Coupling Nuts

Coupling nuts are long hex nuts chamfered (beveled) at each end and used to couple two externally threaded objects of the same size and thread pitch. They can join different parts, like a hanger bolt and a threaded rod, or connect identical items, such as two threaded rods, to extend length. Sometimes coupling nuts function as spacers/standoffs. They are also known as:

extension nuts, rod coupling nuts, hex spacers.

Threads are standard right-hand at each end and Unified inch coarse series (UNC, Unified National Coarse) or Unified inch fine (UNF, Unified National Fine).

Coupling nut size refers to its nominal thread diameter. Typically, sizes range from about #10 to 1 1/2". Sizes less than 1/4" appear as a number size (the larger the number the larger the size) while sizes that are 1/4" and larger are specified in inches, usually fractional rather than decimal.

Nut width and length vary with the size of the coupling nut.

Grade 2, steel, zinc plated, is a common grade, material and finish; stainless steel is also available.

You can make a driver tool for hanger bolts using a coupling nut and a hex socket head shoulder screw. Cut off the screw's head, thread the screw into the nut, insert the shoulder into a drill/driver and thread the hanger bolt in the other end of the coupling nut.

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