Equipment/Laser Cutter Inkscape
Contents
Inkscape tricks
A selection of hints to get the best out of Inkscape with our laser cutter. This applies to Inkscape 0.48.4.x and later, if you have an earlier version you should upgrade.
Outline mode
Inkscape can be put into outline mode, allowing you to see objects which have neither stroke nor fill. This is great because adding a stroke changes the dimensions of the object (slightly, but potentially enough to matter) and adding a fill makes it hard to see what you're doing. Select from 'View->Display Mode->Outline'. As an alternative a default fill with opacity of 10% works nicely when creating compound objects.
Text on a path
Easy to do, create a path, create some text and use the 'Text->Put on Path' menu item. With the text selected you can use the letter and word spacing controls to get the text to completely fill the path (I needed this for the plaque as we wanted the lists of names to butt up to each end of the shape). At this point the text and the path are coupled together, so while you can move the text away if you delete or change the path it'll alter. To get outlines ready for the cutter select the text object and do 'Path->Object to Path', you can then delete the original path object used to flow the text.
Rounded rectangles
If you try to use these the cutter will largely ignore them. Use the 'Path->Object to Path' to convert them into a generic path before exporting.
Alternatively, enable the "use ROBO-Master type of spline output" (an option during saving) if your version of Inkscape supports it.
Dashed paths
The laser won't pay any attention to stroke styles you set in Inkscape. Recent versions, however, include an extension under 'Modify Path -> Convert to Dashes' which will render whatever stroke style you've selected.
Engraving text
Regular fonts used by Inkscape and everything else are outline fonts, that is to say they're defined as a filled shape. When used by the laser cutter the laser will cut the outline of the font, which looks great for large characters but often very badly (and slowly) for small typefaces. There's an extension at http://www.evilmadscientist.com/2011/hershey-text-an-inkscape-extension-for-engraving-fonts/ which allows for the use of engraving fonts where the font is defined in terms of the path used by the cutting tool rather than an outline.
Note - the version of the library at that link is broken with modern (0.48.4) versions of Inkscape, I've fixed the problem and uploaded a patched version to https://dl.dropboxusercontent.com/u/70831580/HersheyText.zip
Exporting
In the latest version of inkscape you have an option from 'File->Save As' to save as 'Desktop Cutting Plotter (AutoCAD DXF R14)'. With the default options this seems to work perfectly with the laser, dimensions are preserved etc. If you don't have this option upgrade your version of inkscape, it appeared some point over the last month or two.
Page and grid setup
I find it easiest to get a sense of how big the piece is going to be if I set the page dimensions to those of the laser cutting bed, i.e. 900x600mm. You can do this from 'File->Document Properties...' then entering a custom size, remember to change units to mm. At the same point you can create a grid, I use a 1cm grid with 1mm minor lines - select the 'Grids' tab and click 'New' to create a new rectangular grid, for the one I use set units to mm, spacing to 1 and major grid line every 10. I change the colours so I can see the major grid lines even when zoomed in fully. By default Inkscape won't actually use the grid, the buttons on the far right allow you to enable snap (first button from the top), to bounding boxes (second from top and subsequent four) and path nodes (the next group down). If you're not getting the snapping behaviour you expect play with turning these on. When snapping to path points it'll use the point closest to your mouse when you're dragging, so it matters where on the path you click!
