Self Tapping Screw or Bolt?

 Even pros are befuddled at times on which fastener is the ideal screw for the job!  I suggest, when you are putting screws in to wood, then they have to be wood screws right? Well, possibly.......but do all of you realize that if a screw is entirely threaded and does not have a substantial shank beneath the head, then you are going to be looking under the wrong category for your screw. Frequently a customer will call out for a lag screw when, in fact, he is wanting a self tapping  Hex Washer Head Sheet Metal Type A  screw.  Here is just a little basic facts to get you started.

 What do you get and why? Screws can be divided into types and after that descriptive features. Simply because the term, 'screw', is so general it can be quite confusing when looking for what you need for any given project. Various sorts of screws have been designed for fastening various kinds of materials together. Some common names are wood screws, self tapping sheet metal screws, drywall screws, self tapping deck screws and masonry screws. Typically, it is a specialized thread that makes the big difference or it could be the color. There are confusing names like 'machine screw' which is actually a bolt but, because it has screw threads on it, it can be known as a screw. Then there are Lag bolts which are really very big wood screws but possess a hex head for driving the screw in and so people have started calling them bolts. Frequently, local names differ but if you ask for a fastener by name of material first, it'll at least get you started. Screws normally refer to threaded cylinders with a point.  

 Bolts are threaded cylinders with a blunt end and take a nut. Who understood there was so much to self tapping screws and bolts?