Trouble Unfolding Building Corner For CNC Cut

I am trying to create a panel to route/cut on a CNC router that will fold onto a building corner with an odd shape.

I have the final shape of the panel as it will look on the wall drawn up in SketchUp. Now, I am trying to use either Eneroth or Unwrap and Flatten extensions to achieve the 2D panel.

It seems no matter how I try and do it, the result breaks the seams in the middle of the shape or does not completely flatten the object. I think my approach to this may be off, as I don’t understand how the shape is supposed to unfold without an changing the proportions anyways, so perhaps I have drawn this wrong.

Perhaps the shape I have drawn is incorrect in some way, so I have uploaded it here. If that is not the case, how can I manipulate the extension so that it flattens in the way I expect it? Or, if I have to do it manually, how would I go about doing that.

To be clear, this shape is to be made with one panel with NO visible seams in the middle section; that is where the fold needs to be. Rather, my understanding is that the edges might change to look “less straight/square” so that when it folds up it is straight.

I will be happy to clarify any information needed; I am aware my explanation of the problem may not be the most clear. I am serving as a middle man to ask this question; please bare with me.

dansh1.dae (331.6 KB)

dansh1. -9865868- -true-.skp (149.8 KB)

You didn’t upload the model!

I know; unfortunately, the site will not let you edit your post after submission until submission approval. Had I known that, I would’ve attached it first. Oh well. I have uploaded it now.

no, it’s just that you’re new. read a few topics, post a few messages, you’ll unlock the full toolset.

standard forum etiquette :wink:

edit : do you have a skp file by any chance ? it’s always better than the dae.

ok, you see the dark blue face inside ? it’s inverted. right click on it and reverse it.
Unwrap / flatten works fine, see picture, BUT it requires all the faces to have the same orientation. either all recto outside or inside, but the same.

in your case, you have a face different. you can see it on the inside, two white one bluegrey.
invert the blue grey and you’re good to go.

you could also group each face separately (double click on a face then group. and then treat them manually.

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Thanks for the quick reply.

OK. That is hugely helpful! I was wondering why some of the faces seemed backwards when painting!

Now regarding the fold, if I also do not want a seam on the two smaller lines, is it possible with the shape as drawn? If not, is it possible to draw a shape that will fold up to the desired shape without breaking any of those 3 center lines?

I’m adding the requested file type now.

A 3D shape that is not planar to start generally can not be unfolded and flattened onto a plane without needing some gaps or distorting of the original shape.

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So how can I unfold it in a way that distorts the outside edges instead of changing the center lines? Or do I need to do it manually? And if so, what’s the best way to approach that?

I don’t understand your goal. First of all, a CNC normally cuts individual flat pieces that you assemble in 3D. Second, you can distort the sections so they will lay flat and abut each other (at least in this simple example), but the result won’t fold up into a 3D shape! The topologies of a plane and a 3D shape are different.


You can’t.
Try it with a piece of paper.
Geometry is geometry no matter what software you use.

Depending on how you are going to make this there are different ways to think about drawing it ie - if this was going to be a copper cap I might consider in 2 parts with tabs and then soldered… same if it was steel. But there isn’t a way to unfold it in one piece.


As @slbaumgartner and @bmike wrote, you’re going to have to have a gap somewhere in the shape if you flatten it.

What is the object to be made from? Have you made allowance in your model for the bends? There’s a “K-factor” that you need to include for bending materials like metal. That will affect the shape that needs to be cut from the flat stock.


I appreciate you guys bearing with me. I did have a feeling that this shape wouldn’t fold down even based on how it “looks” but, as this is what was requested, I had to rule out my own lack of understanding before approaching any changes to the shape.

I spoke with the architect and we are going to be able to add a small seam. After adding the seam manually it will fold fine. That being said, the information about face flipping, K-factors, and ideas for a seam were all helpful is building my understanding of this type of problem. It is greatly appreciated! Thank you guys for what you do!