mathematical figures are obtained. Remember, bend
Computing Bend Allowance
allowance is measured from the inside of the bend but
To compute bend allowance, you must know two
is computed along the neutral axis of the material being
primary facts: the radius of the bend and the degree of
used. Therefore, when calculating bend allowance, add
angle in the bend. Usually, this information can be
the bend radius to one-half of the thickness of the metal.
This will determine the radius of the neutral axis.
found on your blueprints or drawings.
Bend allowance is the product of the radius of the
As you study the following examples, refer to figure
neutral axis of the bend which is multiplied by the size
13-49 to help you understand where and how the
Figure 13-49.--Calculating bend allowance.