Involute gear cutters are a great option when you're looking to make a small number of gears or a replacement gear for one that's broken. Gear cutters work great in mills, and often times allow you to expand the capabilities of machines you already own.

To use an involute gear cutter effectively, you need to know the pitch (or module), pressure angle, and number of teeth of the gear you're trying to make. The cutter will be specific to the pitch and pressure angle, so they need to match exactly. Each gear cutter is also only suitable for cutting a range of tooth counts, and it takes eight different cutters to make every gear from 12 teeth to a rack ("infinite" teeth).

The numbering system is reversed between diametral pitch and module, so we recommend checking out our involute gear cutter chart to make sure your cutter will mill the gear you need.

While you need the right gear cutter to cut the gear you want, it's just as important to be able to hold onto the cutter. A typical gear cutter has a circular bore through its center, with a keyway. This lets the cutter run on a standard arbor in the spindle of your machine.

The other, typically less important, dimensions are the width and outer diameter (sometimes called "cutter diameter"). While literature provides a good reference, we recommend measuring these directly on the cutter you're looking to use to ensure the best quality gear.