Multi colour printing and multi tool printers



  • My last printer build had, among other things, the objective to support two filament printing. I used an E3D Chimera hot end figuring that with the E3D name behind it, it would work very well.
    Being older and wiser now, I realize that is almost impossible to register the two nozzles to the exact same height. Add oozing and you end up with a big mess rather than a practical 2 colour printer. It sort of works if you don't do colour changes often or only do a colour change upon a layer change but there is no way of avoiding one colour contaminating another if the colour change happens within the same layer . For example if you are printing a white electronics enclosure and you want to inset black text, you are guaranteed some black from inside or outside of the black nozzle will contaminate the white enclosure as you travel to the spot were black will be inserted.
    It would seem to me that having multiple print heads that you load and unload individually would make it even harder to register the head height of the individual tools so you don't get collisions. Heck, even with only a single nozzle I can hear the faint evidence of the nozzle touching the current layer as the nozzle travels to areas still to be printed. Yes, I know about Z hop.
    Will a tool changer based printer be able to print multiple colours on the same layer cleanly ? Printing a different colour on a separate layer is in theory at least easier as there is a good separation between the colours but I am concerned with printing different colours on the same layer without getting interference between the colours.
    This is a completely theoretical question to figure out if this new technology can be used to print in the way I want to print. I am hoping to avoid jumping into this new technology only to find out that it still isn't really working the way I expect (like I did with the dual head setup).

    Comments ?

    Edit: I guess I am not giving the multi tool system enough credit. On my two colour printhead setup, because I am dragging the second printhead over all the area that the first printhead travels, contamination of oozing from the second nozzle onto the current stuff being printed by the active nozzle is quite high. The multi tool printer would only experience this dragging and the resulting contamination as the second tool is mounted and while it is traveling to the point where it will deposit material. This would surely result in a dramatic reduction in layer contamination but I suspect it is still there.


  • administrators

    I am surprised you had an oozing problem. My dual nozzle Ormerod had zero oozing problems in dual colour PLA prints. That's right, zero. The problem I did get was that if the non-printing nozzle went over filament that had only just been laid down, it left a mark. However, that machine had no print cooling fan.



  • Hmmmm ...... interesting. I tried to sort things out during several days of experimenting but eventually gave up and reverted to single nozzle use while sorting out other things. I haven't tried since ... maybe I need to spend some more quality time knocking my head against the wall 😞
    Could it be related to me running a 0.8 mm nozzle on a Volcano heat block with an about 800 mm bowden tube?
    I have also seen the marks you talk about but that is not a thing I have ever worried about.

    I am still trying to sort out spider hair like stringing on single colour prints. I print between 0.4 to 0.8 mm layer height and 0.8 mm layer width.



  • @jens55 I've had a bit of experience doing multi colour prints. Like you. I soon gave up on the idea of using multiple nozzles mounted on the same carriage, and for the same reasons as well as the amount of axis travel that this approach loses. In my experience, I'd say you have 2 options.

    a) use a multi input, single output nozzle such as a diamond hot end.
    b) Use a tool, changer.

    The latter gives you ability to print different materials as well as different colours. This is possible using a multi-input, single nozzle approach but only if the materials have fairly similar temperature requirements. e.g. one can just about "mix" PET-G and PLA but PLA and Nylon or Polycarbonate would be a no no. The former (single nozzle) approach eliminates any possibility of nozzle misalignment and negates the time taken to change tools so it's faster and arguably easier to implement.

    There a couple of techniques that I have used to print multiple colours on the same layer using a Diamond hot end. One is to advance the tool change point in the gcode file so that the tool (colour change) happens earlier by an amount that is equivalent to the amount of filament that is in the mixing chamber. In the case of the Diamond hot end, that is about 5 mm of filament and I wrote a little Python script which moves the tool changes. The second approach is simply to move the nozzle away and squirt some filament into purge bucket. If it is absolutely critical that there should be no "bleeding" of colour anywhere, then a combination of both approaches works well. It's also possible to use a purge tower but in my case, I simply "draw a line" about 100mm long so the amount of waste is minimal compared to say a Prusa MMU.

    Here is a video that I did nearly 3 years ago using the technique of advancing the tool change point to print a Union Jack flag (3 colours on the same layer) https://www.youtube.com/watch?v=0tPtn3urQ3g&t=1s
    There is no purge of wipe and you have to look closely to spot the slight amount of "bleeding".

    Here is a video that I made just under 2 years ago using a "purge bucket" to print 5 colour flags using a "purge bucket". https://www.youtube.com/watch?v=zNNmZCXErYY&t=21s. Because of the purge, there is absolutely no "bleeding" between colours.

    I think you oozing is most likely related to using 0.8mm nozzles. I could only suggest that when you finish with one nozzle, do a biggish retract and then wait for that nozzle to cool significantly before continuing the print with the other nozzle.

    HTH



  • Thanks! I will do some more experimenting but it's good to know that it isn't just me having issues with this.


  • administrators

    @jens55 said in Multi colour printing and multi tool printers:

    Hmmmm ...... interesting. I tried to sort things out during several days of experimenting but eventually gave up and reverted to single nozzle use while sorting out other things. I haven't tried since ... maybe I need to spend some more quality time knocking my head against the wall 😞
    Could it be related to me running a 0.8 mm nozzle on a Volcano heat block with an about 800 mm bowden tube?

    I think there are two key aspects to avoiding oozing in dual nozzle printers. The first is to use the active/standby temperature concept that RRF supports. I was printing PLA at 190 to 195C and I set the standby temperature to 150C. At 150C, PLA does not ooze significantly. The second is to use sufficient retraction of the non-printing filament. My hot ends were PTFE-lined and I was able to use 10mm retraction. The Bowden tubes were about 400mm and I think there was around 6mm retraction happening at the nozzle. All-metal hot ends are far less tolerant of large amounts of retraction.



  • I have all metal hotends so retraction is a bit of an issue. I think I will order some lined heat breaks to test that out.



  • @deckingman said in Multi colour printing and multi tool printers:

    utilisez une buse à plusieurs entrées et une seule sortie telle qu'une extrémité chaude en diamant.

    Hello, first of all, I wanted to salute your various work, I'm a little "the four corners of the web" and I admit that it opens my mind on my various small jobs (very modest compare to yours)!

    I still have a small question. You talk about Diamond nozzle. Do you have a reference, mark to put forward, because when I do various research on the sites of sale, I find at all prices without really knowing the final quality?

    Thank you !



  • @jens55 I've had the same experiences. In fact, I've been lightly chasing multicolor multimaterial ever since I got into 3D printing several years back. I believe the industry as a whole just has not figured it out.

    Having said that, I believe the industry is on the cusp of some significant progress because of the E3D "De-Facto" standard around kinematic coupling for tool changing. I have decided to pursue this via the "Jubilee" printer design from @poofjunior. More info here: https://github.com/machineagency/jubilee

    I've got my build up and running, and have recently had my very first successful two color print. Still lots of tuning and tweaking to go... so we will see if this turns into a reliable solution for multi.

    You'll find occasional updates from me here in the Duet3D forums. There is also a Discord for the Jubilee.

    https://discord.gg/ZnKW8f

    (Note: The way discord works, that link will expired 24 hours from Nov 16 2019, 09:45 AM CST).



  • @Rudy2A The original genuine parts are sold by reprap.me. I'm using my phone right now but if I get time, I'll post a link to their web site.



  • @deckingman said in Multi colour printing and multi tool printers:

    Les pièces d'origine d'origine sont vendues par reprap.me

    Thank you so much...




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