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Introduction

Purchase your Hemera here: https://e3d-online.com/e3d-hemera-175-ki...

The printed files can be found here:

https://www.thingiverse.com/thing:405843...

Find the part cooling fan bracket here: https://www.thingiverse.com/thing:403163...

(credit to permanoob)

Please note that this guide is assuming the use of a fully assembled and hot tightened Hemera unit if you have not yet fully assembled and hot tightened your unit please see: Hemera Assembly Guides

Mounting a Hemera to a Prusa i3 MK3 is easy, and we provide most of the tools you'll need. Please note, though, that you should be very careful of the following safety cautions:

  • Be aware of your electronics. Don't work on your printer while it is plugged in or turned on.
  • Be aware when you heat up your new HotEnd not to burn yourself on the heater block nozzle or heater cartridge.
  • The standard Hemera is capable of printing up to 285°C, do not exceed these temperatures unless you have replaced the Thermistor cartridge with a PT100, the Aluminium heater block with a Plated copper heater block, and the Brass nozzle for a Plated copper, Hardened steel or Nozzle X.
  • Firmware modification is not optional it is a mandatory step,
  • Make sure you have ordered and received the correct voltage heater and fan to match the power supply of your printer. All of our current heater cartridges should have the voltage and wattage laser engraved on the cartridge. Taking an ohm reading is the most reliable method of testing what voltage/ wattage you have received.
  • Connecting 12v parts to a 24v power supply can result in overheating, component damage, or fire. If you are unsure double check the rating on your power supply.
  • Your HotEnd and your printer are your responsibility. We cannot be held responsible for damages caused by the use, misuse or abuse of our products.
  • We provide these guides as a reference to show that it is possible to mount a Hemera to a Prusa i3 MK3/3s. Users should be mindful that your specific use case may vary and further modifications or additions may be required.
  1. Gather a Prusa i3 MK3/3S.
    • Gather a Prusa i3 MK3/3S.

  2. Locate the x2 M3 screw that fastens the part cooling fan. Undo the X2 M3 screws with a 2.5mm hex wrench. Undo the X2 M3 screws with a 2.5mm hex wrench.
    • Locate the x2 M3 screw that fastens the part cooling fan.

    • Undo the X2 M3 screws with a 2.5mm hex wrench.

  3. Place the part cooling fan between the belts to prevent damage to the wires.
    • Place the part cooling fan between the belts to prevent damage to the wires.

  4. Locate the x4 M3 screws that fasten the heatsink fan. Undo them using a 2.5mm hex wrench. Place the fan between the two belts in order to prevent wire damage.
    • Locate the x4 M3 screws that fasten the heatsink fan.

    • Undo them using a 2.5mm hex wrench.

    • Place the fan between the two belts in order to prevent wire damage.

  5. Locate the x3 M3 screws on the back of the extruder housing using a 2.5mm hex key. Rotate the printer so the back of the printer is facing you.
    • Locate the x3 M3 screws on the back of the extruder housing using a 2.5mm hex key.

    • Rotate the printer so the back of the printer is facing you.

    Depending on the upgrades on the printer a Mk3 may have 5 M3 screws to remove.

    Neil - Reply

  6. Snip the cable ties that secure the wiring in place.
    • Snip the cable ties that secure the wiring in place.

    • Be careful not to cut any of the wires.

  7. The back cover should now be loose. Disconnect the filament run-out sensor. Disconnect the filament run-out sensor.
    • The back cover should now be loose.

    • Disconnect the filament run-out sensor.

  8. Undo the x2 bottom M3 screws first. Before undoing the last M3 screw hold the motor to prevent it dropping and damaging wires/ the heated bed.
    • Undo the x2 bottom M3 screws first.

    • Before undoing the last M3 screw hold the motor to prevent it dropping and damaging wires/ the heated bed.

    • Undo the top M3 screw.

  9. The front of the extruder body should now be loose, gently rest it on the heated bed.
    • The front of the extruder body should now be loose, gently rest it on the heated bed.

  10. Locate the M3 screw that fastens the PINDA probe. Undo the PINDA probe.
    • Locate the M3 screw that fastens the PINDA probe.

    • Undo the PINDA probe.

  11. Locate the x3 M3 screws that fasten the motor. Undo the x3 M3 screws with a 2.5mm hex key. Undo the x3 M3 screws with a 2.5mm hex key.
    • Locate the x3 M3 screws that fasten the motor.

    • Undo the x3 M3 screws with a 2.5mm hex key.

  12. Locate the x2 M3 screws that fasten the HotEnd cover to the main extruder body. Undo the x2 M3 screws with a 2.5mm hex key.
    • Locate the x2 M3 screws that fasten the HotEnd cover to the main extruder body.

    • Undo the x2 M3 screws with a 2.5mm hex key.

  13. Remove the V6 from the extruder body. Remove the V6 from the extruder body.
    • Remove the V6 from the extruder body.

  14. At this point your Prusa should look as such.
    • At this point your Prusa should look as such.

  15. Loosen the thermistor grub screw. Slide the thermistor out.
    • Loosen the thermistor grub screw.

    • Slide the thermistor out.

