How to adjust the belt tension (Sigma Series)








allen key icon
Allen key 2.5mm
smaller allen key icon
Allen key 2mm
socket wrench icon
Socket wrench 5.5mm 


belts tension test


All printers are shipped from the factory with the belts properly adjusted. Unless you are experiencing layer shifting issues or your belts have lost tension over time, there's no need to tighten them.



To set the belts to their correct tension, you can use our printable tensioner as a reference. You can download the STL file and the instructions on how to use it from the following article:

BCN3D Belt tensioner.

    Note: This tool is not updated and its precision may vary on each print, it should only be used as a reference point and to ensure that the tension is the same in all the belts from the X and Y axis.



    1. With the X belts, make sure that both are adjusted equally. Once the tension is correct, re-tighten the lower screws.  

    X belts


    2. With the belt Y belts, make sure that the external faces of the idler and the frame are parallel before finishing the adjustment.

    Y motor belt adjustment


    Note: The tensioner tool is not suitable for the adjustment of this particular belt.


    1. Loosen the two nuts that hold the stepper to the printer’s structure without removing them. nut-iconx2 M3

    y motor


    2. Underneath the motor, there is a rectangular piece with two hollow screws in its lower part. Adjust them equally to increase/decrease the belt’s tension.

    screw-iconx2 M4 10mm

    adjust screws of Y motor tensioner

    Note: It's very important that the belt is centered in the pulley. To check it,  give it a few turns to the Y motor and see if the belt moves to the sides or remains still. If it moves to a particular side of the pulley, tweak the alignment of the belt by adjusting the same hollow screws. 


    3. Once the belt tension is set, tighten the two nuts that you loosened on the first step.

    Note: When the nuts are screwed back, the belt will gain some tension. Be attentive if the belt needs to be adjusted again in order to avoid damage to the motor or to the belt.




    Check and adjust the belt's tension regularly to prevent issues like layer shiting or ghosting. It's recommended to do this process every 1000 printing hours or when you need to remove the belts or any component that is connected with them.

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    Need more help? Check out our forum community for troubleshooting help.


    It's important to keep your printer in good shape to make the most out of it. In this chart, you can find a list of the extruder maintenance procedures and how frequently these should be done. Maintenance Plan


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