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5 lbs of black ABS plastic.


( 3 comments — Leave a comment )
Oct. 9th, 2009 05:08 am (UTC)
Let me know when/if you and Tugrik are taking project suggestions };>. I can generate .STL polygon files without too much trouble. And I have at least two fractal truss variants that should be possible to build with a Cupcake CNC type machine };>.

Oct. 9th, 2009 06:10 pm (UTC)
Which fractals are you thinking of? Note that overhangs will tend to sag if they extend more than a short distance over the edge. I've thought of doing a 3D Sierpinski Triangle, but I'd have to build it point-down, with some support structure at the base.
Oct. 9th, 2009 06:43 pm (UTC)
This is a fractal version of an octahedral truss, considered seriously as a building primitive. As near as I can tell from past analyses, beams with a 2D fractal cross-section conserve tensile and compressive strength-to-weight ratios on-axis and handle bending deformation a bit better than a thin cylindrical shell would, while bulk matter with a 3D fractal structure has its strength-to-weight ratio decrease with every iteration of the fractal (but can still be made very light while remaining stiff).

I tool the CupCake CNC's properties into account before planning out the truss designs, so they avoid horizontal and nearly-horizontal surfaces.
( 3 comments — Leave a comment )