After doing some internet research I have decided to go with Google Sketch Pro for the drawing of parts to produce a .dxf file., this will cost me a dollar or two but I have gone through the Google sketch tutorials and it is a powerful program. Google Sketch Pro is a CAD program, CAD standing for computer aided design. The CAD program is just the first step in a three step process of drawing the part and from that part drawing producing a .dxf file.
The second part of the process is to import the .dxf file into a program that will convert the geometry into standard G & M code this is a CAM program, which stands for computer aided machining. The program I have decided to use for this is SheetCam. SheetCam is a 2.5 axis program which makes it a little simpler to use. Of course the machine moves in the x and y directions but the third direction the z axis on a plasma cutter is really just up and down without much coordinated motion between the x and y axes while the axes are moving, we aren’t routing a 3D sculpture we are cutting a profile.
The third step is to use a third program which is a Linux based program called EMC which stands for enhanced machine control this takes the G & M code and translates that code into stepper motor signals that are exported through a parallel port to a Xylotex box which controls the motor motion to the 3 axes. Xylotex is the manufacturer/ integrator of the stepper motors and stepper motor drive boards.
At this point I have drawn a 5″ x 5″ square, downloaded that dxf file from Google Sketch Pro and created the code with SheetCam. The SheetCam program has a EMC post processor as a choice and I have the program ready to load into the laptop running Linux EMC to test the motions and accuracy of the CNC machine. I was able to draw the simple rectangle and convert it to G&M Code in about 3 hours this morning. Not a record but this does speak well for a well written intuitive CAM program, I had previous experience with Google Sketch so that doesn’t really count but I do like that program as well.
It hasn’t all been desk work I have also been turning the Bridgeport handles. The Y axis carriage plate has been built and awaits longer screws for final assembly.