CNC Machining Contours | ENGI 210: Prototyping and Fabrication

For this assignment, I used the CNC machine to cut out a contour of Mt. Everest. I ran into quite a few unexpected difficulties, but I found some creative solutions that made it work in the end.

I started by learning about CNC machining generally through the OEDK Training tutorials. The videos were very helpful. I learned about using Carbide Create software to create toolpaths, how to use the BitZero probing device, and about the different types of endmills and toolpaths I can create. I also learned about how to secure the workpiece on the Shapeoko Pro, which turned out to be extremely useful for this project. After doing this, I felt confident about jumping into CNC machining.

My thick stock

I followed the instructions in the homework document closely on my own computer, and I created the .crv file for the assignment with no difficulties. When I finally got to the CNC machine, however, the version I was using was a future version, and since VCarve is not backward compatible, I could not open it on the CNC machine. However, going through the steps on my own was definitely helpful, as I was already familiar with how to create my .crv file. Plus, I was able to accurately measure the stock size being at the CNC machine.

I chose Mt. Everest as my mountain range. In order to have more space for the height of the mountains and not have to shrink the entire .stl file down too much, I opted to use the thicker stock of wood. My measured stock dimensions that I input into Carbide Motion were 5.96 in by 3.55 in by 1.53 in. I initially had concerns about the shape being too small due to one of the instructions on the assignment that said to make sure that the file fits within a box on import, but it ended up not mattering, and I could make the file the size I wanted. This is because later on, there is an option to specify the gap between the surface of the stock and the highest point on the file.

Simulation of the three toolpaths on VCarve

I wrestled with changing the endmill on the Shapeoko. I didn’t realize I could take off the part with the bristles near the endmill at first. Once I did, it made it so much easier to change the endmill. I also had some difficulty figuring out the wrench positioning. I figured out that there was a certain angle that I had to put the wrench at so that it fit. After that it became easy.

Setup for securing the stock to the spoilboard

Stock successfully secured using super glue

I figured out that I had to use three separate passes for each toolpath I had created. This is so that I can give myself an opportunity to change the endmill in between toolpaths. The three passes corresponded to three separate .gcode files I would have to input into Carbide Motion in sequence: roughing, finishing, and profile. The profile cut was required because I created both of my mountains on the same stock.

It finally worked

Post-CNC

I tried to cut a profile through the entire thickness of the stock using the CNC machine, but the endmill immediately got stuck and it made a very loud noise. I decided to opt for the not-so-good alternative of the band saw. It took forever to cut into the wood, but once I did, it went by a bit faster. It was also not at all easy to cut straight. I feel I only got marginally better at cutting straight by the end.