These designs lead to more friction, and that is desirable in fastening although not when threads are made to allow for movement. Lead is the space together the screw's axis that is covered by a single entire rotation of your screw thread (360°). Pitch is the gap through the crest https://types-of-roof-tile12637.theideasblog.com/29843560/considerations-to-know-about-types-of-screw-heads-torx