Aluminium Makercoin Trial
I wanted to have a go at making a maker coin just for fun. The coin has a topographic map of the UK on one side and a 3D scan of my head on the other. Many makercoins that I've seen on YouTube are 3D printed but I wanted to have a go at CNC milling one.
This project is my first foray into flip milling (2 sided milling) so I'm not expecting it to be perfect.
I used a few different programs to put this model together.
The first was Skanect which I used to take a 3D scan of my head. The second is a website called Terrain2Stl which I used to get the depth map of the UK. I also used some software called Meshmixer to tidy both the head scan and the map and scale them to approximately the right dimensions.
The coin itself was put together in Fusion 360. I was able to design the main coin body and then import & place the STL files in the required positions
I used Fusion 360 to program the toolpath.
I used some laser cutter scrap to cut a wooden coin to test the size. This was cut using a 2mm ball nose bit.
For the first side, I used an adaptive toolpath with a 6mm tool to remove the majority of the material before switching to the 0.2mm Tapered bit.
I was so impressed with how the tapered bit worked that I didn't bother with the roughing cut on the second side. Worked well!
Cutting the real thing
To do the flip part of the 2-sided milling I used two bolts. The idea was that the bolts would remain clamped to the bed between the two sides. Unfortunately it didn't quite work as one of the bolts loosened and moved as I undid the top nut. This meant that the second side of the coin was slightly offset against the first.
The next time I do this I will have a 3D Printed fixture that will remain clamped to the bed between the two OPs and hopefully get around this problem.