PETG Sticking to the Nozzle During Printing – Causes & Fixes

A relatively common problem that you can face when printing with PETG is the material sticking to the nozzle instead of the build plate, which effectively causes the print to fail as the 3D printer becomes unable to properly lay the first layer of the print down due to the material building up on the nozzle instead.

In this guide, we will explain the possible culprits behind the issue of PETG filament sticking to the nozzle during 3D printing and take you through the possible solutions that will help you resolve this problem as quickly as possible.

PETG Sticking to the Nozzle During Printing – Causes & Fixes

As there are quite a few different factors that can cause the PETG to stick to the nozzle during printing, going through each of them individually and ensuring that the problem doesn’t stem from that particular factor is the best way to move forward, which will allow us to check all the possible causes off one by one.

Too Low Printing Temperature

Using a printing temperature that’s way too low is one of the primary causes behind the issue of PETG sticking to the nozzle during printing, especially if you have started out with printing PETG recently and haven’t gotten around to dialing your settings in yet.

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When the printing temperature is way too low, your 3D printer’s hotend won’t be able to heat the PETG to the point where it fully melts, which in turn will create a scenario where both bed & layer adhesion becomes poor, and extrusion becomes inconsistent, leading to the plastic clumping up on the nozzle instead of correctly sticking to the build surface or the previous layer.

To ensure that you’re printing your PETG at the correct temperature, the very first step we recommend taking is to refer to the specification sheet for the brand of filament you’re using through the manufacturer’s website, where you can find the recommended printing temperature range that will produce the optimal results, adjust your printing temperature accordingly, preferably toward the middle of this range, and run a test print to see if the problem repeats.

So, as an example, if the manufacturer suggests the usage of printing temperatures between 220 degrees Celsius and 260 degrees Celsius, which we can consider to be pretty standard for PETG overall (feel free to use this range if the manufacturer doesn’t provide recommended printing temperatures for the PETG you’re using), going for a printing temperature value of 240 degrees Celsius as a starting point is what we would recommend.

In the case where your PETG is still sticking to the nozzle, our following recommendation would be to decrease the printing temperature by 5 degrees Celsius, run another test, and keep repeating this process until you either find a temperature value where the issue doesn’t take place anymore, or until you reach the lower end of the suggested temperature range.

Too Low Bed Temperature

Similar to using a printing temperature that’s too low, another factor that commonly leads to PETG sticking to the nozzle is the usage of a bed temperature that’s way too low, which, once again, is an issue you are most likely to encounter when building your PETG print profile for the first time.

cura build plate temperature


In a case where the bed temperature you’re using is a whole lot lower than optimal, the considerable temperature difference between the build surface and the PETG coming out of the nozzle will make it harder for the plastic to adhere to the surface, which, in turn, will either cause the PETG to clump up on the nozzle without sticking to the bed at all, or cause the nozzle to drag the plastic with it due to the plastic cooling down and solidifying way too quickly.

Similarly to correcting the printing temperature, the first step we recommend taking to ensure that you’re using the optimal print bed temperature when printing PETG is to refer to the specification sheet provided by the manufacturer once again, which should point you toward the right direction with a print bed temperature range that will practically guarantee that the value you’re using is neither too low nor too high, and run a test print with a temperature value toward the middle of this range.

As an example, if the manufacturer of the PETG you’re using suggests using a bed temperature value that falls between 60 degrees Celsius and 80 degrees Celsius, which we can consider to be a fairly standard range for PETG regardless of the brand, starting out with a bed temperature of 70 degrees Celsius is what we would recommend to ensure to minimize the chance of coming across issues.

In the case where the sticking issue continues after this adjustments, the next step we recommend taking would be to bump the bed temperature value up by 5 degrees Celsius between tests until you arrive at a value where the problem doesn’t happen anymore (or until you reach the upper limit of the recommended temperature range), which will allow you to test higher temperatures in a controlled manner.

