Sheet metal screws have sharp cutting threads that cut into sheet metal, plastic or wood. They are sometimes notched (Type-17 Point) at the tip to aid in chip removal during thread cutting. The shanks are threaded up to the head or to the undercut. * These screws come in many types of heads, pan, flat, truss, oval, etc. Sheet metal screws make excellent fasteners for attaching metal hardware to wood because the fully threaded shank provides good retention in wood.