Direct-drive hinged extruder for E3D/J-Head hot-end (Prusa i3)

by ffleurey, published

Direct-drive hinged extruder for E3D/J-Head hot-end (Prusa i3) by ffleurey Sep 7, 2013


Here is my attempt at designing an extruder for my Prusa i3.

I took some inspiration from different designs to try to make an extruder which is easy to print, compact, easy to clean and has tight guides for the filament (to be able to use flexible materials).

I made a couple of test prints with it and it seems to work fine so far. I haven't tested any challenging materials yet, just PLA.

Here are the components:

* [E3D all metal hot end for 1.75mm filament](http://www.e3d-online.com/ourshop/prod_2781400-E3Dv5-All-metal-HotEnd-175mm-Direct-Extrusion.html). It mounts like a J-Head so a J-Head should fit as well.
* [NEMA17 stepper motor](http://robotdigg.com/product/7/NEMA17-Stepper-Motor-40mm-Long,-1.2A). I am using a 40mm motor but any NEMA17 should work. The back of the motor is mounted on the X carriage and all the extruder parts are mounted to the front of the motor.
* [Mk8 Drive Gear](http://reprap.me/epages/reprap_nu_4149051.sf/en_US/?ObjectPath=/Shops/reprap_nu_4149051/Products/%22MK8%20Drive%20Gear%22). The Idler and filament guide are very tight around the Mk8 gear so other gears will probably not fit without modifications.
* **EDIT: The design is now for a 5x10x4 ball bearing** and not the initial [Yoyo ball bearing](http://dx.com/p/steel-ball-bearing-for-yo-yo-5-x-11-x-5mm-127059) (It is a 5x11x5 bearing grooved to 10mm in the center) The groove helps guide the filament but it should also work with a flat 5x10x5 or 5x11x5 bearing.
* [50mm centrifugal fan](http://www.ebay.com/itm/3-pcs-Brushless-DC-Cooling-Blower-Fan-5015S-12V-50x15mm-/180389680237?ssPageName=ADME:L:OC:FR:3160) (5015S 12V 50x15mm)
* A Spring. I am using one from an [IKEA PRESSA clothespin](http://www.ikea.com/us/en/catalog/products/30108607/).
* Some M3 and M4 screws and nuts.

**EDIT - Version 1.1:**
After a bit of testing, the grooved bearing worked fine with PLA and Nylon but not with [Flexibel PolyEster](http://www.plastic2print.com/eu/1-75mm-tpe-filament-natural-0-50kg-shore-40d.html) so I switched to a flat 5x10x5 bearing. I improved a bit the "idler arm" to make it able to squeeze the filament a bit further and also made it slightly stronger. I was able to make [a nice flexible print](http://www.thingiverse.com/make:46668) with this new setup. Stay tuned :-)

**EDIT - Version 1.2:**
Here is a new version. This is now designed specifically for a 5x10x5 ball bearing and it includes an even tighter filament guide. I had some issues printing flexible polyester with the previous version, this one works better. I have also tested with PLA, Nylon and PET without problems so far.

Here is a video: youtube.com/watch?v=80q71dtGmuk

I have also uploaded the sources made with LibreCAD and OpenSCAD so you can customize it to your needs. Make sure you upload the remixes! :-)

**EDIT - Better fan duct:**
Here is a slightly more advanced fan duct which help distribute some airflow around the nozzle: thingiverse.com/thing:151555

**EDIT - Two can fit on a 80mm carriage!**
Here is a video of my dual extrusion system: youtube.com/watch?v=Ca-XfL2IUWs

Recent Comments

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Looks great but if I might ask what is the distance between your nozzles?

I agree with exploded view being helpful, and would also like to know if the motors have any motion to them only being held on with two of the four possible screws.

I think he is talking about the aluminum cover on the back of the motor itself

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fourtwnty9 on Apr 11, 2014 said:

Looks great but if I might ask what is the distance between your nozzles?

gregpxc on Mar 12, 2014 said:

I just wanted to post a heads up that printing it as is did NOT work for me. The slot for the jhead or e3d was too tight and I couldn't even come close to fitting the hot end in. Maybe it's a tolerance issue on my printer but I took the model into sketchup and opened up the slot about .7mm and now it slips in snuggly without being a total pain. Other than that the only issues I've had from this is seemingly a jamming problem. It's definitely not this design though, I believe it's my hot end.

