Well, with those radii, the arc lengths come out to be correct. Ideally, the lines connecting the arcs would be radii of those arcs, but I do not think that that is too important. What my purpose here is to make a helix out of a thin sheet of metal, that could be lifted and twisted a little to make the helical shape.
I do not really understand what you mean when you say "an arc length tool to constrain it". I can measure the arc length by using the Measure Loop tool, but I have no idea about
constraining it.
