MMU2S has large amounts of filament-pull friction causing poor prints
 

MMU2S has large amounts of filament-pull friction causing poor prints  

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redsidecustomtools
(@redsidecustomtools)
New Member

I've had the prusa MMU2S for around a year now. I have to admit, this will never be usable by normal populous until they work out these problems. This printer has had such an unbelievable amount of problems that honestly I'm surprised its still available in market with how completely inconsistent this is. Don't get me wrong, I'm not here to bash the printer. When this is working, it makes prints so amazing other printers look stupid. But this printer has had me on the edge of anger and despair more times than I could possibly count. and I absolutely mean that.

 

To the point, the latest problem I have been having is that for whatever reason, there has been a ton of friction in the filament-pull system, or at least I think. To be specific, my prints come out as really poorly done, basically it's spitting out filament, but it seems it isn't extruding fast enough to keep up with movement. Basically the print is still made, but it's really weak as the there are small missing layers here and there and the outside perimeter looks pretty unpleasing.

 

This is particularly odd to me because this wasn't a problem before and I haven't made the printer move faster, it's like it woke up one day and can't pull filament fast enough anymore. After a few weeks of experimentation, it seems that it's struggling to pull in filament as fast as it can use it.

 

To help this, I tightened the screw for the bontech gears on the extruder, hoping to give it some more pulling power. However this hasn't really helped at all. For whatever reason, the top MMU2S block doesn't seem to actually feed the filament into the extruder during the prints, it just kinda moves the bearing out of the way so there is less resistance for the extruder to pull it seems. I've tried loosening the screws on the MMU2S unit so that the bearings don't press as hard on the filament, but all this does it cause the filament to get stuck when its loading filament for the print. I've tried to tighten these top MMU2S unit screws so that the filament will actually load all the way for the print, but this seems to create more friction in the system during the print and the extruder isn't able to pull the filament fast enough during the print. I also thought that maybe it had to do with the PTFE tubes being coiled and the spool being in an awkward angle to pull and this was causing friction. However I cleaned up the setup so everything is very streamlined. The spool is on the rolling mount that comes with the MMU2S and the inside of the PTFE tubes are very clean and slick. It feels very easy to manually load the filament and very little resistance for filament to be pulled, however despite this, the extruder can't pull it in fast enough no matter how tight the extruder bontech gears are and no matter how loose or tight the top MMU2S Unit screws are.

 

I'm a loss here and I'm really not sure what to do. I've even attempted slowing down the movement print speed in the slic3r during prints and this helped slightly, but not enough to be called even a temporary fix. Any ideas? Oh and I've already updated all of the firmware and using latest prusa slic3r

Posted : 21/04/2021 8:09 am
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