Filament Clog | How to resolve them

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Overview

Whenever speaking about a filament clog the following scenarios are meant:

  1. something is obstructing the path from extruder to nozzle (mostly within the hotend to the nozzle) like metal parts, old filament or something else
  2. the heatbreak was clogged because the filament could heat up enough to melt the filament before reaching the hot-end thus being stuck. The latter is usually caused by retractions -> whenever the system is quickly pulling filament to prevent oozing / stringing. Because the heatbreak might be hot enough to soften/melt the plastic outside the heating-area (hotend) this retraction could then create a blob of filament stuck within the heat-break. Once this was caused one will not be able to print.

Fixes:

there are some tips / tricks that could help to resolve a clog within the heatbreak/hotend:

  1. Using something (paperclip or drill bit etc.) to heat and poke through the assembly Heating up the component to use will allow to melt the plastic that is obscuring the path. Denote that it should be smaller than 1.7mm in diameter to fit through.

  2. Heating up the heatbreak+heatsink to soften the filament link

Simply: Remove fan for the heatsink, heat up the hotend/heatbreak until it reaches a temperature where the plastic should soften/melt. Then poke it through with filament or something fitting through the tube.

This method is taken from the given post:

I have had PLA jamming in the heat break for various reasons. I am using a simple method to clear the heat break. I am sharing the method with you all. I’d love to get some thoughts on the safety of this method, possible drawbacks, pitfalls, etc.

My objective is to clear the heat break with the least possible disassembly. I did not want to remove the heat sink, nozzle, hotend, etc.

As a first step, I unscrew the heat sink fan and move it away. I also move away the cooling fan and the PINDA probe. Next, the extruder cover is removed. This completely exposes the heat sink portion. I move things away to make sure that all the sensitive items are as far away from the heat as possible. At this point, things look like this :

Remove the extruder idler screws. At this point I push a length of filament as far as possible through the PTFE tube, take it out, and reconfirm that the block is in the heat break.

By careful measurement, it should be possible to figure out exactly how much filament is stuck inside. Note that the E3D design is freely available - engineering drawings with dimensions are at http://wiki.e3d-online.com/wiki/E3D-v6_Documentation . I haven’t done this exercise, however.

Next, heat the nozzle to 210 degrees. Place a little book or piece of cardboard over the heat bed. If anything hot falls down, this will ensure that the heat bed is not impacted.

Wait a couple of minutes. Regularly keep sensing the temperature of the heat sink. Exercise care to ensure I don’t burn up any fingers. Once think the heat sink is hot enough, try pushing the filament in, through the PTFE tube. Note that the whole heatsink does not need to be hot - only the bottom portion closer to the heat break. That’s where the filament is stuck.

In a few minutes (2-4 minutes maximum - I did not time it), I am able to push the filament down with minimal effort and do some manual extrusion.

I now pull out the filament in quick motion. I issue a “Preheat | Cool down” command. The heat sink is in contact with ABS all the while, so ensure that you don’t keep it hot for any longer than absolutely required. You certainly don’t want the ABS to melt !

After everything cools down, push a filament through the PTFE tube as far as possible, check that the length that you are able to push in is much more than earlier - and something that looks enough to reach the heater block.

If you reached here, congratulations! Your heat break is clear. Put back everything back as it was earlier. Move the Z axis as far up as possible. Issue a Z calibration & check everything is still in order.

Preventing:

  • printing with hotter temperatures
  • reducing retraction (for all-steel heatbreaks - made for ABS - its recommend to stay below 0.4mm)
  • install better fan to increase cooling capabilities for the heatsink