MK4S MMU3 Bogie Idler & Main Plate
Description
PDFI have realized that this design is not suitable with the MMU filament sensor. Please feel free to continue the testing to find a solution.
The Main Plate and Idler have status releas candidates (RC)! I don't have the MMU so I have not made any test of the functionality. I recomend them only for advanced users.
Some users have experianced issues with the filament sensor. In case of issues a new calibration can be neede. Step 15 in this setup and clibration manual.
https://help.prusa3d.com/guide/10a-mk4-s-mk3-9-s-setup-and-calibration_426826
Printing
Printing on MK4S. Material PETG. Nozzle 0,4 and layer 0,2. I use original presetting’s for Prusament PETG structural except for part 1-2 where I changed seam position to nearest.
The design requires fine tolerances. Check your x-y belt tension and use dry filament.
Idler assembly
The numbers refer to the pictures. No glue is needed.
Press bogie parts 1&2 together. Place original bearings 3 (693 2RS) into the bogie and press original pins 4 (3x8.5) in place. Fix a nut 5 (M3) in the idler lever 6. Place the bogie assembly between idler lever 6 and 7. Tighten firmly with screw 8 (M3x6). Don’t overtighten the screw! Push the original tubular spacer 9 (13.2x3.8x0.35) into 6 and 7.
Main Plate assembly
The numbers refer to the pictures. No glue is needed.
Press together part 9 and 10. Check that the total height of the filament guide is not exceeding 10 mm (see picture). The two parts will keep together when assembled in the Nextruder.
Tags
Model origin
The author remixed this model.
Differences of the remix compared to the original
From the original Prusa MK4S MMU3 STL files I made a reverse engineering of the Nextruder main-plate and the idler. When you look at the Idler you get the impression that the two bearings distribute the pressure evenly as they push the filament against the gear. In fact, only the lower bearing is pushing the filament against the gear. This causes very big pressure on the filament. For hard filaments this is not a problem but flex filaments is smashed. This mod is a “nice to have” for hard filaments like PLA and PETG and “must have” for soft Flex filaments.
The new bogie design of the Prusa MK4S MMU3 idler distributes the pressure equal on the two bearings and the filament. The Idler only has guarantied function together with the modified Main Pate!
Regarding the Main Plate there are similar designs to improve guiding of the filament. This Main Plate have geometry adapted to the Bogie Idler. It consists of two parts that are put together witch makes printing of the parts easier and the quality of the Main Plate better.
