Wednesday, July 7, 2010

Good News, Bad News...

I will start with the bad news.  I broke my new nozzle. :-(

I am not sure what I am doing wrong.  I wrapped it once hooked it up and it seemed to not be heating up very well.  When I took it apart and looked at it I realized that I had wrapped the nichrome too close to the tip.  I was directly heating the thermistor, and managed to crack the glass bead. :-(

You can see how close to the tip I wrapped the wire in this picture.

I then re-wrapped the heater with the nichrome more in the middle.  And once again tested pushing the PLA through by hand first.  It had some back pressure but I could push it through.  So I hooked it up to the extruder and tried running it.  It seemed to have some trouble (like it was not hot enough) so I turned the heat up from 180 to 190 and the filament started coming out like it did with my first nozzle (before it had failed).  Then disaster... the nozzle slid out right before my eyes... it just slid all the way out, even with the pipe clamp on the PLA.  Looking at the threads of the brass one can see that they are filled with PLA...

I guess I will have to try again.  But it will probably be a few days as my schedule is getting a little full...

Now for the good news. (actually two bits of good news :-)
First my black-light post was picked up on Fabbaloo and Make: Online. Very cool :-)

Second I designed a wiring block for my Mendel that makes wiring the extruder to the boards much easier.  Which has turned out to be a good thing since I have had to rewire several times and still may have several more...
As you can see it just press fits on the three screws closest to my boards.  The coat hanger supports and guides the wires to the x carriage end.  The idea being that the wires will ALWAYS be out of the way that way.  I caught my stepper wires on my spool holder before... which can't happen with this setup.
You will notice that there is a 9 position terminal block, 4 are for the stepper, 2 for the heater, 2 for thermistor, and the last is just a spare ground.  I also ran a 6 conductor ribbon cable for LEDs (five circuits with one ground).  These are connected to the pins at the front and back: 2 circuits front, 2 back, and a third both front and back.  Watch for some lighting in the near future...

I have not posted formal directions but someone could make one from these pictures.  Once Willow is running again I may write up some directions.


  1. I have the same problem with the PTFE barrel..
    Managed to break 2 of them .. both pushed the barrel right out!

    Perhaps you should try and put the hose clamp a bit lower!

  2. Did you wrap a few layers of PTFE thread seal tape around the brass before you inserted it in the PTFE? That normally helps alot

  3. the PTFE barrier's melting point is around 250C, so I'm not sure that you have accurate temperature readings, or something.

    Typically if you don't have enough pressure to extrude, the drive gear will strip the filament (at least with ABS, maybe PLA is stronger?), so nothing will break. But at 190C, your PTFE barrier should be solid, and definitely shouldn't be stripping anything or sliding out. Are the threads drilled correctly? is the barrel the correct size?

  4. I never managed to get my PTFE barrel to work, ended up designing something more robust.
    Give it a try!

  5. Lols, people should learn by now not to use PTFE, for instance i'm using BakeLite, bought a frying pan for its handle and had it turned in a lathe into a thermal break.

    I've had the thing up to 300 degrees C without any problem

  6. Thank you all for your suggestions. I think I will try rebuilding my PTFE heater again, but I am leaning strongly toward some of the more robust solutions for a more long term solution.

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