Cyborg Geared Bowden Extruder

by mitchnajmitch May 9, 2014
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It turned out to adjust the extruder under 1.75 mm. I had to put on the E motor 317.23 step mm

How to adapt this extruder for 1.75 mm?

does your extruder work with 1.75mm filament too? Thanks :)

How did you do the central piece with the teeth? It's weird

What is the distance center to center on the gears?

I have had some issues with slippage and this would really solve my problem. However, I use 1.75mm filaments - would you be able to help me with a version for 1.75 filament using a 1/8" 4mm OD fitting?

Where did you get the rods for this? I'm not even sure where to look...


Can you provide any other file formats? Step would be ideal

Comments deleted.

for those who asked I made the m3 nut insert for the small gear.

by Bastien

Very nice extruder, I print it now for my corexy. Only one question: how do you hold it to the frame?

could you tell me please what ptfe fitting that is??

Absolutely perfect!!! Had to do this exchange for non-bowden MK8 long time ago, because non-geared extruder has really not enough strength. Bowden + gear is the only reliable solution, adding strength and solving problems with extreme temperatures affecting the filament.
I made a little changes in the solution - I used 608 bearings + inserts to make them bigger. I also used 12mm threaded rod, but making them to 8mm at the ends to fit into 608 bearings. 12mm shaft is really transferring more force to filament than 8mm. Rod was taken from an old printer.

Hey there. I made one. But can you say me how do you do the M8-Screw into the bolt? did you it by hand?
second, randenko has a nice input. do some nut trap in the small gear. Else you did a good job. thank you.

How do the grub screws stay tight on the small gear? Are they threaded into the plastic? Usually a nut trap would be used.


So I've built this bowden extruder. However I'm having problem with it.
Can you please tell me what kind of extruder settings do you use?



what kind of problems do you have?

I believe the extrusion speed is too high. What extrusion settings do you set and which slicer software do you use?

It stucks when extruding. I'm using 3mm PLA. It extrudes well until it reaches the nozzle. Then a very small amount of melted plastic comes out then stops. Either the motor stops turning or keeps running but doesnt extrude the filament. I tried 190, 200 or 220 celsius degrees as well. Any idea?

I regulary print at speeds arround 80mm/s. Retraction is set to retract 4mm at 40mm/s, EAccel is set to 1000mm/s^2. It seems to me this is not problem raleted to extruder. Have you tried another fillament?


I'm almost ready to start assembling :)
Which hotend head do you use together with this bowden extruder? Is it uploaded to Thingiverse?


Hi mitchnajmitch,

How did you do the teeths for the biggest rod?
Also, what's that grey thing on the top?



it is made with a screw tap using drill press.


Thanks for the quick reply!
Some exact steps would be wonderful! :)
Did you just "drill" those tooth with the screw tap one by one?


One more question! In this picture: http://thingiverse-production.s3.amazonaws.com/renders/80/31/8d/51/4c/IMG_6252_display_large.jpg
How much is the distance between the middle of the hobbed part and the end of the bolt (big gear side)?


Hi, it is about 18mm from the center of the groove to the start of the gear.

Hi mitchnajmitch,
Very nice work, will it be to hard to ask you to adjust it to 1.75 as well ?


pretty much only thing that needs to be chnged is the mounting hole for bowden fittings. If you message me a diameter you need, It should not be a problem.

What diameter are you looking for? The width of an aircraft pneumatic fitting thread?

Hi mitchnajmitch,
I like very much your design and want to customize it for my printer (i am designing a brand new one).
Can you post or send me the original design files (I use solidworks). My mail is juanbe at gmail dot com
Thanks very much.

Sorry, but, it's for 1.75 or 3mm filament ?

Hi, it is designed for 3mm (2.85) filament. I will update the description. My mistake.

Thanks for this great work !
I have just one request, could you please give a file for each gear.
I try to print it for two days and i have big issue with the gears "glued" together :-)

I am terribly sorry for this inconvenience. I have updated the gears file, so the gears are spaced better. Also I have uploaded files of each gear. Hope it helps.

Nice design!
Is the m12 bolt hobbed? What kind did you use in the test?

Yes, it is. I used M10 screw-tap to hobb it. It can be seen on the one of the photos.

You said you used an M8 screw tap in the description. So which is it?

could we get a little better BOM. Screws, shaft spec (Thtreaded rod?)

Yes, sure, I have added it to Instructions page.