CNC Machining

I was very excited for this project since it was one of the skills that I was hoping to learn through this class. I started this project during the tutorial 1:2 session where we were shown how to properly use the X carve machine. Because my design was fairly large (6”x6”) I ended up using a large plywood as my canvas. In hindsight, I wished I had chosen a different material such as pine as it would have given cleaner lines, less chipping, and would have had a better overall look without much post-processing (I’ll go more in depth later in the blogpost). I also used a ⅛” downcut bit to cut my shape. I followed the instructions on Easel to position, home, and determine the z axis height. I decided to cut both shapes at once in order to speed up the process. Both together took about 40 mins to cut. I did have to go back and forth on the depth of the cuts to decrease the time to cut. However, looking back, I wished I had also paid attention to the depth of cut in relation to the material I was cutting because the depth of cut of the finishing layer ended up being the same as one of the layers of plywood, so the plywood glue showed in my final cut. Through some sanding in post processing I was able to remove most of it. Additionally, this caused the borders to be chipped and some of them came off since there was very little holding them down to the rest of the material. 

For the post processing, I decided to lightly sand the edges to make them smoother. I also tried smoothing the border down, especially in the parts that were chipped. To give the shapes some color, I decided to stain them with a light coat of dark walnut. I really liked the way the back of my shape and the edges looked, but still was not happy with the front (as the plywood glue was still noticeable). To try to cover it, I decided to spray paint it. I covered the edges, border and back with painters tape as I only wanted the main front surface to be spray painted. I chose a dark red wine color (seemed fitting as the shape is California) and applied two coats of spray paint to each shape. Once the paint was dried, I applied a matte coating and voila. Overall, the process was very painless although there was quite a bit of waiting time between steps. 

Cost analysis:

  • Plywood → I used the scraps from the wood shop (~$35 for a sheet of 2ftx4ft however I only used about 5% of that) → $1.75
  • Labor cost → $20/hour for 1.5 hours (without counting waiting time) →$30
  • Spray Paint → $5/can but used very little → $0.50
  • Matte Finishing Spray → $5/can but used very little → $0.50
  • Since I am using the XCarve machine that is available at the OEDK, I did not include its price in the cost analysis. 

Overall price → $32.75

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