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I am planning to build a 3D printer with dual extrusion. I want to use PVA with one of the extruders and the main material with the other one so color printing isn't important for me and I just want to use dual-material (mostly PLA and PVA). I want to know which of the types below should I use and also the pros and cons of each one, especially oozing and final print quality.

  1. Dual extruder and dual nozzle (eg. E3D Chimera+)

  2. Dual extruder and one mixing nozzle (eg. E3D Cyclops)

  3. Dual extruder with 2 independent nozzles (2 stepper motors on the X-axis each one moving 1 E3D v6 individually)

  4. Dual extruder and dual nozzle using a tool changer and a CoreXY setup (using a servo motor to lock the tool to carriage similar to the E3D tool changer)

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    $\begingroup$ You forgot the option: toolchanger. Which is in general the best one, if you can build it reasonably accurate $\endgroup$
    – FarO
    Aug 31, 2020 at 9:52

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I would advise against mixing nozzle - you would have many jams and clogs and you would have to use purge tower which in my opinion is not worth it. Thats scratching point 2.

Point 1. and 3. are similar to some extent. With both types you have to align the nozzles in all three axes. Crude aligning should be done by hardware and fine tuning done in software (too much difference in Z alignment could cause one nozzle hitting the printed part). Anyway, the aligning is pain and you will have to do many test prints to achieve sufficient results.

In my opinion, point 3. (also called Idex - independent dual extrusion, I believe) will give you best results, because while one nozzle is printing, the other one is parked on the side where it can ooze as along as you manage to wipe it when it is getting ready to print. You can use purge buckets. Also you have to home the extruders indepentently as well (one to right and one to left).

Point 1. will introduce a lot off oozing issues. You would have to use ooze shield, or other methods of wiping the other hotend, if you are comfortable with that.

As for connecting another axis to Ramps 1.4, the board has 5 stepper motor outputs (X, Y, Z, E0 and E1). Therefore there is no output for another X axis, since both E0 and E1 will be used. You have two options I can think of:

Creating your own stepper output and connecting it to auxiliary pins on the board (if you are using legacy stepper drivers, you need 2-3 pins - direction, step, (and motor enable)). That requires some basic knowledge of electrical devices and firmware. However, it is doable. Not easy for someone without sufficient knowledge, but not impossible either.

Or the other option is to buy an existing boar with 6 stepper motor outputs such as Bigtreetech SKR PRO. You still have to configure the firmware but it is much easier this time (it has been made/pre-made several times with tutorials).

I would suggest using Marlin firmware as it supports many configuration types and has very strong community - someone has likely solved your solution or can help you solve yours. I would also suggest not using Ramps board with Arduino Mega2560. That board configuration is so old. 3D printers have moved on, whereas that board has stayed the same for 5 or so years. It is OK, perhaps good for tinkering, but there are far better options (such as the mentioned BTT SKR series boards).

Good luck with your design.

Note: I do not own a dual extrusion printer of any of the mentioned types. This is just my understanding of the theory and how I would do it, if I were to build a dual extrusion 3D printer.

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  • $\begingroup$ So if I use idex with a compatible board and marlin, do slicers eg. cura support it and what should I change in them? This is a rare setup and I think it wouldn't be easy to setup slicers for it. Can you please give some explanations in slicing software configurations? $\endgroup$
    – Mahan Lamee
    Aug 30, 2020 at 17:07
  • $\begingroup$ As far as I know, all major slicers support multicolor/material printing. For them it is pretty much irrelevant which implementation you use. They just copy and paste the "tool change" gcode snippet you give them. The snippet does depend on the type of multimaterial printing as it tells the printer when to change and how to change the tools. Idex is not at all rare and should be supported by all the tools you will need (at least most of them). I think there should be many tutorials on the internet on how to setup multimaterial printing or even Idex in particular. $\endgroup$
    – TurgonTheKingOfGondolin
    Aug 30, 2020 at 18:59
  • $\begingroup$ A quick google search found a Reddit post link. Maybe you will find some useful information there. As a side note I recommend using a board with removable stepper drivers, not integrated, as it makes replacement much easier and is more flexible in which drivers you want to use. Also you might consider using a regular board (4-5 stepper drivers) and adding a premade extension which would add the required stepper driver slots. I am not aware of any particular ones. Just search the internet and you will find something. $\endgroup$
    – TurgonTheKingOfGondolin
    Aug 30, 2020 at 19:05
  • $\begingroup$ And if you find something, do not just jump straight to it. Read articles, watch reviews of various products, watch tutorials,... because if you chose wrong, it might make your construction a lot harder, but does not have to. Or if you find someone has solved at least partially your problem, contact them and ask them for help. They might at the very least point you in the right direction, or even modify their solution to your needs. $\endgroup$
    – TurgonTheKingOfGondolin
    Aug 30, 2020 at 19:10
  • $\begingroup$ Beware, PVA printing is not the Holy Grail! It is expensive, very hygroscopic and easily cloggs the nozzle. I've been using it for some years with mixed feelings. Do you really want/need to print with PVA? I would like to remind you that there are brands out there that sell you a printer that are capable of doing what you want. $\endgroup$
    – 0scar ♦
    Aug 30, 2020 at 22:09

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