Lego Anamorphic Clock Kinetic Sculpture
An example of anamorphosis is where a distorted image is drawn on paper and looks 3D when viewed from a certain angle. More generally, anamorphic art requires the viewer to use a specific vantage point to reconstitute and properly view an image or sculpture. A kinetic sculpture relies on movement to achieve a desired visual effect. I’ve combined both of these ideas to create a mechanical timepiece using Lego.
Uses a minimalistic frame and 147 gears driven from a single motor.
Every two seconds, 6 hands are used to represent time on an analogue clock face. 2 hands for hours (the shortest hands when viewed correctly), 2 hands for minutes (longer grey tipped hands) and 2 hands for seconds (longest red tipped hands). They pause for a brief moment in the correct spot to indicate the current time, then scramble and pause again 2 seconds later in the correct position to show the updated time.
An abridged version of how it works is explained in the video, but in more detail, to achieve this visual effect:
Every 2 seconds, the clockwise second hand has to travel 1 + 1/30th of a turn to pause in the next correct spot around the clock face
The anticlockwise second hand must travel 29/30ths of a turn to pause in that same spot
In one minute, the time is shown 30 times
Do the math and the clockwise hand turns at 31rpm (1 1/30 x 30) and the anticlockwise hand turns at 29rpm (29/30 x 30)
Both differential casings that the hands revolve around turn once clockwise to ensure the hands extend and pause in the correct spot
We can apply similar math to calculate the rotation of the minute hands
The minute hand on a normal clock takes one hour to do one rotation of the clock face
This machine will represent the time 1800 times in one hour
Therefore the minute hands will need to turn at 1801 turns per hour clockwise and 1799 turns per hour anticlockwise (1 1/1800th turns clockwise and 1799/1800ths of a turn anticlockwise every two seconds)
The differential casings that cause the hands to peak in a certain spot will turn once per hour clockwise (1/1800th of a turn every two seconds)
Similar math applies to the hour hand - 21601 turns clockwise and 21599 turns anticlockwise per 12 hours (1 1/21600th turns clockwise and 21599/21600ths of a turn anticlockwise every two seconds)
The differential casings that cause the hands to peak in a certain spot will turn once per 12 hours clockwise (1/21600ths of a turn every two seconds)
On paper, with a motor speed of 120rpm, that means we need the following gear ratios to achieve this effect:
120:31, 120:29, 120:1, 7200:1801, 7200:1799, 7200:1, 86400:21601, 86400:21599, 86400:1
But put more simply, all main hands are reduced 4:1 from the main input, then one turn is added or subtracted from the relevant hands over the relevant time period by use of differentials
All gear ratios are accurately represented in the machine and ignoring wear and tear issues, noise and impracticality concerns, would indefinitely keep accurate time.
The time can also be set as shown in the video. The minute adjustment will change the part of the rotation that the minute and hour hands peak. (The hour hand position needs to reflect the minute hand position.) It also adjusts the amount that these hands are through the current rotation to keep the timing of the hands pausing in sync with each other. The hour hand adjustment will adjust the hour hands only in a similar fashion.