Dimensional accuracy and tolerance: However, from the more colloquial definition of ‘precision’ which means to be accurate and exact, the precision of 3D printed parts can also refer to the level of accuracy and detail that can be achieved in the printed object. How closely can the printed object match the intended design or dimensions of your digital file? Higher precision means the printed object is closer to the desired specifications.
One way to measure dimensional accuracy is through tolerance — which refers to the acceptable degree of variation or deviation from the intended dimensions or specifications of a printed object. It represents the allowable margin of error or the range within which the printed object can deviate from the intended design while still being considered acceptable.
Precision of a 3D printer machine: Another way to measure precision in 3D printing is through that of the machine itself. When discussing the precision of a machine itself rather than its output, the word isn’t so much a specific measure; rather a combination of the machine’s ability to print with accuracy, repeatability, and with high resolution: essentially, how exacting the machine can be in its ability to print parts.
Consider painting as an analogy — while throwing around a wide brush with fast, indiscriminate strokes is more efficient for covering area, a fine-tipped paint brush wielded by the hand of a trained artist can add a much higher level of detail.
Whether a 3D printer is broad or a fine-tipped brush largely depends on two variables of the 3D printer’s anatomy. A 3D printer includes 1.) a tool tip such as a nozzle, laser, or cutter; and 2.) a motion control system that maneuvers the tool tip across the axes.
If you are printing on two identical machines, but one with a nozzle size of 0.4mm wide, and one with a 0.25mm wide nozzle, the machine with a 0.25mm nozzle would be considered more precise. Given identical nozzle sizes, a machine with a motion control system that can operate in smaller increments of movement across the X, Y, and Z axes is considered more precise. For an overview of the role of 3D printing, read our article on how 3D printers work.