Exporting to use with CNC

Hi there,
I’ve designed a curved range hood where the curved sides meet in a miter.
In this thread there is a great discussion of how the angle changes down the piece and why I cannot just lay the pieces out flat and make a 45 degree cut: Measure miter angle for curved hood - SketchUp for Web / SketchUp Free - SketchUp Community

I have found a guy that can possibly help me cut out the pieces on a CNC.
The problem is that he cannot use the .skp files for that.

I’ve done quite a dead of googling and also searching this forum, and a lot of people suggest to export to dxf and then use that for the CNC.

However, in my case a 2D representation of the pieces would not be sufficient, because then you cannot see the miter on the curved pieces, and that is the whole point in why I would need this piece done on a CNC.

What format should I export to in order to be able to see the miter and generate a file that I can use for further processing on the way to the CNC (I guess I would need some kind of file that the CNC guy can use to feed into a CAD program to generate G-code for the CNC)?

2.skp (291.1 KB)

You need to discuss with the guy what file format his CAD supports. Usually it is dxf, dwg, stl and maybe other…

He told me .step, but I guess you can create that from a CAD program. I can output a dxf, but that is 2d and does not show the miter.

No idea what your CNC person is using but VCarve Desktop will accept .skp files. I have VCarve Desktop 11.504

FWIW: If your CNC person has a 3-axis machine, they’re going to have the same issues with the compound miter (“rolling chamfer”), machining as a flat panel, as was stated in the other thread. Cutting it as a 3-d “relief” would be one way to accomplish this on a 3-axis machine. Good luck.

Thanks to you both for the answers!

Fxcutting, could you elaborate what you mean?

I guess the question is how to get a 3d file that can be used to create the cnc code off so that the rolling bevel dimension will also be included.

What exactly is material and process here? This is to be cut on a CNC router in wood (what kind) as flat panels then bent into this position?

SketchUp is a surface modeler and represents curves as facets. It can with some care be made to output true curves in a 2D file that can be converted into a CAM file for all kinds of 2D manufacture (CNC router, laser, plasma, waterjet). However, there is no path way to export 3D data in true curves that can be used in 3 axis manufacture. You could export 3D data and get it into a format your CNC operator can accept, but it will contain facets and be unlikely to be satisfactory when assembled.

Thanks for the reply!

It should be cut out of 15 mm plywood sheets laying flat. Then when cut, I will kerf cut the back of the pieces so that I can bend them into the curve.

Is what you are saying that it is only possible to output 2D pieces representations from models made i sketchup?

And that even though it shows as curves it will not be ‘good enough’ to cut on a cnc?

I managed to ‘flatten’ the pieces by just taking the face of them and using a plugin to lay them down flat. I could then create a 2D dxf from the file, but then the problem is that the rolling bevel is not shown because it is 2D and not 3D.

Don’t know if it will work, but OpenCutList 6.0 has different exporting features for different file formats!

You need to “un-roll” the 3-D part (it still has volume) export that panel (a trapezoid with beveled edges) as a 3-D model. Your CNC person needs to have CAD/CAM software, like Vectric’s V-Carve Pro or Aspire, that can generate toolpaths for a 3-D model. Or they need to be able to write the G-code themselves. This is not, as has been stated, a simple 2-d cut.
UnrolledHoodCoverCenter.skp (42.3 KB)
I think the method that @DaveR described:
“You could also make a fixture to hold the parts with a guide for a hand saw.”
is quite possibly the simplest and least expensive way to make the hood, unless you plan to make multiples. Good Luck.