Thursday, July 29, 2010

Mixed Emotions....

After several nozzle failures I have a design that seems very robust and made several acceptable prints.

But then more trouble...
Most of the PLA prints have decent shells but the infill is spotty at best.  The extrusion seems to just slow and stop then start again. I tried some ABS I had and that seemed to extruded a little better but the layers did not stick.  I think that is a setting issue but I have not tried adjusting that yet.

As far as the PLA goes I have now tried turning up the heat, down the heat, oiling the filament, manual feeding, adjusting the tension on the Wade's extruder, adjusting the current...  But no luck after the initial success.  The one good thing is that the new nozzle design has not fallen apart and seems very strong.

I have some more ABS so I plan to try adjusting the settings and seeing if I can get the ABS to extrude consistently. (Although I hate the smell and the warping issues with ABS, but I will live with them to diagnose my problem.)

Thursday, July 22, 2010

Happy Printer!!! :-)

I received two more tips after my last post, the first was to try turning up the heat and the second was to turn down the extruder current.

I am not sure about the temperature as I WAS printing fine around 180°C before and I had tried turning it up some (to around 190°C).  But I thought why not try.

The current on the extruder however I had been messing with just before I started having problems a while back.  I did not think that having the current to high would cause problems with extruding, but just might make my stepper run too hot.

So I turned up the heat to 210°C and turned the current back down to as low as I could and still have the stepper turn.

And it prints!!! (here are a few pictures of one of my favorite test parts, the "y_bar_clamp_10off")

Maybe not quite as well as before my problems, but I have also messed with all my speeds and feeds in my efforts to fix things so I probably need to tune them back in for the new nozzle.

Thank you for your helpful suggestions Buzz & Tony.

Wednesday, July 21, 2010

Willow is still sad :-(

The extruder skips and seems to have a lot of back pressure (no matter what nozzle combo I put on).
I guess it is time to get some help from my friends at Metrix Create: Space, but maybe not until the end of august, after my brothers wedding (since I am making the dress and a kilt...)  :-(

Wednesday, July 14, 2010

Continued extruder problems...

I cleaned all the parts up and rebuilt my extruder.  I even drilled the brass a little deeper to minimize back pressure.
I also was careful to ensure that the heater wire was not to close to the thermistor and I placed the pipe clamp lower on the PTFE.

Once I had it wrapped I used a high quality contact thermometer to check the brass temperature.  The computer and the thermometer matched at both the tip and the base of the brass.

I then proceeded to hook it to the extruder and try to extrude PLA.  It still seemed to have a lot of back pressure.  I read some online and discovered some people have been using oil to lubricate the filament. I tried this and it seemed to help, so I started a test print only to have the brass pushed out of the PTFE again...

I may have damaged the PTFE to much the first time it slipped out.   I have discovered a few things and have some plans for going forward.
  1. Wade's Extruder can easily put out more torque than the heater can handle.
  2. I was somewhat lucky with my first heater.
  3. I need to be much more careful testing heaters to ensure I don't continue pushing with excess pressure.
  4. I want to get PTFE and brass rod so I can make more parts myself.
I have also made a simple test fixture to hook heaters to and push filament through by hand and see what I can do to reduce back pressure.

I hope to be printing again soon...

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.