# Designing walls and roof for a laser cutter

Hi there

I’m building a house to be cut with a laser cutter. Is it better to build as a solid box (like with the rectangle tool then extrude a big solid box from it) or should I build my walls all 3mm thick (the ply thickness) with open space in the middle.

How do I build a roof for laser cutting? I know how to do it as a solid extruded thing like how the SU tutorials show and a lot of you-tube videos but I don’t know how that will go when I go to lay all of the pieces out to be cut.

Imagine you have a simple rectangle and you do a plain gable roof on top. Is the way I make the roof somewhat like the tutorials where it is a solid extruded thing or is there a way to say, draw a rectangle on top of a couple triangles at either end of the house that is 3mm thick just like it would be if I was making it in real life from actual craft (not real) materials? Also, if I was building this house from real craft materials, the roof would overhang 5mm or so and the soffite area will angle up towards the top of the wall it sits on but in SU, when I do a roof I get a flat soffite in that overhang area but again, I don’t know how to make that work in terms of making parts for laser cutting. Has anyone able to explain how to do a roof for laser cutting or have you seen anything written up online?

Amy

I am not sure either. As far as I am aware, laser cutters don’t cut at angles other than 90 ° from the material. If you need the angle on top of the wall, you would need to do it manually.

Make the parts out of individual ‘slabs’ [3mm thick].
Make them components with logical names - floor#1,… wall#1, wall#2,… roof#1,… etc.
Always make your edges/faces on Layer0.
Use sensibly named layers and assign them to the component-instances as appropriate - this is to control visibility - e.g. layer ‘roof’ can be switched off while you work on the inside walls…
This approach will separate their geometry and facilitate laying them out later on…
You can model them ‘in situ’, so they snap together/overhang as expected.
Because you make them in situ you will find the components’ axes [insertion points] would be confusing when laying out…
This is best controlled by remembering to change each component’s axes immediately after making it - select it and use the context-menu to ‘change axes’ - pick a logical corner and snap to its faces, so the blue axis is always in the 3mm thickness direction…
This way, later on you can then lay out the second instances the ‘flat’ slabs away from the main model - perhaps inside a group on its own layer that can be switched off - because the axes have been adjusted to a logical corner on part they should all lay flat.
You can use the Outliner to navigate to highlight or navigate to the relevant named parts.
Remember that editing one affects the other - so if you add a window ‘hole’ into wall#6 in the model, the laid-out matching ‘flat’ instance of wall#6 will get the same hole added.

With laser-cutting 3mm sheets you are pretty much limited to 90 degree cuts.
However, some post-cutting planing will give you beveled or angled corners…

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