I am modeling structural PT tendons. The tendon must be located knowing exactly where the tangent point is, and the tendon must flow through that point. I have created an adaptive component which has multiple points connected by a spline through points and an extruded circle to create the tendon/cable. I intend to use a spreadsheet of x,y,z values to locate each point. When I do this the nurbscurve and extrusion do not necessarily flow through the points at tangents. What process can I use to do this?

Not a Dynamo solution per-se:

Try changing the Adaptive to have 3 points at each “point” rather than one point. Create an “upstream” and “downstream” point that are a (very) short distance away from the middle point (which is the actual control point) - then have dynamo detect all 3 points rather than the single point. The 3 point method will “force” a straight line segment into the nurbscurve which should essentially serve as a tangent for the curve.

Have a look at this blog: https://vasshaug.net/2013/02/27/post-tension-structures-in-revit/

and these families: https://vasshaug.net/content/

Thank you for the quick reply Ben! I am using a very similar adaptive component family as is used at the site you referenced, in fact that site was the first good reference for PT tendons I found.

My next step was to try the “3-point or more” approach but wanted to see if there was some simple solution. I also have been looking to deconstruct the nurbs curve to see if I could use math to locate control points so the tangent would be located correctly; I found some good references on bsplines from a Rhino reference but have not jumped of that cliff yet.

I will give the 3 point a shot. Thanks Ben