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  1. #21
    Student sdtag's Avatar
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    thank you for that.
    I'm not so interested in mixing colors as I am in being able to print 2 different colors in the same print.
    For example: a luggage tag. I have made these before by pausing the print and pulling out one filament and jamming in another and resuming the print. I would like to be able to print these in one operation without having to be there to pause and resume the print. And other stuff too, this was just an example off the top of my head.
    Thanks for the links. More stuff that I hadn't thought about before, purging one color then advancing the next.
    I can't believe I have to ask this but here I go...
    What exactly is a purge tower? Is it a spot in the print where I want the filament to dribble on to so it won't dribble on random places in my print?

  2. #22
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    Purge tower or waste tower is a additional printed structure for holding the waste that happens when changing the filament. There's going to be some wasted material when changing the filament because it's impossible to pull all material from the nozzle, because some of it is molten. So the old material needs to be purge to somewhere. In slicers this can be a separate purge tower or similar structure. Here's example with the purge tower on the left and the actual model on the right: https://www.dropbox.com/s/d9xsh3mj6p...15.04.jpg?dl=0. Yeah, the amount of waste can be quite large...
    Prusa MMU is a similar system to mine and it uses Prusa Slic3r to do the purge tower: https://www.youtube.com/watch?v=MnOWX4Ujtv8. The newer MMU2 is more advanced, but it still uses same multiple in - one out hotend setup and purge towers.

  3. #23
    Student sdtag's Avatar
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    I don't understand something:
    If you retract the filament to do a change and some molten filament is still in the nozzle, how does that molten filament get purged? Is it when the new color filament comes in, then the 2 colors slightly mix for a brief period before the new color takes over. Is this is what's purging?

  4. #24
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    Yes, new filament pushes the old out. Some filaments purge quite cleanly with quite small amount of new filament, some colors might require a quite long purge, like when printing black and white colors, otherwise the colors "bleed" on each other, usually the black taints the white. And when printing with solubles, I've noticed that in order to get all of the soluble material out, I need to purge something like 80mm+ of the new material, because the old and new material somehow mix in the nozzle and if there's still some of the soluble material, the resulting print will be weak on that spot.

  5. #25
    Super Moderator curious aardvark's Avatar
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    I will add that some idex slicers will use a very small purge tower. But generally you don't see one in youtube videos.

  6. #26
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    Yeah with systems that have multiple nozzles the purge is optional, but I think I'd use one just to make sure the filament in the nozzle is "fresh" when selecting new nozzle to print with, especially if there's parts where only one head is used for a long period of time. And if the nozzle oozes, the purge tower makes sure that there's proper amount of filament ready to go.

  7. #27
    You need also to remember about proper temperature of the room for printer. As low the temperature is then printing could be slower

  8. #28
    i use autocad123, it is a pretty easy solid modeling program to pick up and it is free to use

  9. #29
    Super Moderator curious aardvark's Avatar
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    it's also no longer available. Which is annoying as i have a book on it :-(

  10. #30
    Quote Originally Posted by curious aardvark View Post
    it's also no longer available. Which is annoying as i have a book on it :-(
    Sorry gave the wrong name I use Autodesk 123D Design - it can be found here https://autodesk-123d-design.en.lo4d.com/windows. However you are correct, seems Autodesk does not "officially" offer it any longer .

    Still works great for me though.

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