Cutting Coins with a CNC Router
I have always enjoyed the art of coin cutting. Traditionally coins are cut in an artistic way using very small hand tools like saws and jewelers files.
When I started doing projects using my CNC router, I knew cutting coins had to be one of the first challenges I tackled.
I have a Chinese 3018 CNC router and use the following software to make the designs
The first challenge I experienced was with the stock router motor. I found that the original motor was too small and had too much runout to be precise enough to handle such small details. I decided to replace the original motor with a 52mm, 500W spindle. This also required me to 3D print a new spindle mount and install larger bearings.
Next I had to figure out how to zero the machine. For this I installed limit switches that would trigger on the X, Y, and Z axis when the head of the router was at its "home" position. This ensured that the machine and the software would both know where they were in space at the defined home position.
Once the machine "knew" where it was in space, I had to make sure it knew where to find the quarters. I 3D printed a coin holder and installed hard stops in order to mount it on the router bed in the exact same position every time.
One of the more difficult challenges was figuring out the correct cutting tools to use with the right feeds and speeds. Cutting coins requires fine detail. This means very small cutters, and small cutters break VERY easily. Finding the right combination of cutters, feeds, and speed took a LOT of trial and error, but I eventually got to a point where I figured it out.
In the end I was able to get reliable cuts using this setup. There is still room for improvement, but for now, I am happy with the results.