3Dator Bowden Extruder

by 3Dator, published

3Dator Bowden Extruder by 3Dator Feb 5, 2016

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This is bowden type extruder. It is designed to be in a small formfactor, support hard Filaments like old PLA, but also print flexible materials like Ninjaflex. It uses 1.75mm filament. With the opener you can release the stress from the filament to change it quickly.
The Parts are designed to be printed without Supports.
It can be mounted on the outside of your printer with the adapter. The adapter mounting holes are compatible with the Airtripper Bowden Extruder.
Also you could mount it in your Case like in the 3Dator. The stepper motor goes inside and the extruder outside. The material between should be 4-5mm.

See how it is put together here (German):

See the Printer in action printing Ninjaflex here:

If you don't like to get all parts yourself you can buy the extruder here (Germany only):


  • Optimised filament channel for better flow.


  • Again optimised filament channel (works best with mk7 gear for 1.75mm filament)
  • added a file with the complete extruder ready to print
  • added a hook with a hole to see what your mk7 gear is doing and check if it is aligned (Thanks to 50koruny for the idea)
  • added a mirrored version for dual extruders to our github repo: https://github.com/3Dator/3dator/tree/master/stl/extra/extruder_mirrored


You can find the complete file history in our github repository:

Print Settings




Doesn't Matter








We always print this with 3 perimeters to make it stronger.


To get better results with the M3 holes in extruder_base we closed them with 2 layers. Just open them again with a drill.

Bill of materials

Beside the pla for printing the parts you will need the following parts:
1x MR105ZZ
1x 608ZZ
1x MK7 gear for 1.75mm filament
2x M3 self locking nuts
2x M3 40mm screws
3x M3 25mm screws
1x PTFE fitting PC4-M5 (M5 screw, for 4mm ptfe tube)
1x Nema 17 Stepper Motor


If you want to use a MK8 drive gear instead of a mk7 check out the remix of 50koruny:
He also added a "window" to have a look inside to see what's going on.


Finding the right tension

This Extruder is supporting a wide spectrum of different filaments.
Usually you only need to tighten one screw, which makes it more easy to find the right tension. For Filaments, that need to get squeezed quite hard, like old PLA or Ninjaflex you should tighten up both screws.
For printing Ninjaflex, you may print the Extruder Base with a nozzle as fine as possible and with a 0,1 mm layer height.

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for easy searching - square nuts are DIN 557

or 562. For the M3 size used here, DIN 562 is more common. :)

We're using Din 562 because they aren't that thick. In this case both fit.

I'm updating the files in a second to also fit normal M3 nuts.

Comments deleted.

M3 40mm screws, M3 25mm screws. Couple of questions. First, do these screws require the nuts as well? Looking online, iso, din, do these matter or or do i just make sure i have the correct length and diameter?

The right length and diameter should be enougth. You'll also need 2 M3 squere nuts. If you only have the normal one have a look at the remixes. some people changed the design to fit normal M3 nuts.
Also have a look at the pictures, there you can see the screws we used.

Got it. Thank you for that.

Something is not right. May i be given some feedback regarding what could be? Anyone that has built it can maybe chime in?

So i printed all the parts. I cleaned filament path and is smooth. Assembly went fine. Mk7 drive gear aligned fine. I didnt tighten the (3) 25mm bolts too tight since they may not let parts move when i undo the lever. At first the filament was hard to get in. So i had to keep loosening the 40mm screws. I used lock nuts so they wouldnt vibrate loose. I got filament in, and its doesnt roll smooth, its kind of tight to the point it does move the mk7 drive gear at times as i feed it. If i get it any looser, the 40mm screws will not pull when i close the latch.

So, after i got it in, i tested extruding.... and per my manual command, it extruded 100mm perfect. BUT, when i print, its printing like Sh**.... i think its keeping pressure too much even with 4mm retraction. See below test print pic, thats with 3Dator on the left, and on the right is exact settings except me reverting to my old setup.


How can i make the filament not be too tight when feeding manually and how can i find out why its over extruding so much?

Thanks for your feedback! The filament won't get really loose with the handle. I think this could be further optimised. There are remixes using a spring instead of our non spring mechanism.
You picture looks much like a wrong steps/mm for your extruder. Keep in mind that if you change the gear on the extruder (in this case mk7) you need to adjust your steps/mm.

Jan 28, 2017 - Modified Jan 28, 2017
STIG_ - in reply to 3Dator

Thank you for your feedback. But its not my steps.
My steps are perfectly calibrated. My current setup already uses the Mk7 gear. As i mentioned on my earlier post, i sent a command to extrude 100mm ...and it extruded exactly 100mm (marked on filaments) . So its not that. Its during printing that i noticed this.
Do you have any more ideas?

Comments deleted.

A suggestion for the adapter, put 4 holes, so in my case I need to put horizontal (cannot vertical). So I will able use it without alteration! :)

Thanks mate. Great design. Really saved me. :)

Comments deleted.

Finaly done the conversion on my printer but found the extruder stepper is getting way to hot for comfort.
I think the small wanhao/malyan steppers aren't up for the task so going to switch the stepper out for a bigger one

Congrats! This looks awesome, really pretty design, nice and compact. I am looking foreward to try it out!

Hi, is there a version for an m6 push connector?

thanks, good design

Also having a hard time finding m5 but loads of m6 connectors.

I think none of the remixes changed for a bigger push connector. Maybe you can change it yourself. You can find the step files in our Git repository. Links are in the desciption and below here in the comments.

too late but my MK8 remix have M6 connector (i have used only M6 and R1/8) and i have to draw next version with R1/8 or M10 because i have broken lots of M5 and M6 fitting when tried to print really fast.too high pressure in bowden tube have pulled tube out from the fitting mid-print.need to be M10 for printspeed faster than 150mm/s.

