Over extrusion is a common 3D printing problem that occurs when the printer deposits more filament than needed, resulting in poor print quality and appearance. Over extrusion can cause various issues such as blobs, strings, oozing, dimensional inaccuracy, and clogging. In this article, we will explain what causes over extrusion, how to identify it, and how to fix it.
There are several possible causes of over extrusion, ranging from hardware defects to software settings. Here are some of the most common ones:
Worn-out nozzle: If you have been printing with abrasive materials such as metal, wood, or carbon fiber, your nozzle may have become enlarged or damaged over time. This can affect the flow rate and diameter of the extruded filament, leading to over extrusion. To check if your nozzle is worn out, compare it with a new one and see if there is a noticeable difference in the opening size. If so, you need to replace the nozzle with a new one.
Incorrect filament diameter: When you set up your slicer for a print, you need to input the correct filament diameter that matches the one you are using. If you input a smaller diameter than the actual one, the slicer will calculate a higher extrusion rate than needed, resulting in over extrusion. To avoid this, you need to measure your filament with a caliper and input the average value in your slicer settings.
High printing temperature: The printing temperature affects the viscosity and flow of the melted filament. If the temperature is too high, the filament will become too runny and ooze out of the nozzle faster than intended. This can cause over extrusion, as well as stringing and oozing. To fix this, you need to lower the printing temperature until you find the optimal value for your material and printer.
High flow rate or extrusion multiplier: The flow rate or extrusion multiplier is a setting that controls how much filament is extruded by the printer. If this value is too high, the printer will push out more filament than needed, causing over extrusion. To fix this, you need to lower the flow rate or extrusion multiplier until you achieve the desired print quality and accuracy.
Over extrusion can affect the appearance and performance of your 3D prints in various ways. Here are some of the signs that indicate you are dealing with over extrusion:
Blobs: Blobs are excess filament that accumulate on the surface or edges of the print, creating bumps or protrusions. They can occur when the printer moves from one point to another without retracting the filament, or when the printer pauses or resumes a print. Blobs can ruin the aesthetics and smoothness of the print, as well as interfere with the functionality of moving parts or assemblies.
Strings: Strings are thin strands of filament that form between different parts of the print, creating a web-like effect. They can occur when the printer moves from one point to another without retracting the filament, or when the filament oozes out of the nozzle during travel moves. Strings can affect the appearance and cleanliness of the print, as well as create problems when removing the supports or post-processing the print.
Oozing: Oozing is the leakage of filament from the nozzle when the printer is not extruding. It can occur when the printing temperature is too high, or when the printer pauses or resumes a print. Oozing can cause over extrusion, as well as stringing and blobs, as the excess filament is deposited on the print surface or edges.
Dimensional inaccuracy: Dimensional inaccuracy is the deviation of the print dimensions from the intended ones. It can occur when the printer extrudes more filament than needed, resulting in thicker or taller layers than expected. This can affect the fit and function of the print, as well as the overall accuracy and precision of the print.
Clogging: Clogging is the blockage of the nozzle or the extruder by the filament. It can occur when the printer extrudes more filament than needed, creating excess pressure in the extruder or the nozzle. This can prevent the filament from flowing properly, resulting in under extrusion, layer gaps, or failed prints.
The best way to fix over extrusion is to identify the root cause and adjust the settings or components accordingly. Here are some of the steps you can take to fix over extrusion:
Replace the nozzle: If your nozzle is worn out or damaged, you need to replace it with a new one that has the same size and type as the original one. This will ensure that the extruded filament has the correct diameter and flow rate, and prevent over extrusion.
Measure the filament diameter: If your filament diameter is different from the one you input in your slicer, you need to measure it with a caliper and input the correct value in your slicer settings. This will ensure that the slicer calculates the correct extrusion rate, and prevent over extrusion.
Lower the printing temperature: If your printing temperature is too high, you need to lower it until you find the optimal value for your material and printer. This will reduce the viscosity and flow of the melted filament, and prevent over extrusion, stringing, and oozing.
Lower the flow rate or extrusion multiplier: If your flow rate or extrusion multiplier is too high, you need to lower it until you achieve the desired print quality and accuracy. This will reduce the amount of filament that is extruded by the printer, and prevent over extrusion, blobs, and dimensional inaccuracy.
Conclusion
Over extrusion is a common 3D printing problem that can affect the quality and appearance of your prints. It can be caused by various factors, such as worn-out nozzle, incorrect filament diameter, high printing temperature, or high flow rate or extrusion multiplier. To fix over extrusion, you need to identify the root cause and adjust the settings or components accordingly. By doing so, you can improve your print quality and accuracy, and enjoy the benefits of 3D printing.
