Tabs for folded aluminum model

[Andrew_Bako]

Hi there,

I am working on a model which will be fabricated using 1/8” lasercut aluminum. I need to develop a GH script which will produce tabs to connect the individual surfaces, to allow them to be riveted together with ¼” rivets.

See attached a small portion of the model. I have looked through various grasshopper plugins, but sadly haven’t found anything yet which will allow me to automate this easily. Keep in mind, this is a small portion of a much larger model with roughly ~200 of these units.
221204 - folded tabs.3dm (11.7 MB)

Any help would be greatly appreciated!

[jeremy5 (Jeremy)]

Do the tabs have to be drawn bent to their final positions or in the planes of the pieces for cutting?

[Andrew_Bako]

They have to be modelled into their final positions to show the connection with the adjacent face, in order to model the rivet holes - i did a quick mockup in the attached file

[laurent_delrieu]

Hello
I did some complex shape generation in Grasshopper with some folding tabs.

PatDef low table

Low Table PatDef

Here some pictures of my last project. [IMG_6302_min] [IMG_6296_min] [IMG_6312_min] There will be 9 suction cups to maintian the 800 mm glass [render] The table is done with 235 (62 + 65 + 4*2) laser cutted 1 mm thick aluminium pieces. 65 pieces where painted in black. Non painted piece were engraved. The were cutted by “Le metalist” https://www.lemetalist.fr. Junction pieces were doubled to augment the rigidity. All pieces are hold together by 1981 (1945 + 36) 3.2 mm aluminium alumini…

I don’t think you will find a plugin that do what you want.
You must develop you own tool that iterate over the shapes and generate the tabs. It is good you use your planar shapes as reference but as you have some angles that will make interference you will have to deal with that.
Each object will contain the initial shape
some cutters in order to allow that there will be no interference with overs pieces
Some added pieces (the tabs)
The connectivity (if you want to engrave or mark it)
…

[laurent_delrieu]

What I understand is that you want a tab at each link represented by a line. If it is that and if all faces have a good orientation. This is doable by code. I code in C# so if you need a service I could help you on this project.

[jeremy5 (Jeremy)]

@Andrew_Bako

show the connection with the adjacent face

Andrew,

It seems to me that you will need a z-bend for each tab: a bend backwards to offset it behind the adjacent piece, then a forward bend to bring it into line with the back of that piece. That’s not going to be easy to do tidily in 1/8" ally. Would you consider a separate bracket requiring a single fold to lie on the back of both pieces instead? Downside being the need for twice as many rivets of course, but much easier to produce.

Regards
Jeremy

[Andrew_Bako]

Hi Jeremy, Laurent,

Thank you for your help so far! Jeremy, are you sure that a Z-bend is necessary? Would it not be possible to machine bend the tabs according to a specified angle? The intent for the tabs and rivet holes is shown in the attached photo. Essentially the orange piece would be below the blue ones. The big issue I am having is being able to sort the faces nicely so that I can easily add tabs to the “orange” faces only.

Is there a way to cull faces based on adjacency? Thank you

-Andy

[laurent_delrieu]

Hello
sorting which piece uses tab and the other rivets is easy using topology an ncolor tool

Four Color Theorem in Grasshopper

Here a new version of n Color of faces with non similar color for adjacent faces. I add some improvements. And it seems to give good agreement for most of the uses. it no more uses SandBox. So the script needs : Face-Face topology so it could be brep topology or mesh topology or whatever… Seed : a seed that is useful to change the patterns A number of color wanted (lowest possible =2), but with autonoumous mode the number of color will be augmented if no solutions found nextColorNotRandom, if…

I use one of my tool for the topology but there are some plugins topology.

Sandbox Topology

Here you see that this need just 2 colors so the answer is trivial. If the topology imply 3 colors it will lead to more complexity. Like for the cube

[jeremy5 (Jeremy)]

@Andrew_Bako

are you sure that a Z-bend is necessary?

Well, I was basing that on your example which appears to show the plates meeting at a common front (or back) edge. If you make them meet front to back then, yes, a tab on the rear one would just need a single bend. There might just possibly be an issue if you have plates at different angles connected to a common plate, but I imagine there would be enough flexibility in the material for it to accommodate the slight differences.

While we are talking about fabrication, a separate factor is ensuring that there is enough room to get the rivet tool into position (and bear in mind whatever difference between starting and set positions the tool parts have). You may need to model a clearance object to coincide with each rivet to identify any potential collisions with parts of the structure.

Depending on the layout of pieces, you might be forced to make the tab on the other part to the one you intended to.