Process:

To start this assignment, I chose what shape I wanted to machine from thenounproject.com. I chose an image of a bird. Using the Carbide Create software, I added a contour cut around the outside of the bird, along with tabs to allow the bird to be removed more readily. I then decided to add some pocket cuts to emphasize some features of the bird by using different z-levels for different features. After confirming the cutting parameters and operational order was correct, I exported the file and opened it in the cutting software on the Nomad3 CNC.

Carbide Create to set machine path

The following process was identical for both birds I machined. I set up the Nomad3 CNC according the instructions given during training and also written with the assignment, and started the cut while monitoring closely for any sounds of the process going awry. Luckily, no problems emerged.

Nomad3 CNC in process of machining

After the cut, I removed the piece and thoroughly vacuumed sawdust out of the piece and the CNC machine, leaving the machine clean for the next user.

My measurement for the total depth of the wooden piece was slightly inaccurate, leading to the whole border not being completely cut out, but because the remaining depth was so small, I was able to gently press out the bird.

Piece immediately after machining, lack of complete cut along border seen along with clear path of where border is due to narrow depth of remaining wood

Removed bird from wood

With one bird, when the tab was used to remove the bird, a small amount of the wood was broken in the back of the bird as well.

Small broken part at top of wood on one piece

To post-process, I first used an orbital sander to smooth the accessible edges of the bird, but was not able to reach the pocket cuts. Therefore, after using the orbital sander, I used a finer sandpaper to gently smooth any uneven surfaces in the pocket cut, and also went over the other surfaces of the bird with this finer sandpaper to result in a smoother finish.

Piece after orbital sanding step

Finally, I stained all surfaces of the bird and left it to dry as a last step, yielding the final machined birds.

Pieces drying after applying stain

I then cleaned the spaces I had worked on.

Clean workspace

Final pieces

Cost Model:

Cost Type	Cost	Price	Source	Quantity	Total
Materials	3/4 in. x 4 in. x 8 ft. Cedar Board	$9.87	Home Depot	1 ft/8ft	$1.24
	Sand Paper orbital (15 pack) Sand paper sheets (24 pack, assorted)	$9.97 $20.59	Home Depot Home Depot	~1/15 ~2/24	$0.67 $1.72
	Wood stain	$12.98	Home Depot	~0.25 qt	$3.25
Labor	CNC machine Operator	$23/hr	ZipRecruiter	1.5 hours	$34.5
	Prototyping Engineer	$36.5/hr	Indeed.com	1 hour	$36.5
Overhead	Facility Cost (Machine Time)	$40/month	The MakerBarn	1 month	$40

Total: $117.88

As we work with wood, the cost of materials are fairly low and would be expected to scale about linearly with increased production. As CNC machine operating requires a level of attentiveness, the cost of machine operator labor would also be expected to scale approximately linearly with production, although by doing all the sanding and staining in batches might save some time and therefore slightly decrease costs. The prototyping engineer would also only be used in a very limited capacity I would expect with increased production, decreasing labor costs per item. With increased production, purchasing CNC machines may become warranted when using makerspaces becomes no longer feasible. Purchasing these machines could drive up overhead costs considerably as each Nomad3 CNC machine is about $2800, so the benefits of purchase would need to justify these costs.