Leaking Heaters...

My current heater was working very well extruding PLA at 230C, which seems a little high but the parts are coming out nicely.  It had started leaking like many of the others I have seen with PTFE insulators.

Then it finally plugged up...  I tried cleaning it out without disassembling it, but this did not work.
I then disassembled the hotend to find the plug and remove it.  During this I discovered that the wood retainer I had been using was starting to char away.

So I began work on a new design that I had been thinking about for a while.  This is based on the BfB hotend that many people like but can be built with only a drill press, hacksaw, rotary tool (Dremel), and belt sander (I plan to post directions soon).

I also found an excellent source for bootlace ferrules.

You can buy these at craft stores in the jewelery section.  They are designed for crimping necklace cords and this bag cost $2.99.

So far I have done hand push tests and can easily push filament at 165°C.

Now I have to change out my x carriage for  larger one (http://www.thingiverse.com/thing:3594, which I already printed before my failure).

Some Old School Fabrication and a Parts Delivery

As I have mentioned before, my brothers wedding is coming up next Saturday and I am making the dress, kilts, and belt buckles.  Here are some pictures of the progress so far. (and more over here)

(The design was drawn by me and embroidered by my mom)

(Preparing the skirt to be hemmed)

(Serging the hem before sewing on the horse-hair braid and turning up the final hem)

The dress is almost done and I am going to start my kilt tomorrow (My brother and his friend are making thier own).  It will be a busy week...

On RepRap related news I recently received an order from MacMaster-Carr and once the wedding is over I hope to get back to debugging and building some new heater designs using my new drill press.

(1/4" brass threaded rod, acorn nuts, tee nuts, 5/8" PTFE, and ceramic insulation)

(6' each of 1/4" PTFE and 5/8" aluminum)

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.)

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.

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...

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.