Wednesday, 25 March 2009

Chocolate Extruder

Although my RepRap isn't quite there yet ( the ABS extruder isn't quite working), I have experimented by building a chocolate extruder from copper pipe fittings and a drill:
From choc_extruder_v0.01

A copper tube and bowl hold melted chocolate which is fed to a drilled-out welding nozzle via an auger made from a drill. The heater is a standard nichrome wire and fire cement, along with a 100k thermistor, connected to the standard RepRap arduino electronics.

Drive for the auger is provided from a Tesco Value 3.6v rechargeable screwdriver. Currently, this is manually operated as I'm having a problem driving the motor using the PWM DC driver.

From choc_extruder_v0.01

The heater took a while to heat up, but the entire apparatus reached target at 60 degrees C. Shoving a few chunks of chocolate in, it melted very quickly.

Extrusion worked much better than I expected: when the motor was off, there was a very slow drip of chocolate through the 0.6mm welding tip (approx 1 drip every 5 seconds).
With the motor on, I was able to extrude a steady stream at several mm/sec and drew some lines on the plate. With the motor in reverse, chocolate was actually sucked back up the nozzle!

From choc_extruder_v0.01

All in all, I'm pretty pleased with the experiment so far. I've written up some construction details at chocolate extruder. A couple of photos are on my picasa album.

Still to do :

  • Drive the motor from the RepRap electronics DC motor driver board

  • Design/build a mount (probably when I get my reprap working)

  • Print a chocolate object!

As soon as I've printed something, I'll post some pics. Might be a little while as I'm trying to get an ABS extruder working first...

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