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Under extrusion after retraction  

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Mark Blasco
(@mark-blasco)
Active Member
Under extrusion after retraction

I've had my mini+ up and running for about 6 weeks now, printing almost 24 hours a day, and until recently it was working just fine.  For the last week, I've been getting what looks like under extrusion after retractions.  Basically, wherever it starts printing a new object, there is a small gap in the filament, as if it wasn't coming out when the hot end starts moving.  I've been printing the same files since I got the machine, and it's happening with multiple different files, so I know it's not that.  It also is happening with multiple different filaments (all PLA running between 200-220, which is what works best for these filaments, and has worked fine for over a month).

Where do I start with troubleshooting this?  I know I've read posts about the little ptfe tube inside the hot end shrinking, could this be the cause?  I'm fairly familiar with troubleshooting ender 3's, I've got a few of those, but I'm not sure exactly what to start with on the mini+.

Posted : 01/07/2021 8:15 am
cwbullet
(@cwbullet)
Illustrious Member
RE: Under extrusion after retraction

Have you tried reducing the retraction slightly?  6 weeks to too little of time for it to be PTFE shrinkage.  

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Chuck H
3D Printer Review Blog...
Posted : 01/07/2021 10:07 am
Mark Blasco
(@mark-blasco)
Active Member
Topic starter answered:
RE: Under extrusion after retraction
Posted by: @cwbullet

Have you tried reducing the retraction slightly?  6 weeks to too little of time for it to be PTFE shrinkage.  

I haven't adjusted the settings, I'm using the recommended slicer settings from Prusa.  These files printed just fine for the first month or so, this problem is new, so it's not just an issue of retraction settings being off.  I've looked at the extruder wheel, it is clean with no debris.  The issue is only happening after a move, so I know it has something to do with the retraction and restarting process.  For my enders, when this was happening, it was usually a gap that started happening where the bodin tube wasn't seated tightly enough against the nozzle.  I know that with the prusa hot end the bodin tube doesn't go flush against the nozzle, so I don't know the best way to diagnose the issue here. 

Posted : 02/07/2021 12:18 am
Mark Blasco
(@mark-blasco)
Active Member
Topic starter answered:
RE: Under extrusion after retraction

Just tried reducing the retraction to 3mm from 3.2, didn't seem to make any difference.  I just don't know what could have changed, other than a clog forming at the inner tube.  The retraction issues are happening reliably, every time the printer retracts and moves, it seems like there is a small gap, as if not enough filament is coming out fast enough.

Posted : 02/07/2021 5:11 am
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