Jan 22, 2016: I have had a problem since the beginning with the printer. Once I got it working, I noticed I would occasionally get homing sensor faults in the middle of prints. Essentially, it sees one of the limit switches change state when it knows it should be nowhere near a limit. The printer halts when this happens and forces a reboot. The model print must be started all over in this case, which is really unfortunate.
I thought that the faulty sensor triggers were coming from running the printer in my cold garage. I thought the sensors were getting condensation on them and causing false readings. Sure enough, when I brought the printer in the house, the faults seemed to go away.
One particular fault has recently come back in certain cases. If I am printing a platen full of many parts, it is consistently throwing a family of errors that seem to be traceable back to the X axis end of travel sensor. If I print only one part at a time, I don't get the error!
I replaced the sensor in the hope that it would help, but it didn't. I'm suspecting that printing many parts at the same time results in more vibration and that it rattles the sensor connections, shaking an intermittent connection into failing momentarily.
I plan to test this theory in a few ways. First, I plan to bypass all the wiring and connectors with separate wiring to determine if the existing wiring and/or connectors are to blame. If not, then I plan to short out the offending sensor after the homing sequence to determine if it works then. If there are still issues, I'll have to examine the circuit board to make sure the sensor traces make it cleanly to the control circuitry. If I still have problems, I guess I'll just print one part at a time forever! :)