A DIY Modular CNC Controller That Features a Mini CRT Monitor
Chris Borge built this modular system CNC controller "cabinet" for his recently constructed CNC mill.
Sneak into one of your local machine shops while everyone is on lunch and you’ll see something interesting: every CNC machine has a huge electrical cabinet. Those cabinets are sometimes as big as the machines themselves and there is a reason for that. CNC machines — mills, lathes, etc. — require a lot of power and a lot of control components. A single VFD (variable-frequency drive) to run a spindle could be larger than toaster and that is just one component. Chris Borge needed something more compact, so he designed this DIY modular CNC controller.
In his last video, Borge showed off a very unique CNC vertical mill that he designed. As with his other recent machine designs, it stands out thanks to a frame made from a thin 3D-printed shell filled with concrete. Compared to other construction methods for small mills, that is quite rigid.
But while Borge’s CNC mill was mostly complete, his CNC controller was just some boards sitting in a cardboard box. This new video documents the dramatic upgrade.
Borge designed this CNC controller around a 10” mini rack, which allowed for modularity via an existing standard. He made the rack out of 3D-printed parts, threaded rods, and laser-cut plywood panels. The design of the rack is such that modules of standard sizes can be inserted into any space they fit, like a game of Tetris.
This is, more accurately, a kind of electrical cabinet. The CNC controller itself is one board inside that runs GRBL. Instead of connecting an external computer or putting g-code files on SD cards, Borge added a mini PC to the rack. That runs Candle, which is open-source software for interfacing with GRBL machines. Candle has a nice GUI and Borge needed a display to see that, which leads us nicely to the most interesting feature: the mini CRT monitor.
It would have been easier to use a common LCD panel here, but the CRT looks really cool. It is a small monochrome model that Borge removed from the original housing and put into a 3D-printed module that fits the rack. It requires composite video input, so Borge added a compact video converter box to the rack, as well.
Finally, because this is for a CNC mill, Borge added two other small modules: one with an emergency stop button and one that appears to have a potentiometer for adjusting the spindle’s VFD. As a bonus, there is a Gridfinity setup on top for holding important things and a kind of peg board on the side for notes.