Extruder stuck...again...

Hi all. I have been having the same problem over and over for the past couple of months. I am using Wade's extruder with a modified makerbot hot end (PEEK), After finishing my machine and testing it out, I began to have issues with the filament (ABS) refusing to go through the extruder at some points. Basically after a few minutes of printing, filament no longer flows while the stepper motor and hobbed bolt still spin. This leads to the teeth ripping up the ABS which forces me to take apart the extruder and clean the teeth in the bolt. Initially I though the problem was the hobbed bolt. I originally bought one that had very fine teeth with a very shallow cut. I then bought a bolt from eckertech which has very deep teeth hoping that grip would be improved a lot which would fix this issue. After installing and trying again, I've noticed the same problem happening. Plastic just doesn't want to flow through the extruder sometimes. This happens sometime between 5 and 20 minutes into the print.

I have the bearing assembly that holds the plastic against the teeth cranked down hard against the plastic as recommended. Does anyone have the same issue? I am running my printer at a pretty fast speed and have the extruder temp at 245C which I feel is very hot. Would running at a hotter temp help?

Thanks!

Edited 1 time(s). Last edit at 01/15/2011 09:04PM by hazuki.

Seems like the melting zone wanders up the thermal barrier during the print, and gets longer, until its too long. Mine mostly got stuck after a short extrusion stop into the print. During this short stop the melting zone gets a bit longer. My solution was too cool the thermal barrier, so the melting zone couldn't wander far up and stays short.
In the melting zone abs is above its glass transition temperatur, in an amorphus state, neither solid nor fluid. It can deform but it can't flow. So it deforms into the thermal barrier but can't flow through.

Interesting. I'll see if I can put some fans to cool the barrier. Thanks

maybe your plastic is melting too far up the filament path, expanding into whatever gap it can and getting stuck,

or maybe your hot end is not hot enough, not melting the plastic in time to extrude it.

Maybe your heater block is too close to the tip and only the plastic already sitting in the hot metal has enough time to melt fully so after all that extrudes you get stalling.

try to extrude the filament by hand, see how it feels and maybe try hotter or cooler, make sure it doesn't start stalling just pushing through by hand before trying with the bolt.