I am resurrecting this very old thread, because I think it may be nice to tell the rest of the story. I made a lot of progress on the design and build of my CNC router project, but life somehow got in the way. To be honest, maybe I just found an even shinier thing to start playing with, I can't remember

. The project got mothballed, put under some plastic, and placed in the corner of the shop. That was in 2019. It's kind of embarrassing to say, but it's now 2024, and over the last week, I got the itch to pull it out of the corner, and try to get it over the finish line. I'll try to bring the story up to date, and continue to document my journey.
First, I think it's time for some pictures (see below). Here is the current state of the project. I completed most of the construction, and got the wiring and software rung out to the point that the three axis were properly moving and homing, and the spindle motor was running via the VCP. I also constructed a spindle water cooling unit, using some of the CPU cooling toys that were available at the time. The cooling unit rides on the back of the gantry. Using an Arduino mini controller, I built and coded some controls for the cooling unit to displays the coolant (water) flow, and fan speed. These parameters are monitored, and if they fall below a threshold, a relay (dry contact) is activated. The relay will eventually be used for an Acorn input to signal an issue, stop the running job, and power down the spindle. I also added a inexpensive tool touch plate, which has been interesting to get working. Instead of all the I/O going directly back to the main controller box, I built a sub unit that also provides some LEDs signals for the axis limit switches. The I/O of course all needs to go back to the Acorn, it's just done with a simple DB9 cable, and the sub unit provides a place to plugin a lot of the external stuff (limit switches, tool touch, spindle cooling unit signals and power, ect.). That's about as far as it got before I mothballed it. the pictures below will tell the visual story, and fill the holes in my description.
The first picture is of the sub-unit for interfacing some of the I/O. The sub unit has two relays in it that can be controlled with two of the Acorn outputs. I should point out that I have a rev 3 Acorn that didn't come with a relay module, so I added some relays in the main controller box and the sub unit. If you look at the main control box pictures, You will see a 4 relay module mounted to a plate above the Acorn.

The controller box is nothing special. I used a contactor and safety relay to work the e-stop. I like not having anything software controlled in the loop of an e-stop. Looking at the front of the unit, you'll see a main disconnect switch, which of course controls power to everything. When that is engaged, only the 24v/5v DC power is enabled, as well as a 240v ac outlet for the PC. The goal being to bring the Acorn up and the CNC PC for CNC12 to connect, but the rest of the power is disabled via the contactor. The switch at the front of the panel (labeled START) is used to get the rest of the system powered up. This allows the e-stop to depower all motion controlling hardware and spindle motor, but leave the Acorn, and PC up and running.
Even with the sub-unit I/O box, there is a lot going to the main box. I decided to mount the VFD for the spindle motor outside the controller box. This eliminated any potential electrical noise, and gave me more room for everything else.
More to come...