AutoCAD
How to use CAD software with the laser cutter:
This term, as many of you know, I was able to use AutoCAD to create extremely accurate computer cases and mounting plates for the robotic wheelchair project. For anyone that interested, this is a quick tutorial on this process and how I managed to make it work.
AutoCAD:
First you need to obtain copy of AutoCAD. I happen to own a copy of AutoCAD 2006. You can download a free 30-day trial of AutoCAD 2007 here. The AutoCAD 2007 LT version is sufficient if you want to do all of your drawings in 2D. The full version will also do 3D. I did all of my drawings in 2D for this class. A tutorial on AutoCAD is way out of the scope of this document, but I personally learned with the AutoCAD “Bible” series. AutoDesk has a tutorial that comes with the free trial download and they also have tutorials online.
Making the drawing:
Try to get the mechanicals for just about everything you need to work with. Don’t try to measure it yourself unless you have no other choice. For instance, if you need to mount a hard drive in a case, go find the manual. You will find that there are normally wonderful mechanical drawings in the user manuals of most of the hardware you buy. For instance, look at this manual. On page 39 is a beautiful mechanical drawing that will give you all the information you need including screw offsets, hole sizes, etc. This can be duplicated for motors, switches, and the like. Also be sure to search the manufacturer’s web sites. In many cases you can find AutoCAD native drawings that you can directly import. Motor manufacturers are notorious for this.
Separating the cuts from your drawing:
The real trick is to use layers. Create a layer called “CUTS” in AutoCAD and let this be the layer that is the actual hole or edge that will be cut. In this way, you can have things like alignment tabs, labels, and outlines on other layers. Then, when you are ready to cut the plexiglass, you just turn off all of the non-CUTS layers and you are ready to go.
Importing into Corel Draw:
It turns out that Corel does an especially horrible job of importing even 2D drawings from AutoCAD. What you need to do is first save your drawing in native AutoCAD 2006 or 2007. Now turn off all of the layers that you do not want to cut. Then do a “Save as” and select “AutoCAD R14” and “dxf” as your file format. This is an ancient version of AutoCAD, but for our Corel-handicapped 2D cuts it will suffice.
Adjusting within Corel:
Corel knows nothing of AutoCAD layers, so you will find that everything in the drawing is grouped as one big object. Select everything in the drawing and right click on any of the selected objects. Select "Properties," and click on the outline tab. The line thickness should be 0.001 inches in width. Then select "Color," then "Other," and the "Trotec palette"; then make the color red (RGB 255 0 0). Hit "OK" and then "Apply."
At this point you are ready to cut. Be sure to follow all of the instructions here regarding the adjustment of the laser height and job control semantics.
HAVE FUN!