'Bend' in Two Planes -Distortion


I am trying to ‘bend’ an object that is composed of a poly-surface extrusion, surfaces, curves and a mesh to produce a domed surface/object. The bend needs to be in two planes, X & Y, 30" and 20" radius respectively. The first bending results in a straight and square periphery. However the second bending of the previously curved surface results in a distorted/curved edge.

  • Is there a wat to control the ‘bend’ command to produce all straight edges? and to size?
  • Are there secondary operation that would straighten the curved edge?
  • Is there a better approach the this situation? I’ve tried ‘Flow’ and ‘Project’ neither with better outcomes at my level of competency.

BoxTop-flat.3dm (13.8 MB)

Thanks for looking at this,


If you can afford to sacrifice some accuracy, Cage Edit might be useful in this case. See CageEdit | Rhino 3-D modeling

Perhaps after bending you could use the _Taper command.


Here’s another option…
I used Flow.
In the Right viewport, I trimmed your circle to make an arc from the circle center to the edge of your flat assembly. Then a straight line (for the Base line), on the flat bottom.

BoxTop-flat - FLOW.zip (13.0 MB)

Hi Thomas - see if this does the job - I made a target surface at radius 20 and 30 and used the attached ‘ProjectObjects’ plug-in at density 8 by 8, to smoosh it down onto the target. Note I had to move the objects up a little for the projection to work correctly.

Uploading: BoxTop-flat_maybe.zip…
ProjectObjects.zip (14.4 KB)
Unblock the plugin in Windows and drag and drop it onto Rhino to add the
ProjectObjects command.

@thomas_j_fabian Bend should work fine too, btw - set up the circle at 30 radius in the front view and Bend twice, with symmetrical=Yes. Set the ‘spine’ from the origin to the top of the short vertical (or radial, really) line


Hello John,

Thanks for the input, however that technique gives the same results as ‘Bend’ on the second operation. So unless I’ve overlooked a parameter setting or drawing technique, I’ll still be looking for a solution.

BTW: I’ve stripped a lot of stuff from the attached file to make it ‘uploadable’.


BoxTop-flat - FLOW-2.zip (13.1 MB)

Hello Pascal

Thank you for getting back to me. I did install ProjectObjects with the plug-in manager. Next I’ll learn to use it. I had tried a similar technique but had gotten stuck on creating the 40/60 radii surface. Any hints for that?

Also I have been using ‘Bend’ in the same fashion as you suggested. The trouble has occurred only after the second ‘bending’. The results have been giving distorted edges in the second bend plane.


Hello Tomas,

Thanks for your response. I’ve been looking into the Rhino command ‘wiki’ and will practice using Cage Edit. If nothing else I’ll have learned a new technique.


Hello KevR,

I looked into the Taper command on the Rhino help site. I’ll need to practice. It may work but I’m dealing with multiple object forms. We’ll see…



Hello Pascal,

The zip file you’ve sent will not download, maybe it didn’t upload properly or is too large.
Uploading: BoxTop-flat_maybe.zip…

Any chance of trying it again?


Hi Thomas - is this not it?

BoxTop-flat_Bend.zip (6.3 MB)


Hello Pascal !!

That one downloaded. The first one had some kind of a hiccup.

Would you be willing to share the technique for creating the 40/60 radii surface?

Thank you for your assistance,


Hello Pascal,

Sorry to be a PITA, but think the file BoxTop_Bend is not the file you intended to send. It did not contain the ProjectObjects technique…

I will go ahead and try this on my own, but any advice you might offer will be appreciated.


Hello Pascal !!

I did it !
Thanks so much for your input. With those hints I was able to figure out the rest.
And it looks good!