Bend allowance is the amount of metal to be
added to the total layout. The most important
considerations when bending metal is the min.
bend radius. When bends are made smaller than
the required min. radius, metal will crack at
the outside heel of the bend. The minimum radius
of a bend is determined by the hardness and
thickness of the metal. There are four methods
for finding bend allowances. In the form below I
have used the empirical formula. It is the most
accurate because it takes into account the
shifting of the neutral line, slightly inward,
when the metal is bent. The following form must
be filled in with decimal equivalants.