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I cleaned up my Flashforge Creator Dual tonight, and loaded some transparent ABS prepping for a print. The filament extruded fine, then started to wiggle, then became fine again. Hot end is 0.4 mm and was heated to 230C. What sort of steps should I take to troubleshoot the issue? Has anyone seen this before?

Photo of extruded filament exhibiting wiggles

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    $\begingroup$ Do you actually have a problem while printing? How filament comes out during loading/unloading isn't necessarily indicative of how it comes out during printing. I don't think you actually have an issue you need to worry about. $\endgroup$
    – Tom van der Zanden
    Nov 15, 2016 at 6:57

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It might be similar to this issue (where teflon tube wasn't installed what caused softening filament inside heatsink)

Please check if your extruder is equipped with proper pipe inside (inner pipe diameter).

But the most probable cause is that a pipe had slide out so filament has enough room to get soft and to form such shape going out. Please take a look also here.

Here is a situation and its evolution. enter image description here fig. A: 1. filament 2. teflon tube (well positioned) 3. heatsink 4. nozzle 5. extruded filament

fig. B: 6. slided out teflon tube 7. empty space (heat)

fig. C: 8. bent filament

fig. D: 9. teflon tube 10. no extrusion

How it happens?

Teflon tube is usually well positioned so everything is fine in most cases. Sometimes because of poor filament (not-constant diameter) or because of bends on filament, teflon tube is slided out os its place while retraction. It goes on and on, up and up (fig.B)

Once tube is extended that much so filament starts to bend in empty (heat) space (fig.C) It increases the effect of sliding out teflon tube just because of bend (it works as a hook). But it can still work. Teflon tube can even be pressed back inside the nest.

Now because the empty space is heat then filament starts to melt (for example when there is no extrusion for a second) it becomes soft. When filament is soft enough it doesn't extrude as the force to press it throught the nozzle is too high for such soft material so filement definitely stops extruding itself. (fig.D) This situation cannot be fixed automatically. There is a need of user intervention.

Now you know why some extruders has a rim (or collar) on the top of heat barier tube. It secures a teflon tube from sliding out.

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  • $\begingroup$ Reseated the teflon pipe, and loaded about a meter though the hot end. The problem is gone. $\endgroup$
    – EvilTeach
    Nov 22, 2016 at 2:49
  • $\begingroup$ @EvilTeach good to hear you've managed that. good luck $\endgroup$
    – darth pixel
    Nov 22, 2016 at 6:29
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    $\begingroup$ @EvilTeach I've added a picture and description why it may happend again :P $\endgroup$
    – darth pixel
    Nov 22, 2016 at 7:25
  • $\begingroup$ @darthpixel Perhaps that wasn't the best way to put it. My apologies that I was a bit harsh. In any case, this is now a very good answer (though perhaps you could expand on "similar to this issue" to "similar to this issue, where the teflon tube was not installed..."). I'm actually surprised that the teflon tube was the cause here, as from the photo it looks like the wiggles appeared after extrusion and not before. $\endgroup$
    – Tom van der Zanden
    Nov 22, 2016 at 11:25
  • $\begingroup$ @TomvanderZanden (i also apologize) it looks like filament becomes a bit soft before extrusion (maybe not quite constant) and it causes it to cool down in such strange way (shape) :) it may be conected to hot end heating cycle. So it wiggles and not-wiggles. Maybe when filament gets a bit soft it is compressed a bit on nozzle entry. That's just spoken thoughts. $\endgroup$
    – darth pixel
    Nov 22, 2016 at 11:32
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If the filament displayed in the photo is the result of unimpeded extrusion from your nozzle, you don't have or have not described a problem. Filament extruded from a hot nozzle will react to many things. If a slight air temperature change is created on one side of the extruding filament, it will cool faster than the other side and curve in the direction of the cooler temperatures.

If there is a bit of old filament on the tip of the nozzle, it can cause the filament to hook back on itself, creating an interesting squiggle of filament before the weight is sufficient to cause it to drop.

A typical 3d printer problem is related to the results of a print or an obvious mechanical failure. Wiggly extruded filament is not a symptom of a looming failure, unless you have other indicators.

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