Jump to content
UltiMaker Community of 3D Printing Experts

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

      • UltiMaker Cura 5.3 stable released
        In this stable release, Cura 5.3 achieves yet another huge leap forward in 3D printing thanks to material interlocking! As well as introducing an expanded recommended print settings menu and lots of print quality improvements. Not to mention, a whole bunch of new printer profiles for non-UltiMaker printers!
          • Thanks
          • Like
        • 22 replies
      • Here it is. The new UltiMaker S7
        The UltiMaker S7 is built on the success of the UltiMaker S5 and its design decisions were heavily based on feedback from customers.
        So what’s new?
        The obvious change is the S7’s height. It now includes an integrated Air Manager. This filters the exhaust air of every print and also improves build temperature stability. To further enclose the build chamber the S7 only has one magnetically latched door.
        The build stack has also been completely redesigned. A PEI-coated flexible steel build plate makes a big difference to productivity. Not only do you not need tools to pop a printed part off. But we also don’t recommend using or adhesion structures for UltiMaker materials (except PC, because...it’s PC). Along with that, 4 pins and 25 magnets make it easy to replace the flex plate perfectly – even with one hand.
        The re-engineered print head has an inductive sensor which reduces noise when probing the build plate. This effectively makes it much harder to not achieve a perfect first layer, improving overall print success. We also reversed the front fan direction (fewer plastic hairs, less maintenance), made the print core door magnets stronger, and add a sensor that helps avoid flooding.

        The UltiMaker S7 also includes quality of life improvements:
        Reliable bed tilt compensation (no more thumbscrews) 2.4 and 5 GHz Wi-Fi A 1080p camera (mounted higher for a better view) Compatibility with 280+ Marketplace materials Compatibility with S5 project files (no reslicing needed) And a whole lot more  
        Curious to see the S7 in action?
        We’re hosting a free tech demo on February 7.
        It will be live and you can ask any questions to our CTO, Miguel Calvo.
        Register here for the Webinar
          • Like
        • 18 replies
      • UltiMaker Cura Alpha 🎄 Tree Support Spotlight 🎄
        Are you a fan of tree support, but dislike the removal process and the amount of filament it uses? Then we would like to invite you to try this special release of UltiMaker Cura. Brought to you by our special community contributor @thomasrahm
        We generated a special version of Cura 5.2 called 5.3.0 Alpha + Xmas. The only changes we introduced compared to UltiMaker Cura 5.2.1 are those which are needed for the new supports. So keep in mind, this is not a sneak peek for Cura 5.3 (there are some really cool new features coming up) but a spotlight release highlighting this new version of tree supports.  
          • Like
        • 22 replies
    • Create New...