My first steps in laser cutting were moved to make Christmas small figures, after attending the workshop at PlugnMake FabLab Delft. It was a nice way to get a first contact with the machine and the software required to use it.
The software to use the machine, RDWorks, uses .dxf files. It converts them to .rld files, all ready to be cut according to the settings previously defined. These type of files are based on vector imaging, which means that, when you work with them, all images and shapes must be converted to vector traces.
First trial: Turning an image into a vector graphics and first laser cut
The pictures I selected were taken from a black-and-white colouring book for children, which works wonders for these small projects as those kind of pictures are already drawn in solid black and white blocks, and they are usually quite simple, so transforming them from picture formats (any would do, like a .png or a .jpg) is very easy.
Most image treating software have a setting to make this operation automatically. Therefore the very first try I made was converting the images to vectors with the RDWorks software itself. That turned to be an inefficient idea. In conclusion it resulted in extremely pixelated edges that made the image heavy and slow to work with and, worst of all, it meant that the laser cutting machine cut along every single one of the little pixelated borders along each contour. The result was a wooden figure with heavily burnt and serrated edges, poorly defined details and small holes where the pixels got too close. Also, that took way too long to cut.
Second trial: converting a bitmap through Inkscape
The second time the images were vectorised using Inkscape, resulting in smooth edges and overall better details. The laser machine barely took 5 minutes to complete all figures, and the edges were smooth and clear.
What I learnt
Upon doing some experiments with these latter figures, it soon came clear that distances below 1 mm don’t yield good results, as lines at less than that distance apart are too close and overlap, and parts with less than that width are far too thin and easy to snap. By making the figures slightly larger, the lines no longer overlapped and everything turned much clearer.
Laser cutting settings
The inside of the figures was made with vector engraving at 200 mm/s speed and 16%-20% power. Only the inside of the bows were raster engraved at the same settings and 1 mm separation between traces. The outside was cut using a 40 mm/s speed and 40%-60% power setting.