Location of bend line on sheet metal flat layout?

[gomerpyle]

For a flat layout sheet metal part, is the bend line located directly in the middle of the bend allowance section, or is it inset from one side by a distance of the bend radius? So for a U-channel with an opening of approx. 4.56" (distance between inside of legs), would the distance between the bend lines on the flat pattern be 4.56? This is assuming an inside bend radius equal to mat'l thickness (.188).

 

[Baluncore]

It will depend on the type of bending machine. The line would be offset for a pan-brake, but centred for a press-brake.
Assume the neutral axis is in the middle of the sheet and that extension = compression either side.
You must allow for the arc length of the bend.
https://en.wikipedia.org/wiki/Bending_(metalworking)#Calculations
https://en.wikipedia.org/wiki/Press_brake
https://en.wikipedia.org/wiki/Brake_(sheet_metal_bending)