Personal Project
4th Axis Ball Maze
Was hanging out at the Pasadena City College fab lab and saw the advanced CNC class programming a little ball bearing maze project that recently got added to the course curriculum. I got a little FOMO as it looked like such a fun project I never got the opportunity to complete. At the same time I have been itching to try something using the 4th axis of the HAAS mini-mill so figured why not combined the two ideas and create a cylindrical maze.
Since I lack some level or creativity and wanted to spend more time figuring out how to actually machine the maze rather than creating it, I used a the random maze generator tool located here. This output an image file that I then imported into SolidWorks and wrapped around a 2 inch cylinder.
In the meantime I also ordered a 2 in OD clear plastic tube from McMaster-Carr which would serve as the cover to hold the ball bearing inside the maze.
McMaster-Carr P/N 8585K27
From there I started off trying to generate a tool path. My first mistake was attempting to try and mill it using the multi-axis features available in HSMworks. After struggling for a while I turned to the trusted source of tutorials — Youtube — and quickly figured out I was going about it completely wrong. This is still classified as a 2D pocket toolpath, but there is a nifty little button that can be checked called ‘wrap toolpath’ which will enable it as a 4th axis.
After a few other subtle changes — switching to HAAS with A-Axis enabled, and allowing for G0 rapid movements — in the post processing options we were good to go for making chips.
Prior to actually running the G-code on the HAAS there was some additional work to prepare the stock. The max size the collet can fit is 1inch, meanwhile my design of the maze had a 2in max OD. This meant I needed to turn down a handle on one end for work holding.
I want to give a quick shoutout to my bud Jonathan for helping me use the new Prototrak CNC lathe to setup all the round stock. Its been 2+ years since I used a lathe and was definitely feeling rusty. Also, have not used the Prototrak version of the lathe before so the interface was new to me.
The machining itself went pretty smoothly. Once the part was finished the extra stock used for work-holding was parted off back on the lathe. Then the ends were masked off and the main maze portion was sandblasted. Though I liked the aesthetic of the tooling paths it was a little difficult to see the ball bearing in contrast while solving the maze. The sandblasted finish helps a lot in that regard, making the ball a lot more visible.
Also before I fail to mention some additional details to this project. There is a flat lid piece that was machined using the lathe that helps hold the plastic sleeve around the cylinder. It has a counterbored hole for an M4 SHCS that threads into the main maze body. Lastly, the small ball bearing is a 2mm steel ball.
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