Interested in CNC routing but clueless about tooling? Can’t tell an end mill from a drill bit? Here’s an overview of end mill anatomy, some basic cutter types, and tips on how to choose the correct tooling for basic wood or plastic jobs.
CNC machining is a subtractive process that uses rotational cutting tools called “end mills” to remove material. An end mill, while similar in appearance to a drill bit, is far more versatile. However, in practice the terms “bit” and “end mill” are often used interchangeably.
Here’s the key difference. Drill bits are designed to plunge directly into material, cutting axially and creating cylindrical holes. End mills are typically used for horizontal carving and cut laterally. Additionally, most mills are “center-cutting”, meaning they are able to cut both axially and laterally. This is due to cutting flutes that extend to the end face and enable plunge cutting. To minimize tool breakage and stress on the material being cut, most CNC software will “ramp” the end mill slowly into lateral cuts.