This week we learned how to use the Carvey, a desktop CNC machine. CNC, or Computer Numerical Control, takes in g-code to determine a toolpath for a bit, extruder, laser, etc to follow. In this case, the Carvey uses a rotating bit coming in from above to cut into a plank, resulting in 2.5D pieces that are primarily in a plane but have relief, depth up to ~1/2 inch.

Our project was to CNC a noun. For this we looked at icons on the Noun Project. This is a really fun site, and I quickly found a dancing couple for “tango” that struck my eye. I participated in my first ballroom dance competition last week, so it was in theme.

Upon fiddling around a bit, I realized that the guy’s left arm would get cut off some even if I used a 1/16th inch bit, and doing a fill left many thin walls. I tried an outline and that looked cleaner.

I saw one of the pieces from last year had the wood stained and then cut into, and I liked the effect that gave. I decided to elaborate on that by making a 3 depth design so the guy would be “behind” the girl, and his hand at her back would be less deep than her. To do so I re-imported the file and this time combined each set of shapes as their own group rather than all together. I set the depths to 3/8″ guy, 1/4″ girl, and 1/8″ hand.

At this point I moved over to the Carvey computer, and noticed that my  Easel project was set to Ex-Carve, not Carvey. When I switched it, a nice red zone appeared. …Now what? My piece of wood was small already, and if I scaled down the design that much it’d be tiny. But if I flip the figure upside down- that’s better! A small downscale and they fit again.

I changed the bit to the 1/16th inch down-cut fishtail that I wanted (with help from Allie). I had prepped my wood with light sanding and a dark ebony gel stain, because I wanted to make a multi-color piece. The background would be dark, then the girl a medium stain and the guy unstained to show off the different depths of the cuts. To do this, I split up the file into two, one with the guy and one with the girl. This made for very nice short cuts- just 3 to 5 minutes for each.

Once I had the files ready, I started cutting the girl. It looked really good, albeit full of sawdust. Toothpicks are useful for cleaning out narrow crevices.

Now to stain it. I tried a test piece first, to see what the effect would be on another piece with the girl cut into it. I opened the mahogany stain and oh, it’s liquid. With a makeshift pipe cleaner brush (see: narrow crevices) I got the liquid into the lines, much more thoroughly than I could with gel stain. It went much darker than I expected, which makes sense given the stain is soaking into the end of the grain for the most part. It was darker contrast rather than lighter, but I liked it and applied the stain to my pieces, coating the front as well for consistency.

Next, I cut the guy side. I was pushing the limits for depth of this bit, but it did stay at 1/16th inch diameter just up to 3/8″ down so it was alright. The stain wasn’t super dry (I gave it ~20 minutes), so lots of the sawdust was damp and stayed in the grooves stubbornly. I wish that were my biggest problem, but on the second piece I forgot that I was cutting the figures upside down. I got my piece clamped in and started the cut- oops! The girl had a very large arm (*ahem* guy’s leg), which I stained to match just for fun. However, that was now out of commission to be one of the two final pieces I needed. Remember the test piece? It got a promotion. I cut that one and gave the test girl a partner.

The former test piece had just the mahogany stain and not the ebony gel stain precoat, so it’s slightly lighter/redder. I had to go back and stain the sides and back with the gel stain to match the original piece. I had coordinated the grain on my original two pieces and oriented it along the lines of the dancers’ position, but the former test had none of these considerations. In the end, I did get two finished pieces, but in an anticlimactic manner.

Update: I carefully rubbed a bit of the ebony gel stain onto the front of former test piece, and now it’s darker than the other. Sometimes you just can’t win.

Cost analysis: This was 6 hours at $20/hour, so $120 labor. 20 minutes of machine time at $30/hour would be $10 for the Carvey. As for materials, 1″x4″x6′ pine is $8.62 at Home Depot, and gel stain and liquid stain are $7.99 and $8.76 respectively. All in all, the cost would be $155.37 for the pieces.