extruder jam

I have almost completed a Mendel RepRap, but am still having some problems with the extruder. I am using the old Mendel extruder without gearing. I have followed the instructions pretty much exactly, but the plastic is not flowing through the nozzle nicely. It requires a lot of pressure to get it through.

I have tried turning the heat up as well is moving the melt zone closer to the tip with no luck. I have taken the brass stud out of the heat barrier and done some testing with it separate and don't see any problems with backflow. Any suggestions...?

Maybe a small gap where the end of the brass meets the PTFE. That is enough to completely stop the flow: [hydraraptor.blogspot.com]

You don't say which plastic, but if it is PLA then the top of the insulator can get too hot causing the PLA to go soft all the way up. Pull the plastic out while hot and see how far up it has deformed.

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[www.hydraraptor.blogspot.com]

alternatively, let it cool down, dismantle the extruder and examine the filament shape. You will be able to see whether it has deforemd...

One of the problems I had was that the inner diameter of my thermal break was bigger than the innerdiameter of my barrel. Under pressure, and given the plastic in the thermal break was softened slightly, it expanded to fill the space (3.5mm) and then jammed when expected to enter my barrel (3.1mm)

How did you fix that? I might be experiencing the same problem wile printing larger objects. While printing the infill the extruder seems to jam in the PTFE barrier

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I had this problem with two nozzles when they got clogged with ABS. The tip got too hot while sitting idle and the plastic hardened. Soaking in acetone which would normally dissolve ABS didn't do anything. So, I used a blowtorch to clean the them per spacexula's youtube video.

brupje Wrote:
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> How did you fix that? I might be experiencing the
> same problem wile printing larger objects. While
> printing the infill the extruder seems to jam in
> the PTFE barrier

I assume you are asking me brupje?

My thermal break was of the PTFE/PEEK variety. I purchased more PTFE and drilled out a hole to 3.1mm (same diameter as my barrel) and replaced the old PTFE containing the 3.5mm hole with the new section.