Printer has trouble holding temperature

There are a lot of reasons a printer could have trouble getting to or staying at the right temperature. Here is a breakdown of the possible scenarios and their solutions.

• The extruder reaches a certain temperature and then immediately stops heating (dropping back down to 0 °C).
  • This is most likely due to some kind of failsafe being triggered in the firmware. To see if this is the case, look for any errors being reported in the G-Code Terminal. Here are a couple of possible conditions.
    • Maximum temperature exceeded. This is most likely if you are trying to go above 240 °C. The firmware will report a MAXTEMP error and shut the heater off to prevent damage to the hot end. If you have upgraded the hot end and are certain that it can reach higher temperatures without risk, then you may raise the temperature limit in the firmware configuration. This is covered in our E3D installation guides.
    • Intermittent thermistor connection. Sometimes, if the wires going to the thermistor are broken, they will still make contact when the printer is cool but will loose contact due to thermal expansion when the printer heats up. In this case, the firmware will report a MINTEMP error and shut the heater off. Carefully inspect the thermistor wires for continuity and make sure all connectors are secure. 
    • Thermal runaway protection triggered. Some printers will shut the heater off if it fails to reach the correct temperature after a certain amount of time. This is a safety feature that prevents the hot end from melting itself if its getting bad readings from the thermistor. Make sure that the thermistor is operating correctly. It should read about 22 °C at room temperature (72 °F). It may also be that your heater is underpowered for some reason (see below). Kossel Pro: The stock firmware on this printer is known to falsely trigger thermal runaway protection when switching from one temperature to another. For example, when switching from 210 °C to 235 °C. To get around this, always switch to 0 before setting a new temperature.
• The temperature rises rapidly to just below the target, but struggles to get up the last few degrees.
  • This is undoubtedly due to bad PID values. PID (Proportional Integral Derivative) is the control algorithm the printers use for holding temperature. The parameters for this algorithm control how fast the printer reaches the set temperature and how well it holds that temperature once it gets there. These parameters depend on the thermal characteristics of the hot end. If you have upgraded or made any changes to the hot end recently, you should run PID tuning again. See our guide on PID tuning.
• The extruder heats slowly until it levels off at a low temperature after several minutes.
  • This means that either your heater is underpowered or is receiving too much cooling.
    • Make sure that you have the right type of heater cartridge. If you use a 24V cartridge in a 12V printer, it will be significantly underpowered. You can check by measuring the resistance across the cartridge using a multimeter. A 12V cartridge will have a resistance of about 4.8 ohms. A 24V cartridge will have a resistance of about 23 ohms.
    • Some printers, like the Robo R1, have a black rubber insulator over the heater block. Make sure that the insulator is in place.
    • In some cases your layer cooling fan may be inadvertently cooling the heater block. Try reducing your maximum fan speed settings, or aiming the layer fan away from the block.
    • Check the voltage provided to the heater and make sure it is either 12V or 24V (whichever your printer uses). Only check the voltage when the hot end is cold and has just start warming up. This makes sure that the controller is applying full power to the heater. If the voltage is low, you may have an issue with your power supply. If your PSU has a 110/220V switch, make sure it is set right for the country you are in.
• The temperature fluctuates wildly (±10 °C) and never stabilizes at the correct temperature, or...
• The temperature jumps up way too high at first, but eventually drops back down to the correct temperature.
  
  • These are others symptoms of bad PID tuning. See above.
  • This can also be caused by your heater being overpowered. In this case the temperature is rising faster than the controller can react. Make sure you are using the right heater cartridge. If you use a 12V cartridge in a 24V printer, it will be significantly overpowered. You can check by measuring the resistance across the cartridge using a multimeter. A 12V cartridge will have a resistance of about 4.8 ohms. A 24V cartridge will have a resistance of about 23 ohms.