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Can somebpdy help me as I’m struggling with an issue with my Ender 3 V2 extruder. The extruder is clicking after laying down the 1st layer. The machine had been running with no issues for over 4 months now, I have made various upgrades including BLTouch, tried different hot ends, etc.

I'm mainly printing TPU and have printed it with no issues using a stock Ender 3 V2. However, last week I was changing the hotend back to stock and accidentally snapped the thermistor wiring. I ordered some replacements as below and replaced the thermistor and hot end back to stock.

  • Comgrow Creality 3D Printer NTC Thermistor Temp Sensor 100K for Ender 3 / Ender 3 Pro/Ender 5 / CR-10 / CR-10S

At the same time, I removed the BLTouch, and to be honest, I was finding I was getting just as good prints without it on both a 2nd and 3rd printer I have (both Ender 3 V2’s). This meant re-flashing the firmware back to stock. So effectively, I now have a stock Ender 3, but it has developed this clicking noise from the extruder after the first layer is laid (1st layer is perfect).

I can see the TPU material getting snagged in the extruder when the clicking is occurring, so its clearly not making its way through the hotend and blocking up. Can somebody give any advice as to why though? Everything is fine for the 1st layer but then the problem starts halfway through the 2nd or 3rd layer? I have calibrated my extruder steps (after re-flashing) and they changed from 93 to 114 (which seemed a big change). I'm printing the TPU at 205 °C, and even taking the same file to my other 2 printers has no issue, so I’m not sure what has changed?

If somebody can give any advice, it would be most welcome!

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  • $\begingroup$ You probably have a bed leveling issue. It sounds like you get to a point where there's sufficiently more material already placed than room for it to fit into, and subsequent extrusion becomes impossible (after some give from bed springs, etc.). If not that, if your cooling fan is coming on at layer 2, it might be that you have problem with insufficient heating, and temperature is dropping too much from the fan blowing incorrectly over the heater block. $\endgroup$ Oct 27 '21 at 20:08
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Very likely the clicking is from the TPU slipping in the extruder driver gear.

TPU needs a much slower speed than other plastics, make sure you are using an extrusion speed that is reasonable for TPU.

Assuming you are extruding TPU at the correct speed, there are many reasons that could cause the extruder to get clogged. A few might include:

  • too small of clearance between the nozzle and the preceding layer (or not enough height above the bed for the initial layer)
  • debris in the nozzle (especially if you are switching plastics with a higher melting point or a lower char point)
  • too low of a temperature (i.e., melted plastic is too viscous)
  • gap inside the extruder between the Bowden tube and the hot end causing molten plastic to back up and solidify and bind with the cold filament

Other questions here may answer the clogging issue better.

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  • $\begingroup$ Yes, the extruder drive gear will also click when it can't push PETG through. $\endgroup$
    – Perry Webb
    Oct 27 '21 at 19:25

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