Four-Bar Linkage Pen Arm Assembly

thingiverse

This is a remix of the Pen Arm Assembly for Thing 20398. A big thank you goes out to Glasswalker for originally designing it. By swapping the single pivot arm with a four-bar linkage assembly, this remix improves upon the original design. The single pivot arm works well on spherical objects because their radius remains constant, but when used on an egg with varying radius, the pen leaves behind an arc on the egg's surface instead of a straight line. The benefit of using a four-bar linkage is that it enables the pen tip to move straight up and down as it rides on the egg, allowing the Eggbot to draw a perfect straight line on its surface. This results in significantly better image quality.