Pro Tip: For press-fit applications, print a few test pieces with varying compensation to find the perfect fit before printing the final part.
Tolerance Calibration
Calibrate dimensional accuracy for precise part fitment.
What is Tolerance?
Tolerance refers to the dimensional accuracy of your printed parts compared to the designed dimensions. Due to factors like material shrinkage, flow rate, and line width, printed parts may be slightly larger or smaller than designed.
Why Calibrate Tolerance?
- Parts that need to fit together (press fits, snap fits)
- Threads that need to mate with standard hardware
- Mechanical assemblies requiring precise clearances
- Replacement parts matching existing components
Running the Test
- Go to Calibration > Tolerance Test
- Print the calibration model
- Measure the printed dimensions with calipers
- Compare to the designed dimensions
- Calculate the compensation needed
Measuring Your Print
Use digital calipers to measure:
- External dimensions: Outside width, length, height
- Internal dimensions: Hole diameters, slot widths
- Multiple locations: Take several measurements and average
Compensation Methods
1. XY Hole Compensation
Adjusts hole diameters to account for the way perimeters shrink holes.
- Parameter
xy_hole_compensation- Typical Value
- 0.1 - 0.3mm
- Description
- Makes holes larger by this amount
2. XY Contour Compensation
Adjusts external dimensions of the entire model.
- Parameter
xy_contour_compensation- Typical Value
- -0.1 to 0.1mm
- Description
- Positive = larger, Negative = smaller
3. Elephant Foot Compensation
Reduces the bulging first layer caused by over-squish.
- Parameter
elefant_foot_compensation- Typical Value
- 0.1 - 0.2mm
- Description
- Insets first layer perimeters by this amount
Typical Tolerance Issues
| Problem | Cause | Solution |
|---|---|---|
| Holes too small | Perimeter overlap | Increase XY hole compensation |
| Part too large | Over-extrusion | Calibrate flow, negative XY contour |
| Part too small | Under-extrusion | Calibrate flow, positive XY contour |
| First layer bulge | Elephant foot | Enable elephant foot compensation |
Tips for Accurate Parts
- Calibrate flow first: Correct flow before tolerance compensation
- Use consistent settings: Same layer height and nozzle for calibration and final print
- Account for material: Different materials shrink differently
- Consider orientation: XY dimensions are usually more accurate than Z
- Design clearances: Add appropriate clearances in CAD for moving parts