Help Working With Sheet Metal


I am new to rhino and need a little help understanding how to work with sheet metal. Almost everything I do is with made up of sheets of metal. The final product is 3d but they are made from 2d sheets of metal cnc cut on a plasma table.

In this example I have drawn an octagon which would be made up of 5 sheet metal, 2 end caps all of them 1/4" thick.

Here are the steps on how I created it

_cap (because I could not shell)

Something isnt quite right as rhino treats the “2nd wall” (from 1/4" _shell) separate from the original.
What commands should I research so that the inside and the outside are one plate instead of 2?

Thanks in advance for any help you can give me

sheatmetalhelp.3dm (99.1 KB)

Hi -

You have one single polysurface in that file. Perhaps the wireframe view is throwing you off but there are two end caps that are connecting the inner and outer surfaces.


Thank you for the reply.
So I am basically after 2 things

  1. UnrollSrf will give me 10 panels when I was expecting only 5. Not a problem in this simple example but becomes quite a pain in larger drawings.
  2. Lets say I wanted to move just 1 of the 5 panels, how could I move just 1 of the 5?

Hi -

With your object, you will get 12 surfaces when you use UnrollSrf.
There is no real concept of “solids” in Rhino, nor any specific tools for working with sheet metal.

You probably don’t want the 2 side caps when you are working with sheet metal.

There are a number of threads about working with sheet metal on this forum. The best tip might be to only create surfaces at the neutral axis of the material. Exactly where that neutral axis is situated depends on the material, the bend radius, and the process, and to get those right, usually, one would either use specialized software or have in-depth knowledge about these factors.
For an example of a thread where some of this is discussed, see:


I dont deal much with bends, all of my stuff is T joint welded so K factor in bends isnt an issue really for me.

I will keep playing with the drawing, I have only had rhino installed a few days and its the first cad program I have ever used. What is the best way to delete one of the 5 planes? Right now it is 1 solid object so delete will not work. How would you go about just removing 1 of the planes but keeping the other 4 exactly where they are?

How would you go about just removing 1 of the planes but keeping the other 4 exactly where they are?

Select your model and click on this icon image
or type _Explode in the command line.
This will separate your model in surfaces.

Or if you want a specific surface to be extracted, right click on the explode icon and select the surface you want to extract or type _ExtractSrf in the command line and select the surface you want to extract.

HI -

In addition to what @phos4 wrote, you can simply “sub-object select” a surface by holding Ctrl + Shift when you click on it and then delete it with the Delete key.


you are still thinking 5 physical plates here. Because of the way your object is constructed, it’s more involved than just deleting a single face. You’ll want to delete both the inner and outer face and then need to deal with the 2 end caps that are also part of all 4 other sides.

If you are not bending but actually cutting 5 plates, it might be better to model it that way too. Either make one box and use ArrayPolar to place 4 copies in a pentagon shape and then possibly add some “filler” geometry that will represent welding, or create a bevel on the edges to make them fit.

Ha, that’s nice!

Thanks both of you! For sure I have a lot to learn. I can barely draw anything and most of this is way over my head.

Its not that I am thinking that they are 5 objects as much as I need them to be 5 objects. The way I have drawn them is not good but my lack of knowledge has kept me from doing it the way I need it. I will research _Explode and _ArrayPolar and see if I can draw them ‘manually’

EDIT: Maybe the right way to draw this is with the line tool. (Draw the edge, duplicate the edge and then connect the edges together, then shell it to give me the thickness?

Hello - Are you looking for 2d shapes of the individual panels? If so, just make the solid and UnrollSrf the whole thing at once, no need to deal with the thickness at all unless you have miters to contend with (i.e. not 2d panels but 3d ones)