Flat Head Machine Screw

A flat head machine screw is a threaded fastener with a countersunk head. It sits flush with the surface when tightened.

A flat head machine screw sits flush with the surface when fitted into a countersunk hole. It takes a nut or a tapped hole of the same thread.

This kind of screw is often made in brass, stainless steel 304 or stainless steel 316. Brass suits electrical and decorative work. Stainless steel 316 gives better corrosion resistance than 304.

This is a general guide to checking this kind of part. It says nothing about any supplier's parts.

Ask for a certificate of conformance with the material grade. On receipt, check the head angle and that the screw sits flush. Check the thread form and length against the drawing.