To become familiar with CNC (computer numerical control) machining, we were tasked with using the CNC machine to cut out a “noun” (icons posted on the site Noun Project) from a block of material. The constraints for the assignment were that the noun had to be a minimum of three inches on one side and the final product had to have at least two different milled depths.

At first, I struggled to choose a noun, simply because of the sheer number and variations of nouns available. Since this year marks the centenary of the Bauhaus, I chose a noun related to the design school. Specifically, I chose a noun of Marcel Breuer’s iconic Wassily chair created by Nicole Yip.

I downloaded an SVG file of the noun and edited it on Adobe Illustrator to make it compatible with the format required by Easel, the 3D carving software for the Carvey CNC machine. I then selected my material, a piece of plywood, which I smoothed out using the belt sander. Afterwards, I moved onto measure the material and set the dimensions in Easel as well as a 1/16” upcut bit.

After the two hour carve, I went to pick up the pieces and realized they had definitely not come out the way I had intended- parts of the noun were missing and certain sections of the wood were burnt. Fernando suggested this had happened because of the plywood. He recommended I use MDF for my next cut.

For the second cut, I not only used MDF, but also changed to a 1/32” bit to make the noun more detailed. I also reduced the number of tabs on the chair’s outline from four to two so that I would have to do less sanding to take off the piece from the wood block once the carving was done. The carve would four hours for one chair, but since it was early in the week, I figured I would have enough time to carve both chairs. When I went to check on the piece later that day, I found that someone had removed it from the machine shortly after the carving had begun.

I decided to try the carve again on a particle board, which I colored with a mahogany stain before placing in the Carvey. I had assumed that the particle board would work just as well as MDF, but unfortunately the carving did not work well, so I stopped the job a few minutes in.

Because I was already on my fourth attempt, I chose to pursue a simpler noun with a faster carving time in the case that I ran into additional challenges. I didn’t find another Bauhaus noun that I liked, so I chose a noun based off of another iconic design, Charles and Ray Eames’ molded plastic chair by Pavan N.

I went back to using MDF as my material and stained it with beeswax. I also selected different depths for the legs of the chair and the seat itself. Initially, I wanted to use the 1/32” big again, but decided against it since the carve would take two hours versus a forty minute carve with the 1/16” bit.

The carve of this noun was more successful than the previous ones. However, I still ran across a couple of challenges. Towards the very end of the first attempt, the Carvey’s spindle hit the clamps holding down the material because they were too close to the chair’s outline. While trying to correct the mistake and avoid having to restart the carve, I accidentally moved the drawing on Easel without noticing. The new drawing carved the outline of the chair too close to the chair, so I decided to start the carve over. Another challenge that I faced was that the two of the supports for the legs broke off on the same chair because they were too fragile. Since I had already spent so much time on carves, I decided to simply glue the two pieces back using wood glue.

 

To complete my post processing, I sanded the corners of the part that had the tabs with sandpaper as well the inside of the noun. I also painted the seat of the chair with white acrylic paint.

Here are my final two pieces:

Cost analysis

Labor

• Approximately 7 hours of labor, $15/hour = $105

Material

• MDF board (1/2 in. x 2 ft. x 4ft) sold for $12.99 at Home Depot. I used approximately ½ of that amount, so $12.99/2= $6.50
• Particle board (5/8 in. x 2 ft. x 4 ft.) sold for $8.97 at Home Depot. I used approximately ⅓ of that amount, so $8.97/3= $2.99
• Birch plywood (1/5 in. x 4 ft. x 8 ft.) sold for $14.98 at Home Depot. I used approximately ¼ of that amount, so $14.98/4= $3.74
• Feed-n-wax sold for $8.48 on Amazon. I used approximately ¼ of the bottle, so  $8.48/4= $2.12
• 2 Fl oz. of white acrylic paint sold for $0.99 at Target. I used approximately ½ of that amount, so $0.99/2= $0.50

Equipment

• Membership at a makerspace to use the same equipment (TXRX Labs)= $50

Total: $105 + $6.50 +  $2.99 + $3.74 + $2.12 + $0.50 + $50 = $170.85