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NOTE: See the latest post on this subject: Laser. Cut. Files. (Part III)
Update: I made an error in specifying which DXF export I used. I’ve corrected that below.
In my previous post Laser. Cut. Wood. I talked about cutting wood on the laser cutter at Milwaukee Makerspace, and I mentioned I wanted to talk about files… so read on.
The laser cutter can work with raster files or vector files, and since I last year when I got the Egg-Bot and had to dig into using Inkscape, I’ve become fond of that little open source vector drawing application. I’ve used it for 3D printing and for my cucoloris design.
When I started exporting DXF files from Inkscape for use on the CNC Router, Royce mentioned an Inkscape extension called Better DXF, and then Shane found Better Better DXF and then I found Big Blue Saw DXF. These all have their purposes, but for exporting a DXF file for the laser cutter, they were terrible. :(
Oh, before I tried the DXF files, I exported a PDF from Inkscape. I figured that since the PDF from BoxMaker went into CorelDraw without issues, it might be worth a try. No dice. CorelDraw said the PDF was “invalid” and couldn’t open it. Preview.app on Mac OS X had no issues, but since it didn’t work, I’d suggest not trying to generate a PDF from Inkscape to import into CorelDraw. I also tried an EPS file, and a PostScript file from Inkscape, since CorelDraw should have been able to open those. Again, no luck. On to the DXF files!
Here’s the results of my file tests. For each file, I started with the original SVG file of the Milwaukee Makerspace logo in Inkscape, and exported using the corresponding extension:
| Format | Results |
|---|---|
| Better DXF | The file imported into CorelDraw scaled about 10 times too large. |
| Better Better DXF | The file imported into CorelDraw scaled about 10 times too large. |
| Big Blue Saw DXF | The file imported into CorelDraw scaled about 1/4 the actual size. |
| Desktop Cutting Plotter DXF | The file imported into CorelDraw scaled about 10 times too large. |
| Autocad DXF | The file imported into CorelDraw properly. |
For for the first three DXF files, they didn’t work as desired. It appeared as though the curved segments were made into line segments. This would make sense for the CNC Router, as it would save a step in CamBam, but for the laser cutter it just made the curves not be curves. For the fourth one, this this is the one I originally thought worked, but alas, it imported way too big. (I think the lines remained curves though.)
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So what worked? The AutoCAD DXF exporter. (Which still made the curves into line segments, so I’m not 100% locked into this, but it worked better than anything else so far.) It actually came in at the right size, which is what I wanted.
My warning for these DXF files are this: Always save your original SVG file! I’ve had hit & miss experiences opening the DXF files, even in Inkscape. YMMV, as I think my loading 3 different DXF extensions has somehow confused Inkscape as to how it wants to open DXF files. (Any advice here would be appreciated!)
Oh, it’s also worth noting that your vector file in Inkscape should have just a very thin stroke on the lines. How thin? 1 pixel, or less. Less than a pixel? Yeah, somehow you can use 0.05 px as a width. I don’t know how… You can also use 0.001 inches. Whatever, just make it thin to be safe. (And in CorelDraw, set your line to hairline to be safe.) This is fairly similar to what I do for the Egg-Bot, since the width of the plotting pen will determine the width of the line drawn, not the stroke of the line on your screen.
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So here’s our logo, which we imported into CorelDraw (successfully) and then added a circle around it, in red. To the upper-left of the circle you can see the darker rectangle outline that indicates the upper-left corner of the laser cutter platen.
I then ran the job with the following settings… Black and red have specific settings that match up to the colors used in your file. I also set them to vector output. (I think that if you set it to vector and your file has only raster data, the laser cutter will just beep at you, and not start the job.)
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Here’s where we go off-script and start experimenting. You may end up tweaking the settings and running the job again, or you might just re-run the job right from the control panel of the laser cutter. When I etched my sign, I ended up just re-running the job from the control panel until I was happy with how it looked. (Obviously you don’t want to removed the piece you are cutting from the machine, as you may not get it back exactly where it was.)
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Now here’s where it gets tricky. I was happy with the etching (which was the black lines in the file) but not the cutting around the edge (which is the red circle in the file.) So what I did was, deleted the black lines, left just the red circle, and then sent the job to the laser cutter again. Then I could keep running it until it cut through the wood, without running anymore etching of the logo.
Now, I don’t claim that this is the best way to do things, or the only way to do things, but these are my notes, as I’m learning, and I’ll keep adding to them, and will refer back to them, and if things get better, I’ll write that up as well. Oh, I’ve also whipped up a little Laser Cutter HOW TO you might find helpful.
I’ve got a few more laser cutter tips & tricks, but I’ll save them for next time…
(See Also: Laser. Cut. Files. (Part II))