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Printer stops extruding - NOT CLOGGED!  

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The Grue
(@the-grue)
Eminent Member
Printer stops extruding - NOT CLOGGED!

Hello,

I'm trying to print Moldlay filament and I'm almost there with just a few changes of the settings. Something that really troubles me is that sometimes, after a few layers, the extruder stops extruding. There's no clicking/knocking (I know how a clogged nozzle sounds, unfortunately), it's just that the extruder does not rotate/push the filament.

I've noticed this with the attached file (main changes: extrusion width to 0.5mm, nozzle temp 170C, bed 40C, 0.25mm nozzle), but also when I tried to kalibrate the first layer. What I did is:

  •  load the filament
  • Select PLA (much too hot, but there's no cooler setting)
  • Go to "Fine settings" 
  • Reduce Nozzle temperature to 170C
  • Reduce Bed temperature to 40C

It starts printing as usual, but after the first few lines, before it reaches the square patch, extrusion stops.

To make it more mysterious, sometimes it works. Sometimes not.

To me that sounds like a bug, but I'm only a rookie here. 

Printer is an i3 MK3s with current firmware.

Could you help me somehow, please?

Thanks 🙂

Attachment removed
Posted : 13/11/2020 2:34 pm
The Grue
(@the-grue)
Eminent Member
Topic starter answered:
RE: Printer stops extruding - NOT CLOGGED!

I tried to print again, several times, and it's not possible. But I noticed something: Extrusion seems always to stop after the first layer. As soon as Z jumps to 0.25mm, the filament will not be moved any more 🙁

Posted : 13/11/2020 3:02 pm
bobstro
(@bobstro)
Illustrious Member
RE: Printer stops extruding - NOT CLOGGED!

Moldlay is interesting stuff. I haven't printed with it myself, but I do know that it's not typical filament.

Your 1st layer nozzle temp is 180C. At the 2nd layer, it drops to 170C. The recommended printing temperature for Moldlay is 175-180C. Set the 2nd layer to 180C.

Your fan is also kicking on at 50% after the 1st layer. If this is too high, this might explain why your 1st layer prints successfully but subsequent layers don't. If you're already at the low end of the filament's printing range, the addition of cooling might cause it to become too hard to extrude. Try reducing that fan speed. Make sure the fan is blowing on the print and not the block as much as possible. Adding a silicone sock to your heater block is also an inexpensive way to protect against thermal swings when the fan kicks on and off.

A lower cooling fan peed or slightly increased printing temperatures may be all you need. If you still experience problems, some other observations:

Looking at your gcode, I see that you have Linear Advance enabled. You might try commenting out the following lines as a test:

M900 K0.04 ; Filament gcode LA 1.5
M900 K20 ; Filament gcode LA 1.0

This is usually done in your filament settings custom gcode. Change these to:

M900 K0

I also notice that you have a very low extrusion rate modifier set:

M220 S075

This sets your extrusion rate to 75% which is low. These lines all occur after the prime line is printed, so flow is normal at the very start but changes after the prime line. Unless these settings were specifically recommended for printing Moldlay, they might be contributing to your problems.

 

 

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 13/11/2020 4:08 pm
karl-herbert
(@karl-herbert)
Illustrious Member
RE: Printer stops extruding - NOT CLOGGED!

@the-grue

I would work on the idler spring tension settings and possibly increase the nozzle temperature to 180 degrees C. It might also help to clean the hotend with a cold pull. Also try reduce feed and flow and check filament diameter.

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 13/11/2020 4:10 pm
vintagepc
(@vintagepc)
RE: Printer stops extruding - NOT CLOGGED!

You may also be running into cold extrusion prevention with those temperature ranges; The printer simply will not extrude below a certain temperature, the extruder does not move and the serial log will show "Cold extrusion prevented". 

For cooler filaments like PCL or this stuff - you can adjust the threshold with M302.

This post was modified 1 year ago by vintagepc
Posted : 13/11/2020 4:46 pm
The Grue
(@the-grue)
Eminent Member
Topic starter answered:
RE: Printer stops extruding - NOT CLOGGED!

Wow, so many answers from Illustrious, Famed and Noble members! Thanks a lot 🙂  

(And since this is an internet forum: I mean it. No sarcasm!)

It seems you are right with the Nozzle temperatures: I just set it to 180 and it's printing again 🙂

Regarding this:

This sets your extrusion rate to 75% which is low. 

vs 

Also try reduce feed and flow

I changed the overall speed to a slow value because I have adhesion problems, which seems to be common with moldlay. The ring in the g-code files stands on its fitting and prints very well until almost the top is reached. Then it breaks away from the bed. I thought  slowing down the print might improve adhesion. And honestly: adding the "M220 S075" was much easier than finding out which one of the settings in prusa-slicer would do the same 😉

@vintagepc: This seems to be exactly what happened 🙂  How can I access the serial log? I'm a firmware developer with decades of linux experience, so some fiddling is allowed 🙂

 

Thanks again for this quick and efficient help 🙂

 

Posted : 13/11/2020 5:14 pm
The Grue
(@the-grue)
Eminent Member
Topic starter answered:
RE: Printer stops extruding - NOT CLOGGED!

Can you recommend a source for silicone socks?

Posted : 13/11/2020 5:19 pm
vintagepc
(@vintagepc)
RE: Printer stops extruding - NOT CLOGGED!

You just need to connect the printer to your computer via USB, just like you do for firmware updates. It will show up as a USB serial port, /dev/ttyACM[#]

Open the port with your favourite serial terminal program at 115200-8-N-1 and just watch the output once you start the print. 

Connect before starting the print - the printer is wired to reset on serial connection, which is necessary for updates over USB. 

Can't help you on the socks, I molded my own after being less than satisfied with the official E3d offering.

This post was modified 1 year ago by vintagepc
Posted : 13/11/2020 5:54 pm
bobstro
(@bobstro)
Illustrious Member
RE: Printer stops extruding - NOT CLOGGED!
Posted by: @the-grue

Can you recommend a source for silicone socks?

Where are you located? In Europe, you can order directly from E3D. In the US, Filastruder, MatterHackers and other resellers have them. I've ordered socks from FilamentOne with free shipping and quick delivery.

If the socks sag, you can wrap them with a thin bit of wire to create a retainer (or garter if you prefer).

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 13/11/2020 6:46 pm
karl-herbert
(@karl-herbert)
Illustrious Member
RE: Printer stops extruding - NOT CLOGGED!

@the-grue

Here is an overview of the Marlin and Prusa gcode functions:

https://marlinfw.org/meta/gcode/

https://help.prusa3d.com/en/article/prusa-specific-g-codes_112173

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 13/11/2020 9:02 pm
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