Too High Cooling Fan Speed

While not as commonly encountered as a printing or bed temperature that’s too low, a cooling fan speed that’s too high can also be the factor that’s causing your PETG to the nozzle during printing.

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When you use a cooling fan speed that’s way higher than necessary, your 3D printer can end up cooling the PETG way too quickly to the point where it’s not at the optimal temperature to be able to adhere to the build surface or the layer below, which ends up with the plastic staying on around the nozzle and solidifying there instead.

To fix issues regarding the cooling fan speed, the first step we recommend taking would be to start with a balanced fan speed value, such as 50%, which we can consider to be suitable for general-purpose PETG prints where you aren’t trying to maximize either the strength or the visual quality of the part you’re printing.

While a fan speed value of 50% should never really be high enough to lead to your PETG sticking to the nozzle alone, you can reduce it by an additional 5% across tests if you can’t seem to find the source of the issue anywhere else, as PETG will print perfectly fine even without the part cooling fan running, even though it will be at the expense of a loss in visual quality.

Too High Print Speed

Print speed is another parameter that we can consider simple to get wrong when printing with PETG, especially if you have switched from PLA for the first time, and in cases where it’s way too high, it can lead to the sticking problem you are experiencing.

cura print speed description


When you’re printing PETG at a speed that’s way too high, your 3D printer’s hotend most likely won’t have enough time to bring the filament to its melted state where it becomes capable of optimally adhering to the build surface or the previous layer, which, similar to the case of using a low printing temperature, will end up with the PETG sticking to the nozzle instead.

Our recommendation to rule out the usage of a too-high print speed value would be to go with a safe print speed value that we can consider to be pretty low to the point where it would be impossible for it to cause the PETG to stick to the nozzle during printing, such as 40 mm/s, and run a test print with it to see whether the problem still occurs.

Once you find a print speed value where the sticking problem doesn’t occur anymore, you can keep increasing it by 5 mm/s at a time and keep testing until you find the highest print speed value you can use without issues, which will be the most optimal as it will reduce your print times as much as possible without any negative impact on the quality of your prints.

Misconfigured Nozzle Gap

Even though the nozzle gap (the space between the nozzle and the build surface at Z=0) isn’t something that requires configuration on a filament-by-filament basis, meaning that it would technically create the same issue regardless of the filament you’re printing with, the fact that PETG is susceptible to sticking to the nozzle can exacerbate the problem and make this a possible culprit worth considering.

When the nozzle gap is larger than optimal, with a lot of space between the build surface and the nozzle, your 3D printer will effectively end up extruding the PETG in the air instead of pressing it down to get it to adhere to the build surface, which will naturally lead to a scenario where the plastic clumps up on the nozzle instead due to it having no other point of contact to stick to.

On the other hand, when the nozzle gap is smaller than necessary, there won’t be enough space on the build surface for your 3D printer to deposit the PETG, which will also result in the PETG clumping up on the nozzle, as it will be practically impossible for the plastic to leave the nozzle due to the lack of room.

To fix this problem, the very first step we recommend taking is to ensure you tram the print bed manually if your 3D printer allows it, regardless of whether you’re using an automatic bed leveling sensor, as a bed that isn’t level can create inconsistencies in the nozzle gap throughout the printing process, where the nozzle gets closer to the bed in some areas, and further from the bed in others.

Once the bed is level, the next step you should take is to correct the Z offset value (or probe Z offset if you have an automatic bed leveling sensor installed), as this value directly determines the space between the nozzle throughout the entirety of the print area provided that there’s no warping or tilt that affects the print bed.

Over-Extrusion

Another possible culprit behind the sticking problem you’re experiencing when printing with PETG is over-extrusion, where your 3D printer extrudes more material than required during the print, which can stem from a few different factors, whether it’s the usage of a too-high printing temperature, mechanical issues regarding the extruder assembly, or a misconfigured flow rate.

When your 3D printer over-extrudes filament, the portion of PETG that comes out of the nozzle unwarrantedly will usually not have enough space to adhere to the build surface or the previous layer, which will lead to a scenario where it instead ends up sticking to the nozzle due to it not having anywhere else to go.

