CNC Machine Homework – Making Two Little Bears
For this week in BIOE 555, we were tasked with using one of the two available CNC machines to create something from 3.5″x5.5″ wooden blocks. My chosen blocks were approximately 0.765″ thick and I had to edit the stock height in Carbide Create to make sure the CNC machine drill bit would cut through the entire piece. I used the Noun Project website to find a design I liked. First, I chose a cute seal but found out the details were too fine and broke off after they were completed. I found a simpler design of a cute bear instead.
Figure 1. First Chosen Design (details are too fine)
Figure 2, Final Design Toolpaths in Carbide Create
CNC MACHINE USE
SHAPEOKO – I used this machine to cut out the seals and they looked great but the contoured edges broke easily because the details were too fine for the drill bit size (1/8″). I used the green clips and screws to secure my wooden blocks, initialized the machine, probed for the starting point and tool length, and ran my cuts. Both cuts took about 20 minutes each. The resulting seals were cute but (as mentioned previously) detailed edges broke upon touch.
Figure 3. Shapeoko Set-Up
NOMAD – This machine was a bit easier to set up but was very similar to the Shapeoko. This is the machine I used to make my final product bears. I had to place an extra wooden piece to protect the equipment in case the drill went too far down into my cutting block.
Figure 4. Nomad Pro Machine and Equipment
Figure 5. Bear Cut by Nomad CNC Machine
POST-PROCESSING
To post-process my bears, I sanded the pocketed portions of my design. My second bear did not cut all the way through so I had to use the disc sander on the back until the cut design was able to pop out. When hand sanding, it was difficult to get rid of all of the striations made by the drill bit due to the tight spaces in the more detailed portions of the bears, near the nose and mouth. I ended up breaking the mouth since the wood there was extremely thin, but I was able to replicate the break in the second bear.
Figure 6. Sanding of Partially Cut Second Bear Block
Figure 7. Post Sanding and Staining of Bears
COST ANALYSIS
| Cost Type | Cost | Price | Source | Quantity | Total |
| Materials | 3.5”x5.5” Board | $12.48 | Lowes | 1 board | $12.48 |
| Sandpaper | $10.99 | TCP Global | 1 set | $10.99 | |
| Tried & True Stain | $34.99 | Amazon | 1 can | $34.99 | |
| Labor | Woodworking Operator | $23.75/hr | Indeed | 4 hours | $95.00 |
| Prototyping Engineer (You!) | Included in Operator Rate | Self | – | – | |
| Overhead | Facility Cost (Machine Time)
CNC Machine Access Carbide Create Subscription |
–
$120/year |
OEDK | 3 hours
30 min |
$120 |
| Quality Control | Included in Operator Rate | Self | – | – | |
| Design | Engineering and Development | Included in Operator Rate | Noun Project Files & Self | – | – |
| Iterations | – | – | 4 attempts | – | |
| Misc. | Waste and Scrap | – | – | 60% of wooden blocks scrapped | – |
Total: $273.46
Figure 8. Final Product – CNC Machine Cut Bears
Figure 9. Proof of Clean Workspace
SUMMARY
Overall, this project was more software-heavy but the CNC machines were relatively easy to set up and use. I used the vacuum to clean up any debris and sawdust left from the cutting process. I tried to get a quote for CNC machine use but the website gaslit me so I had to make my cost analysis assuming that CNC machine access is provided through the OEDK. This analysis does take into account the price of the software subscription which totals about $280. This is on the lower end of most of the costs I have estimated for projects up to this point, but I expect CNC machine access and making vector files from scratch (via graphic design) to raise this price to around $500.
Thank you for reading!!
