RE: MMU2 with E3D Revo Six - Tunning filament tip issue
I'm excited to try this later tonight as I've also had intense stringing on retraction even when I was doing test prints at 195C (I'm trying to find a work around for curling on a model that has terrible geometry).
One thing I have noticed though is that I haven't had a SINGLE case of the filament getting jammed in the PTFE tube. Which means even when this has been a problem the solution (for me at least, so far) has been to "just wait longer" as once it retracts and cuts the tip it continues on just fine. Granted if I'm doing a 3 day 2000+ tool change print I might end up with a mountain of tips spilling over onto the build plate, but I've been glad that the MMU overall seems to be having less jams than it used to.
I'll post again after testing these settings to see how they fair.
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I've just started using my MMU2S with the Revo 6.
I'm not having any problems with the tips, but I am having major issues with PLA blobs forming on the tower during the purge, which are accumulating and causing collisions to occur.
I initially thought that the extra reload distance could be a problem, because the filament was making a momentary grating sound at the extruder gear during loading. I tried adjusting the extra reload distance to 0, and predictably the grating lasted longer. Then I tried increasing it to -30. The grating seemed to disappear but the blobs are just as big. Should I be changing the Cooling Tube Length in the slicer?
RE: MMU2 with E3D Revo Six - Tunning filament tip issue
I had an MMU failure to load error. When I checked on the printer, there was a massive blob on the purge tower, it was almost as big as my little finger. The cause was that the extruder's filament sensor wasn't detecting the filament reliably. The MMU just kept shoving it down into the extruder, pulling it back out, then shoving it back in again. The main issue causing this was the axle (orange arrow) in the idler door worked its way out.
The result was that the gear would just flex out of the way and it wouldn't trigger the filament sensor.
The axle has worked itself out now twice, so I put a dab of blue loctite on it recently. Don't know if it will resolve the issue, but bear in mind that if it runs it might gunk up your bearing in there. Also check that your filament sensor tower is adjusted to properly detect the filament. Someone made a mod for it to add a screw to more easily make micro-adjustments. I've found that to be useful.
As far as cooling length, I feel as though it might be beneficial to change it. I changed it myself during my accidental attempts to mix PETG and PLA, but have changed it back since then to stock parameters. When I asked in the Revo Discord channel, I got one or two people telling me to stick to default printer setups and nothing else.
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I checked my idler axle after Henry's post above, and there was a small amount of play, although it hadn't come out. I glued it in which got rid of the play, and very slightly reduced the blobs on the purge block.
Then I adjusted the extruder idler tension to minimum to get the IR sensor to trigger earlier: another slight improvement.
Then I tried calibrating the Bowden from the MMU ( https://help.prusa3d.com/guide/service-menu-individual-filament-calibration_86376).
This is not supposed to be necessary with the MMU2S because the filament sensor is supposed to trigger the final load to the nozzle, however I noticed when calibrating that the MMU was advancing the filament about 10mm too far. When I calibrated it to advance to just level with the middle of the idler gear, the blobbing completely disappeared. I am now getting perfect purge blocks.
The tips remain perfect. I notice now that the MMU advances the filament almost to the gear then stops, and then feeds it much more slowly until the IR sensor triggers. I wonder if just reducing the loading speed would have also helped.
Oddly enough, the firmware only seems to allow the first filament feed, despite the Prusa instructions to repeat the calibration with all five feeds. Further, calibrating the first one seems to calibrate the others as well. Maybe they changed it this way after the firmware was changed to rely on the IR sensor and not the length extruded from the MMU.
So what seems to have caused the blobs was that the MMU was attempting to feed the filament an extra 10mm, and the extruder motor was not reacting quickly enough to the sensor detecting the filament. This meant that by the time the extruder realised that the filament had arrived at the extruder gear there was already a significant amount of filament past the gear, which caused the blobs.
I'm not certain why this happened with the Revo and not the stock E3D V6 extruder. Perhaps the Revo is a bit more efficient at heating the filament, aggravating the ooze while the nozzle is stationary on the purge block.
RE: MMU2 with E3D Revo Six - Tunning filament tip issue
Hey @kodakram by any chance did you have any custom gcode to test your tips? I want to try to tune in my PVA filament
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Someone made a mod for it to add a screw to more easily make micro-adjustments.
@henry-2 Can you please refer me to the mod you talk about?
RE: MMU2 with E3D Revo Six - Tunning filament tip issue
I don't recall from where I downloaded the tower, but I did find the STL. As I don't know what license it was originally published under, I don't feel comfortable reposting it. However, I have sent it to you through a private message.
RE: MMU2 with E3D Revo Six - Tunning filament tip issue
Thank you very much for your message and STL!
RE: MMU2 with E3D Revo Six - Tunning filament tip issue
Found it! In case anyone else wants it: https://www.printables.com/model/72366-mmu2s-extruder-filament-sensor-micro-adjuster/comments/197331
RE: MMU2 with E3D Revo Six - Tunning filament tip issue
I've just started using my MMU2S with the Revo 6.
I'm not having any problems with the tips, but I am having major issues with PLA blobs forming on the tower during the purge, which are accumulating and causing collisions to occur.
I initially thought that the extra reload distance could be a problem, because the filament was making a momentary grating sound at the extruder gear during loading. I tried adjusting the extra reload distance to 0, and predictably the grating lasted longer. Then I tried increasing it to -30. The grating seemed to disappear but the blobs are just as big. Should I be changing the Cooling Tube Length in the slicer?
Did you eventually find a solution? I keep having the same troubles...
RE: MMU2 with E3D Revo Six - Tunning filament tip issue
I replaced the nozzle, which seemed to fix the problem. I have since moved to a MK4 with MMU3, and definitely no problems now.