Below are some common issues you may encounter with FDM printing and their potential solutions:
Adhesion Problems
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Oil Contamination: Often caused by dirty hands. Wash with soap (DO NOT USE IPA or any other solvents).
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Temperature Issues: Common in non-enclosed printers and with engineering filaments. Temporarily resolve by slightly increasing the bed temperature. For a long-term solution, consider using an enclosure. Additionally, print a temperature tower to find the optimal temperature for your filaments.
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Printhead Collision: Occurs when the flow rate is not properly tuned or the previous layer fails to fuse. Perform a flow rate calibration to prevent over-extrusion and adjust the extruder retraction distance. For splitting layers, an extra ironing routine (where the printhead follows the same path without extruding filament) may help. Alternatively, add a z-hop height. Also, gyroid infill performs better. Note that ironing and z-hop may increase total print time.
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Uneven Print Bed: Calibrate with a piece of paper and adjust the z-offset. Older printers use a probe to create a height map for compensation, while newer machines use Lidar for better results. If this does not work, applying a glue stick or hair spray on the build plate may help.
- Nozzle temperature: In general, the recommended nozzle temperature is optimized for surface smoothness rather than Z-axis adhesion. However, in practice, increasing the nozzle temperature by around 10°C can significantly improve Z-axis bonding. For example, with SUNLU ABS, raising the nozzle temperature from 250–260°C to 270°C prevents breaks along the X-Y plane. The tradeoff is that while adhesion improves, the surface may warp slightly, requiring some sanding.
(Note: Z-offset is often misunderstood as the distance between the nozzle and the bed. While not entirely false, it typically refers to the distance between the nozzle and the point where the probe is triggered.)
Surface Blobs
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Straight Line Blobs: Known as seam lines, these are inherent to FDM printers. They can be hidden using slicer settings and reduced by adjusting the retract distance.
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Patterned Blobs: Caused by power loss recovery cycles due to insufficient computational power when creating a timestamp of your progress. This mostly occurs on Marlin OS. Simply turn off this function.
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Random Blobs: Often attributed to default settings. Switching to Orca slicer resolved this issue for me.
Deformation
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Inaccurate Dimensions: Motor step distance may not match configuration settings. Use a ruler on the build plate and manually input coordinates to check accuracy. For example, set (0,0) and place a ruler under the nozzle, then set (200,0) to see if it travels 200mm. If it only travels 198mm, apply a (2/198 +1) coefficient to the default value. Calibrate all axes to fix this issue.
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Severe Deformation: Test print a temperature tower and check the heat sensor.
Layer Shifts
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Uneven Surface on Print: Caused by an unstable build plate or excessive printing speed. Slow down the printing speed and place the printer on a stable surface. Upgrading to linear rails can also improve stability.
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Entire Print Shifted After a Certain Layer: Adjust the belt tension. If the issue persists at the same layer, it may be due to SD card/USB malfunctions.
Rough Surface on Overhangs
This is a known limitation of FDM printing and can occur with or without supports. Slicing the model into multiple pieces may help, but there is no perfect solution.
There are 2 methods to improve the overhangs surface smoothness,
- Tune speed on the part cooling fan (e.g.: bambu X1C/P1S/H2S/H2D)
- customised support
The part cooling fan is used to cool filament during printing, especially for overhangs. If the cooling is too low, the filament may sag or collapse, while if it’s too high, the filament may not adhere properly. In both cases, print smoothness is affected.
Slicer-generated supports typically cover a larger surface area, which means more polishing is required afterward. They are designed with small gaps for easier removal, but this also allows overhanging filament to sag slightly, causing deformation. Using custom supports with minimal contact points is often better, as it reduces post-processing work while preserving smoother printed surfaces.
Obvious layer line on curved surface
Try adaptive layer height.
