The Garage Machinist: Component Testing and Box Wiring (Part 1)

Not long after I had the holes drilled in the enclosure for everything, I bolted everything down excitedly, wired up the power supply, plugged it in and... nothing. The LED would not light, and checks with a multimeter indicated that there was no DC power coming from the output terminals. After dissassembly of everything and using a different power cord with similar results, I opened up the power supply (brand was AGT, for 'Advanced German Technology', looks like a Meanwell clone). I didn't see anything obvious (busted capactitors, burned resistors, etc), so bolted it back together with no success. I will say that these switched power supplies are not simple for the non-electronics type, and I suspect troubleshooting would be a pain.

This was a little over a year from when I originally bought it, and sure enough, long past a return period (though it probably would have been more trouble than it was worse). I sucked it up and bought a new Mean Well branded supply off Ebay, and when it arrived, went straight to checking it with an old cord I had cut up for this purpose.

LED Lit! Success! A Working Power Supply!

My original plan was to reuse some of the D-Sub connectors and wiring that came with the machine, but I decided it was going to be a pain to get these rewired and I wanted to use shielded wiring for the motors to limit interference into the limit switch cables. I really liked the GX16 style connector (4-pin) that is available on many of the hobbyist CNC suppliers, but they often ran $4 to $6 per connector... to pricy for me. I found I could get 10 for a little over $10 on Ebay, so went ahead and order some up.

I decided to use five connectors on the control box, and five connectors on the machine. For each side they would be:

X Stepper Motor (using bipolar wiring, so only four wires needed)
Y Stepper Motor
Z Stepper Motor
Emergency Stop (this uses two wires, leaving two left over if I ever wanted to add spindle speed control)
Limit Switches (common power, one line for each axis)

The only fuses I was reusing in the control box were the main fuse and the spindle fuse, so the remaining fuse holes were good spots for additional connectors. To go along with these three locations I added two more nearby. Unfortunately, the fuse holder cutouts were too small, so I had to enlarge them (the GX16 connectors require a through hole for an M16 thread, or a hair bigger than 5/8". I removed everything from the control box to avoid chips in the electronics and drilled them out with a step bit, which work very well in thin metal like this. Since this is not a tool I use often, I picked up the bit at Harbor Freight for cheap.

Step Bit Used To Drill Connector Holes

Connector Holes Drilled

With that, the box was cleaned back up to get rid of any chips or shavings that wouldn't agree with the electronics, and reassembly began.

First up, putting the wiring back in. I wired from the incoming outlet to the existing switch, then to the main fuse (I will try to find a good way to document the wiring if someone requests it). From here, power was split between the 36V power supply, the 5V power supply, the case fan, which runs on 120VAC, and the spindle fuse. The spindle power runs through the existing solid state relay, then over into the spindle outlet to go to the machine. Wire colors for the AC portions follow US wiring colors, with yellow or green as ground, white as neutral, and black as hot. Don't forget to ground everything.

The open fork connectors below go to the main power supply. The unconnected spade terminals are for the 5VDC supply, and the ring terminals go to the ground point, which I attached right near where the 5VDC supply goes.