The appearance of issues, and as a result, being able to troubleshoot them, holds an essential place in the process of 3D printing, as the complex nature of the process with many distinct components involved means that there are multiple points of failure, increasing the likelihood of something going wrong.
While issues with known culprits are usually straightforward to troubleshoot, the cases where a particular problem has multiple potential culprits that are independent of each other are where things can get complicated, where experience and familiarity with your 3D printer become a significant asset.
In today’s article, we will be talking about the factors that can cause the Ender 3 to under-extrude, in particular, which is one such issue with many potential culprits that essentially causes the amount of filament that comes out of the nozzle during the printing process to be less than it actually should be, causing parts of the models to be missing.
So, what can cause your Ender 3 to under-extrude during the 3D printing process?
Below, you can find the potential culprits behind the issue of your Ender 3 under-extruding:
- The print temperature is too low.
- The print speed is too high.
- The nozzle is clogged.
- The PTFE tube is damaged or bent.
- The filament spool is tangled.
- The extruder tension is misadjusted.
- The extruder gear is worn out.
- The retraction distance and speed parameters are misconfigured.
- The E-step value is not configured accurately.
- The bed is not leveled correctly.
- The Z-offset value is not configured correctly.
Next up, we will take a deeper look at the factors that can cause your Ender 3 to under-extrude, go through the potential solutions to fix the issue as efficiently as possible, discuss the signs that may indicate your Ender 3 is under-extruding, and finally, take a glance at the specific case of the Ender 3 under-extruding only after a retraction takes place.
What Can Cause Ender 3 (Pro/V2) Under-Extrusion?
As under-extrusion is a reasonably complex problem due to the many factors that can potentially cause it, finding the culprit that’s creating the issue in your case can be a challenging process depending on where the problem really lies.
Here are the most common reasons behind the occurrence of the Ender 3 under-extrusion issue, alongside detailed descriptions that clarify how they can contribute to the problem.
Low Print Temperature
The print temperature value is responsible for the amount of heat that the filament gets exposed to during the extrusion process, which directly affects how quickly it reaches its melting point and becomes ready to flow out of the nozzle.
When the print temperature is lower than optimal, the filament won’t be able to reach its melting point quickly enough to turn into its liquid state, which will cause under-extrusion as a result of the plastic not being able to flow smoothly out of the nozzle.
Alongside under-extrusion, you can also face problems such as poor layer adhesion (which can even lead to layer delamination in severe cases), clogging of the nozzle, and warping as a result of using a low print temperature.
High Print Speed
The print speed value is responsible for the speed at which the printhead moves while extruding filament, which is one of the primary factors that determine how quickly your Ender 3 can conclude the printing process.
When the print speed is higher than optimal, the Ender 3 won’t be able to melt and extrude the sufficient amount of filament that is required to keep up with the movement of the printhead (especially when combined with a print temperature that is too low), which will result in under-extrusion.
Alongside the under-extrusion problem at hand, using a print speed that is too high can also have severe adverse effects on the surface quality of your prints, as the printhead won’t be able to move cleanly at such high speeds and introduce the issue of ringing.
Even though it’s perhaps the least complex piece of a 3D printer, the role of the nozzle is essential for the 3D printing process to take place, as it allows the plastic to exit the hotend assembly and make its way to the build plate where the 3D printed model will be formed.
When the nozzle is partially clogged, even with a tiny portion of it being blocked due to various things ranging from dust and dirt to dried-up filament, the amount of plastic that comes out of the nozzle at any given time will be less than the calculated amount, creating the issue of under-extrusion.
Aside from the issue of under-extrusion, you can also observe the filament curling up on the nozzle instead of correctly sticking to the build plate as a result of printing with a partially clogged nozzle, which can be a good indicator that allows you to differentiate it from the rest of the problems.
