A quick add-on to the last post. I wanted to make a striped watch (and design something that could be dualstruded on the Seeedstudio Replicator), but not just any striped pattern… so I turned to nature+mathematics for inspiration, and came up with a fibonacci sequence striped watch band!

With a layer thickness of 0.27mm, the 21.6mm thick band turned out to be 80 layers thick. Thus Alternating between white and black I was able to represent the fibonacci sequence as the number of layers of each alternating colored stripe. I was able to encode the sequence 1-1-2-3-5-8-13-21 and part of 34, since I only had 80 layers to work with.

You can count the layers, and see the fibonacci sequence!

I then took the solid model, sliced it accordingly to the layer counts of each stripe, and saved the two corresponding sliced parts it as two solid models. Then it was simply a matter of following this tutorial.

It took a bit of finagling to get it to print right without curling (since currently the dualstrusion print profile doesn’t include rafts to help stabilize the first layer), but I got it on the 4-th try!
One of the inherent problems of FDM (Fused Deposition Modeling) 3D printing is that there is always “ooze”; since the material being extruded is heated to liquid state, it naturally oozes out of the extruder over time as it is being pulled by gravity. When doing dual colored 3D prints, using two extruders the “ooze” from the extruder that is not currently extruding leaves little ABS droppings on the print wherever the extruder passes over the print. Thus you get residual lines, and bits of plastic inside the print. The question is, is there a way to stop the ooze? maybe a tightly toleranced and actuatable valve/lid? Or designing a nozzle that takes advantage of the surface tension of the liquified print material? This problem must be solved if the open source FDM 3D printing community wants to achieve high quality blemish-free prints, and if one wants to minimize intermixing between two different print materials.

Anyways enough rambling, here’s more pictures of the purdy results!