Uploaded January 2026 | Updated September 2026, 2 weeks ago
Why is a 3D printed part sometimes bigger, even though materials are supposed to shrink?
In this video, I explain dimensional accuracy in XY direction using a simple physical model.
I show that the measured dimension can be described as a combination of:
- material shrinkage (scale factor)
- a constant offset, often caused by overextrusion or wet filament
Using two simple test dimensions, I calculate these values and demonstrate how they can be used to design a part that prints accurately at 100 mm, without guesswork.
The goal of this video is not calibration tricks, but understanding the physical reasons behind dimensional errors in FDM 3D printing.
❤️ Support my work
If you like my work and find these tests useful, consider supporting me on Patreon or Buy Me a Coffee.
Your support helps me keep testing materials, printers, and ideas independently.
- Patreon: patreon.com/mytechfun
- Buy Me a Coffee: buymeacoffee.com/mytechfun
🔗 Mentioned in the video
- 20 mm D6 dice (instead of calibration cube): printables.com/model/399278-dice-as-20mm-xyz-calibration-cube
- Laminar flow video: youtu.be/dhgulN2PQDA
- Vision Encoder video: youtu.be/ZmYj3GvS_B8
⏱ Chapters
0:00 Introduction
0:52 About dimensional accuracy
2:28 What affects the dimensional error
3:37 Equations
4:31 Few notes
5:06 1st example: PETG-CF
7:11 2nd example: PET-GF
8:58 Conclusions
#3DPrinting #DimensionalAccuracy #Shrinkage
#FDM #Engineering #MaterialScience #FilamentTesting #PETG #CarbonFiber #GlassFiber #3DPrinterCalibration
Why is a 3D printed part sometimes bigger, even though materials are supposed to shrink?
In this video, I explain dimensional accuracy in XY direction using a simple physical model.
I show that the measured dimension can be described as a combination of:
- material shrinkage (scale factor)
- a constant offset, often caused by overextrusion or wet filament
Using two simple test dimensions, I calculate these values and demonstrate how they can be used to design a part that prints accurately at 100 mm, without guesswork.
The goal of this video is not calibration tricks, but understanding the physical reasons behind dimensional errors in FDM 3D printing.
❤️ Support my work
If you like my work and find these tests useful, consider supporting me on Patreon or Buy Me a Coffee.
Your support helps me keep testing materials, printers, and ideas independently.
- Patreon: patreon.com/mytechfun
- Buy Me a Coffee: buymeacoffee.com/mytechfun
🔗 Mentioned in the video
- 20 mm D6 dice (instead of calibration cube): printables.com/model/399278-dice-as-20mm-xyz-calibration-cube
- Laminar flow video: youtu.be/dhgulN2PQDA
- Vision Encoder video: youtu.be/ZmYj3GvS_B8
⏱ Chapters
0:00 Introduction
0:52 About dimensional accuracy
2:28 What affects the dimensional error
3:37 Equations
4:31 Few notes
5:06 1st example: PETG-CF
7:11 2nd example: PET-GF
8:58 Conclusions
#3DPrinting #DimensionalAccuracy #Shrinkage
#FDM #Engineering #MaterialScience #FilamentTesting #PETG #CarbonFiber #GlassFiber #3DPrinterCalibration
