Opening idler door for the Prusa Mk3s & MMU2s - Remix

20/12/2023 A STEP model was added for anyone wanting to experiment. 

My thanks go to Martin for providing the model. That has saved me the frustration of fitting the Prusa part and the discover I had to disassemble the extruder to do normal inspection and maintenance of the filament drive gears.  

Comparing the model to the current Prusa model showed the added nut was very close to the extruder body inside, just touching. Also there appeared to be a void under the new nut. I read the comment about the arm being different from the Prusa model. Perhaps this was to improve performance?

I don't know but I saw this model just as I am modifying my MK3S+ extruder for the MMU2S and didn't want to introduce any difference that might affect performance.

So I downloaded the model and compared it with the Prusa model.

The changes made are:-
 

The M3x8 screw and nut have been re-positioned to ensure they do not protrude past the Prusa model outline, expect for the outside if a socket head screw is used. A button head screw is ideal. The model now stays within the bounds of the Prusa model.

The arm uses the Prusa model arm.

Adding the screw and nut does reduce the size of the inspection hole. I have opened the hole slightly, to a rounded shape on the bottom.

I have include a PrusaSlicer file set up for printing with PETG, 0.2mm layer height, with the arm having paint-on support only for the arm blade.

As yet the part is not fitted to my MK3S+ extrude but I forsee no issues as there are no protrusions outside the Prusa model dimensions.

Again, my thanks got to Martin for providing the model.

Comparing the model to the current Prusa model showed the added nut was very close to the extruder body inside, just touching. Also there appeared to be a void under the new nut. I read the comment about the arm being different from the Prusa model. Perhaps this was to improve performance?