How to fix layer shifting in the X axis (BCN3D Sigma)

This is a continuation article of the How to fix Layer Shifting guide.

If you still haven't read it, take a look at it first, you'll know why it happens and other ways to fix it. How to fix layer shifting.

 

Layer shifting in the X-axis is a printing issue where the layers of the object are misaligned on the X-axis direction. It is usually a mechanical problem but it also can be caused by a stepper driver malfunction or a bad configuration in BCN3D Stratos. To solve this issue, follow the points below. If the issue is not solved when you finish a point, go to the next one:

 

1: Cleaning and lubrication

2: Adjusting set screws

3. Adjusting belts tension

4. Changing the X motor

5. Changing the stepper driver

 

1: Cleaning and lubrication.

Clean the guiderail's surface with a clean piece of paper, and apply some lubricating oil while moving both printheads side to side. Pay special attention on the ridges of the guiderail.

Make sure that there are no filament remains or debris between the pulley and the inside of the belts, or under the pulley, around the stepper motor axis. You can easily remove them by using tweezers.

2: Adjusting set screws.

Make sure that both pulley set screws on both X motors are tight, and one of them is facing the flat side of the stepper axis.

x2 M3 3mm

3: Adjusting belts tension

The belts shouldn't be too loose. If the belts don't have the correct tension, they will skip over the X motor pulley teeth and create intermittent layer shifts.

1. Check that the belts are not misaligned. To correct this, you'll have to adjust the pulley height by loosening the set screws from the pulley. There's no need to remove them completely.

Misaligned belts and pulleys:

Aligned belts and pulleys:

2. Once the set screws are loose, correct the pulley position. This will prevent friction between the belt and pulleys, and the printhead will move smoothly.

4: Blocked X motor.

If there’s mechanical resistance on the printing head while manually moving it through the rail, the X stepper may be blocked. Follow the next steps to check if the stepper motor is the problem:

1. Turn off and disconnect the printer.

2. Loosen the belt from the printing head holder and check its motion through the rail. If the head moves smoothly, the issue will most likely be on the stepper.

3. You can check the stepper resistance by manually rotating the pulley to see if it is blocked. Sometimes the driver can be the cause of this problem, so you should check the stepper motion after turning the printer off as well.

If the stepper motor is blocked you’ll have to change it for a new unit. This guide will help you on this:  How to replace the X motor (BCN3D Sigma)

5: Changing the X drivers.

The driver boards control the X motors, if those don't work correctly, the motors could behave abnormally, usually related to layer shifting, to check if the issue is being caused by the drivers, follow the next steps: 

If the printer is only missing steps on one of the heads, you can swap the X drivers between them to see if the issue moves from one head to the other.

1. Turn off and disconnect the printer.

2. Remove the flat cable from the driver by gently unlocking the clip. Disconnect the stepper and endstop cables from the driver.

3. Remove the screws that hold the driver's support.

x2 M3 8mm