Bottom line: TPU prints can come out at the wrong size because of shrinkage, material compression, moisture, flow error and measurement method. Soft parts also deform during measurement, which makes readings unreliable. Fix flow and moisture first, then apply directional compensation.
Sources of error
| Source | Effect |
|---|---|
| Shrinkage | Part smaller than model |
| Compression | Distortion under contact |
| Moisture | Dimensional variation |
| Flow error | Over- or under-size |
| Measurement method | Inconsistent readings |
Method
- Print a calibration block.
- Measure X, Y and Z separately.
- Verify filament moisture.
- Calibrate flow.
- Apply directional compensation and re-measure.
Costly mistakes
- Compensating without measuring.
- Using one direction for all.
- Measuring soft parts with excessive force.
- Ignoring moisture.
- Not re-checking after changes.
Buyer / engineer checklist
- Are all three axes measured?
- Is flow corrected?
- Is the filament dry?
- Is the measurement method consistent?
- Is compensation re-validated?
Describe the part and tolerance and we can help structure the correction.TPU advice