⬢For this chapter, please prepare:
⬢1.5mm Allen key
⬢2.5mm Allen key
⬢Torx key TX6
⬢Torx key TX10/8
⬢Needle-nose pliers
⬢Permanent marker
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- Original Prusa i3 MK3/MK3S/MK3S+ to MK4S/MK3.9S upgrade
- 5. Nextruder assembly
5. Nextruder assembly
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- Original Prusa i3 MK3/MK3S/MK3S+ to MK4S/MK3.9S upgrade
- 1. Introduction
- 1a. Parts check
- 1b. Printer disassembly
- 1c. Parts preparation
- 2. Frame assembly
- 3. X-axis & X-carriage assembly
- 4. Z-axis assembly
- 5. Nextruder assembly
- 1. Tools necessary for this chapter
- 2. Nextruder idler assembly: parts preparation
- 3. Assembling the extruder idler
- 4. Assembling the extruder: parts preparation I.
- 5. Assembling the extruder: parts preparation II.
- 6. Assembling the extruder
- 7. Assembling the gearbox
- 8. Assembling the PG-ring
- 9. Assembling the PG-assembly
- 10. Checking the PG-assembly
- 11. Assembling the Nextruder idler
- 12. Gear lubrication: parts preparation
- 13. Lubricating the gear
- 14. Covering the planetary gear
- 15. Assembling the Idler-swivel: parts preparation
- 16. Assembling the Idler-swivel
- 17. Assembling the Idler-nut
- 18. Mounting the Idler-swivel assembly
- 19. NTC thermistor & fan holder: parts preparation
- 20. Assembling the NTC thermistor
- 21. Assembling the Nextruder
- 22. Attaching the Nextruder
- 23. Connecting the NTC thermistor
- 24. Assembling the hotend fan: parts preparation
- 25. Assembling the hotend fan
- 26. Print fan blower: parts preparation
- 27. Assembling the print fan case
- 28. Assembling the print fan blower
- 29. Assembling the fan shroud
- 30. Mounting the print fan blower assembly
- 31. Connecting the print fan blower
- 32. Inserting the hotend assembly: parts preparation
- 33. Inserting the hotend assembly
- 34. Nozzle insertion check
- 35. Connecting the hotend cables
- 36. Fan door cover: parts preparation
- 37. Attaching the Fan-door-cover
- 38. Connecting the extruder cables
- 39. LoveBoard: Wiring check
- 40. Covering the LoveBoard: parts preparation
- 41. Covering the LoveBoard: side cover
- 42. Covering the LoveBoard: top cover
- 43. Tensioning the X-axis belt
- 44. Belt tension check
- 45. Testing the X-axis belt
- 46. Haribo time!
- 47. The extruder is assembled
- 6. xLCD assembly
- 7. Y-carriage & Heatbed assembly
- 8. Preflight check
- Manual changelog
5. Nextruder assembly
⬢For the following steps, please prepare:
⬢Idler-lever-a (1x)
⬢Idler-lever-b (1x)
⬢Bearing 693 2RS (2x)
⬢Pin 2.9x8.5 (2x)
⬢M3x6 screw (1x)
⬢Tubular spacer 13.2x3.8x0.35 (1x)
⬢Place both bearings into the Idler-lever-a.
⬢Insert the pin 2.9x8.5 into each bearing 693 2RS, as seen in the picture.
⬢Close it up with the Idler-lever-b part and secure it with the M3x6 screw. Do not overtighten the screw. Both bearings must be able to rotate without significant resistance.
⬢From the same side, push the tubular spacer into the assembly. The "bottom" of the tubular spacer must be flush with the bottom part of the Idler assembly.
⬢For the following steps, please prepare:
⬢PG-assembly (1x)
Note: There are two types of planetary gear assemblies shipped. Both are functionally identical, so assembly remains the same. The latest version has several holes around the main gear.
⬢Heatsink assembly (1x)
⬢Main-plate (1x)
⬢PG-ring (1x)
⬢PG-assembly-adapter (1x)
The list continues in the next step...
⬢Extruder motor (1x)
⬢Spacer 5x10x0.1 mm (1x)
⬢Socket set screw M3x25 (1x)
⬢Place the 5x10x0.1 spacer over the shaft on the extruder motor.
⬢Place the heatsink on the extruder motor. Note the orientation of both parts.
