Below are some examples of basic corner notches and the reason for using them.The first example is a corner to corner notch. This notch is where the inside corners of the material just touch each other. If you are welding the corners of the box then thistype of notch will give you 100% weld penetration producing a strong welded joint. There is also less interference with brake tooling which makes forming slightly easier.The next example (below) is a corner where one flange is flush to the outside and the other flange butts into it. This type of corner can be welded with very little or no filler rod (fused). This weld is not very strong. With no welding this type of corner has a nice appearance.
(Good weld penetration)(Easier to bend lessinterference)
(? = Flange - B.D. + mat. thk.)
One flange overlaps another flange after forming.
(Note how D2 lines up with the bottom bend deduction mold line.) D1 = Flange - B.D. + mat. thk. D2 = Flange - B.D