C.N.C. (Can Not Comprehend how cool this machine is)

I had a really good time with this project! It was incredibly empowering- although you are still limited by the reach of the CNC, the ability to design and create objects out of wood or metal rather than relatively weak PLA has definitely reinforced the value of subtractive manufacturing in my book.

I wanted to do something cool and unique other than what I could find on the Noun Project, so I started off by making a pretty simple stormcloud design in Fusion360. This definitely tested my artistic capabilities (clouds are hard), but I’m happy with the result of about an hour of messing around with the revolve function, all working off a single plane. To elevate this design, I think I’d work off of multiple planes to create some more depth to the bubbles.

I exported it as an STL and followed the directions of the assignment to the letter in vcarve to work out my first two toolpaths, using a eighth-inch flat bit for the roughing pass and a rounded 1/16″ bit for the finishing pass. You can see the result of this first try below. I got some practice at this with our final project, so this went fairly smoothly. The most difficult part of this was actually just changing the bit in the Shapeoko downstairs after I lost faith in the Nomad (just a personal aversion to tape). The collet requires a 14 mm flat wrench made of something sturdier than the aluminum parts that come with the machine initially, so I had to source one from Rice Bikes to get the right bit in.

However,  I ran into issues with the bit length. To meet the 3″ parameter for the project, my design had to be about 1″ deep, and none of the bits we have can cut through the 2″ x 4″ available for the project. So, I just inset the design into the 2″ x 4″, but the finishing bit hit against the sidewalls in the deepest parts, leading to roughness and an overall poor finish. My response to this was to set the first roughing tool pass to go to all the way to the material boundary, rather than the model boundary, which was much more successful. I used a larger stepover rate and a quarter-inch bit instead of an eighth-inch, and it actually only extended the cut time by about 15 minutes. Unfortunately, the 1/16″ rounded bit was no where to be found, so I used a flat bit instead that left a rougher finish than I would’ve liked.

Both of these cuts went smoothly. I did make an executive decision in favor sustainability to use this piece of wood with a hole in it because a) it matched the dimensions of my first piece almost exactly, and being frank it was 2 in the morning and I really didn’t want to remake the toolpath to account for 0.25″ of difference in centering the piece and b) the hole was juuuust deep enough to result in a very small divot in one of the lightning bolts. You can see my measurement approximation below.

   

Of course, this results in pieces with slightly different dimension on the top and right sides. I accept that this is definitely a failure in terms of replicability. I tried to compensate for that by making identical outlines for them with the belt sander, but that was a lost cause from the start. I will definitely accept any points off in that area, as the outlines are now very different, but the design itself is the same. Here are the two versions just off the CNC, and then sanded versions.

I finished these pieces with light sanding. I painted the cloud blue with acrylic paint, and the lightning yellow with spray paint. I borrowed some of the polyurethane from the final into the outline created by the quarter-inch bit to hide the fact that the finishing cut didn’t smooth over the edges of the lightning bolt under that plane, and then coated the rest in black wood stain. I do wish I would’ve sanded a little more carefully on the clouds because some areas were still rough under the paint. I’ve definitely learned that finishing touches are not my strong suit. Regardless, I’m happy with how it turned out, and may at some point be making a more refined version to keep. Here’s the finished result!

Print Friendly, PDF & Email