In Dynamo 0.9, selecting an edge of a helix (on like a spiral stair) produces a measurable “curve”.
In Dynamo 1.3, selecting an edge of a helix produces a curve that cannot be measured using the length node. Instead it produces an error with the warning shown in the image and in the subject of this bug report.
The version that works is preferential. Being able to measure the length of the helix is important when trying to stretch out a stringer of a spiral stair for manufacture. I am trying to write a Dynamo that will import a spiral stair from Revit and “flatten” the stringers out so that in the early stage of manufacture of a custom spiral stair, the stringers can be scribed before they are bent. This will make it much easier to mark them for tread and riser attachment after the stringers are bent.
The process I envision right now includes measuring elements in the spiral stair and then creating a straight stairway with the same measurements that I can draw a section through to emulate the “flattened” stringer. I am hoping to use Dynamo to automate the process. If I can’t extract the length of the helix curve, I can’t move past the first step in my process (which is still a work in progress because different versions of Dynamo have different levels of functionality).
In short, please look at the curve length node functionality in Dynamo 1.3. It doesn’t seem to work like it used to.