Jump to content
UltiMaker Community of 3D Printing Experts

ABS prints fine at first, then flow stalls


Recommended Posts

Posted (edited) · ABS prints fine at first, then flow stalls



I'm printing ABS on an UMO+. At first printing works fine. It sticks to the bed, the flow is OK. When I push by hand it is not hard at all to extrude ABS.


But after the first few layers, extrusion starts sucking and the print fails. When I then manually push the ABS through the nozzle I have to push very hard. Also, the ABS that comes out looks more 'dull' and less molten.


If I then 'clean out' my nozzle with PLA (just push through at 230) and then re-load again with ABS, I can print fine for a few layers, but then it fails again.


I have no problems whatsoever printing PLA, PETG or TPE.


Any ideas on how to fix this?


Temperature: I tried 230-260

No fan

Bed: 105C

Speed: 10mm/s for first layer, 40mm for rest

Initial layer: 0,3mm

Other layers: 0,2mm


Edited by jobjan
Clarified title
  • Link to post
    Share on other sites

    Posted · ABS prints fine at first, then flow stalls

    It's probably over cooking in the nozzle.  You can fix this by printing cooler or faster.  Do .3mm for bottom layer (default I think) and 0.2mm for remaining layers.  Until you've experimented more.  You can certainly do 0.1mm if you stay at 40mm/sec and your nozzle is cool enough.


    So what temp is best?  I'm really not sure.  I think you want to stay between 240 and 245C but start out at 230C as an experiment.


    So for now, try 0.2 layer height and also do 20mm/sec print speed on that bottom layer to keep the plastic flowing.


    That's clogging.


    Other problems you will have is layer adhesion and parts sticking to the bed.  You really want the bed at 105C minimum, 110C recommended for the ABS to stick extra well to the bed but I don't think you can get it up to that temp without enclosing the printer - as a minimum enclose the 3 open sides and throw a big box over the top.  Let the air get up to 35C (servos will be fine even at 40C air temp).


    This higher air temp will help with layer adhesion.  Also lower the fan a lot - print at what sounds like 1/4 power (around 30% I think).  If fan is too low then overhangs will look bad.  If fan is too high then part will seem fine until you break it and you will realize it breaks along layer lines which means you didn't have good layer adhesion.  It should break in a way completely (or mostly) ignoring layer lines.


  • Link to post
    Share on other sites

    Posted · ABS prints fine at first, then flow stalls

    Thanks for your advice..


    I've tried 20mm/s for the bottom layer, 40mm/s for the rest

    and 0,3mm layer height for 1st, 0,2mm for rest

    at both 230 and 240C


    but the same thing happened, it stops at a few layers. Interesting is that all prints stop at more or less the same point. See pic:


    Any more suggestions?


    I have no problems with layer adhesion (for the first print after re-loading)

    WhatsApp Image 2020-01-14 at 23.03.46.jpeg

  • Link to post
    Share on other sites

    Posted (edited) · ABS prints fine at first, then flow stalls



    I've not been able to successfully print ABS yet. I'm starting to get frustrated 😞


    So far I've tried:

    230, 240, 250, 260 C


    First layer at 10 mm/s, 20 mm/s

    Other layers at 20 mm/s, 40 mm/s or 60 mm/s


    Layer flow at 100%, 130%, 150%.


    And combinations of those.


    Bed temperature: 105C


    First layer 0,3mm, next layers 0,2


    No luck yet. At first the print starts fine, the print sticks to the bed, but then after a while it fails (the flow of ABS deteriorates).


    Any ideas on how to fix? Thanks in advance!

    Edited by jobjan
  • Link to post
    Share on other sites

    Posted · ABS prints fine at first, then flow stalls

    I don't have much experience with it, but ABS is said to decompose fast in the nozzle, if sitting there for too long (=or too hot, or printing too slow), causing clogs.


    If that is not the case for you, then have you checked that the little fan for cooling the nozzle is working well? On an UM2 this is sitting behind the nozzle, invisible from the front. I don't know where it is on an UMO. This could suck-in hairs and debris, and get stuck.


    Also on an UM2, a severely worn out white teflon coupler could cause underextrusion after a while. I don't know if an UMO has something similar?


    The white filament-end after a cold pull on an UM2 shows a thickening where the teflon coupler is worn out. But I have seen even worse. This hinders the material flow.



