De Luxe selector for prusa i3 mk3 MMU2s

(21.0703: I have now printed Filaflex 60A using the mmu for a few weeks. So far so good, the selector works fine with 60A it seems so no need to make changes - my lucky day! :-)

(21.0602: More than 2200 complete downloads, more than 15000 selector downloads. And I forgot to add the knife parts for the "Gran Turismo" version (selectorIIII.stl)!!! I feel ashamed, and have now (a year late...) finally added knifeIII_FLEXGAP, knifeIIII_SMALLGAP and knifeIIII_INTERMEDIATEGAP. Thanks, Nain_Tech for reminding me.)

(20.0524: More than 1600 downloads, I'm amazed! I made a revised "Gran Turismo" version named "selectorIIII.stl" with some changes you might want:

• The magnet can, if you prefer, now be positioned deeper into the body (equals a weaker magnet effect). This is NEEDED if you plan to load Recreus new 70A filament (it is now available at 1.75mm - I can recommend it, however only try it you are an experienced user - it should not be a beginners first choice).

• The filament pathway is smoother and flattened (I removed part of prusas widening that I do not see why it is there in the first place) and there now is a printed barrier (even at 0.2mm) between the magnet and the filament pathway.

• The input chamfer is more elongated than before to somewhat mimic prusas R2.

• I verified that all features of prusas R2 I could find are there (I added their new snoop hole for a view at the metal ball)

• I did not yet update the knife. I might do so soon as the new firmware takes advantage of it, and I believe a more stringent desing could increase performance..

• Please note that even if I can load 70A through the selectorIIII, even slightest resistance (eg minor fluff in the PTFE tube), will likelymake 70A jam the mmu2s. An updated mmu2s-body would be needed for handling that case. So please take care! And don't forget to reduce pressure - I have both the spring loaded mmu2 screws and the spring loaded idler screw at a bare minimum. Also, don't forget to have plenty of space between the print bed and nozzle for the first layer. Don't expect 70A to flow if space is too narrow.

• I cannot afford the 60A filament I found elsewhere (it really was too expensive) so I cannot adjust the selector for it. If you have a spare 60A roll to give away I would love it! :-)

Please enjoy!
)

(191029: To celebrate more than 900 downloads, I would like to present the GrandLuxe version:

• Unlike selectorII, the knifeholder now holds the filament entry which means, you can easily change between various filament entries at run time.
• There are chamfers for the entry for the "låsbit" in order to make it easier to insert it. Also, there is a "backup chamfer" at the filament entry of the selector, so in emergency you can to some extent use the selector without a knife part (eg for debugging of poor filament loading).
• The knife blade cutout is slightly deeper than in the original selector, as I considered it too shallow.
• There is a handle on the bladeholder for easy removal of the knife parts even if the mmu is at the leftmost slot. This means, you can easily remove the knife during print to access the filament (in order to improve printability, I did not place it as part of the knife part).
• The låsbit has a bigger handle
• There is an "Art Nouveau" part (modifier) to load with the selector if you want a personal touch. If you really want a fancy looking selector, why not print an Art Nouveau selector in two colors?

I did not add a rinse hole for the FINDA: I tried, however, the entire structrure is already pretty hollow so the prints didn't come out good enough.

I pre-computed three variants of the knife holder (the filament entry depth differs between the versions). You can easily create your own version by altering your favourite numbers in column B in the freecad spreadsheet.

All items can be printed without support. Please note that the "artnouveau PART" item is to be added as a part to the "selectorIII.stl" (in slicer, double click on selectorIII, and then "load modifier"), not printed stand alone.

I hope you will enjoy it!
)
(190521: added picture to clarify position of "låsbitII.stl)
(190508: I added a version - "selectorII_1mmFLEXGAP.stl" - with a slight gap to the filament exits at the MMU. This prevents flexible materials (I use flex98, filaflex and ninjaflex) to get dragged out if their idle positions are not entirely inside the MMU body), still tight enough to load them properly.

I added more features to the selector. In short, the benefits with this version compared to prusas original are:

• FINDA will be much less sensitive to filament stringing, as a magnet (that came as a spare part with the mmu2s upgrade) hold down the metal ball.
• The knife holder is now a separate piece that can easily be removed. Simply unsnap a lock item, then pull upwards.
• The filament entry is now chamfered and much tighter towards the MMU2 body (previously the gap was 6mm or more). Soft filament will (hopefully) not take the wrong path anymore (go between the selector and the mmu2 body).

I advice you to use the latest firmware (for i3mk3 I use: 3.7.0 and for mmu: 1.0.5).

Don't forget to trim the knife blade (see text below and describing picture)

I suggest to use my gcode-fix as found at: http://www.frimmel.se/print3D/ for MMU2s-prints (in short, print at regular prusa temperatures and reduce heat during wipe, which, at least for me, gives reliable filament tips in a fast manner and less print failures)

These items are based on STL-files found at: https://github.com/prusa3d/Original-Prusa-i3/tree/MK3S and https://github.com/prusa3d/Original-Prusa-i3/tree/MMU2 under GNU2 license (please read the LICENSE file)