Jump to content
UltiMaker Community of 3D Printing Experts

printing round things without constant reversals of travel direction


Recommended Posts

Posted · printing round things without constant reversals of travel direction

I am printing pipe fittings for 6" pipe. There are three outside walls, three inside walls and a bit of infill. Nozzle size is 0.4 mm, line width is 0.4 mm, layer height is 0.4 mm, speed is 60 mm/sec except walls and first layer which run at 50% of that.

I would expect Cura to print the three walls in a continuous motion (with a step-over between walls of course). So for example printing the three outside walls, the three inside walls and then the infill. Problem is, absolutely nothing seems continuous about what Cura does. It will print a section of the wall, stop, reverse direction and print another section and so on.

This sort-of works with PLA but I am printing in PETG and am having blobs, stringing and burnt bits everywhere.

Yes, I know that PETG is prone to this and I have tried my best to fix it but my best is obviously not good enough 😞

So here is one issue I have noticed: Cura will print a section of wall. I have coasting turned on (default parameters) to take care of the filament that wants to ooze out as the head re-positions and that helps somewhat but I have noticed that when Cura does a reversal, there is still excessive material extruded right at the point of reversal (extra prime is turned off). The next time the head goes past that point there is contact with the nozzle and the extra material and I get stringing and blobs.

I am thinking that if I can somehow tell Cura to do a continuous circle motion without constant reversals I could possibly improve my prints by a large degree. I do not know the number of reversals in a single layer but I would not be surprised if it would add up between 20 and 30, not including the infill section.

I would also welcome suggestions on how to reduce the apparent extra filament feed right when a reversal occurres. This extra feed may happen without reversals when stopping at one point and continuing a bit further ... my eyeballs are not fast enough to catch that action though.

BTW, I am running at 240C for the extruder and am afraid that inter layer adhesion will suffer if I go lower. I am currently running at a flow rate of 90% - I have tried 85% but strength suffers, the pipe becomes even more porous and the stringing/blobbing isn't much (if at all) reduced.

  • Link to post
    Share on other sites

    Posted · printing round things without constant reversals of travel direction

    Thanks smartavionics - could you clarify what you mean by 'project file' please ?

    I am using Cura 3.6 and with the model loaded I have chosen 'file, export' to generate a .3mf file. Hopefully that is what you are referring to ?


  • Link to post
    Share on other sites

    Posted · printing round things without constant reversals of travel direction

    Hello @jens3. Actually, it's File->Save (not export). Exporting just includes the model. Saving, includes the settings and the model. I know it's not obvious, is it?

  • Link to post
    Share on other sites

    Posted · printing round things without constant reversals of travel direction

    H @jens3, thanks for the project file. OK, things you can do to improve this are:


    1 - Enable the Optimise Wall Printing Order.


    2 - Set a User Specified z-seam alignment with x/y values that position the seam where you want it.


    3 - Set the Seam Corner preference to None.


    4 - Set the Max Comb Distance With No Retract to 10.


    5 - Reduce infill density, 70% is OTT for gyroid.


    Hope this helps!



  • Link to post
    Share on other sites

    Posted · printing round things without constant reversals of travel direction

    Thank you very much ! I am currently 8 hrs into a version of this print with a much reduced print speed of 30 mm/sec. It has another 16 hours to go 😞

    It is printing a bit cleaner with less burnt bits (I am printing in white) but with just as many blobs. Stringing is reduced slightly.

    The other change I made was to increase flow to 95% from 85% because 85% was just too porous. Oh, I also went from a 0.4 mm line width to 0.35 mm.

    I am looking forward to trying the settings you recommended !

  • Link to post
    Share on other sites

    Posted · printing round things without constant reversals of travel direction

    Started a new print job a while ago. I have about 2-3 mm down at the moment and I am seeing a LOT of improvement as far as stringing is concerned. I now see a couple or three reversals in a layer when it goes from inner wall to outer wall but there is no more of that frequent reversal issue. There seems to be no obvious improvement re brown bits in the print but I would imagine that with the stringing issue so improved, I will see less brown bits overall.

    I reduced infill to 50%.

    Of course I will not see the overall result until tomorrow (17 hrs estimated) but things are looking very promising - THANK YOU !

  • Link to post
    Share on other sites

    Posted · printing round things without constant reversals of travel direction

    The print with the new parameters is fantastic! ZERO,NONE, NADA stringing ! The only minor problem occurs when a new layer is started and the filament laid down is not a continuous string but seems a bit interrupted. In the following pass the printhead nozzle will connect with the tops of the previous bumps and iron them causing bumps of white and burnt filament on the inside of the pipe within an inch of the z move to start the new layer.

    This is easily sorted in the finishing stages so it isn't a big problem.


    Again, thank you for your help!

  • 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
        • 26 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...