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I have a Creality Ender 3 Pro printer, and just installed the Micro-Swiss All-Metal Hotend for CR-10 S Pro. After installing following the video instructions by Micro Swiss and Teaching Tech, I set it to print a good old Benchy.

Was working fine, until about half way through it blocked up.

The stuck filament appears to be trapped, even when heated to 230 °C, which makes me think it may have melted into a gap somewhere and cooled creating a block. I am using Filamentive PLA.

My questions are a) how should I remove the filament fully without damaging the thermistor and heating element and b) what do I need to do to avoid jamming?

Any suggestions?

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    $\begingroup$ All metal hotends are different in handling than lined hotends. You need to dial in your settings. For example you need to run them on different temperatures, retraction is different. You might need to dissemble the hotend to thoroughly clean it. Also, they need to be hot-tightened... $\endgroup$ – Trish Feb 8 at 23:21
  • $\begingroup$ @Trish thanks. All good points. I have a range of temperatures up to 235 C (above that seems too high - in fact, the boden tubing seemed to have started melting at the top when I managed to get it out during the first test). I hot-tightened. Any suggestions on what to use to clean, and how to get the filament out? $\endgroup$ – Arty Feb 8 at 23:29
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    $\begingroup$ Bowden can't melt at any temperature you can reach. It may start to chemically break down once you get over 250-260 but that's it. $\endgroup$ – R.. GitHub STOP HELPING ICE Feb 9 at 5:10
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The so-called all-metal hotends are sold as upgrades to the lined hotend versions. Actually, they are not. These are different type of hotends that can be used printing at higher temperatures. However, PLA printing at high temperatures is not advised. You rather choose to print a slightly lower temperatures.

What do I need to do to avoid jamming?

This requires that you change the way you operate the hotend/extrusion process. Why? Because the hotend is not lined, the heat from the heating block can more easily creep up the hotend into the coldend. This requires that you have a good performing cooling fan cooling the radiator fins of the coldend. Furthermore, because of the higher temperature (as the liner is not shielding the heat to the filament), the melted and the softened length of the filament in the hotend assembly is substantially longer. This means that excessive retraction lengths can cause soft material to be be pulled back too far. Knowing that the filament diameter is smaller than the tubes or the diameter of the heatbreak, this soft and molten filament can get stuck in the increased diameter section of the heatbreak.

But if it gets jammed,

How should I remove the filament fully without damaging the thermistor and heating element?

You need to ensure that enough heat gets into the hot and coldend to soften all the material. Currently PLA is stuck in the assembly. To soften all the material I would diasble the cooling fan of the coldend and heat up the heater to a temperature of 210-220 °C and keep this warming up for several minutes to allow heat to creep up. You can now try to push the filament through. If this fails wait longer or increase the temperature by 5 °C increments at a time. Too high temperature can cause filament to cook and carbonize. making it effectively harder too clean. If this fails, disassemble the hotend while hot (be careful!) and clean the individual part mechanically or use heat.

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    $\begingroup$ +1 for "not an upgrade", and more if I could. Pretty much everything about this answer is great. $\endgroup$ – R.. GitHub STOP HELPING ICE Feb 9 at 17:23

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