## Posts Tagged ‘PDEs’

### Multi-Colour 3D Printing by Filament Swapping

December 8, 2010

The above picture is solution to the diffusion equation $u_t = u_xx; ~~ t \in [0,\infty),~ x \in \mathbb{R}$ with the initial conditions $u(x,0) = \{ 0 ~ x>0, 1 ~ x\geq 0$. (WordPress doesn’t seem to like the array environment…)

English Translation: If you imagine a metal bar heated up on one side, as time progresses the temperature will even out. This is a plot of the temperature with one side being the length of the rod and the other being time.

But that’s probably not too interesting to most people reading this post. The interesting things is how I got the multi-colour object.

It was made by feeding one short piece of filament into the printer after another, during the print job. It was surprising to see how nicely one colour faded into the next.

Unfortunately, this broke the hacklab.to Break-R-Bot Maker Bot. The problem was that there was a sharp point on one filament that deflected the next one to the side. It was easy enough to fix (thanks to Rob for helping me!), but it seems like a bad idea to test it again oh the hacklab printer. I’m building my own, so the experiments should continue in a few weeks, anyway.

It seems like the problem should be possible to avoid as long as one makes sure that the filaments have flat ends. I am also planning to experiment with using a hot air gun to fuse pieces of filament.

(Thanks to Stefan for taking the picture of the models for me!)