The Process

We were tasked with producing a physical object using CNC machining. I decided I would create wooden coasters with a kiwi bird etched into them.

After navigating through The Noun Project website, I found the perfect file of a kiwi image to base the design off of. I downloaded this file as an .svg, imported it into Carbide Create, and created an outer circle (~4.5″ [later scaled down to 3″] in diameter) that would delineate the circumference of the coaster.

After adding tabs and creating the appropriate toolpaths for the contour edges and inner pocket, I simulated the run, saved the file, then uploaded it into the OEDK desktop program.

After measuring my pieces of wood and adjusting the settings/dimension measurements in Carbide Create, I placed the wood on the Nomad3 stage with a piece of scrap wood underneath. I tightened the stage hold, then placed and taped down the homing device to the lower left corner of the piece wood. I jogged the 1/8″ drill bit over to and into the hole in the homing device and allowed the machine to calibrate itself. I then removed the homing device, and ensured the hood was properly closed before running the 15-minute cut job. I watched the CNC machine cut the pocket first (as I had programmed it to), followed by the full-thickness perimeter cut.

After the 15 minutes was up, I vacuumed up all the sawdust and removed my piece from the stage. After popping the circle out of the 4-tab hold, I was happy to see my piece turned out great!

I repeated the same steps again to cut my second kiwi coaster. I measured the dimensions of the second wood piece and updated the settings in the Carbide Create file accordingly. In opening the OEDK desktop app, I imported the second file. After calibrating the device again using the corner homing device, I started my second cut. Fifteen minutes later, I now had my second coaster.

Before leaving the CNC machine station, I made sure my workplace was completely vacuumed and cleaned for the next user. This included vacuuming inside the machine, under the stage, and on the workbench top.

Moving into the post-processing phase, I chose to sand down the rough edges and what remained of the circumferential tabs. I started with 80-grit sandpaper on the sides and back, and lightly to the front of the piece, followed by light passes with 120- and 220-grit sandpaper. Once I was satisfied with the smoothness of the pieces, I applied 2 coats of teak oil to give the coasters a warmer “woody” look.

I allowed them to set overnight and returned the next day to find my beautiful, completes coasters!

Overall, I am very happy with my pieces and cannot wait to gift them to my Kiwi.

Reflection

This process went relatively smoothly, but I did find myself relying on homework instructions and the TAs during the tutorial more than in other homework assignments, which, in my eyes, is a sign of being really unfamiliar with CNC machining. However, this was one of my favorite machines to use, and I am a fan of how my work turned out. Some things I would do differently the next time I CNC include:

• Add less tabs to my smaller CNC pieces. I added 4 tabs, and had to use a lot of force to push it through after cutting.
• After sanding, not wiping down the pieces with wet paper towel if I planned on staining or applying oil. I realized the stain/oil-soaked towel would work in removing post-sanding particles and I therefore wouldn’t have to wait for the piece of completely dry of water prior to applying this oil/stain, ultimately saving me time.
• Try to apply lacquer. I saw some of my colleagues applying pretty, shiny colors to their CNC pieces, and I want in.
• Add a clear coat of paint on top for better protection. I may do this prior to turning in my final piece, but I love the texture as it currently is.

Cost Estimate

Cost Type	Cost	Price	Source	Quantity	Total
Materials	Wood   Teak Oil	$2.98/plank   $0.56 / fl oz	Lowe’s   Amazon	1   5 fl oz	$2.98   $2.80
Labor	CNC Operator and Post-Processing Engineer (me)	$18/hr	Glassdoor	2 Hour	$36.00
	Prototyping Engineer (Hat-Tech and me)	$36 /hr	ZipRecruiter	2 Hour	$72.00
Overhead	Nomad3 CNC machine	Free access for EDES students	OEDK	2 Hour	$0.00
				Total	$114.37

As I gain experience, production costs will minimally drop as the time required to set up the CNC machine shortens; I spent some amount of time familiarizing myself with the Nomad3, and that time will decrease with experience. Additionally, once the cuts are designed, they can be produced in mass, so this “prototyping engineer” cost will be spread out over more printed objects.