This is the most important and hardest chapter, take your time, don't rush. Properly assembled extruder is essential.
⬢The bag with fasteners includes M3x20 and M3x18 screws make sure you won't mix them! Pay attention to the instructions, when to use the M3x20.
⬢Keep the magnets apart in a sufficient distance. They can break each other!
⬢The hotend for MK3S needs a shorter PTFE tube compared to the MK3 (more info at help.prusa3d.com/PTFE-MK3S). The PTFE tube is already installed, MK3S compatible hotend is marked with a yellow/orange dot on the heater block.
⬢Pay great attention to the cable management, if you miss some important step you would need to disassemble the extruder.
⬢This bag includes extra fasteners. Don't worry if you finish with few unused screws and nuts.
⬢Take two M3nS nuts and insert them in the Extruder-body. Make sure both are all the way in. Push them in, the upper nut must "disappear" inside the printed part.
Ensure correct alignment of the nuts using the Allen key.
⬢Secure the nut using an M3x10 screw. Tighten the screw just slightly, later on we need to add the P.I.N.D.A. sensor.
⬢Take two M3n nuts and insert them in.
Use the screw pulling technique.
⬢Take the smaller magnet (10x6x2) and insert it carefully in the FS-lever. Majority of the magnet will be hidden inside the printed part.
⬢Take a piece of the 1.75 filament. You can use the bundled one on a spool, don't use the black nylon, which is too thick. Straighten the filament as much as possible.
⬢Place the filament along the path and align the gear properly.
⬢The filament will be always slightly bent. Use it anyway for the initial alignment.
⬢For a final check replace the filament with an Allen key. Bear in mind, the key has slightly different size than the filament.
⬢Tighten the screw slightly to temporarily fix it, we will make the final check and tightening later on. Be careful, you can strip the thread.
Don't use any glue to fix the screw in place, you won't be able to release it, in such case you might have to replace the entire motor.
⬢Take two M3x10 screws and insert them in the holes. Doing this now makes the assembly slightly easier, but both holes are shallow and the screws might fall out. If this happens, you can continue without them and put them back later on (you will be notified later). Also note, that in few upcoming pictures the screws might be missing.
Hotend assembly was completely reworked from MK3 to avoid bad placement. Also any future maintenance is much easier.
⬢Place the hotend next to the Extruder-body, see the grooves in the printed part, which are in the shape of the hotend.
⬢Correctly placed hotend. Cables should point in the direction behind the hand, we will align them in the next step.
In order to protect the hotend cables and ensure proper orientation, it is highly recommended to use a box. Use the one provided in the kit.
⬢Place the Extruder-body with the hotend on the box and make sure the cables are pointing down.
⬢Place your finger temporarily on the longer magnet and place the extruder motor assembly on the Extruder-body. The Bondtech gear might pull the magnet out while assembling parts together.
⬢Make sure both parts are aligned.
⬢Place the Extruder-cover on the Extruder-body. Again, make sure that all three parts are properly aligned.
⬢Insert two M3x40 screws, you've prepared earlier. Tighten them, but be careful, they are slightly longer (2-3 mm), than the thickness of the entire assembly.
Place the extruder aside for few steps, we need to prepare another part. Leave it on the box to prevent damaging the cables.
For the following nut insertion USE A SCREW. THAT'S AN ORDER!!! Seriously, use a screw to pull the nuts in, both have to be properly seated in the X-carriage.
⬢Take both M3n nuts and using pliers (or screw) push them in the X-carriage, then using a screw from the other side, pull them all the way in.
⬢Don't forget to remove the screw.
⬢Take all four M3nS nuts and insert them in. Ensure correct alignment using the Allen key.
From now on, keep in mind the nuts are inside, avoid rotating the X-carriage "downwards", or the nuts might fall out.
Following cable management is CRUCIAL for the extruder TO WORK PROPERLY! Read the instructions carefully.
⬢Start by making a small loop just below the extruder motor. Leave a slack about 2-3 cm (0.8 - 1.2 inch) This is comes handy for easier disassembly in the future.
