How to Configure Slic3r on Your 3D Printer

By Kalani Kirk Hausman, Richard Horne

When Slic3r has been installed successfully, you can go about configuring it. Before an object can be sliced up into layers for 3D printing, Slic3r has to know a number of key settings for your particular 3D printer. You enter these settings in a configuration wizard that appears when you first start Slic3r.

Don’t worry — all these settings can be changed later if you need to change them after you use Slic3r. For now, just enter all the specified details you can. You can save different configurations later. This arrangement is useful when you’re running several different machines, testing upgrades, or trying different material types.

To configure Slic3r, follow these steps:

  1. In the wizard, select the particular style of G-code to use with the firmware you’ll be running on your RepRap 3D printer.

    This is usually RepRap (Marlin/Sprinter).

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  2. Enter the size of your printer’s build bed.

    • For a RepRap using a Prusa-style heated-bed of PCB material, enter a size of 200mm x 200mm.

    • A Delta printer has a rounder build area, which has to be considered when you’re printing objects, but you can still enter size as X and Y coordinates.

  3. Enter the size of the output nozzle on your 3D printer’s hot-end.

    Enter the size of your extruder nozzle; common sizes are 0.5mm, 0.4mm, and 0.35mm. Slic3r uses this information to help calculate the space necessary to extrude each layer so that each layer is bonded securely to the one beneath it. This setting serves as a guide for Slic3r; tuning the width and height of the extrusion path is a separate, independent part of the calibration process.

    The actual extruded width of the output also depends on many tiny aspects of the hot-end design. It’s common to have some die-swell from a small hole under pressure: The output filament expands from the nozzle as it exits. Print calibration, then, is important to prevent extruding plastic layers from extruding too close together or too far apart for your 3D models to look right and function correctly.

  4. Enter the filament diameter.

    Be sure to measure the diameter of your filament, get the best average, and enter that result as the filament diameter for Slic3r, preferably after you ponder the cautionary sidebar, “Check your filament carefully.”

    You can trust the information for diameter provided by your supplier, but it’s well worth taking the time to measure your material size, especially if you have different suppliers or different types of material. And note that the actual size of 3mm filament is often around 2.85mm this is normal; it allows the filament to be driven down tubes used in 3mm-diameter hot-ends and extruders.

    Newcomers to 3D printing who discover a lack of material or an over-extrusion on their printed objects often change the filament diameter setting to adjust the volume of material. It can work, but as a rule, don’t do it. Inaccurate extrusion often masks a bigger problem with extruder calibration or machine setup.

    These problems will manifest themselves as poor print quality, overextrusion of material giving poor results, and bad size tolerance for holes and apertures. And any fudge of settings will lead to inaccurate calculation of print time and material being used. Use an accurate measurement for filament diameter, and never adjust this number to tweak the volume of plastic being extruded.

  5. Continue with the Slic3r configuration wizard, setting up your extrusion temperatures, and selecting heated-bed temperature settings.

    The extrusion temperature of a thermoplastic, when used in 3D printing, has to be high enough to allow your extruder to push material consistently into the hot-end without stalling but not so high that the plastic gets runny and overheated, and starts to break down and smoke. For PLA, the temperature is around 200 degrees C; for ABS, around 240 degrees C.

    Printing temperatures usually need to be increased if you print significantly faster than “normal” or if you’re trying to print a tiny detailed object slowly.

  6. If your RepRap 3D printer has a heated-bed, enter a temperature value for the material you intend to print.

    Again, don’t worry if you plan to print different materials; you can set up multiple configurations in Slic3r later. As a guide, use 60 degrees Centigrade for PLA and 110 Degrees Centigrade for ABS. If you want to print without using a heated-bed, then leave this value set to 0.

    Almost every RepRap 3D printer needs to be tuned for specific printing temperatures. It’s fine to use other people’s suggestions as a guide, but exact locations of the temperature sensor and small variations in the electronics and firmware setup may give you a very different reading.