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Flaviu

Comparing FDM multi material options: Prusa MMU2 and Palette 2+

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After several weeks of multi color/material printing with my FDM printer Prusa MK3 (I have other Printers too) with the Multi Material Unit 2 (MMU2) I'd like to share my results with you.

Another interesting product regarding multimaterial is the Mosaic Palette 2. I don't own that unit at the moment but I know people who are using the system and I talked a lot with them about the unit so I will share their experience also with you.

 

First of all, some general info.

 

The Prusa MK3 costs as a build kit 769€ and fully assembled 999€. The MMU2 unit comes only as a kit and costs 300€. It can print with up to 5 materials. It can only be used with a Prusa printer out of the box. (Firmware is open source so in theory you could tinker it to work with other printers). Prusa has also their own (open source) slicer called Slic3er PE.

 

The Palette 2 comes in two versions, the standard and the pro. Both versions can print with up to 4 materials. I highly recommend the pro version because it has a better warranty and comes with better quality parts. I also recommend the canvas hub option because it makes it easier to connect the system to your printer. That would result in a total prise of 878 USD. The Palette 3 can only be used with 3D printers that use 1.75 mm filament. So it can't be used with something like an Ultimaker. 

 

One more thing about filament. Prusa has now their own filament called Prusament. It is produced with a tolerance of +/- 0.02 mm in diameter. And you get a QR code with your spool to check the measuring yourself. Every spool is measured 100%. One (and only) advantage of the 2.85 mm filament that Ultimaker is using is that it is easier to produce precisely. If you are using 1.75 mm with +/- 0.02 mm that advantage is gone.

 

First some thoughts on the MMU2.

 

The MK3 produces very nice quality prints especially with high quality PLA like Prusament or PLA/PHA. That is mainly thanks to the Bondtech direct drive extruder. One other nice feature is the removable (magnetic flex steel) PEI bed. I guarantee you that if you are using this feature one time you will never never ever want a printer without it again. :) 

 

The basic principle of the system is that it adds a bowden system with a selector to the direct drive system. So the direct drive system pulls the filament up until the bowden system takes over. Than it switches the filament and the bowden system pushes the filament back to the direct drive gears. And so on ...

As already mentioned it comes as a kit. And that is a BIG problem. Assembling it is not easy because you have to make sure that the filament path is as smoothly as possible. When you pull filament out from the hotend you can have tips with large strings or increased diameters. That will cause problems. To form the tips Slic3r PE has something called "ramming sequence". It tries to "form" the tips nicely like with no strings. This works good with Prusas own filament Prusament. It works also usually quite good with other filaments especially high quality ones like PLA/PHA. But there is no guarantee it works with the filament you are using so you might have to try different settings.

 

So you have with the MMU2 basically two main problems. Assembling it so that everything runs perfectly smooth. And getting the ramming sequence settings right. A LOT of people are having problems with that. I had also try a lot out and it was frustrating at the beginning. I have now a working unit and prints are imho amazing. 

 

Now some words about the Palette 2 (pro).

 

The principle of the machine is that it cuts the filaments and than splices them (melting) together. So you have one filament going out of the system with the right color combination for your model.

It comes basically fully assembled. Installing the system to your printer takes maybe half an hour or so depending on your setup. So a LOT easier that the MMU2.

One big problem right now is that their own slicer is very buggy and produces (especially on complex models) mediocre print quality. Sometimes it does even the color changes on the wrong location of the part. Combining your own more sophisticated slicer like Slic3er, Simplify3D or Cura with their system works also not reliably at the moment.

 

Some general thoughts.

 

Both systems produce purge towers. Every time when you change the color you have to get rid of the plastic from the old color in the hot end. How much you have to purge onto the tower is color dependent. E. g. switching from black to white or from PLA to BVOH as extreme scenarios. BUT as I mentioned the Palette splices the filaments together. That produces a color gradient in the filament of a few mm. That has to be purged additionally. So the purge amount of the Palette will always be bigger than the one of the MMU2.

