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Under Extrusion Issue  

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Chlo_Z
(@chlo_z)
Active Member
Under Extrusion Issue

Hello all,

To preface, I am new to the world of 3D printing. Just because I put together my printer and have the manual still on the provided USB, I am not an expert, and feel I can only spend so much time trying to fix something before outsourcing for help.

As the title states, I am having under extrusion problems. To detail, a print finished successfully prior to this occurrence. From the same spool on the same day the under extrusion started happening. As far as troubleshooting:
- Noticed clicking sound coming from extruder, and removed filament; filament was grinded at a point and was cut and tossed from the spool. Feeding new filament works as expected, purging works as expected, but printing is where the issue occurs.
- Disconnected PTFE tube and ran filament through by hand. Filament extruded fine.
- Removed M3x40 screw with spring to observe inside of extruder (idler? still learning part names); no issue could be observed.
- Reset M3x40 screw with spring to be flush with plastic rim of extruder (idler? still learning part names) as assembly guide says (page 69).
- Attempted printing at higher and lower temperatures; lower temperature causes nothing to extrude while higher temperature does not fix neither clicking nor under extrusion.
- Used provided acupuncture needle ~dozen times.
- Attempted "atomic" solution read from an external website; disconnect PTFE tube, set temp to 260 C for PLA (my material), insert flat cut filament until first sign of extrusion, reduce temp to 90 C, cleanly and quickly yank filament out. Then re-inserted filament via the extruder, purged, attempted the print, clicking sound with under extrusion.

One last piece of information: Whenever I began a print to test if I had fixed my printer, every single time during the initial "strip"  (at the front most end of the print bed, should leave a strip measuring between 2 and 3 inches prior to printing the actual GCode) the print head would extrude an abnormally large "glob" halfway through said "strip" which seems as an indication of non-consistent extrusion.

I would truly appreciate if someone with more expertise could help me through this problem, or at the very least tell me which part (if any) could be broken and need replacement.

Posted : 28/09/2021 11:29 pm
Diem
 Diem
(@diem)
Noble Member

The commonest fix for a clicking extruder and consequent under-extrusion is to adjust (it can be either way) the pressure exerted by the extruder idler screw.  Flush is first approximation; different filaments may require different pressures.

Cheerio,

Posted : 29/09/2021 12:22 am
Chlo_Z
(@chlo_z)
Active Member
Topic starter answered:
Under Extrusion Issue

I've tried for a couple hours adjusting. The result is that when too loose, the clicking is faster and less damaging to the filament. Too tight and the clicking is slow but gets more intense, and grinds the filament faster. Everywhere in between just follows the trend. Unfortunately this is not the fix.

Posted : 29/09/2021 3:11 am
BogdanH
(@bogdanh)
Honorable Member

If tension screw is about flush with extruder housing, then it should be fine.
Let's agree on one thing first: PLA melts just fine at 215C and so there's no need to raise the temperature for whatever reason.

If there's a need to make "cold pull" to unload filament, or there's in general incosistent (under) extrusion, then you can be pretty sure that you have a jam in hotend. And the only solution in this case is to take hotend apart: clean it, check PTFE tube length (replace if necessary) and assemble hotend properly (don't just put it together).

[Mini+] [MK3S+BEAR]...
Posted : 29/09/2021 8:46 am
Chlo_Z
(@chlo_z)
Active Member
Topic starter answered:
Under Extrusion Issue

First, I should preface; how do I respond without requiring a title every time? I feel I'm just just making the chat more annoying to sift through.

Secondly, I need to order an Allen wrench before I can finish taking apart the hot end, but until I receive it, any tips / instructions on how I should clean all the parts?

Posted : 30/09/2021 1:58 am
JoanTabb
(@joantabb)
Moderator

I just put a space in the title box.

you should disassemble the hot end whilst it is HOT, the old filament is like glue when cold. 

be very careful with the thermistor grub screw... use a square ended allen wrench not a ball ended allen wrench
the Ball ended wrench tends to split the hex cup and make the screw irremovable. 

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 : 30/09/2021 2:36 am
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