End Mill Bit? ER Collets? What You Need to Know


Trying to learn about metalworking, woodworking, and machinery in general can be extremely intimidating. Without some kind of prior knowledge or somebody to help you, the terminology alone can be overwhelming. You might know the broad basics, like what a drill is, what drill bits are, what a clamp is, and so on, but someone mentions “end mill bit” or “ER collets” and everyone can practically see the sparks flying from your brain. Not only that, but it’s hard to do any research on these because people figure that if you’re looking it up, you already know what they are. Here’s a brief rundown of some of the tools that, while simple, aren’t as commonly known as a screwdriver or hammer.

  • ER Collets: A collet is a type of chuck, or clamp used for cylindrical tools. Collets form a sort of “collar” around objects, and clamp down on them when tightened. ER collets are one of, if not the, most widely used system for clamping in the world. ER collets are useful for a wide variety of machinery applications, such as boring, milling, and reaming. Previously, there had been an existing “E” collet that was taken and modified by the company Rego-Fix, who then re-dubbed it the “ER” collet after themselves.
  • End Mills: An end mill is a type of milling cutter. “Milling” doesn’t refer to actual mills (windmill, treadmill, watermill, etc.), but a machining process that cuts materials with the blade either positioned horizontally or vertically. What distinguishes an end mill to other milling machines or drills is its specialized bit. A standard drill bit can only cut in an axial direction, but an end mill bit can typically cut in any and all directions, though some are incapable of cutting axially. So, in layman’s terms, an end mill bit is kind of like the opposite of a regular drill bit.
  • Lathe: A lathe is a tool that allows the work piece to rotate on its axis. This allows you to do any number of things, like sanding, cutting, or drilling. They also vary drastically in size, with some being immense and belt-driven and others being tiny and used for watchmaking. There are several designs with different benefits. A Swiss-style lathe, for example, provides extreme accuracy when compared to other styles, and can sometimes even hold a tolerance of just a few micrometers.

If you’re looking into using or purchasing any sort of advanced (or, at least, less basic) machinery, be sure to ask around before making any purchases. The vast majority of manufacturing purchases are influenced by several people. A good rule of thumb is to ask at least three people before committing so that you know which tool would be best for the job you’re looking to do.

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