Precision Material Shrinkage Calibration Cube for technical materials - AI-Designed

This calibration cube was designed by Claude (Anthropic's AI) in collaboration with myself. 
I provided the requirements, testing, and iterative feedback to refine the design.

What started as a simple calibration cube evolved through extensive conversation into a
measurement tool with features specifically chosen for practical usability.

Key Features

What You Can Measure

Recommended Print Settings
(keep in mind: we want to measure material properties - not the accuracy of the printer)

• Layer height: 0.10 mm- 0.20 mm

• Perimeters: 4

• Top/Bottom layers: 5 (at 0.12 mm) or 3 (at 0.20 mm)

• Infill: 30% (use your typical setting)

• Shrinkage compensation: 0% (for initial calibration)

• Elephant foot compensation: 0

• Extrusion multiplier: 1.0

The OpenSCAD source is included - fully parametric and easy to modify.

How to Use This Calibration Cube

Step 0: Measure Filament Diameter

Before printing the calibration cube:

• Measure filament diameter at 20 points along the first 5 meters

• Calculate the average

• Enter average diameter in filament settings
  (Prusa Slicer will compensate for the "extrusion difference" to 1.75mm automatically)
  
  > If you don't correct this first, you'll mix extrusion errors with shrinkage errors.
  
  Note: With Premium filaments (±0.02mm tolerance), you can skip this step.
  Budget filaments often vary ±0.05mm or more.

Step 1: First calibration print (unknown material):

• Set Shrinkage Compensation XY = 0%

• Set Elephant Foot Compensation = 0

• Use your typical print settings (infill, speed, temperature)

Step 2: Measure

• After printing, turn off the heated bed and let the print cool on the bed until bed reaches room temperature. Then remove and let stabilize for at least 2 hours before measuring.

• Take at least 5 measurements for every dimension

• Calculate the average for each dimension

Step 3: Calculate Compensation 

Formula:

Shrinkage % = (Target - Measured) / Target × 100

Example:
Shrinkage % = (60.00 - 59.76) / 60.00 × 100 = 0.4%

"Shrinkage Compensation ..." can be found here
Filaments -> Advanced -> Shrinkage Compensation 
(you have to use the average of X and Y for Prusa Slicer)

Note: f your print comes out larger in XY than target, something else is wrong since materials don't typically expand. (e.g. Extrusion multiplier > 1, incorrect filament diamater, measuring before part fully cooled, shrinkage compensation not switched off ...)

In practice:

• Some materials (especially ABS, ASA, PA) show measurable Z shrinkage

• Z shrinkage is usually much smaller than XY because layers are compressed during printing

• PLA typically shows minimal Z shrinkage

Examples:

Note:
layer compression during printing can cause slight Z growth as well.
Enter a negative compensation value in your Prusa Slicer if needed. (unverified)
Shrinkage varies by brand, color, production batch, print conditions -> you might have to repeat that  

Step 4: Verify

• Print again with the new compensation values

• Wait until object has completely cooled down (min. 2 hrs)

• Measure again

Success: All dimensions within ±0.10 mm of target.

Design Decisions Explained

Edge Chamfers (1mm)

Problem: Measuring cube edges with calipers includes artifacts:

• Elephant foot (first layer squish)

• Corner bulge (from perimeter overlap)

• Layer lines

Solution: 
chamfers on all edges → calipers grip only flat wall surfaces → pure material shrinkage measurement.

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Orientation Marker (2mm chamfer on front bottom edge)

Problem: After removing from bed, which side is X? Y? Z?
(printing letters in surfaces might create bulges at their edges)

Solution: One edge has a larger chamfer (2mm vs 1mm) → visually and tactilely identifiable.

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Stepped Hole (Ø10mm / Ø20mm)

Problem: Outer dimensions only tell half the story. Holes often shrink differently.

Solution: Two hole sizes in one print:

• Ø10mm → tests small hole accuracy

• Ø20mm → tests larger hole accuracy

• Step at 30mm → verifiable with depth gauge

Practical relevance: If your print needs M10 bolt holes or bearing seats, this tells you if they'll fit.
-adjust to your specific needs in the OpenScad file-

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Size: 60mm

Problem: Small cubes (20mm) don't show enough shrinkage to measure accurately.

Example:

Solution: 60mm is optimal for technical materials (ABS, ASA, PC, PA) without wasting too much material/time. It works for PLA as well.

HAPPY printing and I hope this helps :-)