To improve 3D print dimensional accuracy, calibrate flow and motion, compensate for material shrinkage, choose a precise process, and design fits with the right clearances. Desktop printers can be tuned to a point; for guaranteed ±50 µm, an industrial process with inspection is the reliable route. Here is how to tighten accuracy.
Key Takeaways
- Calibrate extrusion (flow), motion (steps/mm), and shrinkage compensation.
- Holes print undersized; bosses oversize — design or drill to compensate.
- Process matters: SLA & DMLS hold tighter tolerances than FDM.
- Temperature and material shrinkage drive most dimensional error.
- For verified tolerances, use inspection (CMM/optical).
What causes dimensional error?
Over- or under-extrusion changes wall and feature sizes; uncalibrated motion skews dimensions; and thermal shrinkage pulls parts smaller as they cool. Holes tend to come out undersized due to inward pull, while outer dimensions can run slightly large. Knowing the direction of error lets you compensate.
How do you tighten accuracy?
| Lever | Action |
|---|---|
| Flow calibration | Tune extrusion multiplier |
| Motion calibration | Set steps/mm accurately |
| Shrinkage comp. | Scale for material |
| Hole compensation | Oversize or ream holes |
| Process choice | SLA/DMLS for tight tol. |
Design fits for the real tolerance
Add clearance for moving fits and the right interference for press fits — see assembly design. Know your process''s achievable tolerance from the tolerances guide, and design to it.
When you need guaranteed accuracy
For parts that must hit a drawing, Layer X holds ±50 µm on critical features and verifies with CMM/optical inspection — see dimensional inspection. Send a toleranced part.
Frequently Asked Questions
Why are my holes always too small?
Inward thermal pull and over-extrusion shrink holes — oversize the CAD or ream after printing.
Which process is most accurate?
SLA and DMLS (±0.05–0.1 mm) beat standard FDM. See the tolerances guide.