Since I got to play with a drill, I knew that such a tool could be used to create abrasions in materials. Taking that into consideration and comparing the drill to the machine I’m using today, the CNC machine is just a glorified drill that makes these abrasions cooler. The CNC mill is a one-of-a-kind tool, as it can mill many materials at high precision and quality. However, despite the CNC machine being a much bigger and more powerful drill, the machine is quite difficult; nonetheless, the results are rewarding once you become a master at milling.

1. Introduction

Before getting to milling, we need to find a design we want to prepare and feed to the CNC machine. For this particular job, I decided to go with something single: a cat face. It shouldn’t be that hard, right? We will know the answer to that later but for now, we will add specific cuts to the cat’s face and export the file from Carbide Create to have it ready for milling the next time I am at the OEDK.

2. Design

The imported cat design below was scaled to be a 3 by 3 figure that contains eyes and ears. As part of the designing process, I had to decide what lines I wanted to pocket and which ones I wanted to contour. Originally, I wanted to pocket the eyes by .2in, contour the ears, and pocket the face by 0.1n in to create a cool 3D effect with the cat’s nose sticking out while the eyes were sunken in. However, after looking at the time this would have taken (26 minutes) I decided to remove the face pocket and the nose. The designs I went with for the cats were 1) pocketed eyes with contours offset outward, ears contoured offset outside, and a stock bottom contour around the face to cut it out. and 2) pocketed eyes with,  ears contoured with no offset, and a stock bottom contour around the face. This was done to create some variation in the design and to somewhat test the fine detail the Nomad 3 can show off. Once the designs were ready, I rendered a simulation to visualize how the cats might come out. I was quite satisfied with the render, and with this, I saved the file and imported it into Carbide Motion to mill it.

3. Milling and Post-Processing

Once I turned on the CNC mill, I initialized the machine and began taping the pieces of 6″ by 3.5″ wood onto the mill bed with double-sided tape (3-4 lines) and hard-pressed the wood into place.  After feeding the file to the Nomad 3, I began the standard probing procedure: I tested the tool approximately three times, jogged the bit to the probe, and used the probe to find the corner of the pieces of wood I was using, and then tested the tool bit again before drilling. After making sure everything was ready, I began cutting away. The pockets were coming out nice, and the contour cut was coming out smooth for a while, but around the halfway point, the block of wood unstuck from the bed, and I had to emergency stop the machine. I was confused as to what happened because I had used a lot of tape on the Nomad and made sure there was no sawdust underneath it. Since all the information was stored in the machine, I placed the block of wood in the corner and re-did the cut. Again, it was going well, but suddenly, the block of wood was unstuck again. This became frustrating because this inconvenience was taking too much time, however, I found a solution. Instead of redoing the cut again, I modified the file to only cut the contour, and every time I would cut, I would pause the machine, as it pauses almost immediately without me needing to redo all the setup. Doing this method on and off, I was able to the first cat head. Though the second head was also difficult to cut, I had put an excessive amount of time into the block of wood, and though the take was shearing under the mill’s torque, I was still able to get a cut for the second cat almost effortlessly.

After successfully cutting out the cat heads, I noticed that they had a lot of sawdust and splinters. To remove these, I simply sanded the cat’s interior walls and rounded the edges to give it a nice, finished look. This made the end grain look cool and prepared it well enough to apply stain over the cats. After applying the stain, I carefully spray-painted the ears and eyes by using masking tape. The amazing this about this step was if spray paint got on the stain, I could simply wipe the paint away and restain as if nothing ever happened. In the end, I was able to get the nicely colored cats at the bottom!

4. Considerations

After this experience, I have one big thing to take away from this assignment: Find a way to guarantee that your piece of wood does not shear off the plate when using the Nomad 3. From the people that I have seen use this machine, the double-sided tape just doesn’t hold and it messes up so many potentially good cuts. If there is a way to secure the milled wood, I would definitely implement this the next time I decide to CNC mill using the Nomad. Other than the horrendously fastened boards, I have nothing else to really consider. Everything else went smoothly with this project. The only other thing I considered a mistake was the way I painted the cats, as I should have been more careful with the stain seeping down the yellow and pink areas. This created some blotches of black in the eyes and ears, but nothing too noticeable. Aside from a post-processing hiccup and the CNC mill not staying put, there is nothing else to consider or report.

5. Cost Analysis

1″ by 4″ by 12″ Commond Wood Slat = $1.11 (Home Depot)

Verathane Classic Black Wood Stain (8 oz) = $7.98 ( Home Depot)

2 Rust-Oleum Spray Paint Bottles = $12.96 (Home Depot)

CNC Technician Labor Cost (1 Hour) = $24.30

Tax = $1.82

TOTAL = $ 48.17