Fresh MM upgarde and first prints  

Fresh MM upgarde and first prints

Hi all,

I just installed the MMU2 on my printer and it works for now !

With all I saw about issues etc I was ready for long time tuning ,tries, and fails, so much that I started to get angry when I encountered the first difficulties.
I had one fail at first print but then my 4 next print worked without any issue !

Seems incredible to me, I thought I would need 1 week before the first successful print.

So I'm just saying: It is possible that your MMU2 works quickly without hours of tuning !!

I print with only 2 colors for now, black and silver PLA from prusa (not prusament).
I am printing with all stock parameters. I've just been careful of the gears diameter, and arranged them in the right order (from smaller to bigger).
It is also really important to start by the PTFE tube length calibration (in the 3D printing handbook), mine was wrong for 15 or 20 mm !

So I had 2 problems at first print:

- Underextrusion : The first filament used was really underextruding. I eard bad noise in the filament brake system on the spool holder like if it was sticking a lot. Moreover, i used a old filament I had, unsealed since a while (stupid idea).
So I changed for a new filament from prusa and removed the filament brake system on both spool holders (PTFE tube are just flying now between MMU2 and spool).

- Unable to unload : Before changing of filament, printer execute a process to get a nice shape when retracting. At the end, the filament go down and up 2 or 3 times, then is unload from extruder. For me, it wasn't unload from the extruder and the MMU tried to get it back, so the filament were grind a lot and I had to stop the print. This happened while trying to print a gcode from prusa (sheep).
I really don't know if it's because of the gcode but I wanted to control everything so I created my own gcode with two simple cube, and it worked.

Since I made 3 other prints that I sliced on slic3r, 2 models of mine, and a sheep, and they all print well !

I'm just at the begining of testing and I'm sure I will enconter problems while printing more colors or bigger prints but I know that it can work !
First thing is to design a better filament brake system.