This is Correct, and an important bit of process to get right for the OPs workflow. Do NOT use FILE/EXPORT/2D GRAPHIC. When you are ready to send your tool-paths to be made into G-code for CNC, instead isolate just the edges of the object you want. Set the camera to parallel projection and set the camera position to top, directly overhead of your geometry. Then FILE>EXPORT>3D set output format to DXF. This will export a file with true arcs (not segmented) that a CNC router can use.
There are some further tricks to this process, but the takeaway is that it is possible. And as mentioned there are also extensions that can help.
SketchUp is a great tool that you can quickly learn to love. Welcome.
We use both SolidWorks and Sketchup side by side. Sketchup is our master model, SolidWorks ist for everything that has anything to do with “metal-construction”. We usually predesign in Sketchup so our SolidWorks guys know what we want, that makes the SW construction very quickly. The result is being reimported into Sketchup.
So - I kinda know both ways of thinking. What I love about SolidWorks is that I can pick any part or assembly and make detailed “layout-drawings” of them - complete with part-tables, materials, etc. Since you are used to that, Sketchup will make you cry every so often: “You are done - you can see your part - why is it so hard to get it on paper?!”
On the other hand - it is so much easier to actually design that initial assembly in Sketchup because you don’t have to manage so many files. You just add parts in one file as you go along.
Basically SolidWorks goes from small to large and Sketchup goes from large to small.
What might help your workflow is the Eneroth Reference-Manager. With that you can sort of simulate a Solid-Works-Like Workflow, because it helps you saving parts and sub-assemblies out into different files and it keeps it all connected. It’s quite a bargain for what it does.
Sketchup will never be anything close to SolidWorks however. Once you get close to production, you will need additional Tools - at least something like AutoCad LT to smooth out those crinkely curves…
SU is a 3D polygon modeler for fast 3D designs and presentations whereas SWX (or Inventor or Alibre) is a 3D NURBS solids/surface modeler w/ features, history, parametrics and model-to-sheet functionality for exact MCAD conctructions, there’s surely an intersection in purposes but they do not really compete each other.
@endlessfix I’m curious.I have an architectural background and therefore limited understanding of the process that @SolidBob is undertaking. However leaning on my 3D printing knowledge, I imagine that CNC routing is similar, except that2D components are cut and then need assembly thereafter. If my understanding is correct, then one would require a parallel projection of each surface in *.dxf. Question - is there a way of accurately obtaining a surfaces parallel projection that is not parallel to any of SketchUp axis? Possibly a related question would be - how does one maintain the same scale for each projection so that (after routing) everything will fit together correctly?
@Devine The aspect of the process I was describing to the OP has to do with outputting true circles and arcs from SketchUp for CNC routing (or plasma cutting or water jetting, any 2D machine application really). As I’m sure you know SketchUp is a surface modeler so everything is represented by straight edges and connected planes. Circles and arcs are approximated and represented by facets. Different uses of SketchUp deal with this fact in different ways. Those doing Arch Viz generally try to keep the poly count low and use soften/smooth to give the appearance of rounded edges. Many of us doing 3D printing increase the number of faces in a circle to beyond the printing fidelity of the printer, or at least beyond the ability of our eye to tell. But when dealing with 2D cutting there is another option available. When SketchUp makes a circle or arc it records the details of the circle/arc mathematically in the meta data about that object. So even if you have a circle represented by 12 sides as I do below, SketchUp still knows in the background that this is a “circle” with a given diameter. If you explode a circle or arc you remove that information. The workflow I was talking about for the OP is how to export a drawing with circles/arcs and use the underlying meta data to output actual circles and arc into a format capable of supporting them, .dxf or .dwg. This involves outputting a 2D camera angle on the lines only into the 3D format. As you can see this exports a true circle or arc to generate a tool path from.
You are essentially correct in your question about CNC router workflow, a bunch of “parallel projections of each surface” to be assembled thereafter. As @box says Align View will quickly square the camera with any face, however in practice it is rarely necessary to align the camera view. Once a design is ready each sheet is exported on its own, or in a batch, but not in the context of the finished assembly. Personally I have a component instance of each sheet lying flat in another area of the model so that as I am designing and making changes to the assembly the sheet designs are updating at the same time and are ready for export.
Exporting with the above method retains all dimension information as it is a CAD format, not just a screen shot. The zoom of the image in SketchUp at export is irrelevant as you are exporting the actual geometry, the tool paths are the correct size, ready to cut. This image is of some articulating train benches I designed last year, and an image of the accompanying file that gets sent to the CNC router.
This absolutely, utterly and completely blows my mind! EXPORTING TRUE ARCS? Since when does this work? OM-frickin-G! Thanks so much for pointing this out!!!
