Arduino Meets Lego: The Ultimate DIY Robotics Project

Cyrus Tabrizi, 8/29/13
Step 4: From 3D to 2D

      Once we know that all our 3D parts will fit together like we want, we need to turn them back into 2D so that the laser-cutter can cut them out. We will do this from Inventor, but it does get somewhat repetitive.
First, close the assembly that has all the parts in it. Then, go into the folder that you saved all the files and open each one at a time. For each part, right click on the main surface that you designed already (the part that looks like your original 2D sketch) and click “Export Face As.” You will have the option to save as either a DXF or a DWG. Besides issues of compatibility (maybe one program is older than the other), though, both are standard file types, although I end up turning everything into a DWG in the end when I send it to the laser cutter.
With all the part faces exported, you can close Inventor and open a 2D CAD program like AutoCAD. You’ll need this to create the necessary file for laser-cutting. Take the rest of this process with caution, though, because it may not apply so well to your specific laser-cutter (it does work on one I used at school, which is from Universal Laser Systems).
      In AutoCAD, open a blank drawing (DWG). Create a rectangle from the origin and extend it into the first quadrant. This rectangle represents the available cutting area, so dimension it properly (the one I used had a 24” by 12” cutting area). Now you have to insert all the parts you’ve designed. Go to the Insert tab, click Insert, and select the file for one of your parts. Clicking OK will let you move the part around the drawing. Click to place it there—you can always move it again later with the Move tool under the Home tab. You’ll want to do this with all the parts, but it’s important to put them in the right place. For example, it’s okay to put parts next to each other, but leave at least an eighth of an inch of spacing between them (this will help you later when you have to remove that part from the laser-cut plastic and will ensure that the parts are properly cut out). Also, you need to make sure all your parts not only fit within the rectangle you initially drew, but that there is some margin as well. Leave at least half an inch around the borders. What’s important now is that the parts be distinguished from that bordering rectangle. This is done by keeping the rectangle and the rest of the parts on a separate layer (remember the color of the layer because this will be important later during the plot setup). When all of this is done, save the file and head over to the Plot command under the File menu.


To Plot 9
Step 5: Plotting to a Laser-Cutter

      In the Plot window in AutoCAD, there are a bunch of options that you have to set for everything to turn out okay. The ones that aren’t specific to the printer I used include setting the scale to 1:1, selecting the right plot area, making sure that the correct power settings are set, and that the correct material profile be loaded. I’ve attached some pictures of the setting windows that I went through in case they are of some use to somebody, but I don’t have the experience to say if the same will apply elsewhere or if these settings are the best (I can, however, say from experience that having the correct settings are important).