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 5.7 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
        • 7 replies
      • S-Line Firmware 8.3.0 was released Nov. 20th on the "Latest" firmware branch.
        (Sorry, was out of office when this released)

        This update is for...
        All UltiMaker S series  
        New features
        Temperature status. During print preparation, the temperatures of the print cores and build plate will be shown on the display. This gives a better indication of the progress and remaining wait time. Save log files in paused state. It is now possible to save the printer's log files to USB if the currently active print job is paused. Previously, the Dump logs to USB option was only enabled if the printer was in idle state. Confirm print removal via Digital Factory. If the printer is connected to the Digital Factory, it is now possible to confirm the removal of a previous print job via the Digital Factory interface. This is useful in situations where the build plate is clear, but the operator forgot to select Confirm removal on the printer’s display. Visit this page for more information about this feature.
          • Like
        • 0 replies
    • Create New...