Improved MMU2 Buffer for Prusa Enclosure V2

Last crawled date: 4 years, 2 months ago

The first version of this MMU2 buffer ( https://www.thingiverse.com/thing:4138220 ) was a significant improvement over Prusa's stock version, loading/unloading and printing are a lot smoother. I had a 5 days print , with 2400 layers and 2200 filament changes with no MMU failures. But I also had a few under-extruded layers and I've narrow it down to the following root causes and fixes:
1) the 2.5mm Plexiglas on the outer sides can flex. The filament is quite stiff , can squeeze out and ruin your day. Solution: thick printed top and bottom plates, with profiles to hold all Plexiglas dividers in place.
2) there is still some unnecessary friction in the system , the filament can rub against the metal end of the PC4 M6 fittings.Solution: change to PC4 M10 fittings , where the PTFE tube goes through so no metal touches the filament.
Bill of Materials
Plexiglashttps://www.tapplastics.com/
6 x Extruded Acrylic Clear 2.5 mm Thick, 125 mm Wide, 350 mm Long
Fittings
10X Fitting PC4-M10https://www.amazon.com/gp/product/B07V3G71HK/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1
Bearingshttps://www.vxb.com/
5X 10 X 19 X 5 bearing
Screw,Nuts
15X Hex Nut M3
10X Sq Nut M3
25X SHCS M3 X 8
4X FHCS M3 X 10
4X BHCS M3 X 8
7x SHCS M3 x 6
PTFE Tubehttps://fluorostore.com/
I'm using 3/32" ID X 5/32" OD with good performance
So far I've printed a 30 hour Santa , 1010 layers and around 900 filament changes. Perfect print , no MMU or extrusion errors with the new buffer. A 5 days Nefertiti job , with 2400 layers and 2200 filament changes is ongoing.
As always, STEP file included if you want to tinker.