Sunday, 3 March 2013

We have extrusion! I repeat, we have extrusion!

Spent several hours at FabLab setting up and testing my extruder head. (during Open FabLab, so I got to explain it over and over again, in German). And I got it to work, temperature sensing, stepper motor and all. Even though I had to make the temperature sensing by hooking up a resistor and a capacitor by wires. It works, dammit!

Here's a video overview of the setup (sorry about the noise, it was Open FabLab at the same time):

Ran it three times (until I ran out of filament) running the motor when lower than 30, and stopping the heating when it got down to 20. This made some rather random structures - I found I could make wavy things by moving the structure by hand.

And heeere, ladies and gentlemen, are the amazing first three extrusions from The Monster (or the head of it, at least):

The first two were just left alone, but for the third one I started to move it around to get it from clumping up at the nozzle. I found that by moving it about a centimeter at a time, I could make little waves of plastic. Maybe it'll be the next art form?

Notes to self

Stepper motor wiring (

With stepper pin 9, dir pin 8:
Attempt 1: Left to right: Green, black, blue, red. Stepper motor moves erratically

Attempt 2: Left to right: Green, black, red, blue. Stepper motor moves erratically
Attempt 3: Left to right: Green, red, black, blue. Stepper motor does not move.

Swapping dir and step pins, reattaching GND.

Attempt 4: Left to right: Green, black, red, blue. Stepper motor moves forwards.

As expected, had to add washers under the extruder to make space for the wheel. I might want to laser out a hole later instead, as the washers make the setup less stable.

Couldn't see which way the filament was going. Put on a bit of masking tape, turns out stepping negative was dragging it in.

Reversing them all:
Right to left (when looking at the edge of the board): Green, black, red, blue.

Hooking up the heater as well (yellow is signal, black is ground), but the PWM does not seem to react at all. After standing still for a while, the extruder stepper starts to move on its own! Probably overheating, need big-ass heatsink.

Placed a fan right over the transistor, helps enough that it can move when it needs to.

Needed to get a temperature reading. Using the schematics of, I hacked together the resistor (4.7k)  and capacitor (10uF) with cables. It didn't explode, and I got a temperature rating going from ~900 when cool down to 14 at the warmest. 14 seems to be hot enough that the plastic starts to burn, according to my nose.

For next time

  • Build a small board to hold the temperature metering stuff. 
  • Order the right connectors for the stepper motor driver and wire them properly. 
  • Make wires for the temperature metering. 
  • Decide on a distribution of the available pins (I think I'm running out of digital outs, but could hack an analog out, I suppose). 
  • Need a ground bar, as there are 5 things that need ground. 
  • Get a biiig cooler fin for the last stepper motor.

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