Machine Screw Types
Erjavec states that machine screws are similar to cap screws but have a flat point; machine screws can have a round, flat, Torx, oval or fillister head. “Do It Right The First Time” by Gene and Katie Hamilton says that when it comes with nuts, a machine screw is called a stove bolt. Machine screws can be torqued with a standard tip screwdriver
Standard Torque Specifications
Machine screw torque specifications vary based on the type of material from which they are manufactured. According to “Pocket Ref” by Thomas J. Glover, #2 yellow brass machine screws have a standard torque of 2 inch pounds while silicone bronze machine screws are to be torqued to 2.3 inch pounds. “Fasteners Handbooks” by Julius Soled states that the maximum safe working load for 3/16 inch machine bolts and screws is 300 pounds while 5/8 inch machine bolts and screws can withstand 3,700 pounds.
ASME Standard B18.6.3 provides the standard torque specifications for No. 0000, No. 000 and No. 00 machine screws. The American Society for Testing and Materials (ASTM) Standard F738M provides further guidance on recommended torque standards for different types of machine screws based on their size and material.