Our Ultimaker2 now has dual extrusion!

Our space’s most reliable 3D printer has for years been an Ultimaker2 (purchased years ago by Feuermurmel).
You can even see it on the picture of the lab!
It’s really the most reliable workhorse that we have around (for instance most of all
Fillygons have been printed on it).

Some time ago, lsr mused about the fact that the hot-end has space for a second nozzle and some holes in the
case for mounting a second extruder; got curious and had a look under the bottom cover - turns out, even the
mainboard of the Ultimaker2 has all the connectors for a second: heating element, temperature sensor and extruder.
Nice! The next logical step was to purchase some PTFE tubing (inside: 4mm, outside: 6mm), a nozzle, a heating
element, a temperature sensor and an extruder from Ali for a Proof of Concept (PoC). We also needed a compatible
stepper motor - but as one stepper motor for an axis broke down some time ago and the replacement was accidentially
purchased according to the specs of the extruder stepper motor, we just took a (weaker) axis-compatible stepper
motor we had lying around, replaced the “too-strong-anyway” axis-stepper and put in the place of the second extruder.

So - hardware in place! As in every hackerspace, some time went by before we found time for the software part.
The first approach was - after some googling - to find out if there was
indeed already some firmware around.
Turns out, Ultimaker (still) ships
with the firmware for an Ultimaker2 with two hotends. This file can be found (after Cura is installed) in the
directory resources/cura/resources/firmware/marlinultimaker2-dual.hex or on
We installed that on the printer and it worked - kind of. Ari did some tests, and in fact there was filament coming
out of the 2nd hotend!

Dual extrusion example

To actually make use of the setup, we of course needed a slicer to have the printer model with two extruders.
As this is not available out of the box, hellerbarde
created a Printer-model
(by copying the existing Ultimaker2 model) and
it a bit. The files for the
are also available. They need to be put in the
right directories.
Voila - now it is possible to add a new machine in Cura that is an “Ultimaker 2 with two Hotends”.

After some tinkering it turned out that the Cura stock firmware was not that good - so hellerbarde built
and flashed that. Nearly there!

To actually print
a model with two colours,
it’s necessary to import two .stl files into Cura, then - for each model - click on the extruder on the left and then
on the model on the plate. Finally just select both models, right click and chose “Merge Models” from the context menu.

All this worked - we’ll post some pictures of printed dual-colour items soon :-)