Things i learned during assembly (or mistakes i did)
Hello
A week or two ago i decided to buy the MMU2S upgrade for my MK3S and once assembled i had all kinds of problem and didn't know where to start the troubleshooting.
Now it is working (so far) but i did learn a few things that i thought i share.
MMU2S
First of all the 5 short ptfe tubes in the MMU, make sure the chamfered side is towards the 5 gears below the idler that pushes the filaments out.
If you do as i did and get them reversed so chamfered side points out toward selector with blade then you will get load errors a lot.
Instruction was not clear on this (or i totally missed it)
When you assemble the MMU for the first time it is not entirely clear what goes where until you have assembled it completely.
MMU idler door
Don't try to screw it down "properly" (as in way too hard), if you do the idler wont be able to turn properly and MMU will get problem trying to select the right filament.
The head of the two screws with springs on them should be about the same level as the top of the plastic and if you pull on it you should be able to lift it a little.
Extruder
IR sensor, it is important that it works well and reliably.
At first i did not feel comfortable pushing a metal hex key against another metal object (the bondtech gears) so i used a piece of filament instead.
This was a bad idea and resulted in an unreliable IR sensor.
The thing is, you want the ir sensor to work even if the filament has been ground down a little and when the tip contains a blob and then gets smaller directly after it.
When i dissembled the extruder i also took the opportunity to do a few other things i had planed to the hotend.
Like checking the PTFE tube in the heatsink and making sure it is fully pushed down against the heatbreak and that heatbreak gets fully secured against nozzle, i also swapped the heat block to a copper heat block, something i had planed before getting MMU.
PFTE tubes with hole and lock screw
In several places the ptfe tubes have hole and a screw that locks it in place, for example the included buffer.
At first i screwed the locking screw all the way in causing ptfe tube to be crushed a bit restricting filament.
On the buffer i instead only screwed in the locking screw enough so they don't fall out (pull on it and check) that left the screw a few mm away from the plastic
And to better understand what was going on during my troubleshooting i also printed another "extruder visualizer" propeller and attached to the pulley stepper motor on the MMU with a magnet or two.
I also ended up with problems with FINDA probe due to filament strings getting steel ball stuck