Slic3er PE has the option to "purge into infill" so it purges also into the objects infill. That option will come to the Palette 2 in the near future.

 

I print a lot with BVOH and I know that it can work with the Palette too. But in both cases it adds complexity. Slic3er PE has the option for printing only support interface layers or completely supports with soluble material. 

I will start testing flexible materials in the near future.

 

Customer support is pretty good with both companies. The forums are used very actively and you have also a very helpful chat support at Prusa.

 

 

MMU2 Print:

mmu2Print1.png

MMU2 Print: Kidney with tumor and magnet inserts

mmu2KidneyTumor2.png

mmu2KidneyTumor3.png

MMU2 Fun prints:

mmu2Fun4.png

mmu2Fun5.png

Palette slicing problems:

paletteSlicingProblems.png

Palette color gradient:

paletteColorGradient.png

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Wow, nice. Thank you for your true review of MMU2. Unfortunately, new orders for MMU begin in February 2019 and can't wait for it to begin :)

Those prints look great.

Are there any difficulties when printing ABS/PLA and PVA as support together in one print?

 

PS. @Dr. Mike is this Palette Mosaic same thing you told me about in RSNA meeting? 

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As a general rule of thumb: Materials who like to string are not easy to print with the mmu2. ABS does not like to string so it should work well. PETG for example strings a lot therefore it is not easy to be used with the mmu2.

If you want to print with PVA you probably will have a lot of problems. BVOH is easier to print with but has to be stored in very dry conditions.

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This an an incredible review. Flaviu, thank you for sharing your experience with the community.

What kind of print times are you experiencing for anatomic parts, for example, the L spine in the photo? It looks like you are using a 0.4mm nozzle. My experience has been that these parts are very time consuming. With the extra purge tower that time will be extended. What are you experiencing?

kopachini, yes the Palette 2 was what I mentioned to you at RSNA. 

Flaviu, what are your experience with BVOH? In particular, how well does it stick to PLA. PVA is notoriously difficult to get to work nicely with PLA, and I am wondering if BVOH is any better. 

Also, do you know if the palette works with a dual extruder system? I would be nice to use the first extruder for multicolor and the second for soluble support only, as the expensive soluble support won't be lost in the purge block. 

 

Great work!

 

Dr. Mike

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Dear all,

 

I'd like to add something to my original post. I advised to buy the canvas hub. Don't do it!

It's just a Raspberry Pi Zero W with Octoprint on it. Instad you should buy a Raspberry Pi 3 B+ (or newer) and install Octoprint yourself on it. Setup guide at: Canvas Octoprint Guide.

The whole system will work with less lags because the Zero W is a lot slower than the 3B+ and you will save some money :) 

 

Regarding Printing time.

When you have the possibility to purge into infill (available with Prusa system and in the near future with the Palette 2) the purge block will shrink if you print bigger parts (more infill).

 

The lumbar spine I've printed is cut through the middle and I've printed both parts at once:

  • No supports
  • 30% infill
  • 3 perimeters
  • 0.15 layer hight (0.4 nozzle)
  • Total print time 44 hours on my Prusa MMU2. (around 270 color changes) (Palette 2 should be about the same time.)
  • Total print time as a single color print would be 38 hours.

Soluble supports.

I print all my (interface) supports with Verbatim BVOH. It works great with PLA but ...

  • Maximum printing speed is around 20 mm/s (so way slower than PLA)
  • You have to purge a lot (at least 120 mm^3 on every change which is about double the amount for a normal color change and it should be even more with the Palette 2)
  • You have to use a container with low humidity and sometimes dry it. 

 

Palette 2 with dual extruder.

 

It doesn't work atm. Since it is a very closed system it should be extremely difficult if not impossible for some one from the community to add this feature. If the company behind the product is working on this I don't know. 

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