I posted this thread on another site and thought it may be useful here when trying to make a panel with a 90 degree edge on a panel that has an odd shape or has an interruption in of a straight line. This is used when the panel your bending can't be done in a brake or in a vise with a piece of angle iron.
This piece you can see the lines I drew the make the offset needed.
Now this can be done with a blunt ground chisel, but I made a tipping die years ago out of aluminum and the bottom die out of UHMW ( ultra high malecular weight ) plastic.
I'm going to pass the metal threw following the line I drew with some mild pressure.
The first pass makes a light scribe line and a mild stretch along the line.
The second pass I will apply a bit more pressure, causing a deeper line with more stretch.
Now when I pass it threw I will put a bit more pressure and pull up on the outside edge, which will start to guide the metal towards a 90 degree edge.
Now the next pass I will use more up pressure till I reach my 90 degree. Now is when you will start to see some distortion, that I will later correct.
Now I have to straighten out the edge and get rid of some of the distortion from some of the extra metal that gathered on the edge.
Here you can see the edge isn't really crisp.
Now that I have the edges nice and crisp I now have a wave from the extra metal gather from the tipping process.
To relieve that stress I will hammer the edge down.
That was a quick fix however now the extra metal has gathered on the tipped edge that you can see right in the area where my line is drawn.
What needs to be done here is the edge or flange needs to be shrunk. Now that's difficult where the extra metal is right on the point. I will shrink on ether side of my line which will relieve the stress. Then I will very lightly shrink the area the whole length of the tipped edge and the panel will lay perfectly flat.
And there ya have it, the panel is in line and will mate nicely to the rest of the panel it will be welded to.