①,Machine Screw Length of Thread: 1) Sizes No.5 and smaller. Screws of nominal lengths equal to three diameters and shorter shall have full-form threads extending to within one pitch (thread) of the bearing surface of the head, or closer, if practicable. Nominal lengths greater than three diameters, up to and including 1-1/8 in., shall have full-form threads extending to within two pitches (threads) of the bearing surface of the head, or closer, if practicable. Screws of longer nominal lengths shall, unless otherwise specified, have a minimum length of full-form thread of 1 in. 2) Sizes No.6 and smaller. Screws of nominal lengths equal to three diameters and shorter shall have full-form threads extending to within one pitch (thread) of the bearing surface of the head, or closer, if practicable. Nominal lengths greater than three diameters, up to and including 2 in., shall have full-form threads extending to within two pitches (threads) of the bearing surface of the head, or closer, if practicable. Screws of longer nominal lengths shall have a minimum length of full-form thread of 1.5 in. unless otherwise specified.
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