Reading 3D Printing Specs: Accuracy, Layer, Spot, Roughness

Reading the Four Numbers on a Spec Sheet

• Accuracy (tolerance): the stable dimensional deviation, usually XY better than Z. A stated ±0.1mm does not guarantee every feature, as geometry and supports matter.
• Layer height: single-layer thickness, typically 0.05–0.2mm. Smaller is finer with fewer stair steps, but print time multiplies.
• Spot / nozzle diameter: sets the smallest feature size and the origin of surface texture.
• Surface roughness Ra: proportional to layer height; post-processing (sanding, painting, plating) improves it but loses detail.

Trade-offs Between Parameters

Accuracy, layer height, speed and cost constrain each other: minimum layer height improves surface but doubles time; larger spot speeds up but loses detail. Engineer by deciding the single most critical metric (look, dimension or lead time) first, then derive the rest — not blindly maxing everything.

A Common Myth

“Accuracy ±0.05mm” is the machine’s capability ceiling, not a guarantee for your part. Orientation, support placement and post-processing all consume the accuracy budget.