Extruder jams and prints fails at similar height regardless of print
 

Extruder jams and prints fails at similar height regardless of print  

  RSS
Uppsala CNC
(@uppsala-cnc)
Eminent Member

Hi,

I have had my Prusa i3 MK3S for many years now and it is a real workhorse, very seldom that it fails a print and if it does it is usually my fault or a random nozzle clogg. However, my last three prints have all failed in the exact same way. The first two were the based on the same STL, but I changed the G-code and I added some other parts on the same build plate. The third print was a completely different STL. All three prints fail at around 13 mm height. The print starts to show underextrusion and after a few layers no more material is extruded. 

The nozzle is not clogged, but the filament has bulged up below the extruder gear but above the PTFE tube jamming the extruder path. I only use Prusa filaments so filament tolerances are good. 

Is there something damaged in my extruder? Gears, PTFE tube? Hhave I over or under tightened the screw for the gears? Is there something else going on.

I have added a pictures of the failed prints and the mess in the extruder. Thank you for any help with this issue! I'm very sick of clearing this mess now and want to solve it before doing my next print.

 

Posted : 26/10/2020 9:09 pm
--
 -2
(@-2)
Illustrious Member

A symptom of printing in an enclosure.

Do you have an enclosure? If yes, then you need to ventilate it while printing PLA.  Another option is to install a fan and shroud on the extruder motor that WILL get too warm printing in an enclosure.

It is always wise to get more than one opinion... as for trusting Prusa? No way man....
Posted : 26/10/2020 10:43 pm
--
 -2
(@-2)
Illustrious Member

ps: Here's a link to a Thingy that folks use...

https://www.thingiverse.com/thing:2975582

It is always wise to get more than one opinion... as for trusting Prusa? No way man....
Posted : 27/10/2020 5:23 am
Uppsala CNC
(@uppsala-cnc)
Eminent Member

@tim-m30

I do indeed have an enclosure and I do see how it could be problematic. However I have been printing thousands of PLA prints in my enclosure over the years without any issues. Ambient temperatures are not any higher than normal either.

 

Any other idea? 

Posted : 27/10/2020 5:58 am
--
 -2
(@-2)
Illustrious Member

Different versions of firmware play with the motor drive currents. This affects their power consumption and thermal rise. Also, your part may have specific detail that drives a manic retraction storm that maximizes power and thus heat dissipated by the extruder motor.

That you have an enclosure is - well - as they say: caveat emptor.  You need at a minimum a heat sink, but I'd rig a fan. Depending on Mk3 or Mk3S, you can grab power for the two wire fan from the extruder fan or the filament sensor or back at the Einsy.

ps: and I do not know why - but people install these fans blowing downward, fighting normal convection. Install the fan to draw air up over the motor and out the top of the extruder so you don't have to deal with the new fan adding part cooling you probably don't want or need.

This post was modified 1 month ago by --
It is always wise to get more than one opinion... as for trusting Prusa? No way man....
Posted : 27/10/2020 6:09 am
--
 -2
(@-2)
Illustrious Member

Oh, one other thought before I drop this thread: have you changed nozzles recently?  Minor changes in the nozzle/heat_break/heater_block configuration may have an affect on work the extruder motor must do - causing more heat.

It is always wise to get more than one opinion... as for trusting Prusa? No way man....
Posted : 29/10/2020 3:58 am
Uppsala CNC
(@uppsala-cnc)
Eminent Member

@tim-m30

Nope, first time this happened I thought it was a clog so I removed and cleaned the nozzle. But I have not changed it. 

Posted : 29/10/2020 5:59 am
--
 -2
(@-2)
Illustrious Member

Well - r & r is included in "changing the nozzle" ... Did you follow the E3D-V6 assembly guide - to the letter?  In any case, changing the heat break positing in the heater block a quarter turn has an effect. Unless you put it all back together exactly the same, 4.87 turns in on the nozzle, 3.61 turns on the heat break, torque identical -- you have changed things, and this change may be the difference.  Since you did the clean after the problem started... probably not the cause.

Anyway - back to firmware - if you've done an update, try moving back to the prior version; or, just add the fan to cool the extruder motor.

This post was modified 1 month ago by --
It is always wise to get more than one opinion... as for trusting Prusa? No way man....
Posted : 29/10/2020 2:04 pm
Share:

Please Login or Register