Over/under extrusio...

Over/under extrusion after purge investigation.  


Supreme moderator Admin
Joined: 10 months ago
Posts: 173
05/04/2020 8:36 pm  

There have been reports on thingiverse of under/over extrusion after purge blobs are created. This is using PrusaSlicer and the retractable purge mechanism.

This thread is a for investigating the cause and finding a solution to this problem.

"It ALWAYS under extrudes after the blob on the first layer. But then it OVER EXTRUDES after that."-Jagr200

"At the first 2 layer i have under Extrusion and with the next layers massive over Extrusion."-MagicBugsBunny

" it extrudes the first layer correctly, AND changes tools/blobs correctly, but then the second layer does not extrude correctly at all. Filament simply doesn't get put down."-alicedprojects

"has anyone been able to figure out how to stop the printer from missing filament after changes? When I use the mechanism the next mm or so of printing is missing. I've tried to play around with the retraction settings with no luck."-Trutey

Attached is a picture of the issue on a 2 color safety pylon.

This topic was modified 2 months ago by BigBrain3D

New Member Customer
Joined: 3 months ago
Posts: 1
06/04/2020 5:53 am  

Off the top of my head, an accumulating error potentially points at an issue with relative mode vs absolute mode:

[ a quick recap of what I am talking about ]



Another possibility is extruder temperature and retraction settings causing oozing:

[ https://www.matterhackers.com/articles/retraction-just-say-no-to-oozing ]


However, without seeing some of the source files (slic3r version, input file to slic3r, slic3r settings, gcode) to properly debug, I'm grasping at straws. I'd love to take a look if some more information was available.


All the best,


New Member
Joined: 2 months ago
Posts: 1
07/04/2020 1:41 am  

Hi, same AliceDProjects from Thingiverse.

Thanks for investigating this issue.

First of all, one thing that I can see as an immediate issue is that Thingiverse's new UI has completely broken the GCode formatting on the part description on their site. It's completely unusable/unreadable.

What really needs to happen is that someone needs to create a GitLab Snippet or GitHub Gist (or heck, even a full repository) so nobody has to go hunting for the "correct" version of the GCode.

I just got my Prusa MK3S printing correctly again after a rebuild and it's going to be a while before I attempt installing the RPM again. Hopefully by then, a Snippet/Gist will be up with the correct GCode.

It's really easy, you can do it directly from a web browser. Just read: https://docs.gitlab.com/ee/user/snippets.html

Supreme moderator Admin
Joined: 10 months ago
Posts: 173
04/05/2020 6:40 pm  


The gcode and assembly instruction have now been centralized here.