For this project, we were tasked with using one of the CNC machines to cut out two copies of a noun of our choice from wood. I decided to use the Nomad CNC machine and chose a cute leopard seal as my noun. My first step was to select an icon from NounProject.com and modify it with Carbide Create. Given the time I had to work on this assignment, I decided to keep things simple and cut out my pieces in one go, without having to switch the drill bit size. Some details on the seal were too small for the 1/8″ drill bit, so eventually I had to get rid of the tail lines and make the spots and eye bigger.

 

 

 

 

My original plan was to carve out the main body of the seal and cut out the outline. I began by inputting the dimensions of my wood block and assigning the pocket and contour tool paths accordingly. I fit two seals into one wood block to finish both in one sitting. Then, I taped my wood to the base, probed the machine, and installed the 1/8″ drill bit. As the CNC machine began cutting out the outline, I quickly realized that although it looked like it would all fit in the simulation, the actual outline was too big and close to the edge of the wood. Surely enough, when the drill got to the edge, it moved the block, so I had to stop the machine.

For my next attempt, I decided to simplify the process by carving out the details only and cutting out the shape. This required me to make the eye and spots bigger, since the original size was too small to create a tool path. I also made the seals slightly smaller to prevent getting too close to the edges of the wood.

 

 

 

 

 

 

Unfortunately, the seal wasn’t cut all the way through this time, since the thickness wasn’t uniform throughout. In retrospect, I think I was too worried about letting the drill come into contact with the tape underneath. Moving forward, I decided to use the largest thickness for the contour tool path, instead of the average thickness. Since I had to restart anyway, I decided to add another outline to the seal to create a border around the shape. Since my shape wasn’t symmetrical, I couldn’t do this quickly on Carbide Create. I had to add a stroke outline using Adobe Illustrator and offset it by 1 pt. This change allowed me to include the fin outline and give the seals a more complete look. For my last attempt, I decided to carve out the interior of the seal to a depth of 0.1″ and then carve out the eyes and spots to a depth of 0.15″. I also used an outside/right contour to cut out the shape outline and create the border.

 

 

 

 

 

 

This final attempt was a success, although some small chunks of the borders were removed as the drill was cutting out the shape. Now it was time to sand and stain my pieces. Here, I had some challenges removing the seals from the wood block since the tabs were hard to break. Once broken, the tabs left behind rough edges that I had to spend extra time sanding off. It was also tricky to smooth out the edges on the eyes and spots since they’re pretty small spaces. When applying the stain, it was hard to prevent it from creating pools in the inner corners of the tails and fin. In retrospect, I should’ve brought a pointed Q-tip to soak up the excess in these hard-to-reach areas. Overall, I’m happy with the result and I feel much more comfortable using the CNC machine.

 

COST ANALYSIS FOR CNC Machining

 

Cost Type	Cost	Price	Source	Quantity	Total
Materials	4×4 Wood blocks	$12.49 for 4	Amazon	2	$6.25
	Mahogany wood stain	$9.99/can	Amazon	1	$9.99
Labor	CNC Mill Machinist	$25.08/hr	indeed.com	2 hr	$50.16
	Quality	$32.56/hr	salary.com	0.25 hr	$8.14
Overhead	Electricity	17.01¢/kWh	ElectricityPlans carbide3d.com	0.22 kWh	$0.04
Design	Free online	0	Noun Project	–	0
Misc.	Waste/scrap	–	Excess wood	2	$6.25

The total for the CNC machining of my two seals comes out to $74.58, not accounting for waste.