About this tool
Plastic shrinks as it cools, belts stretch and extrusion is never perfectly exact. That is why printed parts often differ from the model by a few tenths of a millimetre. With ABS and ASA the shrinkage can reach almost one percent, with PLA it is usually small. From a measured part the tool calculates the scale per axis: new scale = current scale × nominal / measured.
In FDM printing, holes usually come out slightly too small because the nozzle pushes material inwards at the inner edge. For that the tool gives the X-Y hole compensation that OrcaSlicer and Bambu Studio apply per side, or the diameter you can draw in CAD instead.
How it works
- Print a calibration cube (e.g. 20 mm) or a larger part – the larger, the more accurate.
- Measure each axis several times with a caliper and enter nominal and measured size.
- Apply the new scale per axis in the slicer.
- For holes: switch to “Holes”, enter the nominal and measured diameter and apply the compensation.
Frequently asked questions
Why is a small calibration cube inaccurate?
At 20 mm, a measuring error of 0.05 mm is already 0.25 %. Small parts are also dominated by edge effects such as over-extrusion. For the scale, a part of 100 mm or more is far more meaningful.
Should I correct the scale or the E-steps?
If the walls are off because too much or too little material comes out, use the Extruder Calibration (E-steps & Flow). If the outer dimensions of a large part are off evenly, the scale is right. The axes’ steps per mm are almost always correct with belt drives and can be checked with the Steps per mm Calculator.
What does X-Y hole compensation do?
It enlarges every hole in the model by the set value per side without changing the outer contour. If a 5 mm hole is only 4.8 mm, that is 0.1 mm per side. If your slicer lacks this option, simply draw the hole in CAD larger by the difference.
How much do the materials shrink?
PLA and PETG usually shrink only a little, ABS, ASA and nylon considerably more, often by 0.5 to 1 %. The value depends on brand, colour and chamber temperature and is best measured with a large test part.