Original Prusa MK2.3 extruder (MK2/MK3 hybrid extruder for Prusa MK2/MK2s)

by Tijnv Dec 28, 2017
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Hello! I've been using your extruder for more than a year now and can't be happier! Thank you!
I just wanted to ask if you're planning to do the same with the MK3S extruder?

Hi what hardware should I be using to attach the backplate

I have taken the liberty of remixing this to include the v2 body for MMU as well.
Here is the link for those who would need it.

Original Prusa MK2.3 v2 extruder (with MMU 1.0)

Would it be possible to get a version with space for 12 / 18mm Z probes? Most "fake" 8mm probes only have a 2mm sensing distance..

Is it possible, that you add the MMU Extruderbody_v2 too? Will need this file, to upgrade to the newest version. Would be really nice :)

I think I've gonna give you a tip, when I assembled everything and it works. I wanted to do that upgrade by myself and saw this then. Great Job, and I think a lot of work

please attach source SCAD files. it is required by GPL license. I need to modify this part and it is my right. Please stop ignoring people who ask you to publish source files!

Swapped everything out on my clone to this MK2.3 hotend and now there's a creaking sound. I know it has something to do with the extruder but it's hard to pin point. It's not constant either. I thought it was filament rubbing on the plastic somewhere but I can't quite figure out where.

Anyone else have this issue or any ideas?

You don't need the second screw for the 45 deg. fan on the extruder cover :)

Do you think you may post also a version for e3d clones?
And MMu V2 in the future?

With the updates, it's unclear which version of which files to use together.
If I want to use the latest, am I correct in using the following STLs?

  • nozzle-fan-45deg.stl
  • nozzle-fan-45deg-support.stl
  • Extruder_body_v2.stl
  • extruder-cover-v2.stl
  • extruder-idler.stl
  • MK2.3_X-_carriage.stl
  • MK2.3_X-carriage_backplate.stl
  • cable-holder.stl

So... No changes need to be made to the firmware? I'm using an mk2s.

This can be used with a Anet A8?

Can anybody tell me how much space is between the noctua fan and the z axis rods when hitting the x-axis end stop? I would like to use the noctua af4-20 fan which is 20mm thick (so I need at least 10mm space).

I'm also interested in the answer to this.

I now installed this mod and I can answer the question: It does not work. The af4-10 fan is about 3mm away from the threaded rod when in home position on the x-axis... no chance for the af4-20

Edit: One option may be to use an adapter to install an af4-20: https://www.thingiverse.com/thing:2941843

Prusa MK3 Tilted Fan Adapter

Thanks for taking a look; much appreciated!

Extruder cover doesnt has the same dimensions of MK2, the extruder body doesnt fit well..

Hi, I dont understand why you make X carriage very difficult to insert the belt :(
The nozzle also can't reach the temperature when use more than 80% fan speed.. any idea?

If you're referring to where the ends of the belt insert in to, this is as designed on the latest MK3 revision. Refer to this manual step: http://manual.prusa3d.com/Guide/4.+Z-axis+assembly/509?lang=en#s9978

I haven't used this awesome Thing myself yet, but if the fan you are using is cooling the nozzle too much, you'll need to lower the fan speed as it's working a little too well. :) Some of the Noctua fans ship with adapters to slow them down and make them even quieter. You could either add the equivalent of this to the hardward or change the fan speed in your slicer or GCODE.

Many thanks, I need to modify with knife to the belt teeth but still not fit for the belt.
For the nozzle fan, I modified the file 2mm down so the air flow not directly aim the temperature sensor which make the temperatur drop almost 30C degree from target. and the result was great enaugh.

Hi, awesome remix! Do you mind sharing scad files?


Thank you so much for adding the prusa mmu adapter! cant wait to print this!

Could you please make a version that would make use of the 18mm inductive probe. Similar to https://www.thingiverse.com/thing:2261050.

