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| ①,Edge of head may be rounded or flat. ②,Screws of these lengths and shorter shall have undercut heads. ③,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. ④,Machine Screw Material: 1) Non-heat-treated low carbon steel, such as1006 through 1038; 2) When hardened machine screw are specified, they shall be made from low or medium carbon steel, such as 1018 through 1038, with or without boron, through-hardened to Rockwell C25-38. |
![82° Cross Recessed Countersunk Head Screws [Table 2] (ASTM F837, F468)](https://imgcc.164580.com/upload/48/pic/2023/12/07/1701929142643948965.jpg)