⬢The motor cable must be facing "up".
⬢The heatsink cables must be on the right side.
⬢Place the main-plate on the heatsink. Note the orientation of the part. Use the cutout as a guide.
Before proceeding to the next step, make sure that the 5x10x0.1 spacer is placed on the extruder motor.
The following instructions need to be done correctly and carefully. Achieve better understanding and successful assembly by watching the video alongside the guide: prusa.io/PG-assembly
⬢After watching the video, follow the steps in this guide.
⬢Attach the PG-assembly-adapter on the PG-assembly. Note the pockets for the gears in the adapter.
Do not assemble the gearbox without the PG-assembly-adapter. This tool is intended to ensure that the gears are correctly fit together.
⬢Slide the PG-ring onto the adapter.
⬢Note there is a chamfer on one side of the PG-ring teeth. This side must be facing down (to the PG-assembly).
⬢Grasp the entire assembly in one hand so that it can be rotated with the PG-ring.
⬢With the other hand, slide the PG-ring onto the PG assembly in a wobbling motion (move the PG-ring left and right repeatedly) - a quarter turn is enough.
⬢Stop when the surfaces of the gears are approximately flush with the surface of the PG ring.
Proceed very carefully in this step.
⬢Maintain the position of the PG-assembly and attach it on to extruder motor shaft.
⬢Very gently and freely rotate with the whole PG assembly (PG-assembly-adapter, PG-assembly and PG-ring) until it drops down so that there is no gap between the assembly and the main-plate. Do not push on the assembly.
⬢Remove the PG-assembly-adapter.
⬢Attach the PG-assembly-adapter back on the PG-assembly again to verify that all parts are properly seated.
⬢Rotate with the PG-assembly-adapter. The PG assembly must be easy to rotate without having to exert much force.
⬢Remove the PG-adapter. You will no longer need it during assembly. We recommend keeping it for maintenance.
⬢Ensure that the PG-assembly is not sticking out above the PG-ring. It should be positioned lower than the level of the PG-ring's surface or at the same level as the ring.
⬢Ensure that the gap between the PG-ring and the Main-plate is minimal. If a significant gap is observed, disassemble the planetary gear assembly and reposition it.
⬢Insert the idler assembly between the PG-ring and the extruder motor. There is a cutout for the spacer in the main-plate. Line up the idler spacer with the hole in the PG-ring.
⬢Secure both parts with the socket set screw 3x25. Do not overtighten the screw! The screw protrudes from the PG-ring after tightening.
⬢For the following steps, please prepare:
⬢PG-case (1x)
⬢M3x25 screw (3x)
⬢Lubricant (1x) included in Fasteners & ELE box
⬢Several paper towels to wipe grease from your hands.
⬢Remove the cap from the lube. Use the spike on the opposite side of the cap to pierce a hole in the lube tube opening.
⬢Squeeze a small amount of lubricant onto the tip of the zip tie, then spread it over the gears.
⬢Apply a small amount of Prusa Lubricant all around the PG-ring and PG-assembly teeth.
⬢Close the lubricant; it is no longer needed for the assembly.
⬢Using the paper towel, wipe off the lubricant residue from the face surface of the PG-ring.
⬢Place the PG-case on the gearbox and secure it with three M3x25 screws. Do not tighten them completely at this moment.
The screws on the PG-case will be completely tightened during the self-test in the final chapter.
⬢For the following steps, please prepare:
⬢Idler-swivel (2x)
⬢Idler-nut (1x)
⬢M3x30 screw (2x)
⬢M3x20rT screw (2x)
⬢M3nN nut (2x)
⬢Spring 15x5 (2x)
⬢Spacer 6x3.1x8 (1x)
⬢Push the M3x20rT screw all the way through one of the idler-swivel.
⬢Slide the spacer onto the screw.
⬢Place the second idler-swivel from the opposite side on the screw.
⬢From the other side, attach the M3nN nut onto the screw. Hold the nut using the universal wrench and tighten the screw. Tighten just lightly! The spacer must rotate freely.
⬢Insert the Idler-nut into the Idler-swivel assembly. Make sure that both parts are oriented correctly according to the picture.
⬢Secure both parts together by inserting the M3x20rT screw from the same side, like the first screw.
⬢Secure the screw with M3nN nut. Do not overtighten the nut. It must be possible to move with the Idler-swivel on the Idler-nut.
