What are shells and how to create them?

[spooner777 0]

Are shells the walls on each side that get this zick zack infill? I read "You need at least 5 shells.". What does this meand and how do you make more with cura?

[Daid 306]

"Shells" referrer to the amount of outer lines the printer makes. 5 shells is a LOT, and saying "you need X shells" actually means that you need a certain wall thickness, as the width of each shell depends on your printer (0.4mm for a default UM, but 0.5mm for most RepRaps)

So if something says you need a lot of shells, you need to configure Cura to make a thicker wall.

[jcosmo 5]

On that note, wih particular reference to Cura, what options have I got for controlling the number of shells?

The nozzle diameter is 0.4 mm, but it can print thinner, though I gather less than 0.3 is considered problematic?

I can fiddle with wall thickness, which has an effect in the number of shells, thus should I be setting my wall thicknesses to multiples of 0.4? What happens when I set it to 1 mm? Do I get 2 shells and a bit of fill? Or is Cura smart enough to do two shells of 5mm?

I've tried KISSlicer and it produced very nice edges - it allows you yo specify the number of shells - but I much prefer the infill and support settings in Cura

[Daid 306]

If you use 1.0mm walls with a 0.4mm nozzle, it will put down 2 lines of 0.5mm. Cura is pretty smart in that aspect.

[rewolff 0]

I have a test-object where we print 0.2 mm through 1.6 mm cylinders with 0.2 steps. The 1mm one always comes out more or less as two separate cylinders, an inner one and an outer one.

[adhome 0]

If you must print cylinder it's lite tricky. You must experimaent with the settings and see the slicer result in Cura (without printing it). Only view the 3D Model how it "will" print it.

Change you nozle size to 0.2 and low Shell size. This will make fill the inner side and not only the 2 walls.

[jcosmo 5]

I have not tried changing the nozzle size in Cura. Is it something that should be fiddled with, or should it always be set to the size of the real nozzle?

[Daid 306]

You'll get the best results if you leave it at the real nozzle size, but some people like to experiment with it. If you lower it, then Cura will try to put down thinner lines, which is hard. If you increase it cura will put down thicker lines, which will put more pressure on your nozzle.