AIA/NAS 576-2012 pdf download THREAD LENGTH FOR SELF-LOCKING NUTS
The following establishes standard maximum thread lengths for self-locking nuts.
One of the lengths shown should be used in the design of any new standard for self-locking nuts.
/a/ Maximum thread length is the maximum amount of useable thread in the nut plus locking device and does not include the height of the counterbore or the depth of countersink. (It does include the normal chamfer on hex nuts.) Type 1 is based on NASM21 042 and NAS1 291 ; Type 2 on NASM21 044.
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