While there are a few different factors that can lead to over-extrusion, as we have touched upon earlier, our first recommendation to solve this problem would be to ensure that you aren’t using a printing temperature that’s way too high (you can refer to the previous section on printing temperature to configure it correctly), which is the leading cause of over-extrusion.

In the case where over-extrusion is still an issue after correcting the printing temperature, our recommendation would be to check factors such as E-steps configuration, flow rate settings, partial nozzle clogs, and mechanical issues regarding the extruder assembly, which can all contribute to over-extrusion.

Dirty Build Surface

Considering that there are no issues on the configuration side of things, something that quickly comes to mind in cases where PETG ends up building up on the nozzle is the usage of a dirty build surface, which is especially likely to be a problem if you switch between different filaments without cleaning it.

When the build surface you’re printing PETG on isn’t clean, whether it’s due to the bits and pieces of plastic that have stuck to the surface from previous prints, the dust & dirt that gathers over time, or any other residue you can think of, the strength of bed adhesion will be reduced drastically, which will lead to a scenario where it becomes more likely for the plastic to stick to the nozzle instead of the build surface.

To resolve this problem and bring your build surface back to top shape, the very first step we recommend taking is to thoroughly wash the build surface with the help of a soap & water mixture and a towel, which should allow you to get the majority of the residue off the surface and provide a clean printing environment.

In cases where the soap isn’t able to fully clean the surface, wiping it with some isopropyl alcohol afterward is another technique that will come in quite handy, as IPA can remove some residues that won’t react to soap under normal circumstances.

Finally, one last thing to pay attention to when cleaning the build surface is to avoid touching it with your bare hands after the cleaning and during usage as much as possible since this will contaminate the build surface yet again and create issues regarding bed adhesion.

While the usage of a soap-water mixture and isopropyl alcohol for cleaning purposes is pretty standard and shouldn’t pose a problem for the majority of the build surfaces, we highly recommend verifying that the particular build surface you’re using won’t have issues as a result of using these materials before moving forward.

Dirty / Worn Out Nozzle

Last but not least, even though it’s on the rarer side, especially if you haven’t been using your 3D printer for too long, a dirty or worn-out nozzle is fully capable of leading to your PETG sticking to the nozzle as well, which becomes a factor to consider if you haven’t been able to find the source of the issue anywhere else.

When you print PETG with a nozzle that’s either dirty or worn out, it will become much simpler for the plastic to stick to the nozzle instead of the build surface or the previous layer, as the nozzle will end up having rough surfaces that increase friction, whether it’s due to bits and pieces of plastic residue stuck inside the nozzle or plain wear and tear as a result of prolonged usage.

In this case, the first step we recommend taking to solve the problem is to examine the nozzle for any signs that can indicate nozzle wear and tear, whether it’s roughness around the nozzle or the enlarging of the nozzle tip, which are especially likely to be present if you have racked up hundreds of hours in print time with your current nozzle; and to replace the nozzle if you come across any of these signs.

On the other hand, in the scenario where you don’t come across any signs of wear and tear on the nozzle, the next step we recommend taking would be to clean the nozzle with the help of a wire brush, which should allow you to get rid of minor clogs that can affect the movement of the filament as it comes out of the nozzle in a quick and convenient manner.

Finally, for more severe cases of filament build-up within the nozzle, we recommend utilizing the cold pull technique, which should allow you to fully clean the nozzle’s insides without the need to remove it from your 3D printer first.

Conclusion

With so many factors that can contribute to the occurrence of the problem, resolving the issue of PETG sticking to the nozzle will definitely prove to be a challenging process, with a lot of trial and error required before you can find the correct root cause that’s creating the issue in your case.

That being said, considering that you will most likely be able to print with PETG without any issues once you resolve this particular problem, as this process will effectively ensure that you have configured and calibrated everything correctly for printing PETG, it will be a worthwhile time investment if you’re planning on using PETG filament frequently in the long run.