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[Solved] PLA now giving trouble - diagnosis?  

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Puanow
(@puanow)
Active Member
PLA now giving trouble - diagnosis?

I just switched back to PLA which was printing pretty exquisitely I switched from pet G and now it’s not printing correctly any ideas on why its printing like this?

Best Answer by bobstro:

When you switch from a higher temp filament (e.g., PETG) to a lower temp filament (e.g., PLA), it's possible for a bit of filament debris to get left behind in the hotend and nozzle. If this happens, you can get a partial clog from material that won't melt out. This can result in a number of extrusion problems depending on how bad the clog is. An easy way to clear partial clogs is a cold pull. You use a higher-temp material -- I like eSun cleaning filament -- to ensure everything is melted out.

  1. Heat up the nozzle to a temp higher than your highest-temp filament (e.g., I use 265C for eSun cleaning filament).
  2. Run some of the cleaning filament through the nozzle.
  3. Stop and turn off the heaters and let the filament fully cool.

At this point, you've got the cleaning filament stuck in the hotend with any debris trapped within.

  1. Loosen the extruder tension screws.
  2. Start heating the nozzle again.
  3. As the temp moves above 70C, start a slow, steady pull from above.
  4. At some point, the filament should pull out from above, removing the partial clog.

Here's what a good cold pull result looks like:

More notes here and a Prusa knowledgebase article here for more info.

This topic was modified 5 months ago by Puanow
Posted : 09/07/2021 8:58 pm
bobstro
(@bobstro)
Illustrious Member
RE: PLA now giving trouble - diagnosis?

When you switch from a higher temp filament (e.g., PETG) to a lower temp filament (e.g., PLA), it's possible for a bit of filament debris to get left behind in the hotend and nozzle. If this happens, you can get a partial clog from material that won't melt out. This can result in a number of extrusion problems depending on how bad the clog is. An easy way to clear partial clogs is a cold pull. You use a higher-temp material -- I like eSun cleaning filament -- to ensure everything is melted out.

  1. Heat up the nozzle to a temp higher than your highest-temp filament (e.g., I use 265C for eSun cleaning filament).
  2. Run some of the cleaning filament through the nozzle.
  3. Stop and turn off the heaters and let the filament fully cool.

At this point, you've got the cleaning filament stuck in the hotend with any debris trapped within.

  1. Loosen the extruder tension screws.
  2. Start heating the nozzle again.
  3. As the temp moves above 70C, start a slow, steady pull from above.
  4. At some point, the filament should pull out from above, removing the partial clog.

Here's what a good cold pull result looks like:

More notes here and a Prusa knowledgebase article here for more info.

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 : 09/07/2021 9:20 pm
Puanow liked
Puanow
(@puanow)
Active Member
Topic starter answered:
RE: PLA now giving trouble - diagnosis?

@bobstro

this makes so much sense! thank you for the comprehensive reply! 🤗 

Posted : 09/07/2021 9:31 pm
bobstro
(@bobstro)
Illustrious Member
RE: PLA now giving trouble - diagnosis?
You technically can pull with any filament so long as you can run it at temperatures higher than whatever's stuck. White or transparent is recommended so you can see what's been trapped. A stretchy material helps avoid snapping off, so nylon is also popular. Cleaning filament has the added advantage that it will melt at lower temps, so if a bit of it is left behind, it won't cause yet another partial clog when you next print PLA.
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 : 09/07/2021 9:41 pm
Puanow liked
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