Only a couple of filament slots fully load to the extruder  

RE: Only a couple of filament slots fully load to the extruder

To add a little more context, I have used slot two in order to print a number of things, whereby I have loaded and unloaded the filament from slot two multiple times into the extruder.

RE: Only a couple of filament slots fully load to the extruder

Have you tried swapping which filament you're loading into which slot, or cutting the filament differently? The filament's tip shape can make a big difference to loading success, though I haven't personally had trouble with loading to the extruder.

In the fifth slot, if you push the filament in by hand, does it pass all the way through and come out the fifth hole at the front of the MMU, or does it get stuck? Inside the MMU, is the drive gear clamped to the shaft, and does the idler bearing turn freely?

I don't think a little excess friction will impede the MMU working (my setup uses some fairly long and sharply bent tubes to route the filament from drybox to MMU) — I expect you need to look for obstructions or alignment problems first.

RE: Only a couple of filament slots fully load to the extruder

@kpreid

Thanks for the response.  To have a constant, I actually moved the same filament from slot 1 through slot 5, ultimately loading it back into the extruder from slot 2 when I was done testing (without any issue).  I did try retipping it at an angle between a couple of the slots, as is recommended in the documentation, but that had no change in outcome.

As for the 5th slot, it DID push through all the way.  When checking drive gear and what not, everything looked good (turning synchronously with all of the others).  Interestingly, it now loads properly after checking those things.  I suspect it may have been the screw with the spring holding the "lid" closed, not being tight enough at the end where slot 5 is.  Unfortunately, after getting the load to work for slot 5, it was unable to successfully load to the extruder.

I'll spend some time looking for obstructions / alignment issues for the other two slots.  The puzzling thing for me, is that it fails for one slot at the same point it is otherwise successful in another (at the top of the extruder).

RE: Only a couple of filament slots fully load to the extruder

An update...

Okay, so I've been spending some time going back through the build instructions, troubleshooting guide, etc., and decided to run the IR sensor test again, specifically following the instructions from this Prusa Youtbue "MMU2S - IR filament sensor calibration" video.  Particularly given the issue appears to be when loading from the MMU2S to the extruder.  When I first did this, the IR sensor worked as instructed in the video... going from 0 to 1 when I put the 1.5mm hex key in it.  Unfortunately, this is no longer the case!

..more to come

RE: Only a couple of filament slots fully load to the extruder

I was able to figure out the IR filament sensor issue, ultimately I had to push the IR Sensor Assembly all the way to the right, rather than the left as indicated in the instructions. 

Now I'm working through getting all of the filaments to simply load into the MMU2S.  Some of the slots won't even load the filament at this point.  I've tried factory resetting the MMU2S firmware, confirmed alignment of everything, etc.  I'll then try to get them all to load to the from the MMU2S to the extruder consistently.

I'm getting to a point whereby I am considering an attempt at removing the MMU2S altogether.  My printer has been effectively out of commission since trying this upgrade.  Very frustrating.  I completely understand the MMU2S not ready for public use thread now having attempted this.

RE: Only a couple of filament slots fully load to the extruder

So after taking a break from this and otherwise scouring the forums, I came up with a hit list of things to try (if these things work, we should sticky this list or something).  Regardless of the whether this should otherwise be necessary, is less relevant than at a minimum, trying to compile a succinct list of meaningful steps to take and make that readily available for reference.

1. Ensure up-to-date firmware and drivers are in use for the MMU and printer.
   • If this is the case and problems have persisted, factory reset (not a "soft reset") the MMU following these instructions.
2. Print and install the Prusa MMU2 PTFE Holder M10 Passthrough Adapter created by vertigo235.
   • You will also need 5x PC4-M10 fitting connectors that can be found on Amazon here.
   • NOTE - THIS IS AS FAR AS I HAVE GOTTEN THUS FAR
3. Replace FTE \ bowden tube from MMU to extruder with 2.5mm inner hole diameter tubing
   • Need to find US based source for this
   • 360mm long (~14 inches)
   • Chamber the ends (use 4mm drill bit or 5/16-in Woodboring Spade Drill Bit)
4. Replace the buffer PTFE \ bowden tubes from buffer to MMU with 2.5mm inner hole diameter tubing
   • Need to find US based source for this
5. Enhanced "blade"
   • Need to identity correct thing to print
   • For me, the blade started to come out (I thought I secured it really well), so I just removed it for the time being... this is apparently a step some people of taken... to simply remove the blade
6. Auto Rewind Spool Holders
   1. Need to identify correct thing to print
   2. Does this negate the need for the buffer?
7. Calibrate and update or modify the idler door
   • Print an updated idler and install it, or follow these instructions to modify the current idler door.
8. Install a smaller? PTFE in hotend to be smaller inner diameter? 1.9mm? 1.85mm?
   • Maybe this?

RE: Only a couple of filament slots fully load to the extruder

Posted by: @jason-b26

So after taking a break from this and otherwise scouring the forums, I came up with a hit list of things to try (if these things work, we should sticky this list or something).  Regardless of the whether this should otherwise be necessary, is less relevant than at a minimum, trying to compile a succinct list of meaningful steps to take and make that readily available for reference.

1. Ensure up-to-date firmware and drivers are in use for the MMU and printer.
   • If this is the case and problems have persisted, factory reset (not a "soft reset") the MMU following these instructions.
2. Print and install the Prusa MMU2 PTFE Holder M10 Passthrough Adapter created by vertigo235.
   • You will also need 5x PC4-M10 fitting connectors that can be found on Amazon here.
   • NOTE - THIS IS AS FAR AS I HAVE GOTTEN THUS FAR
3. Replace FTE \ bowden tube from MMU to extruder with 2.5mm inner hole diameter tubing
   • Need to find US based source for this
   • 360mm long (~14 inches)
   • Chamber the ends (use 4mm drill bit or 5/16-in Woodboring Spade Drill Bit)
4. Replace the buffer PTFE \ bowden tubes from buffer to MMU with 2.5mm inner hole diameter tubing
   • Need to find US based source for this
5. Enhanced "blade"
   • Need to identity correct thing to print
   • For me, the blade started to come out (I thought I secured it really well), so I just removed it for the time being... this is apparently a step some people of taken... to simply remove the blade
6. Auto Rewind Spool Holders
   1. Need to identify correct thing to print
   2. Does this negate the need for the buffer?
7. Calibrate and update or modify the idler door
   • Print an updated idler and install it, or follow these instructions to modify the current idler door.
8. Install a smaller? PTFE in hotend to be smaller inner diameter? 1.9mm? 1.85mm?
   • Maybe this?

Anything in green, I'm looking for some community input.

Thanks!

RE: Only a couple of filament slots fully load to the extruder

Did you spend some time properly adjusting your idler screws tensions? Given that your alignments and sensor calibration are correct, idler tension would be the very next place were to look.

As simple as it may sound, the sweet spot for the right tension is not that big, and it may be worthy to spend a little time on it if you didn't already. In my case, aiming for the minimum functioning tension was enought to eliminate all loading problems.