Tuesday, December 18, 2007

Moving Forward

I didn't like the profile of the drive screw. It was too high overall and one end stuck up more than the other. I used a heat gun to heat up the CAPA and a pair of pliers to push it down.

Once it cooled down a bit, I assembled the extruder without the barrel. I used the longest cap screws in the kit to clamp the two halves together, using the tubing as springs. I fed some HDPE through it, just to see if it'd push filament. Did this first with the motor hooked up to 2 AA cells, then switched to the extruder board.

Ran into problems with the RepRap host app. Serial errors. Turns out that the extruder board (or at least the firmware I'm using) gets very unhappy if a) the thermistor cap comes loose or b) you plug the heater into the thermistor connector.

Once I got that working, I determined which way the motor leads should hook up so that the extruder pushes the filament in "forward".

Since I had everything hooked up anyway, I added the heater barrel to the extruder. The clamp wouldn't tighten down quite enough so I wrapped the end of the barrel in electrical tape.

I ran a piece a filament into the barrel until it started to complain and then fired up the heater. Couldn't get the temperature above 140C, though. May need to re-do the heater barrel. Or maybe it just needs a bit of insulation wrapped around it.

Anyway, here's some video of the drive screw pushing HDPE filament.


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