“Accuracy” refers to the degree to which the actual manufactured part matches the original design dimensions and shape; it is a measure of precision. Because 3D printers rely on multiple moving parts, this process cannot produce parts that are 100% accurate (no manufacturing process can). Accuracy is typically expressed as a percentage or in millimeters, such as ±1% or ±0.5 mm. Different 3D printing technologies have varying levels of accuracy. What factors affect the accuracy of 3D printers, and how can they be addressed?
　　1. The 3D Printer’s Intrinsic Precision
　　When purchasing a 3D printer, it is essential to first understand the machine’s printing precision. The manufacturing and assembly precision of the 3D printer, as well as vibrations during operation, will affect 3D printing accuracy. The precision of a 3D printer depends on whether the moving parts within the mechanical system are accurate and properly calibrated.
　　2. Nozzle Diameter
　　The diameter of the nozzle also determines the width of the extruded filament, which affects the precision of the final product. As we all know, 3D printing constructs objects by layering material. Therefore, the layer thickness setting also affects the surface finish of the final product: using a nozzle with a larger diameter results in thicker layers; while this speeds up the printing process, the finished product will be rougher. Conversely, using a nozzle with a smaller diameter increases the printing time but yields a more refined finish. Nozzle diameters are generally limited to three options: 0.2 mm, 0.3 mm, or 0.4 mm. The reason they cannot be made smaller is due to the non-Newtonian flow properties of the filament; a diameter that is too small would result in excessive flow resistance.
　　3. Material Type
　　The glossiness of the final printed model varies significantly depending on the type of material used or the quality of the same material. Users must select the most suitable material to ensure their 3D printer produces the most perfect models.

 
　　4. Nozzle Temperature
　　Nozzle temperature determines the material’s adhesion, layering, filament flow, and extrusion width. Therefore, the nozzle temperature should not be too low or too high. If the temperature is too low, the material’s viscosity increases, slowing down the extrusion speed; if it is too high, the material becomes more liquid, reducing its viscosity and increasing its flowability, causing the extrusion to be too fast to form precise, controllable filaments. Therefore, when setting the nozzle temperature, it should be selected within a certain range based on the characteristics of the chosen filament to ensure that the extruded filament remains in a molten, flowing state.
　　5. Layer Thickness
　　The layer thickness here refers to the height of each layer during slicing. Since each layer has a certain thickness, it creates noticeable step marks on the surface of the finished object (the higher the layer thickness, the more pronounced the marks), which directly affects the dimensional accuracy and surface roughness of the final part. For the FDM process, this is an inherent limitation; it is impossible to completely eliminate these step marks, but their effect can be minimized by setting a smaller layer thickness.