Prusa i3 MK2 Clone Extruder for 8/12/18 mm sensors and MK8 Hobbed Pulley

Yes I’d really appreciate it as well!

A BLTouch version will be awesome!! ;)

Thank you, for your work! Can you make a second Version with adjustment for 16mm for IGUS RJZM-Bearings?

BLtouch version?

Really not a fan of prusa's old habit of screwing screws right into plastic like the part cooling nozzle and hotend fan screws are, I don't get it there is plenty of room for a nut slot or melted in insert, though I guess inserts would have to be pre-installed by prusa's team? Most people can't be trusted with a soldering iron I guess. Pretty tempted to just add nuts lots and inserts to cover those 5 screws.

Prusa has used this design on thousands of printers because it works, just like using zip-ties in various areas. They use nuts where they are needed to keep things simple. I know when assembling my MK2S, the nuts constantly falling out while trying to assemble were so annoying I ended up hot gluing them in place.

What parts do i need (screws, and bearing) if i start from zero?

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To bottom 2 screws... the best design would be with squre nuts because second print and destroyed threads again - not even strong twists

Also diameter for heatsink in extruder cover needs to be bigger, it is too small

Bottom screws are with square nuts..... and heatsink diameter is still the same as in the original Prusa parts....
Must have something to do with your printer settings

Should be fixed now!

It is not working, because the Cable holder is to near on the Case from the Board. So the end Switch does not get hit.

This is fixed in the latest update

I Printed the latest Update an it is still to near. I modified it Again an now it is working. Its Just 2mm to the Right

had no issues with prusa pla. but may add information about the additional required square nuts (+4 i guess)

is it possible to get the STEP files for this? if ok with you i would like to remix this to fit the E3DV6 VOLCANO (nozzle and larger heat block) :)
i will of course give you the credit when i upload on my thingiverse profile.

i have tried to work with sto files in Fusion360 before but it is a nightmare, but a STEP file would be easier i think:)

best regards

Hans, from Norway

Would PLA work as well? If not I would buy some PETG. Any brand recommendations (orange/black)?

Hello there! Could there be a possibility to have a version which supports IGUS DryLin bearings? As I recall they are a bit different, and I do have a different carriage plate printed. :) I use the aluminum shell bushing version.

Does anyone have problems with XYZ calibration after installation? Tijnv, is the pinda probe on the exact same spot as the original extruder?
My printer is failing to complete XYZ calibration, passes the first 4 points and fails on the next round of 9 points. It stops after the first one and says "XYZ calibration failed. Bed calibration point was not found."

Did you use the files from the 16 feb update or files from before the update?

Files are before 16th, but I fixed it. It was the vref on my drivers. Great work!!

What is the bearing size used on this model?

Hi! Thank you! Can you modify a version for the MK8 hobbed pulley and 12mm inductive probe?

there is a 12 probe version in the comments.
best just buy another pulley they are only a dollar on ali express

I live in Ukraine. Price for order pulley prusa i3 mk2 in Ukraine -6$. (((Thank you!

Hi man, awesome job! Thanks for sharing!
Can I use MK8 hobbed pulley with this version?

I noticed that the endstop wont trigger when using the mk3 backplate and cable Management, was this fixed yet?

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Did the modified file work for you? I'm seeing the same thing... not sure how the OP ever got this to work with the current design...

Sry I switched back for the MK2 Carriage which I had in stock

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This file does not work either. It is missing the screw hole and extra material next to the endstop. Also, the hole that accomodates the nylon filament needs centered. When the MK3 backplate is attached the nylon filament is not centered in the opening that cables come through. Please fix this, it has been a nightmare trying to get this on my printer. I've attached pictures of the problem areas

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The MK2 style x-carriage endstop is also not long enough. It needs to be longer than the noctua fan to trigger the endstop and I really like the MK3 cable management solution. Would appreciate fixed STLs

Reworked almost every part today and this new X-carriage should work!

