I think I may have messed up my Z axis stop microswitch setting. I’d like to do it again. Should I press the reset switch on the board first, and will that clear settings? Or will it clear the whole firmware!!
Also I have a problem where the Z motor refuses to go even a short distance down when it is near the bottom – OR UP! – it just buzzes. Should I set the Z motor volts a little higher. I note that the shaft coupler is very slightly eccentric, making the motor flex in its mountings when the Z axis is near the bottom.
With pressing the reset switch you do not erase the firmware of the µ-controller. The only thing you do is to force the µ-controller to restart his opperation, start reading the firmware from the beginning and waiting for inputs from repetier host software or display firmware. that means all temporarily written values which came from these sources were lost and the Printing process immediately canceled if you press the reset switch. But after restaring a new Printing process can be strated trough the user.
Z motor buzzing i had also, dude. I had to enlarge the wiring diameter to the z motor because of a too high voltage drop. But soldering points or a wrong voltage adjustment at the allegro stepper driver boards can also be the source for this kind of misbehave. The shaft coupler you should re drill with a milling tool same diameter as stepper motor shaft to make sure that the whole shaft of the stepper motor fits into it. I think it only seems eccentric because these parts are normally machine cutted or did you’ve measured? Maybe you’ve tightened the screws of the stepper motor and the mounting without making secure that everything fits into the right position. i would gently loose all that screws put the z axis into the lowest possible position and than re tighten them again.
but I’ve figured at the shaft coupler that the drilled hole is a bit oval, so as someone would have taken this part with the deep drilled side into a vice with too much force. but i haven’t proved something in this direction…