For the CNC milling project, I knew I wanted to create something functional. After some thinking, I thought it would be cute (and ironic) to make a lung ashtray! To do this, I found a human lung icon on the noun project that I liked. I wanted to find an icon that had a separate shape for the lungs and trachea and the pulmonary veins, because I wanted to add multiple depths to my piece and cut the pulmonary veins deeper into the piece than the lungs and trachea. In addition to this, I wanted to add a wall around my piece to create a “tray” shape. Because of the unique lung shape, I couldn’t just copy-and-paste the lung shape in Carbide Create. Instead, I had to customize my icon svg in Adobe Illustrator before sending my file to Carbide Create.

After sending my file to Carbide Create, I specified two pocket cuts: the pocket cut for the lungs and trachea, and a separate pocket cut for the pulmonary veins. Since an ashtray has to be pretty deep to hold its contents, I set the lung/trachea depth to be 5.04 mm, and the pulmonary depth to be 10.08 mm. I specified the contour cut to be outside of the outline, so a wall was created around the lung and trachea to hold the ashtray contents.

After setting up my file, I was ready to cut! I had some trouble with the wood block wiggling during the milling procedure on the Nomad 3 because the double-sided tape was not strong enough to keep it in place, so I made sure to let the block adhere to the Nomad 3 base for at least 30 minutes before I began my cut. The cut took around 35 minutes, and I was incredibly nervous the whole time.

The cut wiggled just slightly during the pocket cuts, but I paused the cut, pressed the block down, and continued with no issues. The issues began when I began the contour cut. The block started lifting up off the base and twisting during the contour cut. Due to time constraints (and the suck cost fallacy), I constructed a mechanism to hold the block still as best I could for the remainder of the cut, shown below. I also slowed down the mill speed. Even with these modifications, the block still wiggled, resulting in uneven wall thicknesses around each lung.

After this cut, I went ahead with my second cut. The remainder of the wooden blocks on the ENGI210 table that were not warped had significant splintering on one end, so I resized my lungs to be able to avoid this fragmented section of the block. I did not re-simulate the cut in Carbide to assess the consequences of resizing my piece, though, and it unfortunately ruined the pocket cut for the pulmonary veins as shown below. Due to time constraints, though, I went ahead and post-processed these pieces.

I first used an orbital sander to remove these pieces from their wooden blocks. While removing the tabs from the pieces, though, I splintered the bottom of the piece. In hindsight, I should have sanded down the tabs. I used rough sandpaper to sand each piece, then used very fins sandpaper to smooth them down further. After this, I stained each piece with linseed oil.

Despite the setbacks, I’m really happy with how my larger piece turned out. If I had more time, I would have filled the pulmonary vein cavities with red or blue epoxy. I plan on doing this when I get back to campus after winter break. In summary, I am proud of overcoming the hurdles I encountered to produce this piece, and I think it’s so adorable! Even as an ashtray!

Cost Analysis:

Cost Type	Cost	Price	Source	Quantity	Total
Material	4 x 4 plank	$3.56	Lowe’s	1	$5.48
	Linseed oil	$11.13	Amazon	1	$11.13
Labor	CNC Mill Machinist	$25.10/hr	Indeed	1 hour	$25.10
	Quality Engineer	$32.50/hour	Salary	0.5 hours	$16.25
Overhead	CNC Mill	$50/hour	Wood-cutting CNC mill estimation	1 hour	$50
Design	Noun Project Icon	$0	Noun Project	–	$0
Waste/Scrap	~⅛*4×4 plank	$0.50	Lowe’s	1	$0.50
TOTAL					$108.46