For this project our goal was to use a Computer Numeric Control (CNC) machine to cut out a piece from wood that represented a “noun”. The noun of my choice was “rocking chair”. I chose this design because I planned to cut out a piece that people would be able to interact with!

I couldn’t have a cut out piece if I didn‘t have a design completed of course, so my first step was to select the design I would cut out from the noun project. This is the one I selected: https://thenounproject.com/icon/rocking-chair-4491015/. Then, I uploaded this image to Carbide Create V7.

On Carbide I added toolpaths so the CNC machine would know where to remove material. The constraints were just to make sure the outline of the piece was cut out and because my plan was to cut out the chair itself I achieved this goal with my design! I added five tabs to my design so that when certain parts were contoured (cut) out the piece wouldn’t end up flying out before the cut was finished. Then once this was done I adjusted my settings for my cut of the wood I was using to 3.5″x 5.5″x 0.745″. Once done with this I ran a quick simulation of the cut to clear my download. 

 

I uploaded my download to Carbide Motion. After this I completed these steps: 1. Turned on the Nomad CNC Mill machine to connect to Carbide Motion 2. Secured block of wood to (on top of scrap plywood in case it cuts too deep) 3. Initialize the machine and change the tools if necessary 4. Jog the tool over to get the machine ready to probe to prep for cutting. Once I finished these steps I ran the job so the cut would begin (lasted 20 min).

Result 1:

My first cut did not come out well as it did not fully piece through the wood. I eventually got it out but the wood had a lot of pieces ripped off, and the design didn’t look how I originally wanted the cut to come out. So, in Carbide Create I redid my toolpaths on my holes to cut from the Inside/Left instead of Outside/Right like I originally had them. I also ended up getting new wood and measured this out with a 0.75” thickness. I updated this in the settings of Carbide Create for my wood dimensions. Overall, my chair has dimensions of 3″x 3.0036″x 0.75″. Then I repeated the same steps above to start my print again.

Result 2: 

My next cut came out way nicer than the other cut and all I had to do was push the piece out (due to the tabs holding it in place). Next, it was time to get my second piece out following the same steps above again.

Result 3:

Oh no!!! I’m not sure what happened, my piece of wood was cut from the same long piece of wood so I can’t fully explain why the cut did not go through like the last one. I fought to get it out of the wooden block but once I finally did the top part of the chair broke off 🙁 .So this time I had to repeat the steps another time but I updated the thickness of the wood to be 7.6 as a measured my next piece of wood to be around 7.6” thickness. 

Result 4: 

Yay! It finally worked and this piece immediately came out when I pushed it out of the wood (and tabs). Finally I was done.

Although I would vacuum in between my cuts and during the cutting process I did one final vacuum to have the space cleaned.

Then I went outside to begin post processing. I needed to smooth my pieces out so I utilized sandpaper to get that done. I used sandpaper with grits of 40, 60, 80, 100, 120, 140, 160, 180, 220. It came out nicely smoothed and feels great! Afterward I decided I wanted to polish my piece specifically so it would look like a real piece of artisanal furniture. I used a wood stain with an english chestnut color. I did three coats of this (with wiping in between) and allowed time for penetration of the stain to the wood.

Here is my final product!

Here are my cleaned workspaces once done!

Cost analysis:

Varathane  Provincial Classic Wood Interior Stain – I used about 0.2337662qt and the cost at Home Depot for 1qt of this stain is $23.96. Therefore the cost is about $5.60.

Sandpaper(s) – I used 9 different grits and each sheet of sandpaper per grit costs $1.39 at Ace Hardware for a total of $21.66

Lumber – Costs about $2.16 for 3 pieces of dimensions 3.5″ x 5.5″ x 0.75″

Labor:

Prototyping Engineer: Makes about $35/hr in Houston according to ZipRecruiter. So, this means for about 5 hours of work the salary was $175.

Nomad Mill Operating: According to https://knowcnc.com/cnc-machine-hourly-rate-calculator-estimate-costs it is about $5.88/hr and for 3 hours of operating the costs were ~$17.65.

The total price: ~$222.07