Damaged or Bent PTFE Tube
The PTFE tube is another straightforward but essential component of the Ender 3, as it’s practically the bridge that allows the filament to move as smoothly as possible between the extruder and the hotend while it’s still in its solid form.
When the PTFE tube is damaged in some way, whether permanently (such as the PTFE degrading) or temporarily (such as the tube getting bent), the filament won’t be able to move consistently and smoothly to the hotend, causing under-extrusion due to the filament not being in the correct position.
In severe cases where the PTFE tube is entirely blocked, you may observe that your Ender 3 is completely failing the extrude any filament at all, as there won’t be any filament in the hotend as a result of the blockage.
Tangled Filament Spool
The filament spool fulfills the role of keeping the filament in a manageable state when using it, as it allows the extruder to pull the necessary amount of filament in a straightforward manner.
When the filament spool is tangled, the extruder won’t be able to pull the filament from the spool in a reliable way due to the tangle introducing some tension, creating the issue known as extruder skipping, which will end up with under-extrusion due to the lack of filament.
While minor tangles may be fixed automatically as the 3D printing process progresses, severe cases will most likely lead to the failure of the print due to the extruder not being able to pull any filament at all unless the tangle is manually fixed.
Misadjusted Extruder Tension
The extruder tension is the factor that decides how closely the extruder gear will be positioned relative to the path of the filament within the extruder, which practically determines the strength of the grip that the extruder gear has on the filament.
When the extruder tension is too low, the extruder gear won’t be able to grip the filament strongly enough, causing some steps of the extruder stepper motor not to move the filament, which will end up with under-extrusion due to the filament moving a lesser distance than calculated.
On the other hand, in the opposite scenario, where the extruder tension is way too high, under-extrusion can also take place, as the extruder gear having too firm of a grip on the filament will both restrict the smooth movement of the filament and also cause the filament to be chewed (known as filament grinding), which will cause parts of it to be thinner than usual.
Worn Out Extruder Gear
The extruder gear is directly responsible for filament movement, as it needs to be able to reliably grip the filament for the motion generated by the stepper motors to be passed down.
When the extruder gear is worn out, its teeth won’t be able to grip the filament with enough strength, which practically ends up in a situation where it will go through some of the turns without moving the filament down, causing under-extrusion as a result.
In more severe cases, a worn-out extruder gear can end up with it not being able to grip the filament at all, in which case you will observe that your Ender 3 is not extruding any plastic at all due to the filament being unable to move.
Misconfigured Retraction Distance & Speed
The retraction distance and the retraction speed parameters are the two primary factors that determine the position of the filament when a retraction occurs.
When the retraction distance is too high or the retraction speed is too low, your Ender 3 may not be able to prime the filament quickly enough after a retraction takes place, which will end up with under-extrusion due to a lack of filament.
On the other hand, as a too low retraction distance and a too high retraction speed can also bring problems of their own, such as stringing and filament grinding, respectively, the usage of balanced values is essential.
Miscalibrated E-Step Value
The E-step value determines the number of steps that the extruder stepper motor needs to take to extrude a millimeter of filament, which has a direct impact on the amount of filament extruded.
When the E-step value is miscalibrated, the amount of filament that your Ender 3 extrudes won’t be equal to the amount of filament that it’s supposed to extrude, which can create an under-extrusion situation in cases where the value is lower than it should be.
In the opposite scenario, where the E-step value is higher than it should be, you would be facing over-extrusion instead, as the stepper motor would be taking unnecessary extra steps that end up with more than the intended amount of filament being extruded.
Incorrectly Leveled Print Bed
The print bed being correctly leveled means that it’s a completely flat surface with no tilt, which causes an arbitrary Z position to always be equally distant from the build plate regardless of the X and Y positions.
When the print bed is not correctly leveled, there will be particular areas of the build plate where the gap between the nozzle and the print bed is too small for the entirety of the extruded plastic to fit, which will end up in the partial under-extrusion of the first layer.
