Shopping for Drill Bits
Choose the right one for easy drilling through wood, metal or synthetics.
Synopsis: A survey of the many types of drill bits designed to bore through wood, metal, and synthetic materials. It’s a good look at what’s on the market, with an annotated list of suppliers.
The latest catalog from the Precision Twist Drill Company is like a souvenir from the Rust Belt: It offers parabolic-flute twist drills for boring forged crankshafts, high-speed steel twist drills with 90° points that drill spike holes in railroad ties and even tapered drill bits that trim door sills on 747s.
Truth is, though, I’ve seen builders drill bits that are just as exotic. There are bits that drill carbon steel and stainless steel, fir and Formica, glass and Plexiglas, plaster and lath. There are wood boring bits that cut through nails and others that bore through walls and allow you to pull electrical wires back through.
With the right drill bit and motor, virtually any building material can be drilled fast. In this article, I’ll describe most of the professional-grade drill bits that might be useful on a job site (except for masonry bits and one-of-a-kind specialty bits, which we’ll save for future articles) and tell what features to look for when selecting a bit for a particular drilling task.
Twist drills: Metallurgy and tip geometry dictate performance
A typical twist drill is a metal shaft with at least one spiral flute. There are many variations, but your local hardware store probably stocks most of the twist drills that home builders need for residential work. Twist drills generally are designed for boring metal, wood or plastic. But for best results in a particular material, you’ll need to consider the type of steel used for the drill bit, special bit coatings and the shape of the point, not to mention the diameter…