From FreeCAD Documentation
- When selecting edges on the model, you have the option to select by edge or by face. Selecting by face will select all bordering edges of that face.
- Constant length chamfer or variable length chamfer.
- A constant length chamfer will create a chamfer with edges equidistant to the original edge at the distance specified.
- A variable length chamfer will have edges that may be set to different distances from the original edge, allowing you to create a chamfer at a variable angle.