In this case, you will most likely be observing that the under-extrusion is inconsistent across different portions of the first layer, as the size of the nozzle gap will fluctuate depending on the XY position of the printhead due to the print bed being tilted.
Incorrectly Configured Z-Offset Value
The Z-offset value determines the Z position of the printhead relative to the build plate during the printing of the first layer.
When the Z-offset value is incorrectly configured in a way where the gap between the nozzle and the print bed becomes way too small, there won’t be enough space for the plastic to fit in once it exits the nozzle and tries to make its way to the build plate, which will end up with the under-extrusion of the first layer.
In this scenario, you should observe that the under-extrusion is consistent across the entirety of the first layer (provided that the bed is correctly leveled), as the gap between the nozzle and the print bed should remain the same regardless of the X and Y positions.
How to Fix Ender 3 (Pro/V2) Under-Extrusion?
Since the existence of many potential culprits means that no single magic fix can solve the problem of under-extrusion, going through all the possible solutions that correspond to the common culprits and testing as you go is usually the most efficient way to resolve the problem.
Below, we have listed the solutions we recommend applying to fix the issue of your Ender 3 under-extruding during the 3D printing process as efficiently as possible.
Increase the Print Temperature
Increasing the print temperature will cause the filament to reach its melting point quicker, which will allow it to travel smoothly out of the nozzle during extrusion.
To find the optimal print temperature value that will allow the filament to melt the right amount, we recommend incrementing the current print temperature value by 5 degrees at a time and running a test print after each modification.
Following this methodology will allow you to directly observe how the modification affected the flow of filament, which will make it easier to decide the point where under-extrusion does not occur anymore and ensure that you don’t end up with a print temperature that is too high.
Decrease the Print Speed
Decreasing the print speed will give the 3D printer more time to extrude the necessary amount of plastic to complete a particular portion of the 3D printed model, which will ensure that the printhead does not move away before extruding the correct amount of filament.
To find the optimal print speed value that will give your Ender 3 enough time to melt and extrude the right amount of filament, we recommend decrementing the current print speed value by 5 millimeters per second at a time and running a test print after each iteration.
By decreasing the print speed in small portions and testing after each decrease, you will be able to find the point where the print speed is as high as it can be without causing under-extrusion issues, which will ensure that your 3D printer is still printing as quickly as possible.
Unclog the Nozzle
It goes without saying that completely unclogging the nozzle is practically a necessity for the correct amount of filament to flow out of it at any given time, especially considering that we are dealing with millimetric values.
For clogs that aren’t too severe, our first recommendation would be to utilize the cold pull method, as it can allow you to unclog the nozzle without having to remove it, saving a lot of time and effort in the process.
On the other hand, in cases where you cannot unclog the nozzle with the cold pull method, the most reliable approach is to remove the nozzle and thoroughly clean it by soaking it in acetone, which will soften the dirt inside and allow you to use a needle to push the dirt out conveniently.
Finally, if you seem to be unable to clog the nozzle with either method, it’s always an option to switch to the replacement nozzle that your Ender 3 came with, which will ensure that there are no issues regarding the nozzle.
Re-install or Replace the PTFE Tube
Re-installing (or replacing) the PTFE tube will ensure that the filament’s path between the extruder and the hotend is clear, allowing the extruder to consistently push the correct amount of filament out of the nozzle at any given time.
For this process, we recommend completely removing the PTFE tube from both ends and thoroughly cleaning it by attaching a small piece of sponge that will tightly fit into the PTFE tube to the end of a filament and pushing the filament all the way through as the first step.
After ensuring that the PTFE tube is clean, the next step is to test that there are indeed no blockages, which you can do by pushing a piece of filament through the tube while observing that it can indeed move smoothly through the tube and come out of the other end.
Finally, the last step is to attach the PTFE tube in a way that allows it to be as straight as possible, without any stress points where the tube bends too much, which will make the movement of the filament in the tube a lot more reliable.
