Beautiful MakerBot Printable Sarrus Linkage
Wow, just wow. Check out this Sarrus Linkage by fdavies on Thingiverse.
I printed all this on a ‘repstrap’ that I built mostly from old printers (old dot matrix printers had really great hardware). It uses a pinchwheel extruder heavily inspired by the work of Nophead on reprap.org.
I did design all these parts to print in a 100 mm cube, both so that they would not be too big for a Cupcake, and so that it could print itself.
Why three units? Well, ABS plastic is only so strong, and not very stiff. With just two units at right angles, the bottom one would have to withstand significant torque (twisting) from the weight of the extruder (when I put one on), and would let the top axis tilt out of the horizontal,
Why did i make it as three (mostly) identical subassemblies, rather than as a monolithic entity?
1. I am still not 100% sure that this will be the final configuration, so I want to be able to reconfigure if necessary.
2. The warping of large objects that is plaguing the reprap community means that it is better to make several small pieces that you connect together rather than one big piece. This is why the spine and armature are broken up.
What is a Sarrus Linkage?
The Sarrus linkage, invented in 1853 by Pierre Frédéric Sarrus, is a mechanical linkage to convert a limited circular motion to a linear motion without reference guideways. The linkage uses two perpendicular hinged rectangular plates positioned parallel over each other. The Sarrus linkage is of a three-dimensional class sometimes known as a “space crank”, unlike the Peaucellier-Lipkin linkage which is a planar mechanism.
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