3D Printer Filament: Filament Diameter and Spool Dimensions

3D printer filament is just like the lifeblood of your creation. The filament comes as a continuous, slender plastic thread neatly wound onto a spool. When selecting filament, you’ll encounter two size specifications: filament diameter and spool dimensions. While filament diameter is a critical factor directly impacting print success, spool dimensions are generally less critical and primarily relate to physical compatibility with your printer. 

This guide will clarify both specifications, focusing on the essential importance of filament diameter and the more practical considerations of spool dimensions.

Understanding Filament Diameter: 1.75 mm vs. 2.85 mm

It is the thickness of the plastic string that your 3D printer melts and extrudes to build your 3D printed object. It is typically expressed in millimeters (mm). This measurement is critical because 3D printers are designed to work with a specific filament diameter, and using the correct size ensures proper feeding and extrusion during the printing process.

Filament comes in two main diameters. 

• 1.75 mm: This is the popular choice for desktop 3D printers, compatible with a wide range of materials. It offers a good balance of detail and potentially faster speeds. While excellent for intricate prints, it can be slightly more prone to buckling in some Bowden setups.
• 2.85 mm (or sometimes called 3 mm): This is less common for desktop printers but is still used, particularly in some older or industrial-style machines. It offers robustness and can be easily handled, particularly with flexible filaments. However, it generally provides less detail and may have fewer material options.

Is a 1.75 or 2.85 filament better? Neither is definitively “better” overall. However, 1.75mm filament is generally the preferred choice for most users. It’s more versatile, widely supported, and capable of excellent print quality. Unless you have a specific need for 2.85mm, such as primarily printing very soft, flexible materials or if your printer is specifically designed for it, 1.75mm filament is usually the better all-around option. 

Does filament diameter matter?

Filament diameter directly impacts the quality and success of the print. Using the wrong diameter filament is a recipe for printing failures and potential printer damage:

Printer Compatibility

This is the most critical dimension for printer compatibility. 3D printers are designed to work with a specific filament diameter. If you use the wrong diameter, it can lead to serious problems:

• Clogging: Using too thick filament for your printer’s hot end and nozzle can cause jams and blockages.
• Extrusion Issues: Using too thin filament can cause inconsistent extrusion, under-extrusion (not enough plastic being pushed out), and poor print quality.
• Damage to Extruder: Forcing the wrong diameter filament can potentially damage the extruder mechanism.

Print Quality

The filament diameter is directly related to the precision and detail your printer can achieve.

• Detail: 1.75 mm filament is favored for finer details due to its responsiveness. 2.85 mm can be less precise for intricate designs.
• Flexibility: 1.75 mm filament’s flexibility aids in intricate prints but can be slightly more prone to buckling in Bowden systems. 2.85 mm’s stiffness can be advantageous for very flexible materials.
• Speed & Flow: 1.75 mm filament may achieve higher volumetric flow rates, potentially enabling faster printing.

3D Printer Filament Spool Dimensions

What are the dimensions of a spool of filament? Beyond filament diameter, spool dimensions are also important for physical compatibility with your 3D printer. While not standardized, spools generally adhere to common sizes, especially for standard 1kg spools.

Common Dimensions for 1kg Spools:

• Outer Diameter (Flange Diameter): Around 200mm (7.87″ – 7.93″). Needs to fit within your 3D printer’s spool holder or enclosure.
• Inner Diameter (Arbor Hole or Center Inside Diameter): Roughly 52mm – 58mm (2.05″ – 2.28″). This is the size of the hole in the center of the spool. It needs to be compatible with your printer’s spool holder arm or spindle. 52mm is a very common inner diameter.
• Spool Depth (Outside Width): Approximately 50mm – 70mm (2″ – 2.75″). The spool needs to fit in the width of your printer’s spool holder.

Key Considerations for Spool Dimensions:

• Physical Fit: Ensure the spool’s outer diameter and width are compatible with your printer’s spool holder.
• Smooth Unwinding: Standard spool dimensions promote smooth filament unwinding during printing.
• Accessory Compatibility: When considering spool dimensions, it’s also worth noting accessories that can enhance your 3D printing workflow. For example, the Snapmaker SnapDryer is a filament dryer that works with both 1.75mm and 2.85mm filament diameters. It’s built to accommodate spools up to 205 mm in diameter and 78 mm in thickness. This compatibility with standard spool sizes makes it versatile for most users, but also illustrates why dimensions matter when investing in specialized equipment.

Takeaways

• Filament Diameter (1.75 mm or 2.85 mm) = Thickness of the plastic string. This is crucial for your printer’s extrusion settings.
• Spool Diameter (around 200 mm) = Size of the reel that holds the filament. This is crucial for physical compatibility with your printer’s spool holder.
• Always buy the correct filament diameter (1.75 mm or 2.85 mm) specified for your 3D printer. Double-check your printer’s manual and filament packaging.
• For spool diameter, generally, standard 1kg spools will work with most desktop printers. Be more mindful of spool dimensions if you are using very large or unusual spools.