Very nice compact design.
Would improve reproducability if using 608 also for the outer bearing, and standard M3 nuts instead of the rectangular ones.

Hello !

Very nice design, i am printing it right now. ( and redesigning a bit as well, the axle came out too large and the adapteur isn't the best fit for my machine, i'll share my designs as remixes once i've successfully built it.

the name of the PTFE fitting is referenced as "PC4-M5", i just wanted to share that as i struggled a little finding the right keywords when buying this part.

Great work, THANKS !

Comments deleted.
Apr 15, 2016 - Modified Apr 16, 2016

Looks Really Nice. Rigid no unnecassary knick danger.

But: i would like to adjust it to fit with mk8 gears. can you share some .step files?

Thanks a lot


Hi raffa, if you are going to adjust this design to fit with mk8 gears, may you also share the remix with us/me? I'd love to print it and use on my printer!

Thank you!

Hi, we will release the step files as soon as possible.

How can i download the step files on this Page?

Github is a bit inconvinient at first, sorry for that. Just click on the file you want to download, then right click on the "raw" button and click "save link as".
You can also download the complete repository here: https://github.com/3Dator/3dator by clicking "Clone or Download" and "Download ZIP".

Aug 23, 2016 - Modified Aug 23, 2016
pat126 - in reply to 3Dator

Thanks, Is there maybe a version for 3mm Filament?

not to my knowledge

Ok then i have to change it by myself

Can this work with / printed with PLA? Or should this be printed with other material like PETG or ABS filament?

we always print this in PLA. Works if it won't get too hot.

Can I attach a PTFE tube connector on both ends to have PTFE running all the way from filament to the effector? And is that mount made for mounting on 2020 Aluminum profile? Thanks!

At the moment you have to modify the stl file for a ptfe tube connector. We'll release a second version were we'll add this in. I like the idea.
The mount is just copied from airtrippers bowden extruder. Have a look at the following make of our extruder: http://www.thingiverse.com/make:201280

3Dator Bowden Extruder

Hi great Design. Can u Upload the step from the base? Everything else i found on git. I have to resize the hole for the small bearing. I already have some one with 11 mm. The hole has only 10

Hi there, thanks! Sadly we lost the step file. We habe to redesign the model. When thats done we'll upload it.

A warning about the choice / compatibility / requirements with respect to the stepper motor shaft.

Because of the required positioning of the MK7 gear, very close to the motor itself, you need the flattened part of the motor shaft to extend very close to the motor. The three stepper motors that I bought from Aliexpress had the flattened part finishing too far away from the motor - meaning that the MK7 could not be fixed in the right position for this extruder.

I have had to extend the flattened part of the shaft further down towards the motor (using a dremel) to allow me to fix the grub screw in the right place.

Refer to the pics in 'I Made One'.

Has anyone tried printing flex with it? My airtripper cant even if I put a little piece of TPFE after the MK7 :/

We're printing Ninjaflex with it. Works very well. Printing flexibel materials was one of the design goals of this extruder.

Thanks! Is the MR105ZZ really neccesary? :)

It works without the MR105ZZ but with the bearing it releases some stress on the stepper motor.
We have a video on youtube printing ninjaflex with our printer (and this extruder).
-> https://www.youtube.com/watch?v=mxCev5Obq2g

This is one awesome extruder setup. I have looked at many different Bowden type extruder mounts and this one by far is the most universal. This is upgrading my GeeeJunk i3 pro C which I have made my own hotend mounts. I have had too many problems to list with GeeeJunks setup. The fact that this will now be away from the hotend is a HUGE advantaged in several ways. Less weight, thus less mass to move and less artifacts, also stepper will run cooler as the heatbreak is no where neat the extruder.

Very well designed, I put mine together today, and I am using a MR104ZZ With a flanged side, and I think it works better with a flange. It wont push out.

Thanks for you positive feedback. Does it print well? A flanged bearing is a nice idea, we'll consider that in the future.
The adapter got three holes at the moment, a fourth hole could be added to turn the extruder in every direction.

Havent had time to test with printing but works great with all the tests I have done. Just so you know, there are no modifications necessary to use mr105 flanged bearing. It drops in and sits perfectly. I also hope you don't mind, I have included your feed blocks in an prusa i3 upgrade set/rework set and have given you proper credit and links to your site. All I did was mirror the drive block so there is a left and right. Other than that pretty much all unchanged.

Can I ask why you chose to use a MK7 gear instead of MK8? Would a MK8 work or would the design need to be modified?

MK8 won't fit because it has a smaller diameter (9mm instead of 12.5mm). You could try, but I guess that the filament will be bend too much.

It's pretty cool!! I looks very solid ! I will print one when I have time, but I have to modify some parts to fit my printer 3D.

Thanks, to be solid was one of our design goals.
What do you have to change?
Leave a message when you start modifying, we'll publish step files soon.

That extruder is designed to put it in vertical position and I want to put it in horizontal. I don't know if you understand me, my english is not good enough. if you can send me your desing it will be easier to me to modify, but I'm looking your photos and maybe I just need to rotate the adapter 90º

if you make another hole in the adapter you can turn it in any direction you like.
I'll upload the part in the next days

i will print twice it for dual extruder. what do you prefer for dual nozzle mount?

Feb 5, 2016 - Modified Feb 5, 2016
3Dator - in reply to osem

For dual extruder it looks nice if you mirror one of the extruders. For mounting the nozzles we have our own printhead but I don't think it will fit with your printer.
-> https://github.com/3Dator/3dator/tree/master/stl/printhead

my x and y axis is different. i have a prusa i3. i need only x idler

Grab some E3D Hotends (Original or china clones) and print a dual mount for them (many designs out there)