    Not sure if any of these could be the cause for you, but it might be worth checking?


  • Link to post
    Share on other sites

    Posted · ABS prints fine at first, then flow stalls

    Thanks a lot Geert,


    There is no extruder cooling fan on the UMO. As far as I know,


    But your other suggestion might point in the right direction, because my cold pulls don't look close to your images ar all...

    My teflon coupler is quite new, but might there be something wrong lower in the hot end? Any idea where?



    WhatsApp Image 2020-01-17 at 22.12.41.jpeg

  • Link to post
    Share on other sites

    Posted (edited) · ABS prints fine at first, then flow stalls

    Ultimaker 3 - ABS (I have to use the plastic cage you get on the side or else the ABS will warp).


    Printing Temp: 225 C

    Build Plate Temp: 80 C

    Print Speed: 75 mm/s

    Fan Speed: 2%

    Layer Height: 0.1 mm

    Infill: 100%


    Brim and Z Hop when retacted


    Use the glue stick to as well that came with mine (very thin even layer).




    Maybe this will help. IDK if it will for you, but maybe it will help.


    I print all the time and this works perfectly (basically perfect) for me.




    ABS is not easy to print to as well. I've had problems with ABS myself. It's not just plug in the USB for the most part like PLA and you are ready to go.




    Side note: switching to PC after this due to the dangers of ABS (mostly well ventilated area though) for now.

    Edited by e23
  • Link to post
    Share on other sites

    Posted · ABS prints fine at first, then flow stalls

    Try 25mm/sec on first layer and 40mm/sec on the rest.  Try coolest temp (230C).


    Yes, the UMO doesn't have that fan blowing on the teflon and the fan fixed an issue that looks like this where it prints fine for a few layers but if there's too many retractions the heat slides up and causes clogs in the teflon area or just above.


    I'd probably replace the teflon part.


    Also check the diameter of the filament.  sometimes a 3mm filament really is 3.00mm (very very rare) and that can get stuck in the bowden.  You'd probably notice though when you tried to slide the filament out a bit as part of some test.


    I'm a bit stumped however.


    Oh wait - it could be the extruder driver chip is overheating.  If so it would sound a little different where the extruder turns off for a portion of a second and then quickly turns back on again.  The fix for this issue is usually to *lower* the extruder current to around 900ma.


  • Link to post
    Share on other sites

    Posted · ABS prints fine at first, then flow stalls

    Thanks both e23 and gr5 for your suggestions, much appreciated..! I've tried most of them now.


    Speed settings: With 25mm/s on 230 the first layer doesn't stick, so I've tried 10mm/s on 230. But same result

    Lack of a fan on the UMO: I've tried printing without retraction (this should make a bit of a difference, right?), no luck

    Filament diameter: Measured, it's 2,85mm

    Extruder driver chip overheating: haven't heard the sound you're describing and I don't know how to lower the extruder current... Is there a noob way to test if this is happening?

    Replacing teflon part: I've taken the hot end apart, and to me (but as said, I'm a noob), it doesn't look as worn as some other images I've seen out there. What is your expert opinion? Should this part be replaced?




  • Link to post
    Share on other sites

    Posted · ABS prints fine at first, then flow stalls

    If this teflon coupler was on my UM2, I would replace it, if I had printing problems. There seems to be an indent inside the tube, close to the bottom, and the inner diameter seems to have gotten oval instead of round? But this is hard to see for sure on photo, as there could be weird light-effects too.


    Concerning bonding, I think gr5's method with dilluted white wood glue should also work well. At least it did work well when I tried it for PET some years ago. But my "salt method" will *not* work for ABS.


  • 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

      • 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
        • 10 replies
      • UltiMaker Cura 5.3.0-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
        • 17 replies
      • New here? Get ahead with a free onboarding course
        Often getting started is the most difficult part of any process. A good start sets you up for success and saves you time and energy that could be spent elsewhere. That is why we have a onboarding course ready for
        Ultimaker S5 Pro Bundle, Ultimaker S5, Ultimaker S3 Ultimaker 2+ Connect.   
        They're ready for you on the Ultimaker Academy platform. All you need to do to gain access is to register your product to gain free access. 
        Ready? Register your product here in just 60 seconds.
          • Like
        • 14 replies
    • Create New...