Web4Deb extruder

From RepRap
Revision as of 21:31, 24 December 2010 by Capo (talk | contribs) (Specifications)
Jump to: navigation, search

Introduction

The Web4Deb Extruder is a functional auger based granular extruder that produces perforated HDPE strips for use in aquaponics. A video of the extruder in action can be found [here]. The blog of the creator (Web4Deb) can be found [here].

The extruder Setup

Specifications

  • The barrel is heated with a length of Nichrome wire and and insulated with what appears to be polyimide tape.
  • The auger is a standard 3/4" wood auger bit (bought a set from Harbor Freight) and cut it down to length.
  • The auger is driven by a wind shield wiper motor which is geared down with a bicycle chain and sprocket.
  • The heating element draws around 16A at 12V (192W) from a computer power supply.
  • The temperature for the extruder barrel is controlled with a Teensy AVR micro-controller.
  • The die is appears to be interchangeable.
  • The extruded HDPE is forced through a set of fan cooled rollers.
  • Two individual temperature sensors are located on the extrusion barrel.
  • The Teensy AVR micro-controller appears to be used to switch one or more relays through a transistor array.


Questions

  • How far does the auger drill bit extend into the extruder barrel?
  • what is the RPM of the auger while extruding?
  • What type of thermistor is used for the temperature sensing?
  • Is it really required that the temperature be measured in two places?

Answer: Two individually controlled temperature zones. The first one is supposed to have a temperature lower than the second one. Two stage heating of thermoplastic beads to melt gradually as they are pushed through the barrel and lowers the risk of overheating which may cause degradation in the polymer. Information Source

  • Is there two separate windings of nichrome wire that are individually controllable?
  • What RPM is are the pinch wheels running at?
  • How are the pinch wheels powered?

Further information

Do you have some inside knowledge? Post it here!