Carbide Corner Round End Mills

A Corner Rounding End Mill is typically used to add a specific radius to a workpiece, or in a finishing operation to remove a sharp edge or burr. The pilot diameter determines the tool’s limitations. When pilot diameters are larger, the tool is able to be run at lower speeds. But with smaller pilot diameters, the tool can be run faster because of its larger effective cutter radius. Putting a full radius on a part has the potential to leave a step or an over-cut on a workpiece. This can happen if the tool isn’t completely dialed in or if there is minor runout or vibration. A slight 5° flare on the pilot and shoulder blends the radius smoothly on the workpiece and avoids leaving an over-cut. A flared Corner Rounding End Mill leaves an incomplete radius but allows for more forgiveness. The best corner rounding end mill varies from job-to-job. Generally speaking, opting for a tool with the largest pilot diameter possible is your best bet, as it has the most strength and requires less power due to its larger effective cutter diameter. A flared Corner Rounder is preferred for blending purposes if the workpiece is allowed to have an incomplete radius as this allows more forgiveness and can save on set up time. If not, however, an unflared Corner Rounder should be utilized.