Robo E3 Pro - Prints Stair-Stepping Side to Side or Shifting Mid-Print

If you are experiencing prints where it is stair-stepping side to side or shifting to one side or the other while printing, there are a couple things to check for. 

First, make sure your filament doesn't have any tangles or kinks. Sometimes, a tangled spool can cause a print to shift over. If you're unsure, try a new spool of filament and run the print again.

If you are experiencing this error regularly and you've tried multiple spools of filament, you may need to tighten your X-Axis gantry belt. To do so, look on the right-hand side of your 3D printer for a stepper motor attached to a rubber gantry. You should see one or two set screws securing the motor to the frame.

Loosen those using a 2.5mm Allen wrench. Do not fully remove them. 

Around the back, you'll want to fully remove the L-shaped piece, so unscrew both screws holding this in place. Removing this piece will help you get to the other two set screws on the motor more easily and have better visibility.

On the back, you'll find two more set screws you need to loosen. 

One is located on the bottom (shown above) and other other is on the top of the motor. (See image below).

These two screws are very hard to see. It's recommended you either stand behind the printer to more easily view them, or use a phone with a front-facing camera or mirror to help you locate the screws.

Once all set screws are loosened, you should be able to feel some wiggle on the stepper motor. Push it as close to the printer wall as possible to tighten the gantry and then retighten each of the set screws.

Don't forget to reattach the L-shaped piece before attempting your next print! Failing to do so will prevent your printer from homing successfully.