clogged extruder

hi i seem to be having a problem with my extruder clogging up, iv built a renkforce rf2000 and have it up and printing nicely. the problem is after a few min of printing my extruder clogs up, i have experimented with different temps, speeds, settings etc. i cant seem to get the right force needed to feed the filament through the extruder i can push it through manually but it clogs up a short while after. any suggestions will be appreciated 
thank you 


  • edited November 2016
    might be temperature problem.
    i have a RF1000 in office and from my side of view hotends seem to be not very reliable ( 3 hotends/4Kg Filament ).
    Problem is you cannot change thermistor or heater ...

    just take a look at the temperature logs to see if it comes from that side .

    or may be your extruder is grinding the filament? what about that?

    what material , temperatures,  speed , nozzle diameter etc?

    so please some more informations about that
  • thanks for helping. I'm currently using a 3mm PLA-N material with a 0.4mm nozzle. I have experiment with various temps at 210c up to 240c. ive tried different extrusion speeds as well as bed temp. I'm new to this so still learning I have just did a z calibration and going to try to print at a lower temp. I thought it was to do with the extruder motor feed rate but after a few different changes in the settings i discovered this was not the case. each time the extruder blocked up, the motor was still trying to feed the filament so i manually pushed the filament through the extruder which cleared the blockage but only for a short while. my settings for extrusion rate is default at 1 so i raised to 40mm p/s which didn't help the motor just started grinding the filament so i lowered it back down to 9mm p/s which gave me a nice print time , a nice smooth skirt and brim and first couple of layers. after reading your comment and many other discussions i think you could be right about the problem being a temperature problem. thanks again for your help and also if you would have any tips on extrusion rates will be great please.
  • In general you want a small melting zone. That is often a problem with PLA which melts so easy. So going to high makes it creep up the extruder increasing friction until motor does not have enough force. Seen this on several extruders. Often you can fix it by cooling down to 80-100°C and pulling out the filament. With correct temp. you get a big part of the widened part and can even see how far it got wider. Solution is 
    a) printing with lower temperatures so it does not creep up that much
    b) cooling of extruder part above heating zone (not heating zone!)

    Don't know RF2000 - some extruders have a heat barrier to prevent this and some have cooling ribs and a fan on it to even better cool the upper part.

    The problem also varies between PLA vendors. Polymaker PLA for example claims to have reduced this effect so it prints like ABS. One printer that often has this problem prints at least fine with that filament, but it is not really cheap.
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