Hi all,
I am trying to deconstruct a box in grasshopper, to create geometry on a selection of its faces.
I am having a really hard time to accomplish this, which is very frustrating after using grasshopper for over a year. Even fairly basic manipulations still cost a lot of time to sort out, research online,…So far the venting of frustration part of this post 
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What I want to do is to create a tabbed structure (/finger joint) on a box. Preferably as curves (to later orient to a plane and export for laser cutting), with the posibility to create a 3D model for rendering. This takes 5 minutes in Freecad 
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This is where I got so far:
Box Tabbed.gh (13.1 KB)
why are these planes, while parellel, oriented differently? Why dothe edges of the respective rectangles have different indices? I assume it has something to do with the orientation of the faces?
This makes it so cumbersome to create geometry, having to manage exceptions by selecting or dispatching data…So time consuming and little robust.
There must be something fundamentally wrong with my reasoning on how to do these things in grasshopper (i.e create 3d geometry and apply transformations to its consituent parts), because I keep bumping into such problems.
Thanks!
Hi,
The way Grasshopper orders indices is not really robust, especially after a Join Curves operation.
I’d advise you to select/filter/sort your edges from rules earlier. Here are a few axamples : edges from directions, or longest edges.
When yo build rectangles, it’s also advised to always align the planes to a reference vector, to be sure of the orientation. Align Plane can be helpful.
Keep calm and good luck 
Box Tabbed.gh (21.5 KB)
Thanks!
That sure is a nice way to select the edges, but only works for a box, right? If I would have a non-primitive shape with faces not aligned to axes, this wouldn’t work.
Also, plane orientations are still not correct…
I found a solution in the meantime, by flipping the face in an earlier stage…see attachment.
Still feels like a fairly convoluted solution :s. Also, if I want to apply the same method to another face (oriented differently) I need to make all kinds of changes (horizontal frame instead of curve frame, other face need to be flipped, etc…and the boolean union creates double objects 
)
Box Tabbedv2.gh (26.5 KB)
Yes Edges From Directions only works for a straight box. If you need the edges that are “somehow” aligned with a vector, you can compute the dot product and sort the list.
Anyway I would do it that way, it’s more robust. The only thing that changes is Region Union or Difference.
Box Tabbedv2.gh (23.0 KB)
