This page will show you two different plugins that can be used to export STL files from Google Sketchup. Once exported, you may then open them in a CAM program for generating 3D G-code for your CNC machine. Two cheap examples of 3D capable CAM programs would be CamBam Plus and MeshCam.
Note that STL files are only necessary if you want to make a 3D part. For 2.5D, you can use the Sketchup to CamBam Plugin and the free version of CamBam.
STL files can, of course, be used for other things also, so even if you don’t know what a CNC machine is, this tutorial could still be useful to you.
When first installed, Google Sketchup isn’t capable of exporting STL files. There are, however, a couple of free plugins available to work around this. The most popular of these seems to be the Su2stl.rb plug-in. It can be found at http://www.crai.archi.fr/RubyLibraryDepot/Ruby/em_fil_page.htm
Update: The link has changed to http://rhin.crai.archi.fr/rld/plugins_list_cat.php?cat=8 or, more directly, you can use this link. http://rhin.crai.archi.fr/rld/plugin_details.php?id=429
This plug-in doesn’t always work for every Sketchup drawing, and I’m not sure why that is. There have been some upgrades recently though, so, if you have an older version of it, go ahead and re-download and re-install.
Despite the upgrades, there are still times when I come across a model that won’t export correctly. I have spent a great deal of time experimenting with the Su2stl.rb plug-in to try and figure out why this is, but I have yet to figure it out.
I did have some success with the pro version of Sketchup, but that kind of defeats the purpose because it’s not free (I only have the eight hour demo version). What I noticed is that, by using the pro exporters, it is possible to export a .3ds file from Sketchup and then import it back in. Once this is done, the export to STL plug-in works every time. Perhaps that bit of insight might give someone an idea of how to fix it.
Convert Sketchup SKP files to DXF or STL Plug-in
There are some Sketchup drawings that I have made which won’t export correctly with the Su2stl.rb but will with the plug-in available at this site.
Install them both. If you have trouble with one, you can try the other.
If neither of the above plug-ins work correctly for your particular Sketchup drawing, there is still one option left. It’s a bit more time consuming than either of these plug-ins, but it has always worked well for me. Follow the link to see how it works. Sketchup to CNC