Creating cut thread on internal, cylindrical surface

This is a fairly trivial thing to do, yet I cannot understand why Solidworks doesn't want to do this. It only wants to do an extruded thread. Also, the forum UI has changed significantly since the last time I visited, so I have no idea how to attach a part file within posts now. Whenever I tried uploading a "part file" or "document file", it gives me an error saying the file type is not supported.