Another extruder concept

I've been working on the Bowden cable system, which works very well for me. But if you're nophead, you have concerns because it can limit the quality that you can achieve under some circumstances. I think that with his setup the bowden cable might have a visibly lower quality, in my prints I don't really notice it. BUT: I had no intention to go back to slow printing, but I do want to see if I can address his concern in a different way.

I have been thinking of a way to transduce force very close to the extruder's hot end:



The driving mechanism isn't that much different from the geared extruder. It could be a semi-gear or a full gear. It could spool the steel thread at a certain radius, which would correspond to a good force/speed ratio for the chosen stepper motor.

The hot end side would need something like a pinching system, but not from two wheels but something that grips in one direction and releases its grip in the other. Very much like the hot-glue guns.

The added benefit of this system is that you can use the same drive mechanism for syringe based extrusion (which is also non-continous) and that you'll still have a low moving mass and you need only little space per extruder so you can locate them close to each other.

Please share your thoughts!

Edited 1 time(s). Last edit at 10/05/2010 03:27AM by ErikDeBruijn.

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Regards,

Erik de Bruijn
[Ultimaker.com] - [blog.erikdebruijn.nl]

I like it, but wouldn't the need for the motor to always turn back and forth work against the (more or less) constant pressure needed for a steady extrusion flow?

This could perhaps be countered in software to either wait for the motor, or run backwards between extruder stops or layers. Or in hardware by building a long "grip" area. But wouldn't it be difficult to lay down one long straight bit of filament reliably?

That is, if I understood the idea correctly.

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-Nudel
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