Dual extruder using a single motor.

http://www.kickstarter.com/projects/dglass3d/the-3d-printing-extruder-reinvented-the-dual-and-q

Interesting concept. I'm no where near (without a printer) ready to play with something like this. But I figured I'd point it out as I ran across it while wondering kickstarter.

 

It caught my attention also, but they have some issues to resolve. They use the the extruder stepper motor direction to select which filament, forward extrudes filament #1, reverse filament #2. Retraction is fixed mechanically and only happens during filament change. While they have been able to switch and extrude both filaments they have not been successful in printing anything yet because of filament jamming, which they are blaming on the hotend. The are looking at other hotends while designing one they think will work. I'm sure they will resolve this problem and print some objects. The question is, when and with what print complexity? The also claim to have ideas for a quad extruder but no details yet. If they can pull it off, it could lead to a new generation of full color printers.

 

Another issue is: While there are some dual extruder printers available today. Software to generate dual color gcodes is still a ways off with only a couple companies working on solutions for their own printers, with limited success in very simple prints. A fully functional generic software solution is likely years away. Today's Slicers just cannot handle the complexity of adding color changes without major software redevelopment.

 

A dual extruder with hot ends for the price of a Robo, no thanks. I would buy another Robo. Way over priced for a couple drive gears inside box. Love the design. Love to buy one, if it was half the cost.

 

I guess that the single-stepper-motor version won't work that great.
One issue is that when they change direktion they need to know exactly how much the motor turned so they won't push to much or not enough filament.
This is especially a problem when the gears doesn't match. how can you tell if the gears matched, or where tooth on tooth (and therefore the motor has do turn a little bit more).
So for fine details I think this won't be a good solution.

On the other hand the kraken is really a nice work. So i agree with harry when he said: extremly primising.

 

Did a little surfing looking at prices for metal worm gears and worms and found that they were expensive. Kraken uses two worms, one for each stepper, which explains the high cost/unit compared to other dual extruder designs. Unfortunately this puts it out of the reach of many of us.

I did come across an interesting article about color blending using three extruders and one nozzle at: http://richrap.com/?p=121 which I like better then multiple nozzles designs. The prototype is huge but has potential for downsizing and generating some nice prints. Hope to see more development in this area.