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John Gale edited this page Oct 9, 2019 · 15 revisions

Welcome to the ToolPath wiki!

We have art projects! We want to use images, fancy fonts, and found art to make:

  • plywood cutouts on the 4'x4' CNC router
  • sheet metal cutouts on the 4'x4' plasma torch cutter
  • stencils and lithophanes on a 3D printer
  • vector graphic files for stencils, decals, and posters

So... first we need to convert bitmap images into vector format files.

Wikipedia - Image Tracing describes what that means.

There are many ways to convert bitmap images to vector. SVG is the most popular vector file format, so let's standerdize on that for our vector files.

  • The free (and very powerful) vector image program Inkscape has a tool called 'Potrace'

  • Adobe Illustrator also has an automatic tracing tool.

  • Free web-based 'vectorization' converters

Anna has provided 2 bitmap images that we can use to figure out workflows for making the 'toolpath' files that the plywood router and plasma torch machines use, to cut out or print the objects.

First, let's try one of the free web-based vectorization tools: Autotracer.org

https://github.com/galejohn/ToolPath/blob/master/IMG_7136.svg

https://github.com/galejohn/ToolPath/blob/master/IMG_7137.svg

That works, but because the original bitmap images have shades of grey, the vector images are more complex than we really want for silhouettes.

We could do some pre-processing of the bitmap images, to convert them so that each pixel is either pure black or pure white. Or, especially since we want to learn to use Inkscape anyway, we can try it in Inkscape.

Following the tutorial at:

how-to-trace-bitmaps-in-inkscape

We can adjust settings in the Path > Trace Bitmap tool to get a good-looking cutout. I used Mode > Single scan > Brightness cutoff Threshold=0.500, Colors=2 to get these:

https://github.com/galejohn/ToolPath/blob/master/IMG_7136inkscape.svg

https://github.com/galejohn/ToolPath/blob/master/IMG_7137inkscape.svg

and then, to get just the outline: Object > Fill and Stroke with Fill off (click the X) and Stroke paint set to Flat color

https://github.com/galejohn/ToolPath/blob/master/IMG_7136inkscapeoutline.svg

https://github.com/galejohn/ToolPath/blob/master/IMG_7137inkscapeoutline.svg

Next, with good SVG vector image files, we can make toolpath files for the CNC router or the CNC plasma cutter.

Almost all toolpath files nowadays use gcode, and Inkscape includes a plug-in to make gcode.

Intro-to-g-code

We'll use Inkscape's g-code tool just to get the idea of how g-code works. As they say in the tutorial, it could be dangerous using the generated g-code in our router or plasma cutter, without checking it or pre-processing it. To actually cut our designs, I'll use professional software specifically made for the machines.

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