Trim curves inside closed curve in order to prepare for lasercutting

Hi guys! First time posting in the forum. I really like the friendly atmosphere here and the helpful answers.

I’m making 3D models and than flatten them out on paper. Recently people started to ask me to prepare my models for them to lasercut them (usually 1.2mm sheet metal). So far I’ve done it manually with the help of simple macros. I’ve always wanted to automate it using Grasshopper, but can’t figure out how to trim curves inside closed curve. Let me visually explain what I mean:

Here is a sample model:

and here is one of the parts laid flat - A (before the preparation) and B (done with the requirements from the workshop):

Pretty much I do a lot of manual work. Here is my process … which I’m not proud of:

And here is a test file with one of the model parts:

Test FIle.3dm (81.2 KB)

Read the forum rules, tried to find a solution in other topics, did a lot of tries in Grasshopper and always end up with partial solution.

Any ideas how to automate this process?

this might work for the purpose of generating the final curves starting from the ones you provided
this is more of a prototype thing, it might be simplified a lot :slight_smile:

in particular, you need to:
-set contour curves
-set red curves
-set blue curves

then you can selectAll -> hide everything on Rhino and Bake these on their layers:

these slider controls the following:

I think the most useful and time-saving thing in this case might be to pick a few mesh/surface faces directly on the 3D model, have GH unroll them, and also apply something a definition like this to get the final cutting lines… you’ll tell how it goes :slight_smile: (19.9 KB)


Yesterday I wrote my question just before I went to bed. Now, 7 hours later, I’m checking the forum just to see if there is any answers and there is your answer! Amazing! Thank you very much for taking your time to try the solution and document it well. I’m following the nodes and trying to learn those that you have used in order to understand it completely.

About the process of flattening the faces based on selection over the mesh - I take some time picking the correct faces. Imagining how the cut piece would look and would it be easy to handle it while bending it and welding it afterwards. Currently I’m using other software for that and just import the DXF into Rhino afterwards. All seams are made there.

Thank you @inno!

1 Like