Printing Scherk in Clay

Having a virtual repository is great because it is widely available and doesn’t require space. Sometimes, however, one likes to be able to look at something real, so occasionally I will post about actual objects involving minimal surfaces.

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Two years ago, Malcolm Mobutu Smith and myself set out to make mathematically inspired objects in clay. Malcolm has been intrigued by the relatively new method of clay printing, so he built a small printer, and we got to work.

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The simplicity is challenging: You have a tube full of clay that is providing a continuous stream of clay (unless there are air pockets in the tube), a little motor that moves the tube around horizontally and vertically (don’t stop, unless you really want a small heap of clay), and a little Arduino to whom you can talk in Gcode.

My little mesh.m package has a function that allows to thicken a surface mesh, which can be exported into an stl file. Then we use Slic3R to convert that into Gcode, which is not much more than a bunch of instructions saying “move from A to B in time T.”

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After that, the printing of a 6-ended singly periodic Scherk surface starts with layers of three arcs. Because the printer doesn’t stop printing, it needs to skip fast between the arcs, leaving behind little charming artifacts.

Many things can go wrong: Overhangs can (will) break, the clay dries too fast so that the next layer doesn’t stick, the clay is too soft so that everything sags… But this piece worked out pretty nicely.  I now have a real Scherk surface at home:

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