Jump to content

PVA burning 75% into print, repeatedly


Recommended Posts

Posted (edited) · PVA burning 75% into print, repeatedly

I am slowly coming to the conclusion that the UM3E firmware is not properly maintaining the BB Core printhead temperature during the course of a long print job, and the cause of this is likely the heated printing plate, which at first heats the glass, but then continues on to radiantly heat all the other surfaces inside the UM3E body.


I have decided that since the failures are repeatable, with the PVA burning at nearly the same spot each time, I will just keep trying the same project over and over until it succeeds, damn the waste of filament.  I have been gradually turning down the heat to see what happens.


Also I am using a PVA raft, and that has absolutely no problems whatsoever, looks clean, no faults. It's only right near the end where the printhead is getting to be too hot, the PVA chars, and plugs the printhead.


Model source: https://www.thingiverse.com/thing:34277

"Deer Head detailed" by Takeshi Nov 11, 2012


Uniform scaling 36.51%


PLA Green in AA 0.4

Natural PVA in BB 0.4


Profile: Fine 0.1mm

Speed (default) 70mm/s

Generate Support, using Extruder 2

Build plate adhesion: Raft

Build plate adhesion Extruder: 2

Enable Prime Tower

Wipe inactive nozzle on Prime Tower


Ambient room temperature: 73 F  / 22.7 C


1. Drop print temperature from 200C to 190C. No apparent effect. Prime tower contains small black blobs of PVA. Cleaning printhead BB hot push cleaning: lots of black charred gunk strings out


2. Staying at 190C, drop printhead standby temp from 100C to 80C. PVA gets further along before failing. Prime tower contains small black blobs of PVA. hot push cleaning: lots of black charred gunk strings out


3. Staying at 190C, drop printhead standby temp from 80C to 60C. PVA fails at about the same spot yet again though a little higher before it failed. Hot push cleaning: far less black charred gunk, it's now just a light brown and a tiny tip of black charring. The interior of the prime tower looks much better, and no more black PVA blobs.




So.. how low can I go for the printhead standby temp? I am going to try for 40C / 104F next. Can it be set to turn off completely?


Also through all this I have not changed the print speed. Lowering the temperature has had no effect on PLA print quality for Fine mode.


Once I bottom out the standby temp, I will probably start dropping the print temp to 185C and then 180C while maintaining Fine print speed to see what happens.




So anyway, it seems the PVA BB core is not maintaining correct temperature through the course of a print job, and eventually gets too hot and burns the PVA.. But the PVA works completely fine at the start of the job when the print bed has not had time to radiantly heat up the printhead assembly...
















Edited by dmahalko
  • Link to post
    Share on other sites

    Create an account or sign in to comment

    You need to be a member in order to leave a comment

    Create an account

    Sign up for a new account in our community. It's easy!

    Register a new account

    Sign in

    Already have an account? Sign in here.

    Sign In Now
    • Our picks

      • Introducing the UltiMaker Factor 4
        We are happy to announce the next evolution in the UltiMaker 3D printer lineup: the UltiMaker Factor 4 industrial-grade 3D printer, designed to take manufacturing to new levels of efficiency and reliability. Factor 4 is an end-to-end 3D printing solution for light industrial applications
          • Like
        • 2 replies
      • UltiMaker Cura 5.7 stable released
        Cura 5.7 is here and it brings a handy new workflow improvement when using Thingiverse and Cura together, as well as additional capabilities for Method series printers, and a powerful way of sharing print settings using new printer-agnostic project files! Read on to find out about all of these improvements and more. 
          • Like
        • 26 replies
    • Create New...