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My dual extrusion Idea - Nozzle covering

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Dear Community,

the release of the Ultimaker 3 caused mixed feelings in the forum. On one side, there are a lot of members with much experience who turned out to be like beta testers which say the Ultimaker 3 is so good and on the other side there are a lot of people which feel a bit betrayed from Ultimaker, because they bought an Ultimaker 2 oder 2+ lately, not knowing that there was a new one coming or not knowing if there was ever dual extrsuion coming for ultimaker 2.

I did buy the Ultimaker 2+, I did think there will be an update for dual extrusion. A lot of people are saying things like "there never was dual extrusion promised" etc., but when you don't have an Ultimaker, you are not on this forum and in my opinion it was a bit confusing and unclear when you are new and considering to buy the ultimaker 2 or not. But also, I have to say, you really can't blame Ultimaker for that, you can't say that this was intended by them. They also have a business to run and bills to pay, if they announced a Ultimaker 3 in January coming in October, the sales numbers for the last 10 month would have decreased a lot and it would not have been an good descision.

To make a point here, the situation is like it is, you can't blame the costumers neither Ultimaker, and we have get the best out of that sitiuation.

I think the Ultimaker 2+ is a really good machine. We could afford an Ultimaker 3 too, but I already customized the 2+. I have build an enclosure and I did install an Raspberry running Astroprint with Camera etc, but we defenetily want dual extrusion now. I just made a design in my spare time which might work.

We have two possibilities now. We could sell our machine and buy the Ultimaker 3 or we could try to build that design I made. For making that descision I want to show you the Idea and hope you will give me feedback about it. We are able to manufacture the prototype, we have a CNC lathe and a 3 axis CNC milling machine. So if it works some day, I can offer you a kit. Maybe I will release it as open source, too, because in my opinion thats what an upgrade for an open source machine should be.

Lets come to the design:

My toughts were: prevent oozing, thermally seperate the heating blocks, take as few as possible of the build space and make the change as quick as possible.


The idea is that there is a nozzle lift system. When the nozzle is not used, it will be lifted and the ooze cover will be turned 90° under the nozzle and seal it, that no more material is coming out of it. In the same time the other nozzle will be opened and lowered.

The lift system is something like a "camshaft". The 90° turning mechanism turns the nozzle cover and the camshaft that lifts the nozzle.

The advantages that I see in this:


  • It takes almost no build space. The X/Y-Size of the printhead is not changed, only the size in Z is slightly bigger.
  • It's fast. You don't have to cool down the nozzles to prevent it from oozing. You might have to cool it a little to prevent it from clogging.
  • You don't have to waste material, time and space for a wipe tower that might come unstuck during the print.


Where the problems might be:


  • Heat transfer to the head might be too high, we could try making the isolator part out of PBI
  • I don't know if the nozzles might clog, but as you can cool it down a bit I guess that souldn't happen
  • Get the nozzles on the same height. Theoretically, my parts can be made precise enough. Maybe the mounting system from Ultimaker can be problematic. A workaround could be in the software, we could add different offsets to the nozzle. Maybe we have to build a mechanical height calibration for one nozzle. Calibrating would be the usual heat bed calibration and after that a calibration of the right nozzle with the paper trick.


For moving the machanism I have planned a NEMA 8 stepper motor. It should be contolled by an Arduino. The tool-change signal can be transferred via free PIN on the Ultimaker board and the M42 command in gcode.

An other solution might be like an mechanical one, like the solution of the Ultimaker 3. we could build something like a lever and place something like a lever hard stop on the frame. But that is going to take some build space. I don't know if you get me at this point, it's hard for me to explain that in english.

Aditionally, when we have an arduino in use, we could attach a sensor and some indicator for automatic bed levelling.

It's not an easy project and I can't make it on my own. I might need help especially on software side, because i'm more the hardware guy. The tinkergnome firmware should theoretically work, we just have to create a tool change script.

That's my idea so far. Please give me feedback about it, if a prototype will be made depends on your opinion about all of that. If you have questions or i have explained something poorly, please let me know. Maybe I can make a video, but it has been a time since I used the Inventor rendering thing.


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Interesting idea!

I'm nothing close to an engineer so i'll just give you some thoughts about your idea

About the lifting, it's a good way to go obviously :) i would not put the two nozzles at the same height though because it might cause some crashes in the print, when the second nozzle is lowered i would add an offset to it (like on the UM3 or the magnetic tool changer).

Z calibration would take the two different heights and software could to the trick (i believe this can be done with Tinkergnome dual firmware already).

I would try to something mechanical like the switch for the UM3 because you don't need extra motors or electronics. The extra motor would add extra weight to the head which i think can lower the quality of the prints (if you want to print fast).

The cover could be somehow moved also mechanically i guess.

I don't know how the pressure build up in the nozzle could go, i guess you have to do a good retraction before cooling down the second head (this is critical for PVA!).

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Hi DidierKlein,

thank you for your feedback.

Atm, the nozzle is lifted 3mm and the nozzle cover has a thickness of 2mm, so there is an offset of 1mm.

I did also think of the extra weight of the stepper, even if it's just a small NEMA 8, it will probalbly decrease the maximum accelleration. You might tbe right with the mechanical solution be the better one, it would require less components, modding and also cost less than with stepper+electronics..

The lifting of the nozzles and the turning of the nozzle cover is already one mechanism, it requires just one shaft turned to do both of these actions, so one lever for that will work for that.

A retraction is needed in any way, the cover should just prevent the small amount of material coming out after the retraction.

Edited by Guest

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Hi guys,

Even I have been thinking about something like this . And I think using something like a solenoid or electromagnet would be more simple than using a motor for the nozzle lif ting mechanism .

And if the nozzle height difernce is 3mm , I think that is sufficient enough not to have a cover for the nozzle.

And using a solenoid type actuator we can use spring return type mechanism . that is, when the solenoid is energised the nozzle comes down . De energise it and the spring will pull it back.

What I am thinking is whether I should put the solenoid for both the print cores or just one . Putting it fir both would be like making it more symmetrical , putting it fir only one is like making it more simpler (?) And cheaper .

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Hi Chiranjeevi,

I also thoght about that. But the solenoid consumes power all the time when activated, because you need a current to create the magnetic field. I'm not sure if that is a problem (maybe heat or power supply) but I didn't like that.

The 3mm might be enough that the unneeded nozzle doesn't influence your print, but the main Idea behind the covering is that you don't need to wipe and you wont have a wipe tower. Additionally, you don't have to cool the nozzles down. That consumes a lot of time.

My design is easier with two moving nozzles, because the cover can keep it's height. If you don't need a cover I recommend you to move only one nozzle. It saves you a lot of parts and effort and that's more important than a symmetrical design. With the Tinkergnome Firmware you can configure a height for each nozzle seperatly, as far as I know.

To my project: I replaced the stepper with a lever. Engineering 90% done, but our cnc-machines are not free atm. Expecting to make the prototype in Feb' 16.

Edited by Guest

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thank you!

The engineering is done, I just dind't find the time to build it! Working hard on my bachelor thesis right now, finishing at the end of July.

I'm checking if someone of our employes has the time right now to make the parts as I can't at the moment. But if you are interested, I could show you some more detail of the latest design. Maybe someone has any advice?

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