Sheet Metal > Change length > Corner/Mitre > Mode: Mitre 
In the Mitre mode you can mitre cut flanges with or without lengthening. The flanges can be located in different Sheet Metal main parts.
- On each flange, select one edge of the front surface or, with a right-click, the longitudinal edges..
A preview will be displayed.
- Choose a joint.
By choosing the joint you determine either if the inner edge, flush 
is to be shortened or lengthened or if corners 
of composite panels are to be closed. For the Groove form you can choose the matching milling tool from the Composite panels, groove form catalogue.
- Activate the Lengthen
checkbox if you want non-overlapping flanges to be trimmed. - Click OK to apply the preview and close the dialogue window.
If you click Apply, the preview will also be applied, but the window will remain open.
With lengthening
(1) First front edge
(2) Second front edge
Without lengthening
Mitre cut between flanges of different sheets
(1) Composite panels before processing
(2) After procesing: Flanges with milling edges, milling edge zone linear
