Hey! This thing is still a Work in Progress. Files, instructions, and other stuff might change!

NEMA17 & Bowden geared extruder for the SmartrapCore, V 0.99

by BrunoBellamy Feb 21, 2016
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Can I suggest you a name? "the Wererabbit" :-D

Hey bud. Love this thing. Fixed all my extrusion problems.
But I'm making 2 more, and I don't know what the threads are on the pneumatic fitting.
Is it possible to mix some with different sizes too? I have a pneumatic fitting thats much bigger (from e3d hotend) and one thats slightly smaller.

hallo! Habe ein Anet a6 mit Bowden umbau und wollte diese Getriebeextruder verbauen. brauche ich dafür unbedingt eine Cfw wie z.b. Marlin um die steps zu erhöhen. Wenn ich jetzt 50mm filament Fördern will kommen nur 6,7 mm raus. Mfg matze!!

Excellent design, thank you!

Comments deleted.

How should I proceed if I use the steps would like to adapt via pronterface? is that possible to use the Wade extruder? what is the translation of the gears?

What a perfect design!! Everything fits so perfectly without need to rework after printing it... Thank you very much for sharing!

Hi, nice work! Just one little improvement idea. Could could change the motor mount holes a little bit and the big hole in the middle to make it possible to adjust the distance between the two gears a little bit? I think they would work better if they are a bit closer together. At higher retract speeds I get loud noises from the gears because there is a small gap between them.

How's your motor spinning? Clockwise or counter?

Could you modify the bull gear so that the hexagonal socket can take a bolt with a 13.75mm head width instead of a 12.75mm head width?

hi, cold you provide the model number of your nema17 motor? mine is getting stuck while trying to move the gear at random places...

I can't find the correct hobbed part anywhere that has 25mm from the bottom of the head to the center of the hobbed part. Do you have a link?

Did you ever find a link to the hobbed bolt? I can not find one that matches either.

You can make your own, the bolt is common at most hardware stores. you need a tap screw to create the grub screw search on thingiverse for a grub screw tool..

What variables should I modify or define to use this extruder in Repetier firmware?

I don't use Repetier, sorry.
But I can tell you that I defined steps/mm at 790 in the Marlin firmware, with a reverse direction for E0, and also 5mm at 30mm/s for the retraction in the slicing software, and it works pretty fine. :)

Thank you very much. I will try it.

Hi Piniesta, Did you manage to define repetier? Having problems with retraction. Basically the extruder retracts but does not return to extrude?
If i disable retraction it works fine, is it just me?

Video of problem

How well does this work with flexible filaments?

I never used flexible filament, so I really have no idea, sorry. If you have any experience using flexible filament with this extruder, please share it, I'm sure many will be interested. :)

Hi there wanted to ask this, the m3 bolts you say actually bolt heads or can can use any type of bolt head. Haven't had time yet time to try to put together and my local store doesn't carry m3 bolts like that so. It's going to have to order online to get those type if there all bolt style. Also the M3x50 bolts with hex head do you mean that type with a actual hex head correct? Sorry just trying to order all right bolts for the right time.

Thank You! This is by far the best design I have come across and made. It went together with no issues. The design solves the need of any support material needing to be used and an idea that can be used in other designing ventures.

Thank you very much. I'm really glad if it's actually useful. :)

Hi Bruno,

First of all great job on this one. I really like the design and it went together very easily.

Could you please share your retraction settings, I'm also having a hard time calibrating the retraction.


hi, nice work!! Thanks a lot!

but i have one question: what rectract settings did you use for this extruder?


works great!
Thanks for the design!

Please make a version for PC4-M5 or PC4-M10 pneumatic connector, thanks!

I printed one out and I have to say, everything but the ptfe tube connectors fits perfectly together , bearing fit in nice and snug without having to hammer them in, the hobble bolt fits the nut trap just tight enough to hold it there but not to tight that you have to fight with it ! i'm rather impressed with your 3d printing designing , you seem to have a good grasp with designing for 3d printers in mind ! Well done , its refreshing.

What PTFE fittings do you use in your pictures? This is going to be my first bowden setup and the ones i ordered have a threaded portion that is WAAAY to small.

What are the dimensions of your springs? I've tried a couple, they're either too strong or too long etc...

That's actually a real problem… It took some time but I found a few good springs, by destroying some old mechanical pencils. :)

Pen springs didn't work either. Too long even when cut in half. I then tried it without springs and I think it'll be fine. I mean it pulled the filament so hard that it ground the diameter in half! LOL
Loosened up the screws and will try it when the printer is ready and give some more feedback.
Thanks ;)

Hmm, pen springs! I'll give that a shot, thanks!

What sort of retraction settings are you using on this? I printed one looks great and seems to work really good. Having a bit of trouble dialing in the retraction.

Hi Bruno,

do you have plans to make an adapted version for 3mm filament?
if not, could you please provide the source files, so i can do the adaption myself please?

There you are. :)
I just added the zipped Blender source file.