⬢Then guide the cable in the "channel" all the way to the back.
⬢Slightly bend the cable down to form it around the edge.
Also, prepare X-carriage, both M3x10 screws (if you haven't used them already) and the longest Allen key with the ball-end, you will need it.
Following cable management is CRUCIAL for the extruder TO WORK PROPERLY! Read the instructions carefully.
Before you assemble the X-carriage, check the nuts in the Extruder body are still in place. The upper nut sometimes falls out.
⬢Grab the X-carriage and place it onto the back of the extruder assembly as shown in the picture.
⬢Make sure the motor cable follows the channel both in Extruder-body and X-carriage. In the X-carriage the motor cable will follow the path of the IR-sensor cable.
⬢ENSURE NO WIRE IS PINCHED! Then use the M3x10 screw and Allen key with ball end to connect both parts together. If you are inserting the screw at this moment, it will be slightly inclined in the beginning, but it will "straighten up" after few turns. Don't tighten the screw completely, we need to adjust the IR-sensor cable.
⬢Turn the extruder to the other side and if needed insert the second M3x10 screw. Don't tighten the screw, we need to adjust the IR-sensor cable.
BE CAREFUL with the filament sensor, do not touch the PCB nor the chips on it. Hold the PCB from sides.
Your package includes IR-sensor with black or red PCB. The red is a new version with some hardware optimisations. Filament detection is the same on both.
⬢Place the IR-sensor on the top of the Extruder-body and secure it with the M2x8. Make sure the black plastic "u-shaped" part is facing down.
Tighten the M2x8 screw, the sensor shouldn't be able to move, but be careful the PCB isn't indestructible ;)
⬢Connect the cable, mind the correct orientation of the connector and wires.
⬢Leave a slack behind the sensor like in the picture. Don't create too big loop as it might interfere with the frame. If needed adjust the length by gently pulling/pushing the cable.
⬢Ready? Ok, check once more no cable is pinched and tighten both M3x10 screws installed previously.
⬢For easier fan installation, remove temporarily the black twist tie from the cable bundle and release at least one loop. Then tie the bundle back, see the picture.
⬢Before you move to the next step, take an Allen key and GENTLY PUSH the motor cable to the channel to create space for the fan cable.
The fan has two sides, one has a Noctua sticker. Make sure, this side is facing inside the extruder.
⬢First, create a loop on the cable. Make sure the black protective wrap is close to the edge of the fan. See the picture.
⬢Place the fan on the extruder and proceed in the following way:
⬢Start by placing the fan's cable in the upper channel
⬢Slide the fan close to the X-carriage and GENTLY PUSH the cable in using an Allen key. Before you push the fan all the way to the left, place the cable in the X-carriage channel.
FINAL CHECK! The fan is oriented with the cable facing up, then the cable goes through the upper channel all the way to the X-carriage. In the X-carriage don't forget to use both channels. Make sure the CABLE ISN'T PINCHED along the way!
⬢Use the three M3x14 screws to fix the fan in place. Don't over tighten them, you can break the fan's plastic casing. Also make sure the fan can rotate freely.
Note that the screws are "self-tapping" in the printed parts. There are no nuts.
⬢Insert the pulley in idler as shown in the picture.
⬢Slide the shaft through the idler and pulley. Use reasonable force or you will BREAK the printed part. The shaft should be flush with the surface of the printed part.
⬢Place your finger on the bearing and ensure it can rotate freely.
The fan-shroud was initially designed for M3x18 screw, but based on the feedback and to make the assembly more convenient, use M3x20. If your extruder bag includes only two M3x20 screws, please use another one from the spare bag.
⬢Insert M3nS nut in the Fan-shroud, all the way in.
Ensure correct alignment using the Allen key.
⬢Mount the Fan-shroud to the extruder, secure it using an M3x20 screw. Don't over tighten the screw, you can break the plastic casing. Also make sure the fan can rotate freely.
Due to the multiple vendors, there can be 3 or 4 wires in the connector. Both versions will work correctly, the firmware was adjusted and flashed in the factory.
