PART I: Introduction
In this section, I learned how to operate a CNC machine to create a 3D project, which was an exciting milestone for me. I was thrilled to finally incorporate the “Deathly Hallows” symbol into my design. Previously, I had planned to use a plasma cutter to embed the “Deathly Hallows” into my diamond project. However, the plasma cutting assignment had specific requirements, and the tool’s limitations made it impossible to execute my original idea. For this project, I revisited the concept and searched for the “Deathly Hallows” design on the Noun Project website.
PART II: Workflow
- First: Object selection
In the beginning, I search for the object from the website, Noun Project. Eventually, I selected “Deathly Hallows,” designed by Raunak Dutta, for this homework. Below is the draft.
. - Second: Size adjustment and toolpath design
According to the requirement, the object size should fit in a 3 x 5 inches wood board. So, adjusted my object to 2.7 x 3 inches. Later, I used Contour and Pocket two methods to design the toolpaths. In total, each piece of my object took around 25 minutes to complete.
. - Third: The CNC process
Later, I exported the file to the CNC machine, Nomad 3, to complete my object.
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↑↑↑ 1.5x speed
. - Last: Post-processing
Last, I used the No.200 and No.400 sandpapers to polish the surface of the objects. After sanding, I coat a layer of oil on the surface to complete the post-processing.
↑↑↑ After CNC processing
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↑↑↑ After sanding ↑↑↑ After oil coating
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PART III: Troubleshooting
- [Issue 1]
Since the Nomad 3 lacks a vacuum system, wood dust tends to accumulate and refill the cutting path. This buildup increases pressure and prevents the CNC machine from fully cutting through the contoured areas. In the photos below, you can see that no light passes through the outline of the object, indicating the CNC did not cut through the wood board completely. However, when I paused the process and removed the wood dust, the issue was resolved. As shown in the photo on the right, light can now pass through the outline of the object, confirming the path was successfully cleared.
↑↑↑ Before ↑↑↑ After
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To remove my piece from the wood board, I used a sanding tool to carefully sand the backside. After processing, I noticed that the wood layer along the outline of the object became significantly thinner, making it easier to detach.
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PART IV: The Work Space
The space was cleaned after used.
PART V: Cost Estimation
| Cost Type |
Cost | Price | Source | Quantity | Total |
| Materials | 2 in. x 10 in. x 8 ft. Prime Lumber | $8.98 | Home Depot | 1 piece | $8.98 |
| 1 Quart Teak Oil | $21 | Home Depot | 1 ea | $21.0 | |
| Labor | Machine Shop CNC Operator | $23.5/hr | Indeed.com | 1 hr s | $23.5 |
| Labor
Overhead |
Prototyping Engineer (You!) |
$25/hr | Indeed.com (Engineering Intern) |
2 hrs | $50.0 |
| Machine Time | $180/hr | community.carbide3d.com | 1.5 hrs | $270.0 | |
| Overhead
Design |
Quality Control | $22.5/hr | Glassdoor.com | 1 hr | $22.5 |
| Engineering and Development | $25/hr | Indeed.com (Engineering Intern) |
1 hr | $25.0 |
Total: 420.98
The total cost for completing the CNC objects was $420.98 for two pieces, making each piece $210.49. Most of the expense came from machine time. As I become more familiar with the CNC machine, I might be able to reduce costs slightly. However, for complex designs, minimizing machine time is challenging. On the other hand, if my goal is to use the CNC machine to create a mold for casting, the cost-effectiveness improves significantly. The more casts I produce from the mold, the more the per-unit cost of the CNC process decreases.
