3D Slicer Software: How it Works and What to Expect

3D printing processes aren’t quite as simple as throwing a 3D model into a printer and expecting the object to magically appear. That is to say, there is a required process called slicing sitting between the CAD model and the physical object. Thankfully there are software programs specifically made for this: The slicers.

What Is A Slicer And Why Do We Need It?

3D Printing, as with any skill, is a process learned through the mastery of a tool and experience.

A slicer tells the printer everything it needs to know to print an object in the best possible way. We call it a “Slicer” because of its main function: dividing the model into individual material layers throughout the z-axis or “slices”. The 3D Printer does not receive a geometric file (Commonly STL), but a gcode. A gcode is a detailed command list readable by a printer to optimize everything it needs during the process.

As you get more experienced with slicing, you’ll see there’s a set of other parameters that impact drastically the final result.

Slicing Process

Any process must have an input and end with an output. For a slicer, the 3D model and the manufacturing requirements are the input and the gcode file is the output. The following are the typical steps for slicing a model.

1. Setup printer settings: The slicer needs all the information regarding the printer’s limitations. If this isn’t correctly set from the beginning, the gcode will send commands impossible for the printer to handle. Additionally, there are more settings regarding the extruder type and the material specifications.
2. Import model: Once the printer data is set, you need to import the model you’ll work with. All slicers read STL, but other files like OBJ, 3DF and AMF are becoming more accepted every year.
3. Arrange model: A slicer interface allows control over the position of the part and its contact with the printer bed. There are also scaling and alignment options.
4. Setup commands: Here’s the most important step for slicers. Every printing parameter is set. Further down in this post we’ll get deeper into it.
5. Slice and preview layers: With everything set, the slicer is ready to calculate and cut the part into layers. Here you can preview the resulting elements and how they will be applied in real life. Most slicers calculate an estimation for printing time and material quantity to use.
6. Export: After checking and making sure everything is ok, you can create and save your file. Every slicer has the option to generate a gcode. Depending on which software you use, there are alternative file options.

Main Interface Properties

There are 3 key interface sections: The graphics area, a slicing settings panel, and some general settings.

Graphic Area Elements

Slicers offer a 3D graphics area where you can visualize how the model transforms into a layered representation. Every slicer has its unique interface style, but there are common elements to consider:

• Printing bed plane: It represents the shape and dimensions of the real bed. Here you can visualize a comparison between the object and the space provided by the printer. With this, you have a graphical representation for:
  • Coordinate systems.
  • Model orientation, scale and position relative to the bed.
  • How the model adheres to the bed.
  • If you are printing multiple objects, you can check how they’ll arrange.
• Visualization and camera control: Through icon bars and mouse/keyboard controls.
• Model positioning controls: Same as the previous point.
• Layer preview: Once the parameters are ready, the interface lets you scroll through each layer. It allows you to check how the material would be distributed within. The following are the main types of distributions:
  • Shell: The external lines that define the shape of the object.
  • Outer wall: The material line that defines the surface of the shape.
  • Inner walls: The material lines that define the shell thickness.
  • Infill: Fixes density percentage inside the object. There are many possible patterns to distribute the material within the hollow space.
  • Supports: Structures made for overhangs. We need them to avoid layers collapsing during the printing process if their overhang. You can generate them automatically or manage manually for better control over the result.
• Adhesion layers: Sometimes an object has poor contact area with the bed, considering it needs to stick well during the printing process. There are many more factors that could affect adhesion, like part height, bed surface rugosity, type of material and printing speed. Regardless of the case, slicers offer the following structures as a solution for this.
  • Raft: A thick plate between the part and the printing bed.
  • Brim: Extra lines of material around the first layer, allowing a wider contact area.
  • Skirt: A single line around the part. It allows testing material flow and bed leveling before starting with the part itself.

Slicing Settings Panel

Here is where you really control what the printer will do, through specific settings and commands. This marks the difference between the beginner and an experienced user. Depending on which slicer you use, this could either be an easy task with suggested default settings, basic and approachable settings or a highly complex set of manual options. Every software has its own criteria, but the following are key concepts:

• Layer height: The most important setting. Defines how thick each layer is and whether the object will be strong or weak, print faster or slower. This is also fundamental for resolution quality. It should be clear that almost all other settings will depend on layer height.
• Line width: It refers to the horizontal thickness of each extruded line.
• Shell thickness: Higher thickness allows a stronger and better surface finish at the expense of using more material.
• Top and Bottom thickness: Quantity of solid layers for the top and bottom sides of your model.
• Infill settings: Defines the inner material density percentage and how is patterned. Each pattern is a strategy for adding material depending on design intent like material saving, weight, stiffness and printing efficiency.
• Extruder temperature: Defines how the plastic flowing through the nozzle will behave. Depending on which material you use, there will be a temperature range to work with. Conveniently, the product you bought should have a technical sheet for thermic properties.
• Print speed: How fast the model will print. Yes, you get a quicker result, but you’ll lose quality and the process will be more prone to error.
• Cooling settings: Affects how the cooling fan will work during the process. Setting decisions are based mainly on material properties.
• Support settings: Criteria vary from software to software. Regardless, all slicers will generate automatic supports where needed. Major manual settings are minimum overhang angle and some other settings for specifying areas you want to protect from scaring.
• Adhesion structure settings: Here you define how you want to apply rafts, brims and skirts.

File And General Settings

They are primary options for managing imports and exports, view settings, toggle printer settings, help tab, extensions, undo and redo options. It varies from software to software but it’s important to learn it.

Major Slicers

The following are some slicer programs you should try. In most cases, it is better to stick with the slicer software made for your printer:

• Ultimaker Cura (Free)
• Simplify3D (Paid)
• Markforged Eiger (free)
• PrusaSlicer (Free)
• Sli3er (Free)
• KISSlicer (Free basic version, paid professional version)
• OctoPrint (Free)
• Repetier (Free)
• ideaMaker (Free)
• Makerbot Desktop (Free)

If you have any questions about how slicers work, or what might be the best slicer for you, please get in touch with the Solid Print3D team on 01926 333 777 or info@solidprint3d.co.uk