either a fixed or moving drawing surface…
the video above documents a large 2-pendulum harmonograph constructed by danish artist eske rex…
here, the perpendicular pen arms are attached to the pendulum bob, which allows the drawing surface to be close to the ground…
cast concrete weights are used to vary the periodic relationship between the two pendulums…
more info about eske rex’s ‘drawing machine 02’ at the artist’s website here
the example above has a fixed drawing table, with perpendicular pendulums driving the pen…
here, the pendulum fulcrum is a dowel rod seated in a groove which will create friction that will more quickly dissipate the system’s energy…
friction should be reduced wherever possible in the mechanism…
this 45 secs video documents the example of a two pendulum harmonograph above, built by xhensila zemblaku…
this design has a moving surface and a moving pen – note that the pendulums linear trajectories are perpendicular to each other…