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Here Are the Best Slic3r Settings for PLA

Slic3r is a program that prepares digital 3D models for printing by converting a CAD file into a G-code file. Typically, this program comes with basic settings, but if you’re starting on your 3D printing journey, you’ll want to use the appropriate settings for your specific needs. For example, if you’re using PLA, you must first identify the best Slic3r settings for PLA.

Here are the best Slic3r settings for PLA:

  1. Temperature Range: 374-428 °F (190-220 °C).
  2. Print Speed: 30-90 mm/s.
  3. Infill Density: 10-60%.
  4. Step over Multiplier: 1.0.
  5. Layer height: 0.2 mm for a 0.4 mm nozzle.
  6. External Fill Pattern: Triangular.
  7. Solid Surface Thickness: 0.8-2.0 mm.
  8. Retraction Distance: 0.5-1 mm.
  9. Skirt, Brim, and Raft: Enabled.
  10. Number of Shells: 3.

Read on for a closer look at these settings and what happens when you alter them.

1. Temperature Range: 374-428 °F (190-220 °C)

The first crucial Slic3r setting for PLA is the temperature range. Temperature is critical since all filaments melt at different temps. 

Too hot, and you get burnt ooze, too cold, and you’ll jam up the extruder. In addition, if your print temps are too high, the print may shrink as it cools, causing warping. 

In a nutshell, here are two tell-tale signs that you’re using the wrong temperature range for PLA:

  • Prints are brittle and have rough layer lines or artifacts. This happens when the temperature is too low.
  • Prints are curling, bubbling, and have no adhesion between layers. This occurs with too high of a temperature.

The temperature range of 374 to 428 °F (190 to 220 °C) is just enough to melt PLA, but not so much that it’ll warp and shrink.

Also, the mentioned temperature range gives exceptional layer adhesion. It also prevents layer distortion and creates an excellent finish.

2. Print Speed: 30-90mm/s

Once you’ve set the recommended temperature range, it’s best to check the print speed. In general, a higher print speed is necessary when printing larger parts or objects with a fine, smoother finish.

In contrast, a lower print speed is ideal when printing small objects with intricate details or textures. 

The range of 30 to 90mm/s works well for most PLA 3D prints and gives you the flexibility to choose the right setting for your specific needs.

If you want to switch it up, just remember that a lower print speed means more time in the printer, while a higher print speed reduces the total printing time.

3. Infill Density: 10-60%

The infill density is another Slic3r setting you must take into consideration. 

In general, it’s best for this setting to range from 10 to 60% when printing with PLA. 

For example, the 10% infill density is good for non-functional components, while 20% will be better if the object needs more strength. As for the 60% infill density, it’s great for parts subject to heavy loads.

Here are additional guidelines on the external fill density:

  • 10%: Supports slow printing on a high-quality machine with a capable cooling system to prevent ABS warping and oozing of plastic.
  • 40%: This moderate percentage is a great starting point for beginners since it’s straightforward to fine-tune.
  • 80%: This setting is appropriate for objects printed on a high-end machine with active cooling and excellent layer adhesion between the outer shell and infill.
  • > 80%: This setting is best for quality parts that require extreme mechanical strength or are perfect for ABS that requires high inner shell density. However, keep in mind that elements with a high external fill density need extended heating and cooling time to prevent warping.

Pro Tip: Stick to lower infill densities when printing small objects with thin grid lines since higher fill densities tend to fill in these spaces and cause rough surfaces.

4. Step Over Multiplier: 1.0

The step over multiplier helps reduce print artifacts like ringing or z-banding when printing complex objects with thin walls. 

This setting is best if your object requires excessive retractions or uses a lot of travel moves. On the other hand, if you just want to prototype your design quickly, you might not need to change the default setting.

5. Layer Height: 0.2mm for a 0.4mm Nozzle.

Another crucial Slic3r setting for PLA is the layer height. 

To achieve good quality 3D prints, you should have a reliable knowledge of your printer and its limitations. For example, if you’re printing with an 0.4mm nozzle, the recommended layer height should be 0.2mm. Still, every nozzle size is better for different layer heights, so be sure to look up the specs for your nozzle size.

6. External Fill Pattern: Triangular

It is best to use a triangular external fill pattern when printing with PLA. This setting is ideal since it generates less stress on the printed object, producing more uniform layers and preventing defects like cracking or warping.

However, if you want to change this setting, you can also get good results with rectangular and hexagonal external fill patterns. Rectangular prints work well with a low external fill density, while hexagonal patterns are better for high-density infill areas.

7. Solid Surface Thickness: 0.8-2.0 mm

The solid surface thickness also dramatically affects your 3D print’s quality. 

In this case, the recommended range is 0.8 to 2.0 mm. You can also adjust this setting to your needs since it gives you a good balance between mechanical strength and bed adhesion.

If you want to play it safe, use a greater solid surface thickness, which will give you better part strength and print bed adhesion. The thicker the solid surface is, the faster your print finishes. 

8. Retraction Distance: 0.5-1 mm

Setting the retraction distance is also crucial for preventing defects during printing. If you want clean, bubble-free PLA 3D prints with no stringing and artifacts, then make sure to set this setting between 0.5 to 1 mm.

Pro Tip: A good starting point for beginners is 0.8mm since it gives a wide range of motion and prevents plastic from oozing, even with complex geometries.

9. Skirt, Brim, and Raft: Enabled

You should enable skirt, brim, and raft settings to boost your print’s outer shell quality. These will create an initial outline or base for your 3D prints before starting the job, preventing warping or toppling mid-print. 

Here’s an excellent primer on how to modify the skirt, brim, and raft settings in Slice3r:

10. Number of Shells: 3

Slic3r also provides several shell options so you can enhance the mechanical strength of your print’s outer shell. 

In general, the recommended setting for PLA prints is three shells since it gives a good balance between strength and print time. In addition, it’s perfect for printing solid or heavy objects with small dimensions while preventing warping.