Router bits can do so many things in a woodworking shop, and they’re avail­able in an assortment of general types. Straight bits are very common for cut­ting grooves, dadoes, rabbets and mortises. Flush trim bits have bearings and are used to copy shapes and flush surfaces to one another. Edge treatment bits usually have bearings, and add pro­files to the edges of workpieces. Joinery bits create joints. Decorative bits embel­lish surfaces. Specialty bits do so many tasks. Most bits today have long-lasting carbide cutters, while HSS cutters are much less common. Different-sized bear­ings are sometimes interchangeable to expand the bit’s function or the profile it leaves. Smaller bits have a 1/4″ diam­eter shank, while larger or stronger bits have 1/2″ shanks. A few bits are avail­able in 3/8″ or 8mm diameters for very specific purposes. Some router bits have cutters on their ends and sides so they can first plunge into the wood, then cut wood while being moved forward. Almost all bits can be re-sharpened. Purchasing a set of bits is often far more economi­cal, though if you don’t think you will use many of the bits in a set, it’s likely better to buy bits individually as needed.