After 18 months of almost flawless behaviour, my Shapeoko 3 is refusing to initialise.
The problem appears to be in the Z-axis mechanism. The spindle will rise a mm or two, then judder for a few moments without further upward motion, finally producing these messages: GRBL error. Homing failed. Couldn’t find limit switch. Then: Homing cycle failed.
I observe that when power is turned off, I can easily rotate with my fingertips the Z axis lead screw in a DOWNWARD direction but not UPWARDS. Does this indicate a stepper motor failure (unlikely surely)?
I’m using the Carbide Motion software plus a bit setter.
I have tried all the usual things - rebooted the computer, checked all connections, searched for obstructions to movement etc. but to no avail. Gone over everything with a fine tooth comb.
Typically this has happened when I’m in a hurry to finish a job. The machine has not had excessive use and is normally only used to cut smallish components, which it does very well.
CAN ANYONE HELP PLEASE?
I don’t know if this is relevant, but occasionally after zeroing the Z axis, the machine spontaneously raises the Z axis zero point by about 6 mm. A total reboot is then required.
First thing is to check the connectors on the wiring for the Z motor. Pull each one apart, look for discolored or corroded pins, discolored housings (indicates arcing or overheating), and check that none of the wires are loose from their pins.
Wiring or the stepper motor are possible but not likely. Have you done the maintenance procedure on the Z-Plus with the Vactra #2 oil. Some have reported similar problems and their bearings were dry. The spinning downward is because gravity is helping with the heavy load of the Z-Plus weight and the router. The twisting upward is always harder but much harder if your bearings are dry. Gravity is working against you on the way up.
You have to remove the Z axis to oil the bearings. However you can lube the rails as a temporary fix and see if it improves. The Vactra#2 is a heavy oil made for Bridgeport machines originally. So a heavy oil would work temporarily.
If you have not done your maintenance on the guide rails and bearings that might be your problem.
Thanks guys for your advice. About 2 hours after making my posting, I was taken ill and have not been able to get back to my shop since then. Hope to return next week and try your suggestions. Will get back to you then! Cheers, Mervyn