Sometimes prints fail and other times they fail and try to take the world down with them. If your print head looks like this:
You might despair of 3D printing ever again. But there can be hope. If the connectors are not broken (sometimes they can be pulled from the housing but still intact), the extruder hot end can be resurrected from its tomb.
Please keep in mind that hot ends and build surfaces are consumable. This trick should help some people restore life to their extruder but it still might require replacement.
Make sure to do this in a safe area and wear proper safety equipment. We will be dealing with hot molten plastic, hot metal, and high air speeds. Always point the heat gun away from your body to direct the plastic safely.
The only tools needed are a heat gun and something to grip the needle. Preferably something akin to vise grips to allow better control and reduced chance of dropping. Hex drivers and a knife or razor will be needed for more advanced cleaning but are not required.
If the plastic block is large enough, more than what can be seen in the images, it’s best to cut off parts of the plastic during this heating process and before trying to melt it completely off the extruder.
After removing the extruder hot end from the Series 1, grip the needle tube that sits inside the extruder clamps with the pliers. Using the heat gun, gradually and evenly warm the plastic. A good idea is to hold the heat gun 6-8 inches from the hot end.Take your time as we don’t want to melt the crimp housing or damage the wires.
Gradually, the plastic will soften and begin to fall away. At this point, it is best to direct most attention to the wires, if they are also encased. The metal parts conduct the heat well and will be freed first leaving all the weight to fall on the more delicate wires. Should this persist or turn out to be too heavy, they can break.
Once the plastic falls away, the hot end is ready to use again.
Should you find the temperature not stable or still having issues, then further cleaning is needed. The thermistor cable and block contact faces can be cleaned to improve the thermal contact. Be careful to not twist or strain the cables when disconnecting the thermistor or re-assembling it. They will break or shear unexpectedly. A hex head screw holds the thermistor temperature probe onto the heater block and is likely clogged with plastics.
Using the heat gun, carefully warm the hot end and clean out the screw head. Once the screw is removed, the temperature sensor can be separated, the heater block, and the thermistor casing scraped clean with a blade.
Heater Block Cleaned Thermistor Cleaned
After reinstalling the thermistor, apply pressure to the flat tab and not directly onto the large thermistor bead housing, it can break.
Hotend now re-installed and operational
The following videos show how I cleaned our hot end and made it operational again.