    • If the thermistor is difficult to remove poke from the end of the thermistor cartridge with an hex key rather than tugging on the wires to prevent damage.

  16. Remove the heater cartridge.
    • Remove the heater cartridge.

  17. Turn the printer around to gain acess to the wiring loom. Undo the cable wrap. Your printer may use a fabric wrap.
    • Turn the printer around to gain acess to the wiring loom.

    • Undo the cable wrap.

    • Your printer may use a fabric wrap.

  18. Locate the M3 screw that fastens the control board box. Undo the M3 screw using a 2.5mm hex key. You should now have access to the main board.
    • Locate the M3 screw that fastens the control board box.

    • Undo the M3 screw using a 2.5mm hex key.

    • You should now have access to the main board.

  19. If you are reusing the heater cartridge and thermistor keep them connected.
    • If you are reusing the heater cartridge and thermistor keep them connected.

    • If you are using a new thermistor/ heater cartridge use the board diagram as a reference.

    • Make sure you are using a 24v heater cartridge for a Prusa MK3.

    • Disconnect the extruder motor.

  20. Gather:
    • Gather:

    • x1 Printed Hemera Mount

    • x1 Printed Hemera bumper piece

    • x1 Fully assembled and hot tightened Hemera

    • x2 M3 square nuts.

    • x6 M3 x 6mm screws.

  21. Place the bumper onto the printed mount. The bumper sits on the smooth side/ side that was face down on the bed.
    • Place the bumper onto the printed mount.

    • The bumper sits on the smooth side/ side that was face down on the bed.

    • Fasten in place using x2 M3 x 6mm screws.

  22. Place x2 square nuts into the T-slots on the backside of the Hemera motor. Place x2 square nuts into the T-slots on the backside of the Hemera motor.
    • Place x2 square nuts into the T-slots on the backside of the Hemera motor.

  23. Place the mount on the back side of the Hemera lining up the 4 holes with the square nuts. Fasten the x4 M3 x 6mm screws.
    • Place the mount on the back side of the Hemera lining up the 4 holes with the square nuts.

    • Fasten the x4 M3 x 6mm screws.

    • Be aware it is possible to crack the t slots if you use screws that are too long and bottoms out. Our recommendation is to use screws that protrude 3mm +- 0.25mm from the mounting surface to go into the T-Slots. Over tightening also risks snapping the T slot.

  24. While you have easy access drop an M3 square nut into the PINDA probe holder.
    • While you have easy access drop an M3 square nut into the PINDA probe holder.

  25. Orient the printer so that the backside is facing you.
    • Orient the printer so that the backside is facing you.

  26. Offer the Hemera mount up to the existing mount. Fasten the top M3 x 6mm screw. Fasten the x2 M3 x 15mm screws.
    • Offer the Hemera mount up to the existing mount.

    • Fasten the top M3 x 6mm screw.

    • Fasten the x2 M3 x 15mm screws.

  27. Fasten the back plate on using x2 M3 x 12mm screws on the top. Fasten the bottom x2 M3  x 12 mm screws. Fasten the bottom x2 M3  x 12 mm screws.
    • Fasten the back plate on using x2 M3 x 12mm screws on the top.

    • Fasten the bottom x2 M3 x 12 mm screws.

  28. Orient the printer so that the front is facing you.
    • Orient the printer so that the front is facing you.

  29. Place x1 M3 square nut in the bottom right T-slot. Place the printed part cooling duct on the front side.
    • Place x1 M3 square nut in the bottom right T-slot.

    • Place the printed part cooling duct on the front side.

    • Fasten the fan duct using x2 M3 x 6mm screws.

    • Be aware it is possible to crack the t slots if you use screws that are too long and bottoms out. Our recommendation is to use screws that protrude 3mm +- 0.25mm from the mounting surface to go into the T-Slots. Over tightening also risks snapping the T slot.

  30. Place the part cooling fan in the fan duct. Fasten the fan to the duct using a M3 x  20mm screw
    • Place the part cooling fan in the fan duct.

    • Fasten the fan to the duct using a M3 x 20mm screw

  31. Place the PINDA probe into the PINDA holder. Fasten the PINDA probe using a M3 x 10mm screw.
    • Place the PINDA probe into the PINDA holder.

    • Fasten the PINDA probe using a M3 x 10mm screw.

    • If you are finding the PINDA probe mount is snapping ensure you are using PETG filament for this part.

  32. fasten the heatsink cooling fan using x2 self tapping screws. Pictured is a non stock fan, please do not use the stock Prusa fan, we recommend the use of the supplied Hemera fan instead.
    • fasten the heatsink cooling fan using x2 self tapping screws.

    • Pictured is a non stock fan, please do not use the stock Prusa fan, we recommend the use of the supplied Hemera fan instead.

    The supplied 24v 2 wire fan does not work on the Prusa MK3S. It requires a 5v 3 wire fan. If you don’t suggest using the Prusa fan could you give us some alternatives or specs we need to find to decide if a fan is viable?

