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Progress so far with adding 2nd Extruder

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Well I dont have alot to show so far, but here is current progress with adding 2nd extruder.

My target for this has nothing to do with multi-colour, just to allow the support

to be printed in something I can dissolve with solvent or water. (so ABS or PVA).

Couldnt get the wooden parts from UM, so bashed out a new extruder plate. Which is mostly just the old 3 plates joined together. But has a nice feature which is a thread integrated into the STL file so that you can thread in a proper bowden retainer (which has NO slop at all). This is a "WISKA ESKV Ø3-7 IP68" fitting.


I also modified the V2 extruder upgrade I got from UM, glued in an M3 thread and used the same stud and wingnut arrangement that the original Bertho mod used (which I much prefer as you will always have maximum thread engagement no matter what spring preload you choose).

I also put 4x 0.6mm thick washers inside to space out the plates, so that I could use a ball bearing instead of "ball bearing and delrin ring". So I just pressed the ball bearing over the tiny one that comes with the upgrade. This should offer more longevity. Have seen some pics of failed delrin rings on the forum elsewhere. The bearing is a standard Ø16x8x5mm "deep groove" ball bearing.

Credit for big gearwheel goes to Mooncactus, http://www.thingiverse.com/thing:25501


However, he decided not to add the little hole that the standard one has...so its a pain to

screw in the stepper motor....oh well.

I now have to make a new printhead fan duct that will fit the 2nd nozzle, then wire it all in - then see how to mod the firmware and so on.

Will put STL for extruder plate on the website later today, in case anyone is interested.


Bearing rear

Bearing side

Bowden Retainer

Bowden Retainer 2

Extruder Plate 1

130407 124642

Modified V2 Filament Sprint Assy

Printed M12x1.5 thread

Finished Assy



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Hi snowygrouch,

Thanks for adding this progress thread! Reprinted my extruder using the .stl from your website.

In the first place i was using this one http://www.thingiverse.com/thing:53690 in combination with a all printed bertho-upgrade.

But it turned out to be to big to put it on the ultimaker next to the first extruder without blocking the spool turning.

So thanks a lot!

Happy to see, that you managed to get the right firmware by using cura.

What kind of problems are you faceing with the rest of the software?

And i finally would really like to know how you have been leveling the heads. Could you post please post a pic showing you hotends?

Since i did not recieve my stepper yet, i am unable to start printing but everything else is ready. At the moment i am working on a fan shroud and could let you know about the results!

Regards ji

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Is now working using CURA 12.12A (apparenly later versions have some issue when selecting the

print support from 2nd extruder option). Built own firmware as Daids builder website is down.


1st Sucess Dual Extrusion

Some odd tool movements shown here....


1st Sucess Dual Extrusion - top view


1st Sucess Dual Extrusion - side view (strings removed)

Support (in blue) has printed very poorly as I cannot edit "steps per e" for

each extruder indepedantly. My "top down" feed for extruder 1 likes about 835 steps

but I think the 2nd extruder with the standard position bowden needs nearer 860 steps.

So the support is very under-extruded


1st Sucess Dual Extrusion - part removed from bed, strings removed


1st Sucess Dual Extrusion - part removed from bed, strings removed


1st Sucess Dual Extrusion - part removed from bed, strings removed


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As noted on the other thread, I'm not sure that you can set different steps-per-e for each extruder directly. But also, the difference in steps-per-e that you mentioned 860 v 835 is only a few percent difference in extrusion rates. I doubt that would cause enough under-extrusion to be really noticeable. I suspect that the problem you are seeing is more along the lines of the slicer not properly keeping track of retractions and filament positions when switching between nozzles, so that maybe it starts trying to print with an extruder that hasn't been re-primed after it's last retraction? At the very least, that's something to check... I don't think the firmware is tracking filament position per extruder.

Also - Cura defaults to printing support very under-extruded anyway - that's not what you're seeing is it? I presume if you are using a soluble or otherwise easily-removable support material, you'd probably want 100% support density. (Hmmm... maybe that's also a way to compensate for different steps per e - perhaps in Cura you can specify a density for the support that is over 100%??)


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Yes the support in CURA is fairly fluffy, however it was so thin it was just turning into a ball of


I had to tweak the flow to 120% in the Ulticontroller to get the layers to actually stick (this is with E set to 835)

(so to clarify the main part was printing fine, so after I tweaked the flow up, the main part was slightly over extruded but the support was then just about ok).

For people with 2 identical extruder setups this will be much less of a problem I think


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No idea Ian.

Incidentally latest problem to fix is that the most recent Marlin firmware results in different retraction speeds

because the Vmax E value is changed from 45 to 25 in the firmware (there may also be other things

that are causing the issue too, in the firmware).

So will sort that out over the coming week, I just did some test pieces and suddenly the retraction was

completely rubbish and my KS prints came out looking like the useless rubbish that Netfabb used to make...

Anyway, I will put all details on my website as and when I suceed with this, I think some others have the same

issue (independant of the dual heads) so I am sure that collectively a good fix will be found.




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Hi daid,

any progress so far?

Did not have any time to design a fan-shroud yet... but i am still up to the task! how have you been handling the cooling?

and where did you get your stepper motor?

I have been ordering mor than 3 weeks ago and still didn´t recieve anything. think'll have to order somewhere else!




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I changed the VmaxE to 35 (is 25 in new Marlin). This fixed the retration, but due to another change in Marlin

I could only get reasonable speeds by multiplying all previous travel and print speeds by x0.6

No word back from KSlicer if there is a way to get it to work with Marlin for dual extrusion....hopefully

this means he is working on it....

So at present I can print in dual sucessuflly with CURA 12.08 and nothing else. However as Daid says, at the

moment the results are not really UMaker standard.



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