Why Lightning Infill in Ultimaker Cura is the Best Secret Setting Ever

3D printing can be a bit of an overwhelming experience for the new enthusiast. There are dozens of new terms, a spiky learning curve, and at least a couple of meaty programs that you’re going to need to learn before you can make it very far. And, while temperature might be the most difficult to pin down at first, it’s really the problem of infill and supports that stumps the average newbie.

Infill is exactly what it sounds like, though: something that fills something else in.

For most models of any reasonable size, there needs to be some sort of interior support to keep the middle of the model from sagging under its own weight.

Now, when you print a model you could print it solid (which would mean that you’re printing just one large piece of plastic), but if you do print a solid model you’re going to use a massive amount of filament and your prints are going to take a long time. That’s why, most of the time, people print using one of the infill settings available in their Slicer program.

Infill comes in two important categories: density and pattern. Density is just how much plastic you want sitting, hidden, inside your model. Pattern is just the setting for what shape that hidden plastic takes. There are various benefits to different types of infill, from strength to printing speed, but the gist is that all of them use a lot of plastic to create some type of interior structure that supports your 3D print from the inside-out.

But using infill, even on lower settings, still takes a massive amount of plastic filament to print, and even the fastest options for infill patterns are going to add an increasing degree of time to your prints (after all, your printer has to spend a lot of time printing those internal support structures, which can quickly take up for material and time than the outer shell that you actually care about!).

Lightning infill in the Ultimaker Cura settings offers a whole new approach to producing infill. Instead of building geometric shapes, layer by layer, inside your 3D print, Lightning produces a branching support network, like a “tree” inside the model, that specifically supports only those areas in danger of otherwise sagging.

What’s so exciting about this type of 3D print is that it offers you a way to print using far less material than any other infill setting, while also allowing you to massively speed up your printing time (especially with larger prints).

The biggest problem you’ll encounter using this infill type is that it produces fundamentally weaker prints because there’s simply less internal structure. The “tree” that this method creates provides support for printing, but not much practical support for anything else. That makes this method perfect for any sort of ornamental prints, as well as for proof-of-concept prints that don’t need to take much banging about.

Don’t use the Lightning infill method if you’re trying to create a piece of cosplay armor that’s going to get carted to all the conventions, but feel free to use it for everything else.

The Lightning infill setting is buried in the Infill Pattern selection box within Ultimaker Cura.

From within Cura, select “Print Settings”.

This will bring up your full settings window.

Type in “Infill” into the “Search Settings” bar

It’s a bit faster than scrolling through manually.

Change the Infill Pattern to Lightning

Just click the dropdown menu and select “Lightning”.

Change the density to 30%

Sometimes, the Slicer will hang on larger infill percentages, but going under 30% runs the risk of not creating good supports for your print. Play around with this setting on smaller models to determine the perfect percentage for your printer, model, and filament type. I've had perfectly fine prints with as low as 15%, but I took into account the whole structure of the project before deciding to go that low. Lightning won't be ideal for every print!

See this setting in action in my 3D printed DIY book cradle project!