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  1. #31
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    please forgive my ignorance. What is BVOH? And also let me ask you do you think it is easier / more reliable to use the chameleon or those ptfe tube splice things to get multi material printing like your other setup? Or are you finding they are 2 pretty much equal but different ways of going about the same thing?

  2. #32
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    Quote Originally Posted by AutoWiz View Post
    please forgive my ignorance. What is BVOH? And also let me ask you do you think it is easier / more reliable to use the chameleon or those ptfe tube splice things to get multi material printing like your other setup? Or are you finding they are 2 pretty much equal but different ways of going about the same thing?
    BVOH: https://www.3djake.com/verbatim/bvoh-white. Soluble filament, usually used for supports as it is water soluble. When used properly, overhangs look almost as they were printed against a solid surface. Similar to PVA, but in my experience better, adheres better to the main filament. I had some problems with PVA, with small details PLA and PVA didn't work very well because PLA didn't stick to PVA very well.

    About setups, hard to say which is better, each have their pros and cons. The splitter type of setup is quite easy to get going, especially the typical '2 in, one out' since most of the mainboards have 2 stepper drivers for extruders so it is quite universal solution. But it is inherently bowden setup so getting good quality out of it might be harder. Also software support (purge towers, filament change sequences, filament types etc.) and enhanced features like automatic loading, filament sensors are practically up to the user to implement the way they see fit.
    MMU2S on the other hand is a highly specialized product and has some limitations about what printers can use it. But it does have good features all around, sw and hw and the fact that it detects if there's a problem most of the time will save you from failed prints. Not allways as I've seen, but far better than the other printers that are totally sensorless and will keep going happily until the end of print whatever happens.

    Both suffer from the fact that the range in filament quality will make it hard to get a perfectly reliable multi-material setup; I've seen it quite many times that even same brand filaments work differently in multicolor printing, one color does each material change without problems, but other might have occasional issue with feeding. Good rule of thumb is to stay away from cheap filament and stick to what works for your setup. I've no patience for this so I just throw whatever I have to my machines and see what happens

  3. #33
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    More MMU2S printing. I have some ABS that I normally don't use so I decided to print something with it.

    A Jack Daniels coaster: https://www.thingiverse.com/thing:2395261. Actually modified the model a bit. This could be printed with normal printer by just swapping the filament after last black layer, but that would've been too hard so just loaded black and white ABS and let the machine to it. Sliced with PrusaSlicer
    IMG_20201003_143506.jpg

    A save icon chainmail. My first print of any kind of chainmail. Very interesting model and does test your bed adhesion. I cleaned the bed before the print just in case and it paid off. Blue and white ABS. Not so many color changes so purge amount is small. Should have used bit more purge from blue to white though, few white links have some blue contamination.
    IMG_20201003_143511.jpgIMG_20201003_144202.jpgIMG_20201003_144336.jpg

  4. #34
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    Some prints with Tronxy X5S. I took the experimental PTFE-splitter thing apart and opened some of the junctions as the filament feed was bit restricted at points and printed some stuff to test how it works. I'm doing 2-color prints at the moment with different extruders to see how they work.
    A Ghostbusters logo and a dual color vase in PLA. The simple logo turned out great, even though the model from thingiverse has an unneeded gap so the white and red isn't connected in all places it should. But for this model doesn't matter, it'll hold together well enough.
    The vase has obvious problem with retraction, even though I calibrated it before doing this print. The stringiness is probably caused by 2 things:
    - bit too low retract (4.8mm with Pressure Advance value 0.6)
    - over-extrusion caused by too much perimeter/infill overlap I've had on my KISS profile for a while. My guess is that because of the overextrusion, the pressure builds on the nozzle because there's less room for the filament to go in places and thus it affects the retract. Usually doesn't cause problems, but with this model that has small pillars there's limited space for filament to go to. But the filament changes worked beautifully, no a single failed filament change whicj is great.
    IMG_20201010_175739.jpg
    https://www.thingiverse.com/thing:2588021
    https://www.thingiverse.com/thing:1917553

