Some requests for sheet metal

[ekbeez]

Hello I love this extension and have some very specific feature requests. I designed and made this bear head from printer paper glued to thick card stock. It will be one of the projects I make out of thin sheet steel when I finish building my CNC plasma table. I am not familiar yet with the CAD/ CAM software I will be exporting to so some of these requests may turn out to be redundant.

• I am going to tack weld all the seams to be joined, so that means putting a small weld dot every half inch or so. The issue is that I want the seams to look somewhat consistent all around the sculpture. The island boundaries will be tack welded but the bends will be smooth. I'm wondering if there could be a way to further specify how the dotted lines appear on the bends, such as having very long dashes (cuts) with a connecting space every 'x' distance. In this way the bends will simulate the tack welds after being cut. (I will be tacking as opposed to fully welding the seams for speed/ consumable usage and to avoid introducing heat/ warpage into the thin metal)

• Another huge bonus for the custom perforations option is to allow easy bending by hand without aligning and using a metal bending brake or some other unnecessary jig.

• I was also thinking of an option for adding connecting tabs only at vertices, so that the actual edges would be trimmed back by 'x' distance, and they would become an interesting part of the piece, to possibly allow light to shine out as a lamp.

• As far as the see through edges/ lamp idea goes, it would be super cool to have a way to automatically draw/ cut some interesting incomplete border offsets within the faces so as to let more light out.

• Include material thickness in bend radius, not just glue tab placement like the tool tip suggests - this is not critical for thin sheet metal skins, but for someone using this extension for something functional using thicker metal it could be useful.

There are almost certainly other programs that can do these very specific things but I love Blender since learning it and it would be great to keep this part of the future workflow within. These features could be used for laser cutting or card stock models too.

[addam]

Hi, and thanks for trusting this addon for such an ambitious project. It feels like a tough stress test but I believe it can all be made to work.

• Custom dash pattern is not supported in the UI. You can choose out of several dash patterns but Long Dashes will perhaps still be far from enough. However, if you export to SVG (which I suppose you do anyway), you can edit the stroke-dasharray style to any pattern, specified in millimeters. Just open the .svg file in a plain text editor (Notepad) or a code editor (VS Code), edit the path.convex and path.concave style in the beginning of the file, and save it.
• I'm thinking about adding some more tab styles and the UI is already prepared so I could do this pretty quickly. What exactly do you mean by "tabs only at vertices", can you please provide a sketch?
  • (see add a tab and slot export option #95, Provide tab/space functionality for laser cutting plywood etc #38)
• Compensating for material thickness in all bending edges feels scary to me at this moment; it's been just a month since I implemented the prototype of handling thickness at seams and I'm still not entirely sure it works correctly.
  • That said, what I actually would need is real-world testing and measurements. I want to be sure that the compensations I apply are correct, or at least going in the right direction. It is well possible that the bent edges will work correctly even now, without any compensations.

[ekbeez]

Thanks for getting back to me. Good to know about the editable SVG dash array settings. I might be able to change the line/ cut styles in the CAM program as well, not sure yet.

I made a model in Sketchup to illustrate the concepts I am thinking about. The welding tabs at vertices, and the face border offsets. One version combines both. It is easy to do with all regular identical polygons, but adapting to different sizes and shapes of low poly facets is over my head, that's where you come in :)

I think there might be a native function in Blender to add border attributes, but I don't know about custom 2d profiles like I'm thinking. And then would they be unfolded correctly? Anyway these functions may be hard to implement or easy, all I know is I would use them.

Woops I accidentally clicked close issue and can't reopen, I'm typing on phone.

[addam]

If you had a way to create all these kinds of ornaments, they will unfold correctly. I just tried it with the icosahedron (Icosphere Holes.pdf) but I'm pretty sure it will work with difficult shapes as well.

It would feel the best if these face modifications could be generated by Geometry Nodes but I can't find the necessary node tools for this. How do you create these in Sketchup, is there an easy method?

[ekbeez]

Nice it unfolds with the cutouts! But how will it look on a low poly model with irregular faces? My idea is to have each face procedurally processed to calculate minimum tab widths and such especially for sharp acute angles.

Honestly I am very new to Blender and have not explored nodes at all. In Sketchup I had to manually create the shapes and used components, meaning editing one face will change all associated faces. But Sketchup is not great for mesh editing. And it would be difficult to apply the edits to a variety of shapes of faces.

The goal is to create a solid low poly model and then be able to apply edge/ offset 'modifiers'. I don't know how I would do this though.