⬢Attach the spring 15x5 on both M3x30 screws.
⬢Push the two screws with the springs through the holes in the protrusion on the heatsink. There are no threads inside.
⬢Attach the Idler-swivel assembly on the screws. See the correct orientation of the Idler-nut. The side with version marking must be visible. See the picture.
⬢Tighten both screws. Stop tightening as soon as the screw tips reach the front face of the idler nut.
⬢For the following steps, please prepare:
⬢NTC thermistor 90 mm (1x)
⬢M3x12 screw (3x)
⬢M3x4T grub screw (1x)
⬢MK4S fan holder (1x)
⬢Heatsink spacer (1x)
⬢On the extruder motor side, insert the NTC thermistor into the hole in the heatsink.
⬢Secure it with the M3x4T grub screw. Screw it all the way in. Tighten gently, but firmly using two fingers and the short side of the T6 Torx key. Applying more force may cause permanent damage to the thread.
⬢From the front side of the Nextruder (side with the printer logo pg-case), insert three M3x12 screws in the heatsink.
⬢From the opposite side of the Nextruder, fit the heatsink spacer onto the three screws.
⬢Make sure the protrusion protrudes towards you (like the screws).
⬢From the extruder motor side of the heatsink, attach the MK4S fan holder to the heatsink.
Avoid pinching the NTC thermistor cable. Guide it through the cutout as shown in the detail.
⬢Place the Nextruder assembly onto the spacers on the X-carriage. Line up the three screws with the three spacers.
⬢There is a cutout in the plastic part. Guide the thermistor cable through this cutout.
DO NOT PINCH ANY OF THE CABLES!
⬢Align the heatsink screws with the spacers on the X-carriage and join both parts together by tightening them. Start with the middle one.
⬢Locate the cable channel on the left side of the X-carriage. We will guide some of the cables through this channel in the following steps
⬢Guide the NTC thermistor through the cable channel in the X-carriage up to the LoveBoard and connect it to the top right slot.
⬢For the following steps, please prepare:
⬢Hotend fan (1x)
⬢M3x18 screw (2x)
⬢Attach the hotend fan onto the heatsink with two M3x18 screws on the left side. Tighten the screw gently, but firmly, otherwise the plastic housing may crack. The cable must be pointing towards the lower-left corner.
There is a sticker on the hotend fan, the sticker must be on the rear side of the fan - not visible.
⬢Guide the fan cable through the cutout in the fan holder.
⬢Guide the fan cable through the cable channel up and connect it to the lower slot on the LoveBoard.
⬢For the following steps, please prepare:
⬢MK4S Print fan blower (1x)
⬢Fan-case (1x)
⬢Fan-case-cover (1x)
⬢Fan-shroud (1x)
⬢3x8sT screw (2x)
⬢M3x5rT screw (5x)
⬢M3nS nut (5x)
⬢From the flat surface of the Fan-case, insert two M3nS nut all the way into the holes.
⬢Double-check from the side that the inserted nut is aligned with the hole in the part.
⬢From the opposite side, insert two M3nS nuts all the way into the holes. Check that nuts are fully inserted.
⬢Insert one M3nS nut into the hole in the Fan-shroud.
⬢Insert the MK4S print fan blower into the print fan blower case.
⬢Guide the print fan blower cable through the cable channel in the Fan-case.
⬢Close the fan with Fan-case-cover.
⬢Secure the cover with two 3x8sT screws.
The screws cut thread directly into the plastic, so there might be some resistance.
Attach the Fan-shroud to the print fan blower assembly. Notice two teeth on the fan shroud and two rectangular holes in the blower assembly.
⬢First, insert those teeth into the rectangular cutouts.
⬢Close the Fa-shroud and secure it with the M3x5rT screw.
Tighten the screw gently until it resists significantly. Do not overtighten; otherwise, it can crack the parts.
⬢Take the print fan blower assembly and guide the fan cable through the cutout on the left side of the fan holder.
Use the same cutout through which the heatsink fan cable already guides.
⬢Slide the side pockets of the print fan blower assembly onto the two “forks” of the fan holder.
⬢Ensure that the holes of both parts are aligned.
⬢From the left side of the fan holder, secure both parts together using two M3x5rT screws.
⬢From the right side of the fan holder, secure both parts together using two M3x5rT screws.
