[Fold] Wrong calculation for length after bending

[eht8]

I think there is a bug in the calculation for the length after bending with the fold tool.

Steps to reproduce:

1. Create a flat plate of 100 x 100 x 1 mm
2. Create a sketch with a single line along the middle of the top surface of the plate
3. Use this sketch to bend the plate with the fold command; leave the properties of the fold at the default values (r = 1, k = 0.5)

The expected bend allowance is
BA = pi / 2 * (r + k * T),
where r denotes the inner radius of the bend (r = 1), k is the k-factor (k = 0.5) and T is the material thickness (T = 1), so

BA = pi / 2 * (1 + 0.5 * 1) =~ 2.3562 mm.

Subtracting this from the original plate length (100 mm) and dividing by 2 gives an expected length of each leg of 48.8 mm. However, the model has legs with a length of 48.5 mm. (Larger values for thickness and radius give larger errors.)

Another indication of a bug is the fact that when the folded model is flattened again with the unfold tool, the resulting plate is of a different length than the original plate.

[shaise]

Thanks for the report. You are probably right.
In any case, I highly not recommend using this method for creating a design, as it depends on metal (k factor) properties, and also you need to design the unfolded sheet in advance - very counter productive.
The correct way is to design with sketch tools and bends to get the correct final model, and use the k factor only for unfold.