Deciding on the machine axis was a useful piece of information for configuring Grbl ESP32 settings, but it was also an important decision for which wire connects to which pins. All of these could potentially be changed later if we change our mind, but hopefully spending a few minutes thinking now would save us that effort later.
The wires for both axis were put into JST-XH connectors for connection with perforated PCB. We could use other form of wire terminals but these polarized plugs seems like a good way to keep things orderly.
The Parker ZETA4 motor drivers offer a wide range options in microstepping. While it is tempting to go up to insane number of microsteps just because we can, for the immediate future we’ll go with “merely” 10 microsteps for a total of 2000 pulses per revolution. This lead screw is cut for 5 turns per inch, which made things a little tricky as Grbl uses metric values. Using 25.4mm to represent an inch, a setting of 2000 pulses per revolution works out to 393.7 steps per mm. It is not perfect but should be close enough for our purposes. If this causes a problem down the line, these ZETA4 drives do have a metric-friendly option of 25,400 steps per revolution. This will divide evenly but we may be trading off torque or run into problems with generating pulses fast enough.
For now, using 393.7 steps/mm is enough for reasonable precision in movement, and this machine homes on both X and Y axis according to newly decided axis alignment. Our dreams of a mini CNC is a little bit closer, and we can start thinking about how we want to approach building the Z axis. Part of that process will be deciding how everything will be bolted down to a table.