Trying to flatten a polysurface

template
polysurface
flatten
unroll

#1

I have a closed polysurface that I’d like to flatten so I can create a template and then cut the part in the workshop.

I have tried the unroll command but I’m not getting the result I’m after. I’ve played around with Smash and Squish too with no luck.

Should I be using another command?

Crest Rail Unroll.3dm (10.5 MB)


(David Cockey) #2

Disclaimer - my experience is with Rhino for Windows so some of my suggestions may not be valid for Rhino for Mac.

Your rail is a closed polysurface with 2000 surfaces My guess is your imported or created a mesh, and then used MeshToNurb to create a polysurface from the mesh. That is usually not a good way to obtain a polysurface for future work.

A shape like this won’t “flatten” without distortion due to the compound curvature.

The end caps will probably cause problems with any attempts to flatten, etc.

Several ways to proceed.

a) Go back to the mesh, remove the end caps and try Squish. No idea what you might get.

b) Rebuild as much simpler surface or polysurface. You should be able to get a good surface using Sweep1 or Sweep2 with a few cross sections and one or two rail curves. Then try using Squish or Smash on that surface. Depending on how the part will be made you may need to split the surface into a top and bottom or a front and back.


#3

Thanks David.

I rebuilt it as you suggested and tried Squish and Squash and ended up with the following:

Are there particular settings I should be trying?

Crest Rail Simpler.3dm (3.7 MB)


(David Cockey) #4

Let’s go back to what you are trying to accomplish. In your first post you said[quote=“jeremyp, post:1, topic:42573”]
I have a closed polysurface that I’d like to flatten so I can create a template and then cut the part in the workshop.
[/quote]
How will you make the part - from a thin sheet? Or will it be milled from a solid? Or somehow else? What does the template need to represent?


#5

In the end I created another surface using EdgeSrf and unrolled that. Worked well. Rebuilding it was definitely the way to go. Thank you.