Finishing a long 3D print only to realize the parts don’t fit together is one of the most frustrating experiences for any maker. This issue, commonly known as a “tolerance problem,” usually stems from your printer’s dimensional precision. Whether you are printing mechanical gears or a simple box with a lid, mastering 3D printing tolerances, dimensional accuracy, and calibration cube tests is essential for a perfect fit.
In this guide, we’ll dive into 3 simple calibration steps to ensure your 3D prints slide together perfectly every time. (3D prints not fitting together)
1. Calibrate Your E-Steps (Extruder Calibration)
The most common culprit for parts not fitting is over-extrusion. When your printer pushes out more filament than required, the walls of your print become slightly thicker than the digital model intended. This closes up the tiny gaps needed for assembly.
Calibrating your E-steps ensures that when you command your printer to extrude 100mm of filament, it pulls exactly 100mm. Even a 5% deviation can cause significant fitment issues in tight assemblies.
2. Use “Horizontal Expansion” in Your Slicer
Even with perfect hardware, molten plastic tends to expand slightly as it is laid down. You can compensate for this using software settings. In Cura, this is called Horizontal Expansion, while in PrusaSlicer, it’s referred to as XY Size Compensation.
- How to Apply: If your holes are too tight or pegs are too thick, try entering a small negative value like
-0.1mm. This slightly “shrinks” the outer dimensions of each layer, providing the necessary clearance for parts to fit.
3. Run a Tolerance Test Print
Before starting a large project, always print a Tolerance Test. You can find these 20-minute models on platforms like Printables or Thingiverse. These tests feature various gaps (ranging from 0.5mm down to 0.1mm) to show you exactly what clearance your specific printer and filament can achieve. (3D prints not fitting together)
Knowing your printer’s limits allows you to adjust your designs or slicer settings before wasting time and material.
Summary
Achieving perfect 3D prints is a balance between hardware calibration and smart slicing. By mastering E-steps, utilizing Horizontal Expansion, and testing your tolerances, you’ll eliminate the guesswork and save yourself hours of frustration.
f you are using high-speed machines like the X1C or P1P, choosing the right software is just as important as calibration. Don’t forget to check out our Best Slicers and Software for Bambu Lab 3D Printers (Complete Guide) to maximize your print quality.
