Unroll gives unexpected output

Hey everybody!

I am working on something were I want to get the unrolled surfaces from tubes that together form a circle. I just discovered this:

The unrolled surface is actually less long than it should. I start with a 50mm radius tube with mitre ends that I want to unroll. If this is done correctly it should end with an length of 314.159. BUT when I unroll this and measure this length I only get 308.838…

Does anybody has a clue of what’s going on? I am going nuts :frowning:

File attached

HELP.gh (74.8 KB)

Just pipe your 12 sided curve.

Try extracting an isocurve from the midpoint on one of the sections of the loft you created, or project a curve on the surface, I get a curve length of 308.830.

Pipe the curve and do the same, I get 314.159.