Darkblade48 on Feb 28, 2014 said:

I was wondering about how the motor attaches to the X-carriage. You mentioned that:

"The carriage is attached to the back of the motor with 2 long M3 screws (which go into the motor and replace 2 of the motor screws)."

What length M3 screws did you use? I have some M3x40, and they still do not seem long enough! I don't think I have seen anything longer either...

ffleurey on Feb 28, 2014 said:

Hello, the one I am using are probably longer than 40mm. It is not common but possible to find. One alternative I used in the beginning is to use a piece of M3 threaded rod. It is inexpensive and you can cut it to the size you need. just screw it in the motor and than put a nut behind the x carriage. Cheers, Franck

Eaglezsoar on Feb 17, 2014 said:

What holds the belt to the carriage? Will the 5x10x4 bearing work with the new design?

ffleurey on Feb 19, 2014 said:

Hello! I typically use some zip-ties to secure the belt to the carriage. Yes 5x10x4 bearing will work, that is what I am actually using. Cheers! Franck

3DPartsUK on Feb 12, 2014 said:

Hi, i love this design however when i print the extruder v1.2 all the holes sizes / nut traps come out to small, i can get round this by drilling however the inset for the j-head also prints to small and doesnt fit, have you had similar issues? i tried to edit the settings using openscad but it only exports the idler and doesnt show the extruder itself, and suggestions?

ffleurey on Feb 19, 2014 said:

Hello, I have not had that problem but the callibration of you printer is probably different than mine, you could try to scale up the whole part if all the dimensions are too small. If only the "holes" are too small you could try calibrating your extrusion, it typically means that too much material is being extruded. If you want to export the different parts from the source, there are different modules in the openscad script, you have to uncomment the ones you want to export at the bottom of the file. Cheers! Franck

trublu289 on Feb 9, 2014 said:

are you using the external thermocouple for your hotends?

ffleurey on Feb 9, 2014 said:

no, I have only used the stock thermistor which came with my E3D hot-ends. Cheers!

qrius on Feb 7, 2014 said:

Is there any possibility of you also publishing this design with standard J-Head mount? Or could you post the source files or export as .stp ?

ffleurey on Feb 9, 2014 said:

Hello, I think that the E3D hot-end uses has a "standard" J-Head mount. I haven't tried but normally a J-Head should fit. The source are available in OpenSCAD and DXF if you need to do some modifications. I am using LibreCAD and OpenSCAD which are both free and open-source tools. Cheers!

StevenTodd on Jan 19, 2014 said:

What changes did you have to make to your firmware settings to use direct drive? I assume the gear ration would affect some configuration.h setting somewhere. I run Merlin v1 and the Prusa i3 Greggs extruder.

ffleurey on Jan 19, 2014 said:

Hello, I am using Repetier-firmware and I had to change the extruder "step per mm" in order to match the Mk8 gear. I did it by trial and error by extruding and measuring some filament (normal extruder calibration procedure). Cheers, Franck

gregpxc on Jan 17, 2014 said:

How do I go about attaching the carriage to the frame or will it be obvious once I've printed it? None of the images you have show how it attaches so I'm a little concerned I'll get it printed out then be stuck.

ffleurey on Jan 17, 2014 said:

Hello, it is not designed to work with 3mm filament. It might work but it will probably not be 100% reliable.

The carriage is attached to the back of the motor with 2 long M3 screws (which go into the motor and replace 2 of the motor screws). The carriage is mounted on the frame with two LM8UU linear bearings (standard Prusa i3).

I hope this clarifies. Cheers!