⬢Insert the zip ties in the X-carriage like in the picture.
⬢Lower the X-axis at about 1/3 from the top.
⬢Turn the printer like in the picture with X-axis motor and shorter extrusions facing towards you. Align the bearings similarly to the picture. The exact position of the lower bearing doesn't matter for now.
⬢Place the extruder on the bearings, the top couple must fit perfectly. Make sure the X-carriage is facing towards you (together with the shorter extrusions).
⬢We will adjust the lower bearing later on.
⬢Tighten and cut the zip ties.
Before you assemble the X-carriage, check the nuts in the Extruder body are still in place. The upper nut sometimes falls out.
⬢Using right hand rotate the motor to its original position and hold it (tension is applied to the belt).
⬢Using two fingers on your left hand push the belt together. Very small 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 amount of the belt in the X-carriage.
⬢When done, rotate the motor to its original position and tighten the M3 screws again.
⬢Use the technique described below to test if the belt is properly stretched.
⬢Use pliers to hold the X-axis motor shaft.
⬢Move the extruder towards the X-axis motor. Don't use excessive force.
⬢If the belt is stretched properly, you should feel a resistance and the extruder won't move at all. If the belt is too loose, it will deform (create a "wave") and jump over the teeth on the pulley.
Belt too loose? Return to step 49 and repeat all steps until now. You have to rotate the motor and retighten the belt in the X-carriage. Shortening the belt length by moving one or two teeth outside X-carriage should be enough.
For the following step we recommend getting a white marker, but you can also trim the belt without it.
⬢Measure the part, which must be trimmed and gently take the end of the belt away, from the X-carriage, but make sure at least 3-4 teeth are still in the X-carriage, as you don't want to lose the tension. If possible make a mark, where to cut the belt.
⬢Ensure again your mark is in the correct position and the belt is still stretched.
⬢Using pliers cut the belt and push it inside X-carriage. Use screwdriver or Allen key, if needed.
In this step, we will finish tensioning the belt. Please read the instructions first, your belt might have proper tension already, then there is no need for additional screw adjustment.
⬢First, slightly release all the screws holding the motor, otherwise, the upper "tensioner" won't work (the motor must be able to move).
ATTENTION !!! BE EXTREMELY CAREFUL WHILE TIGHTENING, YOU CAN CRACK THE PART IF YOU OVER TIGHT THE SCREW.
⬢Using Allen key start tightening the M3x18 screw inside the X-end-motor, but after each turn or two check the tension in the belt.
⬢For the optimal performance, the belt must be a bit harder to press 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 optimal tension, please tighten the screws again.
In case you experience X-axis failure during calibration or skipped layers in the X direction, you can adjust this screw accordingly. Tightening the screw stretches the belt. Releasing the screw has opposite effect. Each time don't forget to release the screws on the motor first.
⬢Locate the hole for the NYLON filament. Using the smallest Allen key ensure there are no obstacles inside.
⬢Using the pliers insert and twist the NYLON filament in the slot. Hold the extruder with your other hand.
BE EXTREMELY CAREFUL as the pliers tend to slide and you can easily damage the wires!!!
⬢To check if the filament is seated properly, gently pull it with your hand. The X-axis should bend a little, but the filament must remain in the slot.
⬢If you have issues, try to adjust the tip on the filament.
⬢Open one end of the textile sleeve and slide it on the cable bundle leading from the extruder. Don't forget to include the black nylon filament inserted earlier!
⬢Leave the cables from the hotend out for now.
⬢Length of the first wrap should be slightly longer than the cable-holder part, about 5 cm is enough.
⬢Gently twist the sleeve to make it smaller and tighter around the cables, orient the sleeve's seam downwards, then slide the sleeve towards the extruder.
⬢Take 3 zip ties and insert them into the lower row of holes on the cable-holder.
⬢Twist the sleeve again (without twisting the cables inside) and tighten the zip ties.
IMPORTANT: Cut the remaining part of each zip tie using pliers as closest to its head as possible. Note the correct position of each zip ties's head (slightly off-centre to the left).