Harmonograph Mk. II

More than a year ago I posted a video on my YouTube-chanel of a two-pendulum and a three-pendulum harmonograph. The latter created rather nice drawings, but not extremely beautiful. I also needed square paper I had to cut to fit the large baseplate (15" x 15"). So I quickly started thinking of a new four-pendulum harmonograph, where the length of the pendulums in X- and Y-direction would differ slightly to make the pen movements fitting for standard A4 paper. It also had to be a very sturdy construction because I wanted to add more weights. When I took apart my Painted Ladies I had a collection of more than a thousand 1x16 Technic Bricks. I tried to design a sturdy structure that wouldn't require the purchase of many new parts (in the end I only bought 1 kg of 15397-plates, unfortunately in White, because it's not available in Light Bluish Gray).
The pendulums are very, very sturdy... and heavy: if a similar machine would be made out of lighter materials, it would stay in motion for a lot longer, creating even nicer drawings...

• Left: the lower table is running on rails in one direction, while the upper table is running on rails (mounted on the lower table) in the other direction.

• Right: the lower table needs 10 kg of weights on the pendulum to keep it running for approximately 50 oscillations, the upper table requires only 6 kg for the same amount of oscillations. The pen is driven by two pendulums holding 4 kg and 4,2 kg (a slight difference to avoid circular movements).

• Left: just like the previous versions, every drawing of the harmonograph is unique and cannot be duplicated with the same machine.