[TheForge] Precision Forging

[Bob Rackers]

I'm curious to hear how everyone calculates the amount of material (i.e.
length) required when the piece will have at least one bend.

I figure there are four types of bends, and each requires a different
calculation.

Assuming a 90 degree bend, you could have
 A. Radius inside the bend / Radius outside the bend
 B. Radius inside the bend / Square corner outside the bend
 C. Square corner outside the bend / Radius inside the bend
 D. Square corner inside / Square corner outside
 E. Long radius (many times the thickness of the material, e.g. a 10" radius
made from 1/2" rod)

Assume making something with the following shape and dimensions from 1/2"
square.
If the lengths of the horizontal portions (left to right) are respectively 3",
6", and 3", and the two verticals are both 2", (in other words, the portion
UNDER the middle horizontal line is 2")....
 1. What is the total length of the item (horizontal distance S to E)?
 2. For each of the above types of bends A - D (ignore E), how much material
length is required?
           ____________
S______|                 |______E

The straight portions are easy enough to add, but I'm curious how everyone
calculates the required bending allowances for the different types of bends.

Please show your work. :-)

Bob