3dcad on Jan 10, 2014 said:

I broke the 3rd idler, the plastic shaft that holds the bearing is breaking off. I'm thinking about making one with a bolt instead of the plastic. Has anyone else had this happen?

ffleurey on Jan 10, 2014 said:

Hi! Sorry about that, this has not happened with my PLA extruders but from the design I suspected that it was a weak point. If this would happend I had thought about using a bolt instead of the plastic shaft but I also had another idea which was to keep the plastic shaft and add a "cap" on top of the idler in order to support the shaft and keep the bearing in the right place. I have not yet implemented that solution because I did not have any ploblems so far... Are you parts printed in PLA or ABS? I suspect that PLA is a bit better for the idler. Cheers!

boorain on Jan 4, 2014 said:

Do you have files for the hot end cooler on your machine

dubtec on Dec 12, 2013 said:

Looks fantastic, I mainly print PLA using a bowden, but that has issues... what speed can you get upto? I'm looking to get 100mm/s is that possible with this setup? Would really appreciate your advice. :-)

debasish on Nov 14, 2013 said:

do you remove the almunium cover???do i have to remove it if i want to place dual extruder???

ffleurey on Nov 14, 2013 said:

Hello, what aluminium cover are you referring to? What printer do you have? Cheers, Franck

debasish on Nov 14, 2013 said:

can u help me...i made it but cannot make it work....i do not know how to calibrate dual extruder...please help me...

ffleurey on Nov 14, 2013 said:

Hello, you have to be more specific, I am not an expert but it very much depends on what controller board and firmware you are using. You should find the information you need in the documentation of your firmware. I use Repetier firmware and the callibration basically consist of setting the X and Y offset between the extruders. Cheers!

jneilliii on Oct 5, 2013 said:

This looks to be a very elegant solution to direct drive extrusion, but was curious about the mounting of the nem17 motor to the carriage. Since you are only using 2 screws to mount to the carriage and they are on the same axis (both top screws) do you have any issues with the motor wanting to flip up from the bottom edge or not? It seems that the weight of the assembly would put a lot of stress on those top 2 screws.

fourtwnty9 on Apr 11, 2014 said:

I agree with exploded view being helpful, and would also like to know if the motors have any motion to them only being held on with two of the four possible screws.

MatthewLaBerge on Oct 1, 2013 said:

Hello Franck,

Where might I find an 80mm Carriage? I have searched high and low and cannot find anything.

ffleurey on Oct 1, 2013 said:

Hello, the 80mm carriage is one of the options when generating the STL files for the Prusa i3 from the OpenSCAD sources. I have uploaded my STL file here so you can get it easily. Cheers!

mattmc on Sep 27, 2013 said:

I downloaded the source files both in DXF and Scad and all I am finding when I open the files is the Idler Arm. Am I doing something wrong or are these files not the complete source?

Additionally, I posted on reprap forums, but will ask here as well.

5x10x5 and 5x11x5 are not common bearings, at least in the US.

I have found several 5x10x4, do you think I could raise the infill below the bearing at the inner race .5 or .6 mm to account for the smaller width of the bearing?

I tried raising it by a full millimeter, but it looks like the bearing would not be centered on the filament base on looking at the filament hole.

ffleurey on Sep 27, 2013 said:


The source should be complete but you might have to uncomment the part(s) you want to build at the bottom of the OpenSCAD file.

I will check you post on the forum but for the bearing, I measured mine and it turns out that it is only 4mm wide... Sorry about that :-) I'll will change the description. I think that my yo-yo bearing was 5mm wide so I got confused. The bottom line is that no changes should be needed for a 5x10x4 bearing.


dkbe1983 on Sep 9, 2013 said:


The extruder looks great! I've been looking for something like this for a while to take advantage of some of the mk8 Drive gears we have left from a workshop.

In what program did you model it? I'm looking to make a 3mm filament version.

ffleurey on Sep 9, 2013 said:

Hello! I modelled it with a messy combination of FreeCAD and OpenSCAD (I am a beginner). I will try to post the source after I do some clean-up. In the mean time I uploaded a remix which should work for 3mm filament. All the parts are slightly different to be well aligned with the 3mm filament. I have not tested it because I do not have any 3mm filament or hot-end. Cheers!

Jean-Alexandre on Sep 8, 2013 said:

Nice work! But what is a operation should be used for setting up the distance of the filament?

ffleurey on Sep 8, 2013 said:

Hello, I am not sure what you mean by setting up the distance of the filament.If you are thinking about calibration, I have used typical procedures and ended up with 168 steps per mm. Cheers!

MatthewLaBerge on Sep 8, 2013 said:

Looks great, I think I will use this in you i3 build. Which NEMA 17 motor are you using and where did you get the bearing, are there any specs for it?

ffleurey on Sep 8, 2013 said:

Hi! Thanks, I added some more details in the description and some links to the components I am using. Cheers!