose that a standard cap nut cannot. Both one-piece and two-piece cap nuts are designed with lower domes than the acorn style, a shape that allows the external threads of the bolt to come in contact with the cap.
This point of contact can result in thread wear and deterioration, especially when vibration and movement are issues. An acorn nut is designed with a larger or taller dome, eliminating any point of contact with those external threads that extend beyond the hex nut base.
Other Differences Between Cap Nuts And Acorn Nuts
Cap nuts come in a variety of materials, from stainless steel to plated steel and brass (commonly used for decorative projects). Acorn nuts come in a more limited selection of materials, most often plated steel or stainless. Both types are commonly polished to a shiny finish.
Both are available in coarse and fine threads, but prices vary. Depending on your ordering needs, cap nuts may be less expensive than the larger sized acorn nut. This price difference is more consistent in bulk quantities.
Nut sizes tend to be the same, meaning you can use either a cap nut or acorn nut on every standard bolt, but the finished sizing is different. If your application involves tight spaces, choose a cap nut with a low profile for the smoothest finish.
Started my career in the fastener world in 1969 at, Parker Kalon Corp. a NJ based screw manufacturer located in Clifton, NJ working in inventory control, scheduling secondary production and concluding there in purchasing. In 1971 I accepted a sales position at Star Stainless Screw Co., Totowa, NJ working in inside sales and later as an outside salesman, having a successful career at Star I had the desire with a friend to start our own fastener distribution company in 1980 named: Divspec, Kenilworth, NJ. This was a successful adventure but ended in 1985 with me starting Melfast in August 1985 and have stayed competitive and successful to date. Melfast serves the OEM market with approximately 400 accounts nationally.