![美标ASME B18.6.3 (T29) - 2013 ASME18.6.3 1 Plain (Unslotted) and Slotted Regular and Large Hex Head Screws [Table 29] (ASTM F837, F468)](http://img.globalfastener.com/upload/48/pic/2024/03/14/1710396827146474173.jpg)
![美标ASME B18.6.3 (T29) - 2013 ASME18.6.3 1 Plain (Unslotted) and Slotted Regular and Large Hex Head Screws [Table 29] (ASTM F837, F468)](http://img.globalfastener.com/upload/48/pic/2023/08/21/1692577377381696899.jpg)
![美标ASME B18.6.3 (T29) - 2013 ASME18.6.3 1 Plain (Unslotted) and Slotted Regular and Large Hex Head Screws [Table 29] (ASTM F837, F468)](http://img.globalfastener.com/upload/48/pic/2020/08/04/1596508387830655007.jpg)
| ②,A slight rounding of all edges and corners of the heax surface of indented hex heads shall be permissible, provided the diameter of the bearing circle is equal to no less than 90% of the specified minimum width-across-flat dimension. ③,Unless otherwise specified by purchaser, hex head machine screws are not slotted. ④,7#,14#, 20#, 24# are for tapping screws only. ⑤,Unless otherwise specified by the purchaser, rgular hex heads shall be funished, and both regular and large head styles may be intented head, trimmed head, or fully upset head construction, at the option of the manufacture. ⑥,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. ⑦,The diameter of body on machine screws having other than trim heads shall not be less than the Class 2A thread minimum pitch diameter nor greater than the basic major diameter of the thread. ⑧,Slot depth beyond the bottom of the indentation on indented heads shall not be less than one-third of the minmum slot depth specified. |
