by RetireeJay » 2018-Jun-Mon-08-Jun
You may have flashed a wrong version of the firmware. Some Printrbots have the Y endstop at Y = 0 while others have it at Y = Max. And some Printrbots have larger Y axes than others. So if the firmware you flashed thinks Y endstop is at Y Max, and if it thinks that the Y axis is longer than it really is, then when you try to go to Y = 0, it moves away from "Max" toward "zero" but hits the physical limit before it stops.
Your belt should be tight enough that the toothed pulley doesn't slip teeth. The motor will chatter, but ultimately your motor is skipping magnetic "poles" which is entirely harmless to the motor.
Does the motor stop driving beyond the end of travel after a second or two? If so, that would tend to verify my hypothesis - it thinks it has reached the true zero position. (Printrbots don't have any way to sense actual position except the "endstop" switches, so they keep track of position by counting steps delivered to the motor).
Printrbot Plus operational January 2013
Brass threaded rods (5/16" X 18) & nuts for Z axis
GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally
PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan
Injection molded extruder gears
Optical Z "endstop" (custom designed and built)
Have used many pounds of T-Glase filament. Now also doing some work with Ninjaflex SemiFlex
Print on glass with Scotch Craft Stick or other glue stick
"My next printer is..." Prusa i3 MK3, upgraded to MK3S