For this project, I designed and programmed a 20-sided die (d20) using Fusion 360. I modeled the geometry in CAD, created the CAM toolpaths, and machined it on the Pocket NC 5-axis mill. This project challenged me to work with complex angles and multi-axis toolpaths, making it a great learning experience in precision machining and 5-axis programming. I'm really proud of the final result.
For my design, I followed a YouTube tutorial that used 3D sketches and the Patch tool to create the 20-sided die. To ensure accuracy, I placed the origin at the center of the hole, which helped align the toolpaths precisely. I also modeled the stock in Fusion 360 to improve positioning and setup accuracy. I originally planned to engrave the numbers on the die, but due to time constraints, I wasn’t able to complete the engravings.
For the programming process of the die, I started with an adaptive cut to rough out the overall profile. One challenge we faced was getting a clean finish on the sides using the side of the cutter. We solved this by adjusting the Z-axis to optimize tool contact.
A major issue we encountered was that our stock pieces had different radii. Some were turned down on the lathe, while others ended up being too small. In my case, the stock was undersized, so I had to scale down my part in Fusion 360 and adjust all of my sketches and toolpaths accordingly to ensure it would fit within the available material.
After the initial roughing, we used a contour toolpath to finish the top faces. Once the top row was complete, we rotated the part and used another adaptive cut to rough out the side profiles, followed by contour toolpaths to finish those faces as well.
For the final set of faces on the bottom, we added a tab to prevent the die from falling during machining. To accommodate the tab, we adjusted the finishing pass heights so that only part of the face was cut, leaving the rest intact for stability.
To ensure the toolpaths would run correctly on the machine, we uploaded the program to Pocket NC’s simulation website. One issue that came up was that the machine didn’t recognize the G254 N9 code. To fix this, I simply removed that line from the program, and it still ran perfectly without any problems.
Setup and Initial Preparation
The first step in preparing to cut the part is ensuring you have the correct stock material. Begin by measuring the stock to confirm it matches your setup specifications. Once verified, insert it into the collet and securely clamp it in the machine. With the material in place, upload your program to the computer, load it into the machine, and you're ready to run the operation.
Issues Encountered and Resolutions
While running the part, I encountered several issues. The most significant was related to tool setup: the program was set to use Tool 2, which had not yet been touched off. As a result, the Z-axis offset remained at the default — approximately 5 inches off — causing the machine to throw an error stating it was out of Z-axis limits. We attempted several fixes, including lowering the stock and reviewing the program, but none resolved the issue. Ultimately, we discovered the tool assignment in the code was still set to T2. The fix was straightforward: we touched off Tool 2, set the correct offset, and the program ran without further Z-axis issues.
Another issue I encountered was the plastic burning during cutting, caused by excessive friction. To resolve this, I adjusted the feed rate either increasing or decreasing it depending on the specific section of the cut to reduce heat buildup and prevent burning. Additionally, plastic began to accumulate on the tool due to the same friction, which forced us to stop the machine. I mistakenly hit the E-stop, not realizing it would restart the program from the beginning rather than pausing it at the current line. When I tried to resume from where we left off, the spindle didn’t spin because the spindle speed was only defined at the very start of the code. To fix this, I went back into the program, located the relevant toolpath, and manually inserted the correct spindle speed command. After restarting from the correct line, the program ran smoothly.
After removing the stock from the collet, I used a handsaw to cut off the die. I then used a handheld sander to remove the bulk material, doing my best to preserve the sharp point in the center to keep the final piece looking seamless. While a few minor mistakes were made during sanding, nothing significantly affected the overall result.
Check out the file!