Best way to use SketchUp 8.0.16846 for CNC?

I’ve made the parts for a lock in SketchUp and made components out of them. It may sound like a daunting first project but I’ve made the parts. I only need about four basic pieces, with a couple trivial variations on each, and I can draw them out now in about 2 minutes or less each. So the CAD stage is arguably kind of done.

The parts should be easy to CNC in aluminum or brass on a 3-axis machine: they can all be made with cuts from the top to rectangular-prism (i.e., brick-shaped) stock. Further, their heights are mostly 2mm and 8mm so if I can get workpiece stock in such sizes I’m really not doing much work at all.

I don’t have a CNC machine and was hoping to find some service bureau here in Tokyo that I could simply send files to then go pick up or be mailed the parts.


  1. Are there tool chains available to convert file formats from SketchUp to CNC (hopefully free)? Note Windows 7/32 would be the first choice though I have Linux (Fedora) and Win10/64 available.

  2. Should I need to upgrade my SketchUp? (Again prefer free) [ANSWER: I am told 2017 is the latest or final free version, but requires 64-bit.]

  3. what is the smallest detail I should be able to carve on a face with CNC? Is 0.5mm wide troughs up to 1.5mm deep possible with usual CNC?

  4. what is the accuracy of common CNC? For instance if all my parts in theory have clearances of 0.01mm apart, will the fit together and move? Or is there a fair chance a part specified to be 4mm will bind in a channel specified to be 4.01mm?

  5. I assume 3-axis CNC uses round bits coming down and thus cannot carve out a square corner or hole (concave as seen from above; I assume convex corners could be razor sharp). So when I design a piece, I assume instead of a square corner to a hole, I should make a "round-cornered rectangle) whose corners are some small radius. What radius would be a good idea? OR, should I assume that any good CNC machine has a square-cutting bit system?

  6. Same question but now for vertical. Further, for bottom corners, can CNC make square corners or are bits’ tips rounded as well? In other words can I simply apply a round-cornered rectangle on a brick shape’s top face, and push it down a bit, and expect to get that?

  7. I need a half-dozen pieces 2x4x15mm with little troughs carved on one face (the pieces being featureless rectangular prisms, i.e. bricks, except for that. I’m having trouble picturing how a CNC machine would work on such a part. Should I instead perhaps design the half-dozen pieces on one larger piece that I then use non-CNC means to cut apart? Obviously if I could find stock the right thickness, then I’d only have to cut the troughs, then the piece itself (or scribe lines showing a human where to cut them apart later), but are there common stock sizes I should expect a CNC bureau to have or be able to order? (For instance is there a website you can point me to with common stock for such machines?) For instance if such stock is commonly available in 1.5mm and 3mm, then perhaps I can alter my design to use one of these sizes instead of the 2mm I currently envision. Likewise all the major pieces except one are 8mm tall with a substantial portion of their top surface at that 8mm level, so starting with stock that thick would cut drilling further.

  8. Do I put one component per file? Or if I randomly array components around in one file, will a utility converting the SketchUp .skp output files to whatever format CNC routers like, understand that they’re separate work pieces?

  9. What special features does a component need to have to allow securing the workpiece to the mill’s table? I’m assuming it needs some place on it where it can be clamped down?

  10. I assume conversion programs complain if the component has features that can’t be rendered. For instance I assume if you specify a perfect square be milled into the top of a workpiece, the conversion program would complain that CNC cannot do that? But I assume the conversion program needs to know capabilities of the actual machine, for instance the size bits it has, whether it’s 3/4/5 axis, maximum size, and possibly other things?

  11. Is there a single format all CNC machines take and if so am I advised to use that? Or is it a lowest-common-denominator and I’d get better results using a less-universal format?

  12. I need 4-8 holes tapped to take screws. I assume any CNC service bureau has this capacity as practically any project would need it. If such a thing is done by a different CNC machine, how is the part alignment figured out? In other words, when the mostly-finished workpiece is put on the second machine, how does it determine the exact position of the workpiece to the micrometer?

  13. Or if this is done by a human, I need to leave a mark where to do it. But I assume on the SketchUp I should just make a notation of where that goes? Scribe a circle? A + sign? A + sign in a circle? And how do I put this kind of carving onto a componenent in SketchUp? Obviously I could cut a tiny tiny trench but I have no idea what smallest width etc. would work. I’m also thinking of simply making a circular indentation of 0.1mm deep or whatever the smallest step I can expect a CNC machine to make.

  14. Or if this would be done by the first CNC machine, what do I do in SketchUp to result in that ending up in the CNC control file? (Note I’m a software developer and from what I’ve seen of CNC control files I’m sure I could append instructions to the file to do such things.

  15. I want to do a dry run, assembling my lock more or less in SketchUp and making sure none of the components overlap in space. How can I go from having the individual components laid out for the CNC conversion program to find and make instructions for, to maneuvering them around? I’m especially finding it hard to move pieces in 3D, is the only way to do it to look down the Z axis or close to it, and move things XY, then orbit to another axis and move them vertically? Then how specifically do I check for overlaps? [PARTIAL ANSWER FROM TUTORIALS: select, right-click, and form “groups” from any parts or even sub-parts that you won’t copy, or don’t want changes to one copy to be reflected in other copies. Alternatively do the same but choose “components” any time you want any edit of one occurrence of a thing to be made on all the other occurrences.]

Hi Tiger, welcome to the forum!
There is an extension called Fabber witch can create toolpaths for CNC and laser from a SketchUp drawing. You can get more information at or ask @ericschimel about this.

A lot of your questions are specifically about CNC and not SketchUp, I think those questions are best asked on a CNC forum as that is where the CNC-experts will be…

Good Luck!


If you have a good CNC forum in mind let me know. The best I can find only has 1-2 posts a day, worldwide. There must be something more active than that…

Happy to answer any questions you might have! We’re about to roll out a totally new version of Fabber too!


Hi Eric, wow, this is service, direct contact from the Fabber team!

I listed a dozen questions above and if your time allows I’d love your expertise on the ones related to Fabber.

Many thanks in advance!