two Z-axis issues

[WayOutWest]

1. The TinyG needs to have the machine size set in order to home properly. I find this counterintuitive, and it isn't clearly explained anywhere in the TinyG documentation, but it is undeniably true. If the machine's Z-size is set too small, or the Z-motor configuration is set such that the machine doesn't move as far in the Z-direction as the TinyG thinks it does, the TinyG goes into a "fuge state". Basically if you ask it to go into Z-homing and it thinks that it has traveled more than what it thinks the machine's Z-size is, the TinyG simply stops responding. No error, it just goes out to lunch. I encountered this developing my own software. Moreover, the LitePlacer software does not cope well with this situation at all.

2. The Z-axis motor uses 1.8-degree steps, unlike all the other three motors. I somehow didn't notice this and had it set to 0.9 degrees, which caused a cascade of other problems (see above). Once the machine is assembled the part number on the Z-axis motor is no longer visible, and the setup instructions don't list the part number, so it was hard to check if I had this set right. I suggest the software gently warn the user if they set this incorrectly, because it throws off all sorts of other stuff.