Understanding how to troubleshoot and repair your Creality 3D printer hot end is an important skill to ensure your printer continues to run consistently and produce quality results. This article takes a deep dive into the standard Creality hot end, looking at how the hot end works and how to troubleshoot problems with extrusion and other printing issues. The hot end we’re discussing in this article is used on the Ender 3, CR-10, and all other Creality 3D printers, but the information is applicable to most 3D printers from other brands as well.
If you have experienced any of these issues with your 3D printer, you most likely have an issue with your hot end:
3D Printer is jamming frequently
Your 3D printed parts look inconsistent or under-extruded
You are seeing Thermal Runaway errors
The 3D printer is making a clicking sound when you print
We’ll discuss the causes of each of these issues, and how to fix each one to get your 3D printer back up and running and producing great results.
Introduction to the Creality Hot End
Before starting, take a minute to find the hot end on your printer. The same hot end design is used on the majority of Creality’s 3D printers, with a characteristic red heat sink. If you follow the path of your filament, you will see that it first travels through the extruder on the side of the printer, which is what pushes the filament to the hot end. Next, the filament travels through a PTFE tube to the hot end and finally is deposited on the print bed to form the printed part.
Before getting into the inner workings, it is also important to understand how the hot end works on a high level. Put simply, the hot end is the component that melts your filament so that it can be deposited layer by layer to build a 3D printed part. While this sounds simple, there’s more than meets the eye, since the hot end must maintain a specific temperature to ensure quality printing. Another important job of the hot end is to make sure the filament melts only when it reaches the nozzle, but stays cool and solid before that point.
The blue box shows the location of the hot end on your printer.
The hot end after the enclosure is removed. The red heat sink helps keep the filament cool and solid until it reaches the heater block and nozzle, where it quickly melts.
Once the hot end is heated, the filament is melted by the nozzle and deposited onto the print bed layer by layer.
The Hot and Cool Zones
The hot end has two distinct temperature zones, the lower hot zone, which is heated by a heater cartridge, and the upper cool zone, which is cooled by a heat sink and fan.
As filament enters the top of the hot end through the PTFE tube, it stays cool and rigid as it moves through the cool zone. As the filament travels into the hot Heat Block and Nozzle, it rapidly heats to the point of melting before being deposited onto the print.
You’ll notice that the Heat Break, which surrounds the PTFE tube and spans both zones, is very thin in the empty space between the hot and cool zones. This minimizes heat transfer to the cool zone. Some heat still escapes to the cool zone, however, so a Heat Sink and Hot End Fan (not pictured) are also needed to keep this area cool.
This cross-section shows the components of the hot end
You may be asking: why is it so important to keep the filament cool as long as possible before it reaches the nozzle? The answer is to prevent filament jamming in the hot end. If the filament begins melting or softening too soon, the pressure of pushing the filament will cause it to widen. You don’t want that. The friction of this widened filament against the walls of the PTFE tube causes the filament to jam in the hot end and fail to print.
How the Hot End is Heated
You’ll notice that there are two sets of wires leaving the side of the heat block. These wires lead to the Thermistor and the Heater Cartridge, which work together to ensure the hot end stays at the desired temperature:
The Heater Cartridge generates heat when supplied with power by the printer. This heat spreads through the heater block and the nozzle, and eventually to the filament. The larger red wires connect to this component to the printer mainboard.
The Thermistor measures the temperature, which the printer controller uses to turn off the heater cartridge once the temperature exceeds the set point. The smaller white wires connect the thermistor to the printer mainboard.
These components are both removable and can be replaced if needed. The thermistor is held in place with a small Philips head screw, while the heater cartridge is secured with a small grub screw near the nozzle. We’ll discuss how to replace these in more detail later on.
Common Issues with the Creality Hot End
Now that you have an understanding of how the hot end works, let’s look at what happens when things go wrong. In this section, we’ll take a look at some common symptoms and describe the root cause and how to fix it.
3D Printer does not heat up to the set temperature
If the 3D printer is getting close to the desired temperature but not quite there, for example reaching 165-170C, ensure that the hot end is insulated with a rubber hot end sock. This helps keep the heater block hot, and makes sure the hot end fan doesn’t cool the heater block. If you are still seeing issues with reaching the desired temperature, calibrate the PID tuning to make sure the printer’s controller is correctly regulating the temperature.
3D Printer temperature readings are incorrect
If the temperature is not rising at all and staying around 30-40C, it is likely that the Heater Cartridge is not functioning correctly.
Resolution: Follow steps to repair the Heater Cartridge in the Solutions section of this article.
If the temperature reading is clearly inaccurate, such as a reading 0C or -15C, the issue is most likely that the thermistor is disconnected or defective.
Resolution: Follow steps to repair the Thermistor in the Solutions section of this article.