Dual Extruder in space of single or Quad in space of two.

Stratasys has been doing it that way for ages, this is nothing new. I'm surprised there isnt a patent on it.

Edit: there is: http://www.google.com/patents/US7625200

No video of it actually working. Kickstarter is starting to leave a sour taste in my mouth. There's really no vetting or accountability.

They use one servo, no steppers. Its a lot like what these guys (D3D) called their "early prototype".

Here's a Stratasys machine using the system:

http://kisslicer.com/forum/index.php?topic=375.0

In the patent game, it doesnt matter how similar your widget is. All that matters is who has more money. Look at Formlabs for a recent example.

Here's another, even more general patent:

http://www.google.com/patents/EP2003954 … CD0Q6AEwAQ

I mean, the title of the patent is "single motor extrusion head". It has one servo motor. No steppers. No solenoid. It has a bistable spring that gets pushed on by a rod on the side of the case when switching extruders is needed.

So, lets recap:

Kickstarter version:                    Stratasys patent:
One drive motor                         One drive motor
Passive extruder switching          Passive extruder switching
No money for patent attorneys   Lots of money for patent attorneys

I'm not sure you understand how patents work. Only one claim of the patent needs to be infringed in order to have infringement of the entire patent.

That sounds a whole lot like what D3D is attempting to do.

Moving on...

Their system can't do retraction (at least not in a software controlled fashion), it doesn't lift the head that's not in use - this will mar the surface of each layer, and it has not been demonstrated actually printing. I'm not sure what there is to get excited over.

They could make it always retract a certain amount when reversing/switching.... that way you could still run it as a normal extruder with retraction capabilities(to a certain extent), this would have to be in the hardware design though.