A Simplified Guide to Different FDM Infill Patterns for Beginners

Introduction: In 3D printing, infill is the inside design of a printed object. Instead of making it all solid, we use patterns inside to make it strong but not use too much material. It's like finding a balance between being strong and not wasting stuff. Different patterns help make things stronger or more flexible, depending on what we need for the print. Below is a summary of different infill types and their properties. 

Gyroid
The Gyroid is a really good infill for 3D printing. It supports the object well in all directions, and it's quick to print. It also saves material and looks nice. There are no overlapping layers. The unique shape lets you fill it with liquid like resin.

Cubic
This is an infill with paths that cross each other within one layer. It creates cubes oriented with one corner facing down. This way it makes numerous air pockets that might serve as heat insulation, or cause the object to float on water.

Adaptive Cubic Infill
The Adaptive cubic infill is like the cubic infill but smarter. It uses cubes with corners facing down, and the lines cross in one layer. Unlike simple cubic infill, this one adjusts automatically to be more or less dense based on how close it is to the edges. This is handy for big prints with lots of space inside. The top, bottom, and sides will have more support, but the middle will have less, saving time and material. It uses about 1/4 less material than the rectilinear infill.

Support Cubic Infill
This infill becomes denser as it gets closer to the top layer (only in the up-and-down direction). Its main job is to help the top layers while using as little material as possible. It doesn't make the model stronger. It uses the least material and takes the shortest time to print compared to other supported infills.

Rectilinear
Rectilinear is a simple infill pattern. It makes a grid by printing one layer in one direction, then the next layer turns 90°. This saves material and doesn't build up at crossings. It's one of the quickest infills to print. Compared to the Grid pattern, Rectilinear gives double support for top layers with the same amount of material. It's the only recommended infill for 100% infill printing.

Aligned Rectilinear
This infill has lines inside the model, like the outer support structures. It's like the previous type, saving time and using an average amount of material. It also avoids building up material at crossings. But be careful, if the lines in the infill are exactly the same as the first solid top layer, there might be issues with the top layers connecting properly.

Grid
This is a simple and quick infill type. Unlike rectilinear, it's printed in both directions (rotated by 90°) in each layer. This makes material collect where the paths cross. The grid infill is stronger and sticks layers together better than the rectilinear infill. But sometimes, it can make noise or even cause the print to fail if the nozzle goes over the crossings with too much material.

Triangles
This infill is like the grid infill, with paths crossing in one layer. But here, they're printed in three directions, making a triangle structure. It uses about the same material and time as the grid infill.

Stars
The Stars infill is made of triangles, but the paths are shifted to form six-pointed stars. Like before, the lines cross in one layer. It uses about the same material and time as the previous infill.

Line
The Line infill is different because its paths don't cross in one layer. The paths are like the rectilinear infill, but not parallel – they're printed at a slanted angle. This infill is similar to rectilinear in terms of printing time and material use.

Concentric
The concentric infill follows the model's outer lines and makes them smaller toward the center. Imagine a cylinder – it would create circles inside it. This is handy for see-through parts or flexible models like RC tires. The downside is that it takes more time to print, but it doesn't use more material than other infill patterns.

Honeycomb
This infill makes a grid with hexagons. It's great because it's strong and has good paths without crossings. But, it uses more material (about 25% more) and takes longer to print – up to twice as long as other options mentioned before.

3D Honeycomb
The 3D honeycomb makes columns with bigger and smaller squares and octagons. It changes thickness regularly. Like before, there are no crossing lines in one layer, but it makes small gaps between layers. It uses a bit more material and takes a bit longer to print compared to the regular honeycomb pattern.

Hilbert Curve
The Hilbert curve makes a maze inside the model in a rectangular shape. It looks different and can be filled with epoxy resin or liquid easily. Instead of many small "bubbles," it has a few large cavities. The downside is it takes more time to print, somewhere between honeycomb and rectilinear infills. The material used is about the same as rectilinear.

Archimedean Chords
This spiral-twisted infill makes it easy to fill with liquid. The simple shape saves material and time, compared to the rectilinear infill. Like the concentric infill, the Archimedean chords help the model be flexible if you print it with flexible filament.

Octagram Spiral
The Octagram spiral makes it easy to fill the object with liquid because it has larger compartments. It can also make certain models more flexible. Mostly, it's used for looks and supporting the top layer. It uses about the same material as Archimedean chords, but it takes a bit more time to print.

*****Model/Settings Used For Statistics: M3 Hex Nut, 98x112x32mm, 300µm, 5% infill. *****

This guide provides a simplified overview of various infill types for FDM 3D printing, highlighting their strengths, weaknesses, and unique characteristics. Choose the infill that best suits the project's requirements for optimal results.