A flat screwdriver can be used with a machine screw.
A machine screw, sometimes also known as a machine screw, is a screw that is usually designed to be fixed into an existing threaded hole in a metal surface, usually in conjunction with a corresponding nut. These types of screws are not as large as the average screw, typically ranging in size up to three-quarters of an inch (19.05mm), but can be larger still. Variations among machine screws exist primarily in overall size, head shape, slot type, length, material, and thread characteristics.
One of the main ways to categorize a machine screw is by the type of slot in the head, which will determine what type of driver should go into its hole. The two main types of screwdrivers used with machine screws are flathead screwdrivers and Phillips screwdrivers, but there are several other smaller types of screwdriver holes, such as Torx (six-point star holes), that require more specialized slotted keys. Specialized types of screw holes can be important when you want screws out of the way for security reasons, as specialized types of screwdrivers are more difficult to acquire. A hazardous electrical panel, for example, is a good place for a machine screw with a specific type of hole. Other machine screw heads may be similar to a hex or square head screw that does not have a screwdriver slot and must be turned with a wrench.
The shape of the head of a machine screw will determine how it will look once it is set in a hole. Round and flat heads will protrude from a flat surface once attached. Flat head screws are designed for holes drilled so that they are flush with the surface when screwed in. The head of a set screw is smaller than the diameter of the screw threads, so when set, it can be inserted through a hole and set to the desired depth.
More of the main differences between machine screws are in the characteristics of the thread. This part of any machine screw is one of the most important, because the corresponding holes they attach to will typically be tapped to fit only a specific size and type of screw thread. The system used to characterize different threads generally follows ISO (International Organization for Standardization) standards, which were established to maintain uniform design specifications on machine parts produced throughout the world. Two of the main characteristics of the thread are the diameter and the pitch, the latter being the distance between the threads. These threads can also be screwed in clockwise (right handed) or counterclockwise (left handed).
While the size of a machine screw is usually relatively small, there can still be a wide variation between size, shape, and length, primarily determined by their intended purpose and how strong they need to be. Custom screws can also be made for specific machines that don’t even need to follow ISO standards. Machine screws can be made from a variety of metals or plastics.