I’m really interested in more information on the mixing nozzle, it’s similar to many experiments I have tried, but you only get limited amounts of material mixing with a passive system.
The best simple system I managed was on 3DR with a passive-active PTFE rotating threaded rod (with differential material flow on two feeds) inside the hot-end heater.
Really interested in what everyone else thinks of this super RepRap FDM based printer from Autodesk.
Or a crazy inkjet white filament, print after layer technique is a more realistic solution. Mixing high viscosity fluids is hard… Sudden changes will be near impossible.
@Whosa_whatsis Yup, my thoughts exactly. And then my second thought was that their helical section looks exactly like this, which was disclosed a few months before their patent priority date. http://www.thingiverse.com/thing:106611
Nothing new here. And furthermore what they are proposing with the helical section doesn’t work properly, at least in my experience of having tried. Extensively.
@Nick_Parker yes, many attempts, and lots of ways it can be done, not just using a motor to ‘stir’ - most work just fine, they just add a little extra complexity. it’s much easier now, but a nice solid-state passive mixing system would be ideal really for FDM. For almost all pastes it’s so much easier, you just use a standard two-part epoxy passive mixing nozzle.
From that article we seem to be pretty in agreement - mixing seems far less useful than switching, which for me points to a cammed idler solution, not 5 extruder motors.
I also think mixing several materials has very rapid diminishing returns. Mixing 2 hard and soft materials could be very worthwhile for select applications. I can’t really think of a strong case for 3 way mixing, and I doubt one exists for 4 way.
You mentioned standardized filament to make color mixing work, and I’m sure I’m barking up a well travelled tree here, but what about much lower viscosity plastics? I know the polycarbonite variety Techshop has for injection moulding is nearly water when molten. Perhaps radically different plastic and a new anti-ooze solution is the way to go?
@Nick_Parker my guess (and it is just that) the lower viscosity materials will either have a high thermal expansion coefficient, or be soft. My logic is that the space between the molecules needs to grow to decrease viscosity, but it is just a guess.
botObjects supposedly made machines that would actively mix colors. 3D Systems bought them out and are selling them as CubePro C. There’s videos of it running on YouTube.
@John_Driggers Yes, I do have one from the Kickstarter campaign. I have it mounted and just need to find some time to get it tuned in and printing. I’ll update when I get it all working well.
@Nick_Parker@Camerin_hahn The guys at E3D did a really interesting experiment recently (I’m sure they will share the results) but it basically showed how printing a batch of identical things with (many) different materials ended up with quite significantly different lengths of finished printed object (around 0 - to - +2mm). All printed very accurately with same infill. They are the same size when on the heated bed, after cooling shrink at different amounts. Understanding this is a good thing for building objects, mixing materials can also help with these issues. Lots more to do in this area of 3D Printing materials.
As you would imaging some plastic’s simply do not like being mixed…
@Jeff_DeMaagd The Botobjects ‘printer’ did exist for a while, I spotted a few people that had one, but not many seemed all that happy. They still had a lot of angry customers last time I checked. We had a lot of discussions on twitter. It also had a good portion of Open-source stuff in it - like the RepRapPro Extruders - I never managed to get to see one in person, but I always wonder what 3D Systems actually bought? - They claimed IP and Patents but none ever came to light. I doubt we will see 3D Systems do anything more with it.