2011-07-04

extruder design

Being unsatisfied with the filament drive of the Thing-o-Matic
(way too little pulling force),
I'm in the early stages of designing my own extruder.
Design-intent:
  • geared down stepper motor
  • spring-loaded lever to adjust the pressure
  • mount for a rotary-encoder that meassures the filament being actually pulled in
  • integrated compartment for a sponge to clean the filament
  • use herringbone-gears
  • mounting holes for a fan for the stepper motor
  • low center of gravity (reduced stress in transport and backlash)
  • allow ToM and RepMan hot-ende and allow both extruder mounts (I want to design this only once for both my printers)
  • 3 point mouting (use 3 contact points to mount the extruder to a Thing-O-Matic z-stage as opposed to the flawed arc-like 2-point design of the default MK6-steptruder. Doesn't matter on a Repman.)

Originally I wanted to use 2 drive-grears to grip and pull the filament from both sides instead of clamping it between a drive-gear and a 608-bearing but I found that this would require a more complicated gear because the only stationary point on the lever is it's axis and that is not the axis of the intended second drive gear.
So that would require 2 more gears in a very small space.

Don't hold your breath. This will take me a while to get right but I'm working on it.




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