Joshua Woody: CNC Router

The first thing I did was figure out what I wanted to make with the CNC machine. When I saw the cnc tutorial example of a terrain map holding something. I had the perfect idea of what I wanted. I would learn from the tutorial, find my own terrain stl generator, and plan the perfect spot for a picture holder. My fiancée and I traveled to Enchanted rock Texas in 2019 and we loved being there. We took a pretty memorable photo that I thought would be perfect framed in a holder that would sit on our shelf. Having that picture holder be Enchanted rock itself would be amazing, so I set out to do that.

My first model had way too many triangles in it and fusion 360 kept crashing because it was trying to process way too many calculations every time I moved the viewer. With some help I was able to get an initial model that was smaller. I found it difficult to work with even in this mode and so I decided to use and search for a different STL generator. The STL generator I ended up choosing enabled me to change the elevation and angles so that it would fit my specifications for the design and I was quite happy with the initial results and size of the triangles / polygons.

When I imported the file into Fusion 360, I was initially confused about the process for creating a mess, thankfully my instructor had listed the new process in the newer version of fusion that I was using that day. The next problem I ran into was when I had to find a way to fit the design into the specifications that the CNC machine would cut. My elevation change was so different between all of the various parts of the design because I chose a mountainous structure, Enchanted Rock. The main issue I was having was that whenever I tried to move the 3D model mesh in any direction it was skewed based off of one of the polygons on the tip of Enchanted Rock, and so every time I moved it in a z Direction, it would also move in the X and Y even though I was only moving what I thought was the Z. I found that I needed to change a setting that would enable an absolute x y z movement instead of a XYZ movement based off of the orientation of the groups of polygons that I had selected.

When I got in the design to fit within the specifications, the next challenge was finding a way to create a slot. I wanted to create a slot in a very specific plane behind Enchanted Rock and not cut through it. the initial tutorial showed the slot cutting right through my centerpiece of the design, so I had to find another way to create this slot to put my picture in. when I spoke to Ryan about it he suggested that I create a new plane based off of a line in a sketch. So I turned on the sketch line, I made the model transparent, and Drew the line across the plane that I needed. The next issue I ran into was during the manufacturer preparation process where you convert the 3D model into a G-Code that will create the design based off of the different types of movements that the drill can make. During this phase, I continually got errors pertaining to different aspects of the Milling process.

The first error was the step down count and safety was higher than the ability of the drill to reach. This was due to inches being the dominant form of measurements in the design process, but I do not know for sure. The last problem I had was with the process of cutting the outside into a circle shape. Every time I said it to make a circle cut around my object it wanted to have the center of the drill be on the inside edge, cutting through all of a quarter inch of my design on either side. What I didn’t know was that Fusion 360 does not have an option a plane to make cuts on other than a visible Arrow whenever the drill line is created. In order to swap it you need to flip the design upside down and click on the bottom of the plane. Doing this will set the drill to move and cut on the outside of your object rather than the inside. Once I fixed that problem it was on to actually manufacturing the picture holder. Both of my pictures actually come from this part because I couldn’t capture screenshots nor capture pictures very easily during the design process.

During the manufacturing process I had to screw my wood into the CNC router board in order to keep it secure while the drill moved over the wood and pushes it and cuts through it. I always want to have a stable plate when I cut with anything but lasers. the process I used to cut the design using the CNC router followed four steps: first I did an adaptive cut which took off a majority of the material using a larger ¼ inch flat bit. Second I did a refinement circle pattern using a 1/8 inch ball drill bit. This refinement pass allowed me to get greater detail into my design. In order to avoid making the first cut the final cut, I had to choose a safety space around the design for the ¼-in pattern to follow so that that one instant bulb it could actually remove stuff in order to refine the design. The third cut I did was a simple slot cut that is centered behind Enchanted Rock and along the formation. This slot cut will hold the picture with a piece of board behind it to keep it steady. Lastly I cut the square STL file into a circle so that it would take up less space and look better

The last step I took was to polish and sand the product . doing this helped clean up the shredded edges that the drill bit and made it very pretty. I think that I did a good job on this product and can’t wait to surprise my fiancé with the gift. I learned a lot about fusion and CNC and the process of cutting something out of a piece of metal or wood instead of building something up from the ground up like with 3D printing. I think I grew a lot in my knowledge of how to make something using a CNC machine and how to mitigate some of the problems using certain machines and techniques.