Avoiding corner breaks is another radius-related, cost-cutting measure. In an attempt to remove burrs and break sharp corners, designers will often smooth external part intersections with chamfers or corner radii. It's understandable, and sometimes quite necessary, but it can also be expensive. With stainless steel parts, Protolabs provides an automated deburring option, but all other materials are delivered as-machined. If the part design calls for an edge break, we have to call up an additional tool (a ball end mill) and machine these corners using a 3D profiling motion. We generally run these tools at very high rpm, and very small amounts of material are removed, but it's still a lengthy process to go back and forth until each corner is smooth. Many customers opt to save a few bucks by deburring these parts on their own with a file, some abrasive paper or a buffing wheel.