Plastic shrinks as it cools, so a printed part comes out slightly smaller than the model, more so for ABS and nylon than PLA. This turns a measured part and its design size into the exact scale factor to cancel the shrinkage out.
How to use it
- Print a test part or use one you already have.
- Measure the real dimension with calipers.
- Enter the size you designed it and the size you measured.
- The tool gives the shrinkage percentage and the scale factor to enter in your slicer.
What it does
Scale factor, ready to use
Not just the shrinkage percentage but the exact number to type into the slicer's scale field so the next print is on target.
Per material and part
Shrinkage depends on plastic, geometry and cooling. Measuring your part beats trusting a generic figure.
Works in any unit
Design and measured just have to match. Millimetres, inches, it cancels either way.
What people use it for
Press fits and hardware
A bearing seat or a bolt hole that has to be exact. Compensate for shrinkage and it fits first try.
Engineering plastics
ABS, ASA and nylon shrink enough to matter. Dial it in once per material and reuse the factor.
Multi-part assemblies
Parts that mate need the same real scale. Correct shrinkage so pieces designed together fit together.
Good to know
- Measure a dimension in the print plane (X or Y) rather than height: Z shrinks differently and is set by layer count.
- Let the part reach room temperature before measuring: a warm part is still contracting.
- ABS and ASA shrink more with an unheated chamber. A stable, warm enclosure reduces and steadies the shrinkage.
- Apply the scale factor per axis if X and Y differ, which they can on some machines and geometries.
Questions
Why does a print come out smaller than the model?
Plastic shrinks as it cools from melt to solid. The effect is small for PLA and larger for ABS, ASA and nylon. A part designed at 100mm can measure 99mm or less once cold.
How do I compensate?
Measure the printed part and compare to the design size. The tool gives the scale factor to enter in your slicer so the next print comes out on target.
What is the formula?
Scale factor equals design size divided by measured size. If you designed 100mm and got 99mm, scale to about 101 percent and the shrinkage cancels out.
Does shrinkage matter for every print?
Only when dimensions must be exact: press fits, threads, parts that mate with hardware. For decorative prints a percent either way is invisible.
Also called
Known as a shrinkage calculator, material shrinkage compensation tool, print scale calculator, or dimensional accuracy calculator. It makes the printed size match the designed size.