filament get stuck

It happens quiet often that the filament gets stuck and the cold extruder is not able to push the filament any more.
To get out of this bug, I stop printing the part and I push strongly manualy the filament until fluid PLA comes out of the hot extruder. Then I check through the Pronterface interface if I can extrude 5 mm of filament. and start again to print from scratch.
As this bug occurs quiet often, I'd like to understand the root cause of it to solve it.
One of my suspect is that I still don't have any spool holder. So maybe after a while the filament gets too twisted and for some reasons generate this bug.

Are there any pictures / design of the hotend anywhere ?

Specifically, what kind of nozzle is used and does the hotend include a fan on the thermal barrier (may not apply depending on the design).

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Most of my technical comments should be correct, but is THIS one ?
Anyway, as a rule of thumb, always double check what people write.

The hotend includes the fan for the thermal barrier.
Anyway, since I use this basic filament holder, I haven't got any stuck issue. The supposed explanation is that when the filament is lying on the table, after consuming several loops of filament, it becomes twisted. This deformation of the filament sticks it.

There are several possibilities :

-printing too fast (the brass insert that grip the filament need to be used some weeks before going higher than 30mm/s)
-not enough pressure on the idler (tighten the bolt, but if there is already small marks of bite on the filament you don't need to)
-temp too low (but if already at 200°C it shouldn't be that)

(or a mix of the three)

Or as you may have found, if the filament is too much tangled, that can cause some troubles ^^'
(maybe it can rip on the sides of the pneumatic fitting entrance and that require more force to goes in).

@deuxvis, there is some pictures on the wiki, but it's basically the same hotend as on reprappro machines

[reprap.org]

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about // liberapay // flickr // wiki // thingiverse - github

I have the same issue and someone recommended this extruder: [www.hotends.com]
I tried the solution on this thread and it did not help unfortunately...
Many thanks,
A

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Arthur Mamou-Mani
Architect, AAdipl, RIBA III
Tutor DS10 Westminster University
Mamou-Mani.com ¦ WeWantToLearn.net