Setting up infill: how much fill does your print need?
are explained briefly when you hover over or tap them.
Printed parts are almost never solid inside. Instead, the printer prints a lattice pattern that supports the outer walls and saves weight, material and time. This fill is called infill and is given as a percentage.
How much infill do you need?
| Use | Infill density | Note |
|---|---|---|
| Decoration, figures, vases | 5 to 15 % | enough for the top surface to close |
| Everyday parts, brackets | 15 to 25 % | good standard |
| Loaded functional parts | 30 to 50 % | together with more walls |
| Very heavily loaded parts | over 50 % | rarely worthwhile, see below |
More than 50 % usually adds little extra strength but costs a lot of time and material.
Walls are often more important than infill
A common misconception: more infill automatically makes a part stronger. In fact, the outer walls (perimeters) carry most of the load. A part with 4 walls and 20 % infill is often stronger than one with 2 walls and 50 % infill, and it prints faster.
Rule of thumb for functional parts: 3 to 4 walls, 4 to 5 top and bottom layers, 20 to 30 % infill.
Which pattern for what?
| Pattern | Properties | Good for |
|---|---|---|
| Grid | simple, fast | everyday parts |
| Gyroid | wavy, similarly strong in all directions, good for flexible materials | functional parts, TPU |
| Cubic | strong in all directions, fast | functional parts |
| Honeycomb | very strong, but slow | heavily loaded parts |
| Lightning | supports only the top surface, extremely material-saving | decoration, figures |
The names differ slightly depending on the slicer, but the patterns are similar everywhere.
Infill and surface
With very low infill the top surface can sag or develop holes, because the top layers have too little support. The remedy is more top layers or slightly denser infill. If the pattern shows through on the top surface, there are usually too few top layers.
Infill with flexible materials
With TPU, infill determines how soft a part is. Little infill makes it yielding, a lot of infill makes it firm. This lets you print different hardnesses from one material. More on this in Printing TPU.
Reinforcing selectively
Many slicers allow you to change infill and walls only in certain areas, for example around a screw hole. This function is often called “modifier” or “region settings”. This gives you strength where it is needed without making the whole part heavier.
Continue with: Layer height and Supports.