Talk to me about dual extruder setups

Mostly Printed CNC - MPCNC Advice
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I’m looking to add a dual-extruder setup to my MPCNC. Currently, I have a DW660, vinyl cutter, and $100 laser working and just want to add another tool to the toolbox, so to speak.

I want to do some fairly large prints and use a 1.2mm nozzle for interiors to save a lot of time, but still use a .4mm nozzle for detail and exteriors. My print area is about 18" x 18"

I haven’t really been able to find folks that have dual or multi-extruder setups. I know folks have asked and Ryan’s advice has been to do a bowden style extruder with the motor mounted to the center assembly and use short tubes. Has anyone actually done that? I’m interested in more details on how to achieve that. New C-XYX with motor mounts built in? Something else?

I’ve found the dual MK8 extruder mount out on thingiverse but I’ve read that it’s a bad idea to put that much weight on the z-axis.

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The Prusa style single nozzle bowden setup is ideal. The code is in the firmware to run it but you will have to set it up.

Seeme cnc has a nice mixing style tube to make the all very easy.

You don’t see it much because I don’t think many people use dual or quad on any machine. Now that the nozzle adjust issues are gone the others are, harder to design for dual color, and the waste tower is wasteful (hopefully a good way to do this with infill would be awesome). water soluble support is the only thing that would be cool to me but it is expensive and slow.

If you have a use for it, it is dam near magic, but if not I really don’t think it is worth the time or effort.

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Do you have a way to slice it like that? To use the bigger nozzle on infill?

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If you use two nozzles you can designate one as the infill, or if you use the one nozzle we can already use different thicknesses for the exterior and interior.

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It should probably be ok if you print a bit slower and don’t go crazy with the acceleration. You have to print a bit slower and use lower accelerations with a 1.2mm nozzle anyway if you want good results.

 

I wanted to do dual extrusion, exactly for the same purpose you are describing, but I’m really not sure this is doable currently, the main issue being the software. First, I’m not sure any software is capable of managing different nozzle sizes for any given layer, plus I’m not sure it would give good results.

The best way to get decent printing times and quality would be to do:

-One or two perimeters with a 0.6, 0.4 or whatever nozzle you’re using.

-Repeat these perimeters for as many layers as required to reach 0.6mm or 0.8mm (the height corresponding to the one you set for the 1.2mm nozzle)

-Then, do one or two perimeters with the 1.2mm

-Finally, the infill with the 1.2mm nozzle again

If you don’t use this method, you will end up with a very strong infill and a weak outer shell, the infill will pull on it and probably warp everything or leave ugly artifacts. That’s why you need at least one 1.2mm perimeter no matter what.

So, simply using two different height values for infill and perimeters wouldn’t work… You’ll need different values for different perimeters too, which I’m not sure any slicer is capable of.

I see many problems to be solved here, especially regarding over extrusions in corners, overlaps from big nozzle to tiny nozzle paths, nozzle alignments, nozzle crashes on some paths and so on. I cannot say if this will work or not, but it will be for sure a huge challenge.

Anyway, good luck, and keep us posted if you actually try !

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Another thing: bowden tubes work but they are not ideal, especially with big nozzles, since they introduce quite a bit of pressure lag. This makes corners and paths starts either over or under extruded a bit. So, direct driven extruders are a bit better if you can limit the weight.