David Krooshof

A 24h clock

I’ve been wanting  clock that has an hour hand that rotates once a day, and points up at noon. They are hard to come by commercially. My friend Vasilis (who built this site for me) inspired me to actually make it. The mechanism behind it, found on Ali, sits in a housing and mounting plate, that I 3D printed in glow in the dark PLA. Not that you really see that glow...

This is not a freehand drawing, this is the result of little computer code that I wrote. My colleague Daan Westerdorp loaded my design into a plasma cutter that cut it out of a 2mm plate of steel in seconds. It's 40cm in diameter.

A clock, cut out from a steel plate. It's rusty. It looks like an ancient artefact with a deeper meaning.

It was two minutes to seven in the evening when I took this photo

Here is what the clock face depicts

The wide spoke on top is noon. Midnight is down, and both six o’clocks are horizontal. From noon on top, 13 through 16 o’clock are at the thin spokes, like 9, 10 and 11 before noon.

The minute hand rotates normally.


From 16:25 o’clock onward, the clock face depicts the early and dark winter evenings. The spokes are inverted, like light behind the windows of the houses.

On the other side, 6, 7 and 8, until 8:49, illustrate the dark winter mornings, the latest morning being on January the first. Note that the winter night is rotated clockwise relative to noon. That is due to the decision in The Netherlands to follow Berlin time, even though we live closer to London.

It’s timing is based on the earliest winter evening on my location, Hilversum, which is the 12th of December. In Nijmegen or Amsterdam, all times would be earlier or later respectively, which would change the face of this clock a bit, like closing the small gap near 9 o’clock for Amsterdammers. It would be narrower than the width of the plasma cutter.


The short spokes, between 22 ans 5, or 22:03 through 5:18 to be exact, depict the shortest summer nights, from the 17th through the 25th of June. The timing for the summer night is also exactly based on my location.

It does not get fully dark those nights, just nautical twilight, hence the shape of the spokes.

Note these times are rotated again, relative to the winter night. This is due to the daylight savings time settings of the clock.


I did not protect the steel in any way. The rust is another way of telling the passage of time.