When to use screws
After I wrote about nails a few months back, I received a couple of emails asking why I use nails instead of screws in furniture projects. The short answer is that I don’t; I use both. But if there’s no compelling reason to choose one over the other, I typically use nails simply because I prefer the way they look. (I’m talking cut nails or square-shanked nails, not wire nails.)
Before I discuss my “compelling reasons,” let’s take a brief look at the mechanical holding differences between the two: shear strength vs. grip strength. Shear strength is the amount of force a fastener can handle from the side. Because furniture nails can bend a little bit, they have superior shear strength to screws. Screws are more brittle and can break under shear forces (or more likely, split the top piece of wood on which they’re being used). Grip strength (or tensile strength) is the ability of a fastener to pull two pieces of wood together (or the amount of vertica