    Doug Robertson - Reply

    We would recommend wiring the heatsink cooling fan directly to the power supply.

    Dan Rock -

    I used the 2 wire fan, but kept getting “Err: EXTR FAN ERROR” when I started preheating. Had to disable “Check fans” in mk3-settings.

    https://help.prusa3d.com/cs/article/err-...

    Kristian Thorsen - Reply

    I don’t like your solution of wiring the heatsink cooling fan directly to the power supply.

    1. If I do a print overnight the fan will keep on running after the print is done. This could be for several hours.

    2. The prusa fan checking function is disabled.

    I would like to know what speaks against using the Prusa fan? and 2nd is there any other Prusa compatible fan on the market that you could recommend?

    Frans - Reply

    There was discussion on the fan issue on the E3D Discord today: https://discordapp.com/channels/75650185...

    Someone on the Prusa forum found a suitable 5V fan, Sanyo-Denki 109P0405H901: https://forum.prusaprinters.org/forum/or...

    Brian Lalor - Reply

  33. Insert the motor cable into the top of the Hemera motor.
    • Insert the motor cable into the top of the Hemera motor.

  34. Route the motor and part cooling fan cable between the bottom rod and bottom belt, similar to the PINDA probe. Route the motor and part cooling fan cable between the bottom rod and bottom belt, similar to the PINDA probe.
    • Route the motor and part cooling fan cable between the bottom rod and bottom belt, similar to the PINDA probe.

  35. Turn the printer so you are facing the backside.
    • Turn the printer so you are facing the backside.

    • Gather the wires together, the heatsink fan wires and hotside wires should come below the bottom rod. These will fasten to the underside of the cable guide.

    • The motor cable wire and part cooling wire should be between the bottom rod and bottom belt, and rest on top of the cable guide.

    • Fasten the wire bundles with cable ties.

  36. Trim the excess cable tie with a side cutter or pair of scissors.
    • Trim the excess cable tie with a side cutter or pair of scissors.

    • Be careful not to cut any of the wires.

  37. Use a plastic or textile cable wrap to tidy up the wire bundle. Re-make the electrical connections to the board using the diagram as a reference. Double check the voltages of components you are using.
    • Use a plastic or textile cable wrap to tidy up the wire bundle.

    • Re-make the electrical connections to the board using the diagram as a reference.

    • Double check the voltages of components you are using.

    The Hemera motor cable works without modifications (red, blue, green, black).

    The original mk3 motor cable is (from the top) blue, red, green and black, but the Hemera one is red, blue, green and black.

    Don’t match colors with the original one. I switched the red and the blue wires and then both gears rotated the wrong way. I had to revert back to red, blue, green and black.

    Kristian Thorsen - Reply

  38. Close and fasten the electronics case.
    • Close and fasten the electronics case.

Finish Line

One other person completed this guide.

Dan Rock

Member since: 06/07/2018

21,640 Reputation

40 Guides authored

18 Comments

are the necessary firmware changes that are needed documented somewhere?

Chandradat Thakoor - Reply

Thank you very much.

Chandradat Thakoor -

I would love to see the filament run-out sensor incorporated into the mount, but it looks like it’s removed possibly?

Melissa LeBlanc-Williams - Reply

Link for cooling fan is invalide

Christian G - Reply

Hi, does it work for MK3S? ty!!!

@imag3n3d - Reply

This guide sucks. Terrible mount design. The pinda probe snaps of too easily. And it’s impossible to get the printer to calibrate. The firmware flashing does absolutely nothing.

Eric Smith - Reply

The mount could be better, I would build in holders for nuts for the mount plate and concur the pinda holder is very weak (typing as I reprint it)

Also I concur I can not calibrate the printer, fails on the X axis.

Drew -

My modded mount is here with beefed up PINDA mount :- https://www.thingiverse.com/thing:407333...

Drew -

Another design if this one does not fit:

https://www.thingiverse.com/thing:407623...

Alex - Reply

OMG, you are a lifesaver! the one they provided is hot garbage and I have been fighting with it for hours. Keeps failing on the rear left point.

Chris -

I did an adaptor plate that fits with the MK3s carriage. No need to downgrade to MK3 or MK2.

Mesh bed levelling also works with this.

https://www.thingiverse.com/thing:409522...

In the given modification here are a lot of firmware changes missing. The printhead will crash a few times into minus X and evetually even causes your prints to be cancelled.

dim.lei - Reply

Where is the filament sensor fitted?

tony kangsung - Reply

This guide loses filament sensing functionality.

Dan Rock -

Can we please get a version of this that allows for the use of the MMU2S and the filament run out sensor? Not being able to use my MMU2s Is the only thing stopping me from getting a Hemera

Azure Skies - Reply

Can you post the adapter plates somewhere more reliable than Thingiverse please? I love the site but it’s not getting any quicker as time goes by…

Also I second the question about keeping the original filament sensor! There is plenty of room on the adapter plate above the Hemera.

Paul Scott - Reply

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