    Another vase. With bit more retraction and reduced the perimeter/infill overlap. This one failed, not because of failed filament change but because the red filament broke during print while coming from the roll. In this case a filament sensor would have been nice. Kinda wonder what caused the break, the brand is 3DJake which isn't the cheapest. Anyhow, measured the position where the red stopped extruding and printed the rest of it, hopefully I can glue the parts and get a proper vase.
    IMG_20201003_150308.jpg IMG_20201010_132025.jpg
    https://www.thingiverse.com/thing:1917508

    So 4 extruders tested, 2 more to go. Perhaps another vase, that gives a good exercise to filament change setup if the colors go all the way, this one looks interesting: https://www.thingiverse.com/thing:1917511

  5. #35
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    Woa. That ghostbusters logo came out right. White is a hard color to get without the bleeding. So let me ask you the real question here. Do you know how to make multi colored 3d models? This is my next step to overcome. I understand how to load them into a slicer and tell each extruder what part to print and get it sliced and started to print. And I know how to make things in autodesk 123d design(don't hate). But it is absolutely beyond me how i would make seperate models that stay seperate but know where to go in relation to each other when they are loaded together? Also I want to see how that vase came out after the repair.

  6. #36
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    Yeah, color bleeding is an issue with some colors. Only way to mitigate that is to increase the purge which means more waste.

    I have done some multi-color models, here's one: https://www.thingiverse.com/thing:3167549, OpenSCAD source here: https://github.com/spegelius/3DModels/tree/master/UFO. The head is designed to be printed as multi-color part.
    Also some test models I've used with testing my post-processing software: https://github.com/spegelius/3DModel...ter/Multicolor
    Designing multi-color parts isn't that hard, basically it's just designing the main body and the other parts that are then removed from the main part. The stls need to exported so that they are on their correct positions, helps a lot when importing to slicers. At least with OpenSCAD, this just happens.

    Different slicers do the multi-color thing bit differently:
    - when mporting multiple models, PrusaSlicer asks if the models are part of a multi-color model and assembles them automatically. Not sure if it's possible the adjust individual model position after this so make sure the models are exported with proper positions. It also assigns an extruder for each model, but there's no real logic, it just starts from 1 and increments it per model so you'll need to update the assignment yourself.
    - Simplify3D does some automatic arrangement an the parts are spread around the bed. To get them positioned correctly, I select them all (Ctrl +a ) and then Edit-> Align Selected Model origins. If the models are exported with proper coordinates, the parts should be properly aligned. If not, you'll have option to modify each model's coordinates, but that's like herding cats, would not recommend. After this it's a good idea to select all and Edit->Group Selection so the models are kinda locked to each other. To assing extruders, you can use Tools->Dual Extrusion wizard, but that's limited to 2-colors so if you are using more than two, you'll need to add more processes and configure them manually
    - KISSlicer just arranges the models based on origin coordinates when selecting multiple models so it should just work. No fancy manual positioning in KISS so you'll need the models to be exported in proper positions. You'll need to assing the extruders, by default they are printed with the default extruder.
    Last edited by spegelius; 10-11-2020 at 05:49 AM. Reason: typos

  7. #37
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    Printing ~3 years old PVA is a b!tch. PVA is a water soluble maerial, similar to BVOH but not as good. I bought a roll of FormFutura PVA some time during 2017 I think, with the intention of actually using it. Well after some tests the roll went to the back of my filament storage and was kinda forgotten, because with my first dual color setup, Prometheus, the results weren't very good. The PVA didn't stick too well to PLA and during filament changes it would break way too often when it was being pulled out of the nozzle.

