Jump to content

Shell thickness


Recommended Posts

Posted · Shell thickness


I've noticed that the shell thickness is done in a way that allow for compression a bit if you have a thickness of a little less than twice the nozzle size but wont allow it if you go above double the nozzle size.

I like to set the shell thickness to 0.7mm because it cause the inner and outer shell to overlap a bit and gives good adhesion depending on the material. I had cases where faster print would leave a gap between inner and outer shell and increased case of separation on some parts. I could have been printing at too low temp for the speed of print... Ninja flex is another case I like to overlap inner and outer shell.

So I was wondering if in the future versions of Cura there could be a way to specify the number of lines the shell should have and the overlap percentage (like the current infill). This way you could tell to print with 3 lines that have 15% overlap.

I want to start playing a bit more with shell thickness especially for translucent material that I would not want to have 100% infill but would want to have the same feeling.


  • Link to post
    Share on other sites

    Posted · Shell thickness

    They don't truly overlap - it's more complicated.

    I believe it will print from 75% to 150% of nozzle diameter so for .4mm nozzle that's .3mm to .6mm per pass. If you ask for a shell that is .7mm it does two .35mm passes. That means it positions the nozzle .35/2 mm (.175mm) inwards from the final finished edge and puts consecutive passes .35mm apart. Another way to think of this is that cura treats your nozzle as though it is a .35mm nozzle and extrudes only what a .35mm nozzle needs (underextrusion) and puts two passes .35 apart just like you would do with a .35mm nozzle. Even though in reality you have a .4mm nozzle.

    I can see how this would improve adhesion between the 2 shells but you might be better off just increasing the flow by 10% or so. Or fix the belts to remove any backlash or play. Or print slower or hotter because maybe you don't have backlash but instead have underextrusion (too much pressure in the nozzle - plastic can't get out fast enough).

    I always (almost always) set shell width to a multiple of nozzle diameter (e.g. .4, .8, 1.2, 1.6) as I get much better results that way (in my opinion). The only exception is for thin walls such as when I do text in which case I will often do .3mm shell. This comes out much better. I often simultaneously set the flow to 133%. But this is a special case.


  • Link to post
    Share on other sites

    Posted · Shell thickness

    I'm trying a print right now that uses 0 infill and 2mm shell. So far its doing great. I'll have to run the test again for this specific need cause this print is in wood fill and is set to flow at 130%. At least its the first time it doesnt clog at all :)

    I'm happy to see that you also boost the flow... I'm always having the impression its more a hack to counter real issues

  • 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
        • 56 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
        • 29 replies
    • Create New...