Monday, June 28, 2010

Extruder Heater Problems...

I had my first major problem with my extruder.  I had been having strange flow problems.  As I tried to diagnose this I noticed that I had some PLA leakage and then suddenly my nozzle was jamming into my build plate!!  Upon closer examination the nozzle had slipped out about 0.25"!!!

The polyimide tape was wrapped right up to the insulator before.

This picture clearly shows the threads that are white (from the teflon tape) that have jumped out.
After taking it all apart there was a large blob of PLA stuck in the insulator.

I was never very happy with how close the nichrome had to be to the insulator and have read several articles about alternative methods of holding the heater to the nozzle.  So I thought I would try an alternative with a T-nut and a brace. Here are some pictures of this experiment.
I needed some sort of plate at the extruder to hold the screws to the plate by the heater.  So I made this adapter plate that also turned my extruder.  Because my insulator/nozzle combination was already marginally long enough I made a short extension from wood.

I then bolted it all together and re-wrapped the heater and tried it out.  I had concerns about the heat-sink that the aluminum plate created.  These concerns I believe were warranted as the plate got quiet hot.  I was able to get the nozzle hot enough to manually push the filament through but had trouble trying to push it through with the extruder.

I still am not happy with how short the heater section is and do not like how hot the plate and the screws up to the extruder get.  So rather than continue to struggle with this design I bought a new nozzle set (from reifsnyderb) and am going back to a more traditional design for now.

For now I am out of commission but hope to have it all back together soon and start printing again.

1 comment:

  1. I had this identical problem, which is aparently a known issue with different types of PTFE rod having different ridgidity/stiffness. I fixed it simply by putting a hose-clamp around the thermal barrier ( like you did), and nothing else. I put the clamp further from the hot ( perhaps 10mm more than yours), so it's clamping around the section of PTFE and threaded rod that is cooler, as this seemed a better way to me to stop the threaded rod being dislodged. ( the clamps is near to the area of pressure build-up).
    good luck!