RepRap Universal Mini Extruder

by adrian-bowyer, published

RepRap Universal Mini Extruder by adrian-bowyer Apr 22, 2011
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RepRap Universal Mini Extruder by adrian-bowyer is licensed under the GNU - GPL license.

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This printable extruder is intended to work on RepRap Mendel (both standard and Prusa), RepRap Huxley, and virtually any other open-source 3D printer you can find.

It features:

  1. 1.75 mm filament
  2. Adaptable mounting plate to attach it to virtually any 3D printer
  3. Very compact high-torque NEMA 11 motor
  4. Active ducted fan cooling for high reliability
  5. Wade-style hobbed bolt filament transport
  6. Wing-nut drive to spread the torque loading on the plastic gears
  7. Push-fit hot-end parts - no thread cutting
  8. Easily replaced PTFE liner for the hot end
  9. A single M3-threaded rod cut to lengths makes all the fixings
    1. Lightweight: 420g
    2. Compact design (110 mm x 90 mm x 80 mm)

I based this design (loosely) on Jstkatz's extruder (http://www.thingiverse.com/thing:7037), in particular, the idea of using a lever to trap the filament against its drive.


The full Bill of Materials and detailed construction instructions are on the RepRap Wiki here: http://reprap.org/wiki/RepRap_Universal_Mini_Extruder.

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Awesome Extruder!

I was thinking of adding this to a hobby mill, not sure how with "Mach-3" and I don't use "EMC" yet, but I found something interesting about the "ModBUS" and "Arduino" Here: http://www.buildlog.net/blog/2011/02/modbus-arduino-mach3-and-brains-oh-my/http://www.buildlog.net/blog/2...

Maybe there is a way to have Arduino work as the Extruder Axis controller using ModBUS?

Also what Nozzle are you using in the image?

I'll post findings when I take on this project, I have plans to start later this week.

There are several free RepRap packages that would allow you to control your mill plus an extruder from an Arduino. See here:


Best wishes


the motor plate that fixes the nema11 to the assembly doesnt seem to have a fan clip?

Ooops! Sorry - should have read your actual question...

The motor plate does have a fan clip, but it's printed separately. You then glue it on. This is to make printing easier - no overhangs.

Thank you :)

Found it.

Can you confirm the motor type you used please (pictures show SY28STH45-0674B but link on wiki is a 6 wire motor) People making this may buy the 'wrong motor'

Ive gone and bought the SY28STH45-0674B

The SY28STH45-0674B is a 4-wire motor I think, and should be fine. I have been using it for a couple of weeks with no problems. The six leads on other motors are just because they have central taps - if you're driving them with H-bridge electronics you can chop them off and ignore them.

No - the Mendel version has a fan support. For Huxley there is a spacer that goes under two screws that attach bearings underneath; the spacer lifts the screw heads up to support the fan. In both cases the fan is clipped either side, but just held up underneath.

Im thinking that this could be adapted to become a Bowden cabled extruder for the huxleys, as it seems a shame to add a (small) lump on the axis.

Im currently printing one and seeing if this will be suitable, so will add the derrivitave after :)

Cool! I look forward to seeing if that works. I can see no reason why it shouldn't.

The air flows first over the pinch between the small bearing and the bolt. All pinch extruders work a lot more reliably if the pinch point is kept as cold as possible. Even slight warming will soften some plastics a bit, and then the drive starts to abrade the filament, rather than driving it.

Next the air is ducted past the motor. This is just a courtesy call really - it doesn't touch enough of the motor to cool it a lot, and the motor runs quite cool anyway.

Finally the duct folds back on itself to cool the tops of the M3 threaded rods where they enter the drive and the top of the P
EEK insulator down which the filament runs.

The air exhausts horizontally just under the fan, going in the opposite direction to the way the fan is blowing.

I've added an airflow picture to the RepRap Wiki page.

I've been looking at this and at the reprap site, but I can't quite figure out where the ducted air goes. Is it just cooling the motor, or does it also blow down on the parts as they are extruded like http://www.thingiverse.com/thing:6173http://www.thingiverse.com/thi... ?

Around-the-nozzle cooling ring

Wow, a small and complete extruder. Good job !

I've been following the updating of this on the wiki page. Can't wait to build one!