When two pieces of trim meet at an inside corner, you could miter the joint, but most professional carpenters prefer to cope. An airtight coped joint is easier to produce: It doesn’t require the perfectly square corner that a mitered joint needs. A coped joint is also less likely to open up after a few seasons of expansion and contraction.
Although you need a miter saw for coping, the only specialty tools you need are a $10 coping saw and an assortment of blades. A 15-tooth coping-saw blade is the best all-around performer, especially for simple chair rails and baseboards. But you’ll want 18 teeth (or more) to negotiate the intricate cuts that crown molding requires.
When installing a new blade, make sure the teeth face forward (the same as a standard handsaw) and tighten the blade securely.