Can parts be CNC machined from an stl file

  • As title really. I know next to nothing about CNC machining but I have a need for some small prototype parts to be milled from aluminium. Can this be done from an stl file? Alternatively, they have been designed using OpenScad so I think I could export them in some other format if I knew what would be best for CNC machining.

  • @deckingman Yes!

    You will need a CAM software, such as Fusion 360 if I am not wrong.

    Our slicer is nothing more than a CAM tool path planner and the gcodes are a heritage from CNCs. 😄

    So if you CAM software can import a STL file then parts can be CNC machined from an STL file.


  • @brunofporto Thanks - but I think something might have got lost in translation. I have designed the parts in OpenScad and I can generate an stl file (and various other formats as well). I think you have answered my question but what I wanted to know was, if I supplied that stl file to someone with a CNC machine, could they make the part in aluminium. It seems the answer is yes which will be a lot easier than supplying a drawing.

    So my next question is, are there any UK based CNC users on these forums who might be interested in making me some parts at a reasonable price?

  • Hey @deckingman,

    You are best to ask who is going to do the machining what they like to use as everyone is different. I got some parts machined by a rapid machining place is China, and the three I inquired with all had the ability to use different file formats.



  • And if you can’t find anyone in the UK, I highly highly recommend StarRapid in China. It is run by a foreigners and the quality was fantastic. They do a lot of stuff for big companies and have a great reputation.



  • Hi, you can use STLs with most cam softwares, but the trajectories generated from it will copy the facets of the model. Instead it's way better to use a solid model or a surface model (IGES, parasolid, STEP, and nowadays you can import native CAD data directly to the CAM) since you can control the amount of points and / or the tolerance of the trajectories. So instead of having a curve machine as a series of facets, you'll end with a true curve on your part.
    Most modern industrial CNCs (from 10 years ago) don't have any problems with the amount of points in the gcode. I don't know how hobby CNCs behave.

    I'm not near the UK but if I can give you some advice just ask.

  • I think your best bet is to get FreeCAD, which can open OpenSCAD files, and then use FreeCAD to export to STEP.

    STL isn't an ideal format for anything really, and since you have the source files, you might as well give your machinist something they will have the greatest flexibility to work with.

  • I had some toothed supercharger belt pullies CNC'ed from STEP files I drew up. That was his particular file type of choice.

  • @phaedrux Many thanks for that and especially the YouTube link. I think even an old guy like me could cope with that.

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