Abstract: The invention refers to a corner trimming device for machining the joint of frames, respectively frame parts, welded from profile parts, where the corner trimming device can move at least in the direction vertically to the plane of the frame defined by the profile parts, as well as along the joint region. A machining tool is arranged on a holding device between two tracers, and each of the two tracers sits close, at least at times, to a profile part, at least at times the tracer can move versus the holding device.