Define: Rack Screws (10-32, 12-24, M6)
Description
Rack screws are used to attach equipment to the vertical uprights of a 19″ rack. Racks do not have a standard thread type. There are three common thread types for rack screws: 10-32, 12-24, and M6. Since the introduction of the square hole rack and Cage Nuts the exact thread can be selected and changed at will.
10-32 Threads
10-32 threads are historically the original rack screw type. The term 10-32 comes from Unified and American Screw Threads for Bolts, Nuts, and Machine Screws standards published by ANSI B1.1-1974. The number “10″ is simply a size designator with no numerical meaning. The number “32″ refers to 32 threads per inch. You can identify a 10-32 screw by measuring the diameter with a ruler at exactly 3/16″ (0.190″).
12-24 Threads
12-24 is now more common than 10-32 in pre-threaded racks. 12-24 fasteners are slightly larger than 10-32 and have courser threads. The term 12-24 comes from Unified and American Screw Threads for Bolts, Nuts, and Machine Screws standards published by ANSI B1.1-1974. The number “12″ is simply a size designator with no numerical meaning. The number “24″ refers to 24 threads per inch. You can identify a 12-24 screw by measuring the diameter with a ruler at slightly less than 7/32″ (slightly larger than 3/16″ or 0.210″).
M6 Threads
M6 refers to a metric 6mm screw. The outside diameter of the threads is 6mm. The standard metric rack screw is actually an M6 x 0.1mm. The number “0.1mm” refers to 0.1 threads per millimeter. M6 screws are commonly used by HP. You can identify an M6 screw by measuring the diameter with a ruler at slightly more than 7/32″ (0.228″).
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