⬢Guide the print fan blower cable through the cable channel in the X-carriage and plug the connector to the middle slot on the LoveBoard.
⬢For the following steps, please prepare:
⬢Hotend assembly (1x)
⬢Thumb screw (2x)
⬢Insert two thumb screws into the heatsink. Do not tighten them completely. Two turns are enough for now.
⬢Look closely at the underside of the heatsink and find the hole for the hotend assembly.
⬢Insert the hotend assembly tube in the hole and slide the whole thing into the heatsink.
⬢Push the hotend assembly all the way into the heatsink. There should be approximately a 2 mm gap between the heatsink and the brass part of the nozzle.
⬢While pushing the hotend assembly in, firmly tighten both thumb screws.
Avoid pinching any cable between the screws and the heatsink!
⬢From the underside, check that the hotend is oriented correctly. It must fit between the cutouts in the X-carriage.
⬢Verify that the nozzle is fully inserted. The copper ring on the nozzle should not be visible if it’s properly seated.
If not fully inserted, poor heat transfer may occur, potentially leading to issues like nozzle clogs.
⬢To adjust the nozzle position, loosen the thumbscrews, reposition the nozzle, and then retighten the screws, while pushing the hotend assembly up.
⬢Guide the hotend thermistor through the cable channel in the X-carriage and connect it to the LoveBoard.
⬢Guide the hotend heater through the cable channel in the X-carriage and connect it to the LoveBoard.
⬢For the following steps, please prepare:
⬢Fan-door-cover (1x)
⬢M3x30 screw (1x)
⬢Attach the Fan-door-cover hinge into its counterpart in the X-carriage. Holes in both parts must be aligned.
⬢Insert the M3x30 screw in the hinge on the fan-door. Fully tighten the screw, then loosen it by a quarter turn. The fan-door must move freely!
⬢Connect the Extruder motor cable to the connector on the top side of the LoveBoard.
⬢Connect the Loadcell cable coming from the right of the heatsink to the upper slot on the right side of the LoveBoard.
⬢Connect the filament sensor cable to the lower slot on the right side of the LoveBoard.
Before covering the electronics, check the connection of all cables. Click on high-resolution preview in the top left corner.
⬢Close the idler mechanism before proceeding to the next step if you haven't already done so. Use the following sequence:
⬢Close the extruder idler to the extruder
⬢Close the idler-swivel and lock it over the extruder idler assembly
⬢For the following steps, please prepare:
⬢LoveBoard-cover (1x)
⬢LoveBoard-cover-right (1x)
⬢M3x10 screw (1x)
⬢Curve and arrange the cables on the right side of the extruder as you can see in the picture.
⬢Cover the cables with the LoveBoard-cover-right.
Do not pinch the cables!
⬢Secure it with the M3x10 screw.
Make sure the LoveBoard-cover-right fits snugly against the right side of the extruder. If not, it may cause the X-axis test to fail during the self-test because it will prevent the X-carriage assembly from moving all the way to the right.
⬢Push all cables to the extruder to make more space around them. See the picture.
⬢Slide the Loveboard-cover on the extruder. And push it all the way down. The cover must go behind the X-carriage-back.
Be careful not to pinch any cables.
⬢Ensure that the two plastic covers fit together perfectly.
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 "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 optimal performance, the belt must have some resistance when pressed with your fingers. Move the extruder 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.
This step is recommended, but optional. If you don't have a phone at your disposal, continue to the next step. You can do this check later on.
⬢To verify or fine-tune the X or Y-axis belt tension on your printer, visit prusa.io/belt-tuner and open up the webpage on your mobile device. Or using your phone, scan the QR code in the picture.
⬢Watch the instructional video on prusa.io/belt-tuner-video and fine-tune your X belt tension, if required.
The belt tuner app was tested on multiple phones and should work across all most common phone manufacturers. However, in some rare cases it might not work as expected. Please state your brand and model in the comments below the step.
⬢Use the technique described below to test if the belt is properly stretched.
⬢Grasp and hold the flat part of the X motor shaft with pliers. This will prevent it from rotating in the pliers.
⬢Move the extruder towards the X 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.
⬢Eat five gummy bears.
Did you know that gummy bears have a long shelf life, typically lasting for up to two years if stored properly in a cool and dry place. But don't do that now.
⬢That was tough. But we made it!
⬢Let's go the next chapter: 6. xLCD assembly
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