I've seen someone on YouTube create a LEGO Clock with all the wheels and a pendulum, but I was wondering if there is any project or building instructions available to build such a clock with an efficient movement. LEGO Technic seems ideal to build such complex mechanism.

  • So are you trying to build something like youtube.com/… ??
    – chicks
    Sep 19, 2017 at 17:26
  • Kinda, but now that I think about it, maybe the best would be a mechanism with a spring barrel and power reserve instead of pendulum.
    – pbonnefoi
    Sep 20, 2017 at 8:37

4 Answers 4


Building a clock is easy, building an accurate clock is hard, even without lego.

To have accuracy you must have something happening at a fixed frequency. A pendulum is the easiest way to provide a regular timing.

Next you need a power source for the clock. Weights falling down is classic, and easy to do with lego : a pulley and a string.

The force generated by a spring is not constant, it decrease with time as the spring wound down. You need a constant force to have accuracy. Real clocks have mechanisms to compensate this variations by I am not sure it is possible to replicate with lego.

An electric motor is better, but the charge of the batteries determine the power generated by the motor.

Then you will loose power with friction so you must limit the number of moving part or limit friction with lubricant for example.

I have built a clock myself, it works but stops after 15 to 20 minutes for too much friction. You can search the web for other lego clocks, but the best I have seen works for about 6 hours.

A lego clock is a fun project but you won't use it to tell time.

  • 1
    Welcome to Bricks.SE! I'd love to see pictures or links to your clock model. That sounds great!
    – jncraton
    Sep 22, 2017 at 14:01
  • It's okay if it doesn't last long, it's more for the fun of mechanics and to show to other people how a mechanical clock works.
    – pbonnefoi
    Sep 25, 2017 at 12:06
  • unfortunately i don't have any photo and the clock is 800km away, a quick search show one good example at nico71 - clock
    – arkades
    Sep 26, 2017 at 11:01

I built a high accuracy pendulum clock with LEGO.

As far as the monthly rate (error per month) is concerned, it has achieved high accuracy comparable to that of quartz clocks!

It utilizes technologies such as an improved gravity escapement, a durable pendulum support point, and a temperature-compensated pendulum.

Summary of experimental results

  • Experiment period:30 days
  • Daily late(error per day):-5.1 to +2.9 s
  • Monthly rate(error per month):-4.7 s

The following is a link to YouTube. It explains the details of the clock.

A prototype of an accurate LEGO pendulum clock "ChronoBrick-1" https://www.youtube.com/watch?v=tzuKKuLGjqI

  • Great work ! Thank you for sharing !
    – pbonnefoi
    Mar 15, 2021 at 9:47

There are limited instructions for a clock in the 8888 Expert Builder Idea Book from 1980. I'm sure there are better designs out there today, but I thought this could be helpful for ideas and a bit of nostalgia. I can't speak to the accuracy of this model, as I haven't actually built it.

Step 1

Step 2

Step 3

Final model

  • That's quite interesting but there is only one hand which is less fun. I know for a fact that you can display two hands as seen in a video with a special wheel that I found in my old legos.
    – pbonnefoi
    Sep 25, 2017 at 12:44

According to this video of tuning a LEGO clock by KEvronista, he was able to get the accuracy within a few seconds per day. The key is to use a small amplitude of oscillation (angle) for the pendulum swing, so that the pendulum approximates a harmonic oscillator. The LEGO clock has an amplitude of about 2.3° degrees. Also important is making the drive chain and pendulum swing as independent as possible by reducing recoil, which the Galileo's escapement shown has as a major disadvantage. The Wikipedia article on the anchor escapement gives a good explanation and in theory a well-constructed deadbeat escapement made in LEGO could be even more accurate.

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