# How to give upper and lower limits to the radius of any curve before designing it?

I have requirement to make a free-form model with radius more than 1000 mm. How can i give a compand to the Rhino from the beginnig so that my free form design has curves with radius more than 1000 mm.

Well there’s no function to do that, it’s not really a thing you could do since the radius(and location!) of a freeform curve at some given point depends on more than the next point you pick, each point influences a region of the curve multiple points ahead and back, so trying to automatically limit things ahead of time is ridiculous. There are tools for finding areas of the model that are too tight.

The obvious question is, why? Is this some academic exercise?

Thanks alot for the reply Jim.

Its not an academic exercise but a way to reduce the manufacturing complexity. The radius of freeform is governed by its manufacturability and that is why it is important to have this kind of constrains. Is there any Plugin where I can code this feature?

Manufacturing how? Are we talking about compound curvature or developable shapes? There are analysis tools for finding areas of too-small curvature. As I explained, trying to restrict this as-you-work is basically impossible, where you pick point D influences what the curve is doing around points A, B, C, D, E, F, and G…

Hi Jim,
The shapes are developable as well as the compound curvatures. Although the limitation of tooling constrains the minimum achievable radius. You are right! changing the location of control point D will affect the curves around all the adjacent control points. I am looking for a solution (or rhino script) where the movement of control point is restricted based on the curve radius pertaining to it. But it seems that its not possible!

What sort of tooling has a constraint where you’re trying to keep the radii over 1m, except bending extremely large steel sections…or wood?..where the problem isn’t just the radii, it’s the “freeform” part? What’s the goal here?

No it’s not something you can constrain, how is that possibly supposed to work? And not be incredibly irritating? You can point-edit surfaces with CurvatureAnalysis on and see the results.