Laser Cutting Information

Due to some ongoing technical issues with the laser cutter, I have not had access to it for the last few days. However, I hope to get access to it in a couple of days time. As soon as I do, I’ll cut out the designs I have already received by email, provided that I can access the files. In some cases, however, I have received files in formats I can’t open, so please read the guidelines below if you have sent me files or intend to in the coming days.

Guidelines for submitting designs for laser cutting

The basic guidelines are as follows:

  1. All pieces will be cut from 3mm acrylic (Perspex) sheet. The maximum sheet size we can use in our laser cutter is 600mm x 300mm, which should be more than adequate for anything used in a RoboSumo design. The colour will just be whatever colour material happens to be in the machine when your pieces are cut.
  2. Submit all the pieces you want cut in a single file. Please do not send a separate file for each piece because that makes the process extremely labour intensive for me.
  3. In your drawing, please leave a little space around each object, so that I can easily select individual objects and move them around if I need to prior to cutting.
  4. The drawing should contain nothing at all other than very thin black lines wherever you want the laser to cut the material. There should be no labels, dimensions, filled shapes or anything else shown. Everywhere there is a line the laser will cut.
  5. The file format should be SVG, DXF (2007 version), or AI, depending on the software you use to draw the pieces (as explained in more detail below).
  6. If you draw your pieces in AutoCAD, please send a DXF file (2007 version). Some versions of the DXF file format will not work, so please make sure you use the 2007 version. You can specify DXF 2007 when you “Save As…” in AutoCAD.
  7. If you draw your pieces in Inkscape, just send me the SVG file. That’s the native file format in Inkscape.
  8. If you’re drawing the pieces in SolidWorks, you’ll need to convert the pieces to a single 2D drawing and save it as an Adobe Illustrator “.ai” file (see below for a video explaining how to do this). You can either send me the AI file or use Inkscape to convert it into an SVG file and send me that.
  9. When you email me the file, please include the dimensions of an easily identifiable piece. For example, you might say “The biggest piece is 65mm wide and 85mm high” or “The diameter of the only circular piece is 80mm” or something like that. This will allow me to verify that the dimensions have remained as they were intended when I open your file (sometimes dimensions can get scaled up or down when converting between file formats).

Daniel Murray produced this great tutorial video showing how to export 2D drawings from SolidWorks for laser cutting. Please take a look at it if you’re drawing your pieces in SolidWorks because it explains exactly how to export your pieces in a single drawing in the correct file format.

Some additional useful tips:

  1. If you’re the person who has been given the job of drawing the laser cutting plans for your team’s robot, please ask your teammates to review the drawings with you before you get them cut out. Extra pairs of eyes make it easier to spot errors or oversights in advance.
  2. Another great way to verify that your pieces will fit together the way you expect is to print them out at their actual size on a normal sheet of A4 paper, then stick the printout onto an A4 sheet of foam board. If you then cut it out very carefully using a craft knife and a metal ruler, you can produce an excellent working replica of each piece. Cutting out curves is tricky, but straight lines can be cut very accurately this way, which allows you to test interlocking pieces. This is exactly what I do myself when I’m working on a design at home.
  3. The last time I checked, you could buy ten A4 pieces of 3mm foam board for €10 in Eason’s stationery shop on Nassau St (formerly Reads of Nassau St).
  4. Depending on the design of your robot, you may find that your foam board prototype is good enough to carry out some testing, or at a pinch even to compete in the tournament. (It wouldn’t be the first time.)
  5. If you need to laser cut gears for your robot, Inkscape has a really great tool for drawing them. Go to “Extensions menu -> Render -> Gear…”. There are a couple of good tutorials on YouTube for using this gear tool.
  6. If you want to make very precisely fitting parts, remember that the kerf (the width of the laser cut) is approximately 0.1mm when cutting 3mm acrylic. Roughly speaking, this means that the laser removes material 0.05mm either side of the line it follows. For most purposes, you don’t really need to worry about this, but in some instances it can be significant.
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