Hi Morten, one thing to be aware of with arcs for a 3D curve is that each arc is going to be a planar curve, so if you string many of them together you will get a curve that has a kind of abrupt change in a certain sense where the arcs touch one another, rather than a continuous gradual change.

You might try using the Rebuild command on it to reconstruct a new smooth curve from points sampled on the original curve.

There isn't any icon for Rebuild, to run it you need to type it in (press Tab first, then type Rebuild and push Enter), or set it up on a keyboard shortcut.


You might have an easier job of this if you start with a straight cylindrical type helix and then use some of the deformation tools in Rhino to warp it into the final shape.

- Michael

Hi Morten, also if you can describe what you need with enough detail so an equation could be written for the position of each point on your curve, it would then be possible to write a script command that would make the curve for you by generating a bunch of points for a control point curve.

That's how this sine wave plugin was done:
http://moi3d.com/forum/messages.php?webtag=MOI&msg=1519.38

- Michael