CNCing a tactile OpenStreetMap

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CNCing a tactile OpenStreetMap

Post by koppi » Thu Apr 14, 2016 9:39 pm

I came across : it exports STL files from OpenStreetMap data. This allows for creating a tactile map for blind people 8-) . Because I do not have a 3D printer, only a small CNC mill, I decided to write an STL to G-Code converter in C++: see: ... tl2ngc.cpp

Result of stl2ngc in CAMotics:
camotics.png (429.85 KiB) Viewed 1844 times

CNCing the tactile map (8x8cm) with a 2mm cutter took about 45min:
touch-mapper.jpg (221.92 KiB) Viewed 1844 times
For more details see:

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Re: CNCing a tactile OpenStreetMap

Post by WillAdams » Thu Apr 14, 2016 10:11 pm

Very, very cool. I’m surprised that I hadn’t found the map conversion program, and glad to add it to the CAD page.

Surprised that you chose to write your own CAM program though, bet very glad of it — there aren’t many opensource CAM options, and even something this specialized is a welcome addition.

Or, is it specialized? Could it be used for general purpose CAM? If so, what do you view as the relative strengths and tradeoffs compared to other programs?
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Re: CNCing a tactile OpenStreetMap

Post by Jimf » Thu Apr 14, 2016 10:35 pm

I'm amaze that someone can just wake up and say I want a stl to gcode converter, lets program one up. Good work. I think this will be useful for all the stl files you can download.

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Re: CNCing a tactile OpenStreetMap

Post by koppi » Fri Apr 15, 2016 12:39 pm

@WillAdams: I have tried many CAM programs over the years, but ultimately decided to look into how the CAM algorithms work and write my own G-Code creation toolchain.

A good starting point is imho the source code of the open source computer aided manufacturing algorithms library:

The author of this library has written many good explanations of the algorithmic details at:

@Jimf: I ran stl2ngc.cpp on a number of STL files from Works pretty well. The stl2ngc.cpp I've posted on GitHub could be turned into a more general CAM program, but I leave it as it is (- please send pull requests). You can easily add support for different cutting tools and cutting path strategies, for more demos/examples of the opencamlib, see:

* ... er/scripts

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Re: CNCing a tactile OpenStreetMap

Post by AnonymousPerson » Fri Apr 15, 2016 1:04 pm

That's definitely pretty awesome. Now we just need someone to make something for colouring in the sides of the buildings using something like google Street View (if there's an open data source that is). :D
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