The mk2 style will work just fine

I will work on another X-carriage when i have time

Have you tried this with the V2 X carriage? I printed 2 of these in PETG and I can not get the square nut in the slot that is next to the endstop piece. It is friggin impossible.

Do you know of any other issues with this? Luckily I tried to fit all the nuts before install but I am about to tear my only printer apart to install this. Would hate if there was another issue and I would have to put it all back together just to print a new piece.

There should not be any other problems i have 2 printers running with this extruder right now.

So I finally got around to installing all this and this just isn't true. I'm not sure how you have this working with the MK3 backplate and cable management but the X-Endstop is not triggerable with the current design. I now have my only printer tore apart and am unable to complete the process due to faulty design. I ruined my original parts getting the square nuts out... not sure what to do now.

I have been putting my 0 cad skills at work but i cant do it. Can you please include a version for a 12mm inductive probe?

Thank you

i quickly made this, hope it works for you

Could you please upload a 12mm version of the new, updated file (from February)? Or didn’t that part change?
Thank you in advance!

There is a problem with this design, the motor part and extruder part are printed like two differents bodies. In the attachment there is the 12mm design and the 2.3 original design, it clear the separation.

Thank you very much for the super fast reply! I will print the whole extruder in a few days and post here .

Can you release the SCAD source or modify a version for the MK8 hobbed pulley? I cannot source the Prusa's hobbed gear which is about 1mm smaller than the MK8 that I have. Much appreciated!

I have the same request for mk8 hobbed pulley?

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Hey! First thanks for taking the effort to convert the design. Second, I did not entirely understand from the comment section if the MK3 x-carriage and back plate are actually usable or not. Specifically about the end-stop issue. Has this already been taken cared of?

There is a modified MK3 X-carriage with endstop and backplate in the files!

So these modified work then, i will go on and print them instead.
Thanks again!

Hi, did you check the comment on the first person who made it:

"Problem - the x-carriage left opening (see last picture) for the belt was slightly too wide and the tooth of the belt could slip when some force was applied"

Is this fixed now?

The MK2 style X-carriage has just very little adjustments and the belt part he is talking about is still exactly the same as the original MK2 X-carriage. So it probably had to do something with his print / settings..

Yes I agree. This might be just my belt being slightly worn off or just a small inaccuracy in the print.

Can I print and use the new Mk3 xcarridge and back plate for better cable support with your design, I currently have a Mk2?
Thanks for your work

MK3 style X-cariage added so you can use the MK3 cable support!

That's exactly the same question I have. The stl.-files look like this should work well with the MK3 x-carriage (and back plate with cable support).

Can you confirm?

(I already printed the extruder for now. I will post pictures when I have everything assembled. :-) )

Apparently you can not use the original X-carriage intended for the MK3 on a MK2 because of a necessary mod for the xstop. If you see PineappleSystems Mk3 Mod you can see he has a moded Mk3 X-Carriage that may work... he has an extruder body mod like you have but with a mount for the pinda probe that has yet to be determined if it will work in its current location when placed on a Mk2...but it is closer in other ways to the Mk3 setup...so many things to consider...

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You are completely right. I was aware of that yesterday, but apparently forgot the endstop aspect completely today, when I noticed that the distance of the mounting holes match well. LOL

I don't see a huge benefit for the cable management with the MK3 carriage, so I will probably use the MK2.3 part from here. I will report with pictures after assembling everything.

Thats exactly what I need, just one question:

Can I use the new prusa mk3 cable holder with that?
Also it would be nice if you could add a variation for a 12mm inductive probe.

Thank you

Any recommendations if I should print the fan nozzle from PETG or ABS?

both are fine
i printed in PETG

Complex, bulky, fragile, heavy ! How people can draw (not design) such complex parts for such a simple purpose is amazing.

take care:


The MK3 hotend has a little bit more distance from the x-axis then the MK2(S). When you try to use the x-carriage and the extruder-base and -cover of the mk3 (after you edit the mk3's carriage to trigger your endstop(!) ) the center of the nozzle isn't any longer at the same position.

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