What Causes Heat Creep in the Ender 3 (Pro/V2)? (Solved!)

While 3D printing is both exciting and incredibly useful at the same time, it’s impossible to ignore the many issues that can arise during the process, with some being very straightforward to notice and the rest not so much.

A problem called heat creep, in particular, is perhaps one of the most challenging issues to identify in 3D printing, where the heat that should remain at the bottom (known as the melt zone or the hot zone) of the hotend travels upwards, melts the filament before it reaches the hot zone, and prevents the filament from flowing outside as a result.

In today’s article, we will examine the potential culprits that can cause the heat creep issue in the Ender 3, which is a problem that requires solving as quickly as possible before using the 3D printer again due to its highly adverse impact on the printing process that can lead to print failure.

So, what can cause the problem of heat creep in your Ender 3?

As there are a few different factors that can cause the heat creep problem in your Ender 3, we have listed the most common ones below:

  • Higher than optimal nozzle temperature
  • Lower hotend cooling fan speed than required or higher cooling fan activation point than the needed 
  • Insufficient or malfunctioning hotend fan
  • Filament not flowing quickly enough through hotend
  • Heat transfer issues in the hotend
  • High ambient temperature
  • Printing in an enclosure
  • Printing with an all-metal hotend

Next up, we will be diving deeper into the potential causes behind the heat creep issue, discussing ways of resolving the problem as efficiently as possible, and finally, looking at the common signs that point towards an Ender 3 potentially having heat creep issues.

What Causes Heat Creep in the Ender 3 (Pro/V2)?

As heat creep is a critical problem that can cause the printing process to fail by preventing the filament from flowing freely out of the nozzle, it is essential to find the cause behind it before moving on with another print to avoid further issues.

Below, we will be going through the common culprits that can cause the heat creep problem in your Ender 3, along with their detailed descriptions:

  • The nozzle temperature is higher than optimal. When the nozzle temperature is way too high, it’s more likely for the excess heat to travel upwards from the heatbreak, causing the heat creep problem.
  • The hotend fan speed is too low, or the hotend activation point is too high. When the hotend fan isn’t spinning quickly enough or not activating at the correct temperature, the hotend won’t be able to cool down fast enough to contain the heat around the heatbreak.
  • The hotend fan is insufficient or malfunctioning, making it unable to provide the required amount of cooling. Fans aren’t the most durable components, and it’s highly likely for them to malfunction due to wear and tear or simple clogging due to dust. In some cases, the quality of the fan may not be enough to provide enough heating either, which is something to keep in mind.
  • The filament is not flowing quickly enough through the hotend, ultimately causing it to melt inside. When the filament stays in the hotend for too long without coming out, due to factors such as a slow print speed or travel speed, it will eventually melt inside due to the heat exposure.
  • There is a problem with heat transfer between the parts of the hotend. As the heat block is connected to the heatbreak, and the fan is connected to the heatsink, the heatsink and the heatbreak should be tightly connected for the heat to be dissipated, and an issue with the heat transfer will cause heat creep.

Alongside the culprits we have mentioned above, which are essentially problems that require fixing, there are some other factors that aren’t necessarily issues but can potentially contribute to the heat creep problem:

  • The ambient temperature in the room is too high. When the room’s ambient temperature is too high, it can throw the temperature balance in the hotend off, making way for the heat creep problem.
  • The Ender 3 is placed inside of an enclosure. Printing inside an enclosure that gets way too hot due to lack of cooling can create a similar effect as a high ambient temperature and tip the hotend temperature over the optimal level.
  • The Ender 3 has an all-metal hotend instead of the stock PTFE lined hotend. An all-metal hotend is more prone to heat creep problems than PTFE-lined hotends, as the lack of PTFE lining means that the heat can travel easier through the metal.

While the factors we have listed above aren’t problems by any means, we believe that they are worth keeping in mind if you have gone through all the main offenders and haven’t found an issue related to them in your case.

How to Fix the Heat Creep Issue in the Ender 3 (Pro/V2)?

While the heat creep issue is one with a handful of potential factors behind it, fixing it shouldn’t pose too much of a problem once you find the root cause behind it and apply the appropriate solution that corresponds to the cause you have found.

Below, we have listed our solution recommendations for the common potential culprits behind the Ender 3 heat creep issue:

  • Reduce the nozzle temperature to the lower end of the recommended temperature range. You can easily do this in slicer software, such as Cura, and doing so should still allow you to achieve successful prints while reducing the inner temperature of the hotend.
  • Increase the hotend fan speed and decrease the activation threshold. You can conduct this process by editing the EXTRUDER_AUTO_FAN_TEMPERATURE and EXTRUDER_AUTO_FAN_SPEED values in the Marlin firmware Configuration_adv.h file. While 255, which is the full speed, is the default, it’s possible to lower the activation threshold further.
  • Diagnose the hotend fan, clean or replace it if necessary. We would recommend removing the hotend fan, cleaning it, and testing it by hooking it up to an alternative power source. If the fan isn’t spinning as quickly as it should, you should be able to observe it easily.
  • Increase the print and travel speed values. While the optimal print speed value depends on the filament you’re printing, bumping it in increments of 5 mm/s can be helpful. For the travel speed, we recommend going as high as possible until you start facing issues such as artifacts or layer shifting.
  • Ensure that the hotend is assembled correctly. To be on the safe side, we would recommend disassembling the hotend and carefully assembling it again, especially paying attention to the heatbreak and the heatsink in the process. 

If the fixes we have mentioned above did not help to fix the problem, we would also recommend going through the steps below if any of them is applicable in your case for the purposes of eliminating the possibilities:

  • Try to print at a time when the ambient temperature is low.
  • Print without an enclosure if possible; else, try to use a filament that you can print without an enclosure.
  • Try to print with a PTFE-lined hotend instead of an all-metal one.

In the case that you’re entirely stuck and unable to resolve the heat creep problem of your Ender 3, our recommendation would be to replace the hotend with a new one or use the stock hotend if you have replaced it before.

How to Identify the Heat Creep Problem in the Ender 3 (Pro/V2)?

The heat creep issue may not be easy to identify at first due to its somewhat cryptic nature compared to many other problems in the realm of 3D printing, which is why ensuring that the problem you’re facing is actually heat creep is vital before moving on the solution process.

The most apparent sign of the Ender 3 heat creep problem is a considerable loss of quality on the 3D printed model due to the filament melting earlier than required, making the model look like a melted mess, especially in areas where the temperature of the hotend at is at its highest.

In more severe cases, the filament that prematurely melts within the upper parts of hotend can also cause the hotend to become clogged, and unlike a standard nozzle clog where the plastic gathers around the nozzle, in this case, the plastic will collect in an area that is closer to the upper regions of the hotend.

Wrapping Up

While heat creep is a silent and critical problem that will cause your prints to fail without giving too much away about what exactly is happening, especially at first look, resolving it shouldn’t be too complex once you know the real cause behind it.

To quickly recap, anything that causes the heat to reach the filament in the hotend before the filament makes its way to the heatbreak can be a culprit behind the Ender 3 heat creep problem, with issues like too high hotend temperature and too little hotend cooling immediately coming to mind.

While there is some technical complexity in applying some of the necessary solution steps, we can consider the heat creep issue to be pretty easy to narrow down as the bulk of the factors is related to the hotend itself.

Happy printing!