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Under extrusion on 50um  

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ChristianR
(@christianr)
Active Member
Under extrusion on 50um

Hi,

I have a MK3S since a few weeks and it works great. I'm blown away by the print quality I get and how well PRUSAMENT PLA works.
BUT: If i print things with a layer height of 50um I have some serious under extrusion issues, or is it clogging? I don't know.

This is my setup: i3 MK3S, latest firmware, original PRUSAMENT PLA (Galaxy Black)
What i want to do: The part in the picture is printed with 0.15mm layer height, only the radius on the top will be printed with 50um. The part on the left is only 0.15mm, the part on the right is sliced to have 50um on the top few mm, rest is 0.15mm.

Does anyone have a tip for me why i have this issue?
I tried printing something bigger with 50um layer height. It printed, the print finished, but every few layers I got a few layers that looked like the top of the right part in the image.

Cheers
Christian

Posted : 15/04/2019 10:26 am
JoanTabb
(@joantabb)
Veteran Member Moderator
Re: Under extrusion on 50um

Hi Christian,

Galaxy Black seems to have particles in the PLA, which may be causing a clog.

could you try a test piece printing just the last 5mm of the model, (use the cut command, un-tick keep lower part) my sample part was 20mm tall, so I cut at 15mm.

your slicer is probably set up for minimum variable layer height of 0.7mm

use your mouse to set the variable layer height from the top of your test piece , down to below the rounded edge, and the minimum layer height setting should restrict the layer height to 0.7mm

then see if that prints for you, without having to print the whole piece
(don't forget to remove mesh modifiers if you used that to change to 0.5mm layer height, with the original model.)

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 15/04/2019 1:39 pm
ChristianR
(@christianr)
Active Member
Topic starter answered:
Re: Under extrusion on 50um

Hi Joan,

thanks for your reply.
I have to correct a few things I from my original post first. The layer height is actually 70um if I use the layer editing feature in Slic3r PE. I didn't knew that. Nevertheless i used the 50um profile (real 50um layer height) and it has the same issue.

I was suspecting the silver flakes in the filament too, but in the datasheet for the filament it says "Only this material is proven for 50 microns layer height" so I thought i give it a try. I have some Prusa branded silver PLA at hand. See the result below.

For the Prusament PLA Galaxy Black the result was the same. I could hear the extruder "klicking" after a few seconds of extrusion. It built up pressure until the motor slipped and the feed gears turned back rapidly. On parts where the retracts and the normal extrusion movements were following in quick succession no klicking or rapid movements were visible.

For the generic Prusa PLA (without any particles) it worked flawlessly.

I could have figured this out by myselfe, but I was mislead by the explicit mentioning of the 50um capabilities of the PRUSAMENT PLA.

Posted : 15/04/2019 2:40 pm
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