On the other hand, in cases where there is permanent damage to the PTFE tube that prevent the filament from moving smoothly inside, the best course of action is to replace it entirely, especially considering that it’s a cheap component that you can find everywhere.
Untangle the Filament Spool
Untangling the filament spool will ensure that the filament’s path to the extruder is clear, which will allow the extruder to consistently pull the correct amount of filament from the spool whenever necessary, without any inconsistencies.
Untangling the filament spool is highly likely to be the most straightforward process on our list, as all there is to do is to unwind the spool until the point where the tangle is, fix the tangle, and wind the filament back onto the spool.
Once you untangle the filament spool, we highly recommend utilizing something like a filament clip to prevent a tangle from occurring again down the road, as prevention is always more convenient than fixing.
Correctly Adjust the Extruder Tension
Correctly adjusting the extruder tension is required for the extruder’s grip on the filament to be balanced, where it’s not too weak not to be able to move the filament down and also not too strong to chew the filament and prevent it from moving smoothly.
To correctly adjust the extruder tension, you will need to tighten or loosen the adjustment screw located next to the tension spring on the extruder to the point where the extruder gear can grip the filament strongly enough.
As this process requires some trial and error for optimal results, we recommend making minor adjustments to the extruder tension and testing how it affected the extrusion with a small test print after each iteration.
Maintain or Replace Extruder Gear
Maintaining or even replacing the extruder gear can eventually become necessary due to prolonged usage since they are simple (and cheap) metal parts that are susceptible to wear and tear, which will allow your Ender 3 to grip the filament correctly once more.
Maintenance of the extruder gear primarily involves steps such as cleaning and lubricating it, which should allow it to turn smoothly and move the filament down without problems.
We recommend using silicone lubricant for the purposes of lubricating the extruder gear and a wire brush, preferably combined with acetone or isopropyl alcohol for cleaning it.
In cases where maintenance is not enough, it’s also entirely possible to completely replace the extruder gear, which is a cheap component that is fairly simple to remove and reinstall.
Reconfigure the Retraction Distance & Speed
Correctly configuring the retraction distance and retraction speed values will allow your Ender 3 to retract and prime the correct amount of filament at the right time, which will be necessary for extrusion to be reliable and consistent.
Regarding the process of retraction distance and speed reconfiguration, our recommendation would be to drastically decrease the retraction distance and increase the retraction speed as the first step, purely for testing purposes.
After running a test print with the new settings, you can determine whether retraction was indeed the culprit behind the issue of under-extrusion in your case and move further accordingly.
Recalibrate the E-Step Value
Correctly calibrating the E-step value is what will ensure that the filament your Ender 3 is extruding is equal to what it thinks it’s extruding, which is practically a necessity for the 3D printed version of the model to be the same as the 3D model you’re seeing on your screen.
In a nutshell, the process of re-calibrating the E-step value is all about setting it to a value that allows your Ender 3 to extrude the exact amount of filament that you have specified.
While it’s a rather detailed process, we can summarize the steps as follows:
- Remove the PTFE tube.
- Note down the current E-step value.
- Heat the 3D printer up to standard temperature levels.
- Load the filament into the extruder.
- Measure an arbitrary length (larger than 110 mm) of filament between the extruder opening and the filament spool, and mark it.
- Extrude 100 mm of filament.
- Measure the length between the opening of the extruder and the mark you have placed in step 5.
- Subtract the value you have found from the length you have used in step 5.
- Multiply your current E-step value with 100, and divide the resulting value by the value you have found in step 8.
Following the above steps will give you the correct E-step value, which you will need to set and save by using the M92 and the M500 G-code commands.
Level the Print Bed
The purpose of ensuring that the bed is correctly leveled is primarily about making sure that the first layer is not under-extruded, as a flat surface is necessary for the gap between the nozzle and the build plate to remain consistent.
