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Prusa MMU for the MK2s

I think I can call the multi-material upgrade of my Prusa Original i3 Mk2s a success. It took me about a day to put together and another day of tuning but I like the results and the prints look good.

Here's what you get with the upgrade kit.

  • A new E3D v6 with multi-material heat break
  • An additional daughter board to drive the extruder motors
  • All of the new plastic parts in ABS
  • Bondtech gears for the extruders
  • Bowden tubes
  • Spool holders for 4 rolls
  • All the fasteners needed

The instructions on Prusa's site are very good. I setup my laptop on the kitchen table, put the printer next to it and got to work. I took my time and spent 7 hours last Saturday just assembling it. A few quick tests and all was right in the world.

The Bowden tube setup is different and I need to get used to it. I had a clog on extruder 2 and had to  unscrew the Bowden tube from the print nozzle to clear it out.

I did have to butcher my Lack table enclosure. I run my printer in the basement and that gets cold. Enclosing the printer guarantees that I'll get better prints.

Less S3D, more Slic3r PE

The one thing I am not thrilled with is the software. I use Simplify3D a lot because I generally get better results. S3D's supports are magical and just pop off. In the past I would use Slic3r PE only when I needed to.

S3D does not yet support the Prusa MMU. There is a single color profile that I found on the Internet and that works well. But for multi-color prints it's Slic3r PE or nothing. This isn't too bad for me because once the bed is level and the z height is adjusted (-0.867 mm on mine, I set the PINDA probe a little higher) I get good first layers.

The default printer profiles generally work. The only adjustment I make is to set the first layer speed to 20 mm/s. After that it's full speed ahead.

The Purge Block

If you look at the image with this post, you'll see that each multi-material print has a block next to it. When the printer changes filament the head moves to the block and prints a 60 mm by 10 mm layer. By the end of that the nozzle is primed and the color can be applied.

That layer of block either gets completely filled in or if there's not filament change a small infill is applied for the next layer. Here's a closer look at the 2 color Moai.

That print has 2 filaments on every layer. That purge block is solid at 60 mm x 10 mm x 60 mm. I don't really think that's wasteful as it keeps the results clean. I may play with those settings to reduce the size.

Here's the fun thing: if I printed 1 or I printed 10 on the same job then the purge block is still the same size. It has to be the same height as the print itself because the print nozzle cannot descend. That would risk hitting something else on the print bed. Next time I'll print more than one and lay it on it's back. That should reduce the purge block and get more use out of the filaments.

Where to Get Objects to Print?

You can make them yourself but Thingiverse is loaded with many good models. There's more than a few that my kids already want me to print. It will be a while before I really make my own.

In the meanwhile I have a printer that can do up to 4 different materials in one go. That's cool and I'm having fun with this hobby.

Categories: Cool Geek

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Jan Dembowski

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