Single, Dual, Tri or Quad Extrusion?

[dannyg 0]

As a new UM Owner I have noticed a couple of things:

 

• In Cura there is the possibility of selecting up to 4 hot ends
  
• The existing UM has holes for a 4 bowden tube/hot end set up.
  

Does this mean that theoretically one could use up to 4 hot ends and print 4 materials?

I had a good search on Google and the forums but no joy.

Forgive my ignorance if I am way off base here.

Danny

 

[codemaven 0]

I can't say for sure, buy my guess is that this was on their minds when they originally designed it. There are now 3 and 4 extruder printers out there, but when the UM came out dual extrusion was rare and anything more was unheard of. I think that the designers of the UM originally may have planned for up to 4 extruders when they were initially designing it.

However... moving from concept to implementation is a whole different story... They originally only brought out a single extruder machine and though they may have intended it to be upgradeable to multiple extruders I think that proved in reality to be more difficult than expected. There were multiple changes to the print head during the course of the revisions which involved moving around the thermocouple amplifier and such... These incremental improvements were necessary just to get dual extrusion working. I don't think there is room (when you consider wiring, thermocouple amp, etc) for any more than two. Also, the addition of more bowden tubes will put extra strain on the movement of the head and could limit the speed that's possible.

That's not to mention the complexity of aligning two print heads... It just gets more complicated the more you add, and for little benefit.... Two extruders is a huge improvement over one... But, although 3 or 4 extruders would be cool, I don't think there are really that many practical uses that would justify the extra complexity. For me the biggest use case of dual extrusion is dissolvable supports. I can't see ever wanting to print more than two colours enough to justify the complexity... maybe 2 colours and a dissolvable support structure... another possibility is a head with a larger diameter nozzle for quicker in-fill printing... But I think I'm quite happy with two extruders for now...

Cheers,

Troy.

 

[Daid 306]

I think only Protospace (FabLab Utrecht) made a 4 extruder machine as experiment. The reason why you can select it in Cura is because I wanted to design Cura around multiple-extruders, not just dual extrusion. So by already having the option to select up to 4 extruders I forced myself not to be limited to only dual-extrusion and this gives hardware tinkerers the option to move up to more extruders if they want.

Ultimaker however, only supports up to 2 extruders right now. The electronics are only suitable for up to 2 extruders.

 

[dannyg 0]

Hmmm might be an interesting hackerspace project , I would love to see a more rigid design UM frame (say Al extrusion) with beefier stepper motors and a 4 bowden tube setup (one from each corner).

Would look epic . Shame the software wouldn't integrate the models though.

Edit: or is it just the extruder driving?

 

[Daid 306]

It's just the extruder driving, firmware+electronics. Cura will generate GCode for 4 extruder models just fine.

 

[dannyg 0]

Would it be possible to bolt on a secondary uController with 2 stepper motor drivers and intercept the gcode somehow? Or split the gcode up and send it to two usb com ports and use the PC to synchronise?

Also are there enough hot end heater connections and thermocouple connections on the main board?

 

[Daid 306]

You could hack 2 extra motor drivers and 2 extra temperature sensors + heaters on the current board. You would need to update the firmware a bit to support the 4th heater (as up to 3 are supported in Marlin right now), but it could be done.

(The RUMBA board from RepRapDiscount supports up to 3 extruders, and already has more temperature circuits, so that could be a better base to start off then the Ultimaker electronics)

 

[Arie_Dub 0]

Ya, I was thinking about that.  Couldn't I use Adriano Shield expansions boards

How about what I was thinking. ...not only extraction of filament, but extraction of the hot end itself so it won't bump into or get in the way of the newly printed item while printing it. So only the hot-end doing the printing at that moment is 1-2mm lower that the non-printing heads and could be controlled by a 'off-head' stepper motor & flexible shaft & 'on-head' rotating disc/spring mechanism for retraction/extraction of hot-ends.