Drum extruder design

Hi guys,
i would like to share a design i thought up a couple of months ago.
i was looking for something simpler to build than the darwin extruder with the equipment that i have so i choose a drum design (kind of like a wood chipper) that uses two metal gears, one fixed to a shaft connected to a motor and one spinning freely.



the springs are used to push the free spinning gear and apply enough pressure grip the plastic filament.
Unfortunately it couldn't push HDPE through the extruder and into a nozzle very well, but it did work out fairly well with abs.

here's an old video of it pulling a filament of plastic..
[www.youtube.com]

Wow, that cruises through there. Now if only my cartesian bot could keep up with it!

Demented

Very Nice!
I was thinking about something like that too when I was looking for ways to prevent kinking of the filament.
Thought it wasn't mentioned here because there might not be enough power/grip to feed the filament constantly.
What's your experience in combination with a heater?

Edited 2 time(s). Last edit at 08/09/2008 07:20AM by uplift.

well, since the two halves of this design can be assembled and disassembled easily, i decided to cut out a space for a nut to sit in and surrounded it in hitemp silicon so that the heat barrel just screwed into the bottom of it all.

i think it had plenty of gripping power, the filament comes out flattened with deep teeth marks. if i stop the motor with the filament still inside, it's very difficult to pull it out. i added an extra nut to make the springs adjustable, but the clutch would go off when i increased it too much. I think i could get HDPE to go though if i deal with some of the friction with bearings on the motor shaft and possibly gear down the motor.

Yes it is going way too fast for extrusion because you have lost the reduction comes with screw thread. You would need a worm drive or several sets of gears to get the correct speed.

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[www.hydraraptor.blogspot.com]

i was actually planning to find a geared motor that runs below 5rpm
i was able to find one that had planetary bearings and an insane amount of torque