What Is a Slicer? How 3D Printing Software Works

A slicer is software that turns a 3D model into the step-by-step instructions a 3D printer follows. It cuts the model into thin horizontal layers, then works out where the nozzle should move, how much plastic to push out and how hot everything should be. This page is desk research from the slicer makers' documentation and Wikipedia, not a test of the programs.

What a slicer does

Wikipedia defines a slicer as toolpath generation software that converts a model, typically an STL file, into printer commands in G-code format. The slicer first divides the object into a stack of flat layers. It then describes each layer as a series of linear movements of the extruder, plus commands such as nozzle and bed temperature. All of this ends up in one G-code file that is sent or copied to the printer.

In short, the printer cannot read a model file directly. The slicer is the translator between your design and the machine.

The basic workflow

1. Choose a printer profile. The slicer needs your printer, nozzle size and filament so it knows the build volume and limits.
2. Import a model. Bambu Studio lists .3mf, .stl, .stp, .step, .amf and .obj as supported files, and OrcaSlicer lists 3MF, STEP, STL, SVG, OBJ and AMF. Our page on STL, 3MF and G-code explains the formats.
3. Pick settings. Layer height, infill, supports and adhesion are the main ones.
4. Slice. The software generates the layers and the G-code, and shows a preview with an estimated print time.
5. Send or save. You send the file to the printer over the network or copy it on a card or drive, depending on the printer.

For a full walk-through from model to finished part, see how to 3D print.

Settings that matter most

Layer height

Layer height is the thickness of each layer. OrcaSlicer's documentation says smaller layer heights give smoother surfaces, less visible layer lines and better detail on curves, but increase print time. It gives a typical working range of 20% to 80% of the nozzle diameter, which is 0.08 mm to 0.32 mm for a 0.4 mm nozzle. Bambu Lab's wiki notes that for most prints 0.20 mm is the norm. See layer height explained.

Infill

Wikipedia explains that slicers convert solid volumes into hollow ones with internal structures, and the proportion is the infill density. In Cura's generic definition the default infill density is 20%, though printer profiles change this. Read more in infill explained.

Supports

Overhangs cannot be printed in mid-air, so slicers can generate supports. Wikipedia names two main types: the standard lattice in a zig-zag pattern, and tree supports, which grow from a trunk and are considered easier to remove and lighter on filament. Cura describes the same two as "Normal" and "Tree". Details are in supports explained.

Skirt, brim and raft

These help the first layer. Wikipedia defines a skirt as a band around the base that does not touch the object, a brim as extra lines touching the base, and a raft as several layers printed underneath. Cura's generic definition lists skirt, brim, raft and none as adhesion types. See brim vs raft vs skirt.

Presets, profiles and beginner modes

Modern slicers group hundreds of settings into presets. Bambu Studio splits them into three categories: printer, filament and process. Printer presets hold hardware details like the nozzle diameter, filament presets hold temperatures and flow ratio, and process presets hold job settings such as layer height and support. Its documentation says system presets cannot be edited directly, but you can copy one and save your changes as a user preset.

To keep things manageable, OrcaSlicer has four option modes: Simple, Advanced, Expert and Developer, and describes Simple as ideal for beginners. Cura offers a Recommended view with a smaller set of controls such as strength, support and adhesion, and a Custom view with the full list.

Popular slicers

All four are free to download. Printer makers also ship their own forks, such as Creality Print and Elegoo's slicer, and Wikipedia lists many more. Our Cura vs Orca vs PrusaSlicer comparison helps with choosing, and there are beginner guides for Cura, Orca Slicer and Bambu Studio.

Common beginner mistakes

• Wrong printer or nozzle profile. The G-code assumes the build volume and nozzle you selected, so a mismatch gives bad results or failed prints.
• Wrong filament preset. Temperatures and flow come from the filament preset, so pick the right material.
• Changing many settings at once. Bambu Lab's wiki warns beginners not to change parameters randomly. Change one setting, then compare.
• Ignoring the preview. The layer preview shows missing supports and odd paths before any filament is used.

If a print goes wrong, many problems trace back to slicer settings. Our guide to a bad first layer is a good first stop.