    But occasionally I have thought about using it, it wasn't cheap. Now that I have the MMU2S, I thought to give it another go. There was a mention somewhere that the roll should be used within 12 months, but f that.
    So the first attempt resulted in a hotend jam so bad that I had to remove the nozzle and use 1.5mm hex to push the clog out. Was not fun. After that I did get it flowing, but there was intermittent popping and hissing and very uneven extrusion so I put the roll to the oven (~60c) for few hours since PVA seems to like to suck in moisture. This helped quite a lot, the filament flow is consistent with only very occasional pops I can't seem to get rid of no matter how long I let the roll cook in oven.
    Actually doing multi-material printing with this particular PVA seems to be very time consuming, not sure if the filament has actually gone bad or if it's just this way. At first the filament changes would fail practically every time when switching from PVA to PLA. The PLA just jammed every time with extruder clicking or the gears eating a hole in the filament. I tried tuning the temperatures and ramming settings in PrusaSlicer for the PVA, but lowering the temperature just made PVA print quality worse, didn't help with the problem. After a while I ditched PrusaSlicer. I sliced the model with KISSlicer and post-processed it with filaswitch because in filaswitch I have much more control over the filament change sequence. After some tuning and retries I got it working quite reliably, with something like 8 to 1 success/fail ratio. The problem seems to be that the PVA leaves long strings to the nozzle after it's pulled out, which cause the PLA to jam.

    The result is this, a hilbert cube printed with PLA and PVA https://www.thingiverse.com/thing:16343. I didn't use PVA as slicer generated support, instead I printed the main model with PLA and the provided 'support' model with PVA which is a solid block. I tried using PVA as regular supports, but that just resulted in a great big mess of bits of PVA all over the place. Printing solid stuff with this PVA seems to work better and actually results in better overhangs.

    The print itself took some 8 hours of actual printing, but it happened in a span of 3 days. I had to babysit the machine all the time because of the high possibility of failed filament changes. Each night I paused the print in Octoprint and turned off the heaters and just continued the next day when I felt like it. Also I stopped the print at least 3 times, edited the gcode file by hand to change the filament change sequence and started the print with the new file. Luckily the machine doesn't loose track of it's position when print is stopped from Octoprint. Supprisingly all this worked, although there were a couple of issues that could have resulted in a fail.

    Not sure if the time sitting beside machine was well spent. Still, it was mostly playing mobile games and reading a book, occasionally tending a clog which luckily was mostly just selecting 'Change filament' from Prusa's menu, cutting the tip of the PLA, refeeding the filament and continuing the print. Not that bad actually, especially when it's possible to pause the whole ordeal for longer periods of time.
    IMG_20201010_161815.jpgIMG_20201011_121943.jpgIMG_20201011_121947.jpg

    PVA isn't very fast to dissolve. The pic above is after the part had been soaked for about 12 hours. Apparently having the water flow would help. I think I have a aquarium pump somewhere, might try putting it in the vat to speed up the process. I'm also dissolving PVA in the purge block, I'm thinking about building a filament recycling setup in future so I'll be saving the waste.
    Last edited by spegelius; 01-22-2021 at 05:40 AM. Reason: pictures

  8. #38
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    So time for an update, been a while. Got the vase glued, the seam isn't the most prettiest but good enough for me. With more post-prosessing it could be made nicer looking.
    Before gluing I filed the ends so they were flat. I used a Loctite superglue which doesn't allow very much time to work with positioning so I glued only one part at first and just went around the model as the previous parts were dried enough.

    IMG_20201109_201212.jpgIMG_20201109_201219.jpg

  9. #39
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    Some more PVA printing. I saw this interesting model and wanted to try printing it: https://www.thingiverse.com/thing:2429742. Used ABS and PVA. Had a couple of goes, the first try didn't work as the PVA didn't bond to the PLA properly and the second try needed some manual tuning for speeds etc and disabling fan for the PVA layers. But in the end the print was successful.

    I let the part dissolve in water for quite a long time, about a week or so. I did change the water a couple of times. Could've been faster, but I wasn't in a hurry.
    IMG_20201012_215759.jpgIMG_20201012_233248.jpgIMG_20201109_201104.jpg

  10. #40
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    Man that came out great. Do the gears turn smoothly? And why does that say palette? Does that name imply it is possible to splice pla to pva?

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