Four-Bar Linkage Pen Arm Assembly

thingiverse

This is a remix of the Pen Arm Assembly of thing 20398. Thanks to Glasswalker for the original design. This remix exchanges the single pivot arm with a four-bar linkage assembly. The original single pivot arm design works well for spherical objects because the object radius is constant, but when the single pivot arm is used on an egg with variable radius, the pen traces an arc on the egg rather than a straight line. The benefit of the four-bar linkage is that the pen tip traverses straight up and down as it rides on the surface of an egg, enabling the Eggbot to draw a straight line on the egg. This results in significantly improved image quality.