While there are so many different methods of correctly leveling the print bed, ranging from manually adjusting the leveling knobs to using an automatic bed leveling sensor, our recommendation would be to go with an automatic bed leveling sensor for best results.
Even though it’s entirely possible to achieve success with manual leveling, automatic bed leveling takes the unreliability out of the process while improving user experience by a considerable margin.
Correct the Z-Offset Value
Correcting the Z-offset value is another necessary step to prevent first-layer under-extrusion, as it will ensure that the gap between the nozzle and the build plate is sufficient to accommodate the plastic that comes out.
The process of correcting the Z-offset value is practically as simple as setting it in a way that allows the size of the gap between the nozzle and the print bed to roughly be equal to the thickness of a piece of paper when the printhead is located at the Z0 position.
This way, there will be enough space between the print bed and the nozzle to fully accommodate the plastic during the printing of the first layer, and under-extrusion won’t take place.
What Are the Signs That Your Ender 3 (Pro/V2) Is Under-Extruding?
Even though severe under-extrusion will definitely catch your eye and make you think that something is not working as intended, minor under-extrusion can fly under the radar while having adverse effects on the 3D printing process.
As under-extrusion essentially means that the 3D printed model is receiving less plastic than it actually should, the most common signs to look out for are the presence of gaps and holes, no matter how small they may be, which indicates that the printer is not extruding a sufficient amount of filament.
In more severe cases, under-extrusion can lead to thinned-out layers or even layers that are missing huge chunks, which would cause your 3D printed model to become visibly hollow in the areas affected by the under-extrusion issue the most.
Ender 3 (Pro/V2) Under-Extrusion After Retraction – What to Do?
A specific case of under-extrusion is when it only happens after retraction, which essentially narrows the potential culprits behind the problem by a large margin due to it being an isolated problem that is connected to one thing.
When the issue of under-extrusion only occurs after a retraction takes place, our primary recommendation would be to decrease the retraction distance and increase the retraction speed (or the retraction prime speed individually) significantly.
Since the most likely scenarios are the filament being retracted too far back or not being retracted and primed quickly enough, which will both result in under-extrusion after a retraction due to the Ender 3 not being able to move the filament back into the nozzle in time, modifying the retraction distance and the retraction speed (or retraction prime speed) should solve the problem.
To find out whether the changes have been successful, we would highly recommend going for a test print instead of moving forward with an actual print, as the retraction distance and speed values will require proper optimization for a successful print after ensuring that the issue was indeed related to them.
Since under-extrusion is a critical issue that will have many adverse effects on the 3D printing process, and potentially cause the print to fail, it’s vital to identify the cause behind the problem, apply the corresponding solution, and run tests to ensure that it’s solved before moving forward with another print.
To quickly recap, let’s summarize the potential culprits behind the occurrence of the Ender 3 under-extrusion problem:
- Issues related to configuration on the software side, such as a print temperature that is too low, a print speed that is too high, misconfigured retraction parameters, or an inaccurately calibrated E-step value
- Problems that directly block the filament’s movement, such as the PTFE tube being damaged or not being straight enough for the filament to move smoothly, a tangled filament spool, or a clogged nozzle
- The extruder not being able to push the filament down to the nozzle correctly due to mechanical issues such as the extruder tension being misadjusted or the extruder gear being worn out
- Factors that cause inconsistencies in the first layer, such as a bed that is not correctly leveled, or a Z-offset value that is not correctly configured
While it can definitely be a long and arduous journey to find the culprit that’s causing the issue in your case with so many different factors involved, our recommendation is to be patient and attentive when going through the solution steps not to miss any minor details that could very well point you towards the root cause.
Mike started his 3D printing journey with the Anet A8 when it first came out back in 2017, and has been obsessed with 3D printers ever since. Nowadays, he primarily uses his Ender 3 to print functional parts that make his life more convenient whenever possible.