Background
I have never heard of a CNC machine before this class, so I was excited to learn how to use it and create something with it.
During our CNC training, we had some issues with the wood sticking to the “sacrificial wood.” The wood we were cutting into would become loose, even after a good amount of tape, and would start spinning out of control. Going into this assignment, I knew that this was something I would have to look out for.
Creating the Design
I wanted my design to be simple, so I found a flower design from the noun project and then placed a circle around it. After placing my design into Carbide Create, I set up the workpiece by changing the material size to the size of the wood block I was using. I then scaled down the size of my design so that it fit into the size of the wood.
Left: initializing the size of the wood; right: scaling down the design
Lastly, I designated which cuts I wanted to be pocket cuts and which cuts I wanted to be contour cuts. I made the flower inside to be the pocket cuts (with a depth of 0.125 inches) and the circle bordering it to be a contour cut. When selecting the max depth of the contour cut, I made it 0.1 inches less than the height of the wood. Doing this would prevent the wood from losing contact with the bed once the drill bit cut into the bottom of the wood piece.
Designating which cuts are pocket cuts vs. contour cuts
Setting up the Machine
After saving the GCode, I began setting up the machine. First, I noticed that the drill bit in the machine was not the 0.125″ bit (#102 Tool) that I had designated in the GCode. I switched it out by unscrewing the bit that was currently inside and putting in the new one.
Next, I taped up my piece of wood with 5 short strips. I placed the piece of wood firmly on the bed.
Lastly, I initialized the machine with the probe. I placed it in the lower left-hand corner of the wood block and let the machine detect the corners.
Left: taping the bottom of the wood; right: initializing the machine with the probe
Starting the Cuts
I started the job for my first piece. The first thing I noticed was that it started cutting the outside circle first before doing the pocket cuts. I thought that doing the pocket cuts first would probably be a better idea, just in case the outside circle started moving while doing the contour cut. I let the machine finish the rest of the cuts and decided that I would change the GCode later to switch the order of the cuts in the second piece.
Still, the first piece turned out well! Because I set the max depth of the contour cut to be 0.1 inches less than the height of the wood, the piece was still “attached” to the wood. In later steps, I will explain how I cut the final piece out.
Left: the machine cut the outer circle first; right: finished result right after cutting
In the second piece, I followed the same steps above. I altered the GCode so that the pocket cuts would be done first. I honestly didn’t really see a difference in the final result, but it was interesting to try out switching the order anyways.
Altering the GCode for the second piece
Post-Processing
Next, I needed to actually cut the shape out of the wood. I used a bandsaw to cut the remaining 0.1 inches out so that I would be left with just the circle. The result of the cut left rough edges on the bottom of the circle, so I needed to sand them down. I repeated this with the second piece as well.
Left: using a bandsaw to cut out the circle; right: rough edges on the bottom
I first used sandpaper with a rougher grit to smooth down the edges. I then finished off the sanding with a finer grit. I also folded a small piece of sandpaper so I could also get within the grooves of the flower design on top.
My final product is shown below!
Reflections
Overall, I was satisfied and impressed with how quickly I was able to complete this assignment. I was especially happy with how I was able to avoid the wood from losing contact with the bed, which happened several times during my training.
Cost
- Two 6″ x 3″ x 0.7″ wood planks = $4, Lowe’s
- Double-sided woodworking tape = $19, Amazon
- 0.125″ drill bit = $2, Amazon
- 2.5 hours of labor x $12 per hour = $30
- TOTAL = $4 + $19 + $2 + $30 = $55
