⬢2.5mm Allen key ball-end recommended

⬢Needle-nose pliers

⬢Cloth or piece of fabric 15x15cm

⬢Permanent marker

⬢Take the steel sheet off.

⬢Press the LCD knob for 1 second and rotate to lift the Z-axis to approximately half of its height.

⬢Use a thick enough piece of cloth or fabric to cover the heatbed. This is to ensure you don't damage the heatbed surface during the disassembly.

⬢Turn the printer OFF and unplug it from electricity.

⬢Cut all zip ties on the extruder.

⬢Remove the textile sleeve. There is no need to remove the entire sleeve. Keep the other end attached to the electronics box.

⬢Release the four screws on the x-carriage-back.

⬢Remove the x-carriage back from the extruder. Keep the x-carriage-back hanging on the cable bundle.

⬢Loosen the tensioning screw on the backside of the x-end-motor part. No need to remove the screw.

The tensioning mechanism may be a bit different on earlier MK3/MK3S printers. Although this guide is intended for MK3S+, it is also applicable to the earlier ones if you are aware of the difference.

⬢Release two M3 screws from the X-axis motor. No need to remove them from the plastic part.

⬢Rotate the X-axis motor as indicated towards the frame. And slightly tighten the upper screws to fix the position of the motor. It's just temporary.

⬢Pull out both ends of the X-axis belt and remove the entire belt from the printer.

⬢Release two screws on each z-axis-top. Remove both z-axis-tops from the printer.

⬢Use your fingers and manually rotate both threaded Z-axis rods equally to move the Z-axis up.

⬢Stop rotating when both smooth rods are sticking out 1cm (1/2") from the x-ends.

⬢Pull both smooth rods out of the printer.

⬢Release four screws on the right z-axis-bottom. No need to remove them completely.

⬢Carefully place the Z-axis motor onto your work surface.

⬢Repeat the last two steps for the left Z-axis motor.

⬢Slightly tilt the X-axis outwards.

⬢Manually rotate both threaded rods some more until the X-axis comes out of the rods.

⬢Carefully place the X-axis next to the printer as can be seen in the picture.

⬢Hold the x-end-motor (left printed part) with your hand and pull out the x-end-idler (right printed part) with your other hand.

⬢Carefully slide the extruder out of the X-axis.

⬢Cut both zip ties on the bearings.

⬢Remove three bearings from the extruder.

⬢Place the extruder together with the cloth onto the heatbed as seen in the picture.

⬢Make sure the hotend cable bundle (3 cables) and the extruder cables (5 cables) are separated from each other. See the picture.

⬢New linear bearing (3x)

⬢Zip tie (7x)

⬢Several paper towels to wipe oil and grease from the bearing surface.

⬢Make sure the X-axis motor is on the left and facing up.

⬢Gently slide one bearing onto the rod further away. Do not try to slide the bearing onto the rod tilted. Do not use excessive force!

⬢Carefully slide the two other bearings onto the rod closer to you. Same here, do not use too much force and not tilt the rod vs. bearing!

⬢Place both smooth rods into the channels in the extruder x-carriage. This is to make 100% sure cables are guided correctly.

⬢Slide the X-end-idler back onto the smooth rods. You may need to use a lot of force, but yet be careful. Do not use a hammer, F clamp or a similar tool. Keep the part perpendicular to the rods during insertion.

⬢Make sure that both trapezoidal (plastic) nuts are pointing towards you.

⬢Place the X-axis assembly with the black nuts pointing up onto the tops of the Z-axis threaded rods.

⬢Turn the threaded rods simultaneously counter-clockwise to move the Z-axis a little lower.

⬢Leave a gap of approximately 1 cm (1/2") between the X-axis and the frame.

⬢Gently insert both smooth rods through the bearings inside the X-axis all the way down into printed parts. Do not apply too much force and do not tilt the rods!

⬢Mount both z-axis-top parts onto the frame and secure each of them with two M3x10 screws.

⬢Manually move the Z-axis to half of its height.

⬢Turn the printer around so that the electronics box and PSU are facing you.

⬢Align the bearings so that the markings are facing you too.

⬢Insert the zip ties in the X-carriage like in the picture.

⬢Look carefully to see if any of the square nuts on the back of the extruder have fallen out. Later insertion would be difficult.

⬢Guide the X-axis belt through the X-end-idler and around the 623h bearing.

⬢Continue guiding the belt through the X-carriage.

⬢Guide the X-axis belt through the lower part of the X-end-motor, around the GT2-16 pulley and back to the X-carriage.

⬢Before you attach the belt into the x-carriage, please release the two upper M3 screws holding the motor on the X-end.

⬢Rotate the X-axis motor as indicated towards the frame.

⬢Insert the flat part of the X-GT2 belt into the X-carriage as in the second picture.

Use a screwdriver or the smallest Allen key to push the belt in.

⬢Using the right hand rotate the motor to its original position and hold it there (tension is applied to the belt).

⬢Using two fingers on your left hand push the belt together. Very little force should be needed for bending the belt, BUT the belt shouldn't be bent by its own weight before being pressed with your fingers - it must be straight.

If you are struggling to rotate the motor back into position, the belt tension is too high.

⬢Depending on the belt being under or overstretched, adjust the position of the belt in the X-carriage.

⬢When done, rotate the motor to its original position and tighten the M3 screws up again.

In this step, we will finish adjusting the belt tension. Please read the instructions first, your belt might have proper tension set already, then there is no need for additional screw adjustment.

⬢First, slightly release all the screws holding the motor. Otherwise, the "tensioner" won't work (the motor must be able to move).

⬢Using ball-end Allen key start tightening the screw on the rear side of the X-end-motor, but after each turn or two check the tension in the belt.

⬢For the optimal performance, the belt must feel stiff if you pinch it with your fingers. Move the extruder all the way to the X-end-idler and try the belt tension in the middle of the X-axis.

⬢When you achieve an optimal tension, please tighten the screws up again.

In case you are experiencing X-axis failures during calibration or skipped layers in the X direction, adjust this screw accordingly. Tightening the screw stretches the belt. Releasing the screw has the opposite effect. And don't forget to release the screws on the motor first :)

⬢Place the x-carriage-back onto the extruder. Use all four M3x10 screws and tighten the X-carriage-back up.

⬢Wrap the entire cable bundle with the textile sleeve.

⬢Guide the hotend cables into the textile sleeve like in the picture.

⬢Take 3 zip ties and insert them into the lower row of holes on the cable-holder and secure the textile sleeve.

⬢ATTENTION! Before tightening the zip ties, add the cables from the hotend. Use the channel in the printed part to arrange them properly.

⬢Secure the hotend cables with two zip ties in the upper row. Do not overtighten the zip ties. You may damage the cables.