Wiring up the controller for a small CNC mill such as this always takes longer than I expect. I start by laying the components out on the work bench – to determine how big a box will be needed.

This gives me a feel for the size of the box, and the location of the components (not as shown above).

I made the box using my laser cutter – just a plain rectangular box, with nothing fancy.

I then mounted the components in the box, with short stand-offs, so there is air space between all the boards and the box.

Power distribution is always a challenge, and I’ve ended up using a rather pricey solution of DIN rail power blocks. These are extremely handy, and quick to wire up. Nice.

I kept the box sides off for most of the assembly. I wired up the back panel items first – soldering the wires into the DB9 connectors for the motors, and the limit switches, and connecting the 115V power input, circuit breaker, power switch, and the output connector for the vacuum. Also, the spindle power. I tried to use different connectors for most items (such as the spindle) so that it would reduct the problems that could occur if one was plugged into the wrong connection.

I wired up the 115V power stuff first – getting the thicker wires set for the power to the 3 power supplies, and the wiring for the vacuum wired up to the relay board.

I then worked on the higher current stuff – the spindle output (also through a relay), and the power to the motor driver boards.

And, then the wiring of the 12V power to the relay board, and fan. This used a small 12V power supply that snaps onto the DIN Rail.

Finally, I wired up the motor outputs, and the connections to the control panel, and the relay board – the relay connections went through a couple of switches on the font panel, so I can override the vacuum and spindle – turning them ON, OFF, or AUTO – under control of the CPU board. The Vacuum is wired into the Flood output on the board – so I simply have to make sure that the G code generated includes the M8 and M9 commands to turn the Flood coolant on and off.

Astonishingly, everything ran perfectly when I powered things up. The motor drivers have all kinds of warnings about powering them up without a motor connected (which is a bit worrisome – are they that delicate???). The spindle didn’t work at first, but I finally realized that the speed control was set to its lowest setting – not enough power to drive the spindle motor!

And, on to the next step – calibrating the PC software which drives the Planet CNC board.

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