Clock Escapement Uses Rolling Balls

The escapement mechanism has been widely used for centuries in mechanical clocks. It is the mechanism by which a clock controls the release of stored energy, allowing it to advance in small, precise intervals. Not all mechanical clocks contain escapements, but it is the most common method for performing this function, usually hidden away in the clock’s internals. To some clockmakers, this is a shame, as the escapement can be an elegant and mesmerizing piece of machinery, so [Brett] brought his rolling ball escapement to the exterior of this custom clock.

The clock functions as a kitchen timer, adjustable in 10-second increments and with several preset times available. The rolling ball takes about five seconds to traverse a slightly inclined, windy path near the base of the clock, and when it reaches one side, the clock inverts the path, and the ball rolls back to its starting place in another five seconds. The original designs for this type of escapement use a weight and string similar to a traditional escapement in a normal clock. However, [Brett] has replaced that with an Arduino-controlled stepper motor. A numerical display at the bottom of the clock and a sound module that plays an alert after the timer expires rounds out the build.

The creation of various types of escapements has fascinated clockmakers for centuries, and with modern technology such as 3D printers and microcontrollers, we get even more off-the-wall designs for this foundational piece of technology like [Brett]’s rolling ball escapement (which can also be seen at this Instructable) or even this traditional escapement that was built using all 3D-printed parts.

15 thoughts on “Clock Escapement Uses Rolling Balls

  1. These types of escapement were actually used in old clocks. I remember seeing one working at some museum somewhere in my youth. Invented by Sir William Congreve at the beginning of the 1800’s.

    Google “rolling ball clock” to see several examples from historical periods.

    One problem with pendulum clocks is that the arm of the pendulum changes length with temperature, making all such clocks drift over time. You sometimes see more complicated pendulums using several rods in parallel made of different metals. The change in length of one rod is compensated by a different change in another, &c.

    Perhaps a rolling ball clock has less drift than a pendulum clock.

    The big problem with clocks was on ships, and I don’t expect the rolling ball clock would be useful in that environment. Everything got a lot easier when the balance wheel escapement was invented.

    1. Ignoring the fact that this doesn’t appear to really be an escapement, a true rolling ball escapement would exhibit wear and thus lose or gain time. I believe it would also be somewhat temperature dependent as the size of the rolling track would be affected by temperature as well. Though, one could use materials with a lower coefficient of expansion.

    2. Pendulum on a ship is obviously a no-starter, but the temperature issue was (and still is, in mechanical horology) still a problem. One of the major innovations wasn’t the escapement per se (itself an achievement) but accurately calibrating the “going” of a naval chronometer, so that the changes over time were known and able to be compensated for. In re: temperature effects themselves, the chrono itself was carefully protected down in the ship somewhere and only manipulated for daily winding. For sights, a “deck watch” was set to the chronometer and used for marking time on deck. Any messing with the chrono itself meant a lengthy and laborious re-calibration at an observatory. Even today with essentially zero-expansion alloys used for escape wheels, temperature is still a finicky thing to get right.

    3. Hello PWelsh,
      hello Bryan,

      happy to meet someone who cites Sir W. Congreve. Besides his driven ball escapement he also made more useful advances in horology as mentioned in “my own right time” (Philip Woodward) an excellent read for all interested in horology.

      Friction, dust, geometrical changes due to temperature and uncontrollable influences due to impact make “rolling ball” escapements unpractical. By nature they have a liberated balance (for a long time) but the “complementing arch” is highly compromised. For a kitchen timer a nice idea (if it would use the ball’s position for time keeping) but not useful for timekeeping.

      To me such an escapement remains in the category friction rest -with a constant friction force-. This reminds me of the H4 by Harrison or any cylinder/duplex escapement with remontoire.

      To me the first significant step in horology was the conversion of the folliot to an oscillator by introducing the balance spring (Huygens/Dr. Hooke), this introducing a mechanical oscillator to the escapement. Thereafter comes the liberation of the balance from recoil, friction rest to detached escapements (LeRoy/Mudge).

      The next problems were temperature and degradation of oil. Inventors like Arnold, Breguet, Earnshaw as well as LeRoy work on these problems (“John Arnold” by V. Mercer), the grid iron pendulum or the “natural impulse” (mainly rolling, minimal sliding contact) spring up to mind. Propelled by Queens Anne’s “Longitude Act”, portable and motion inherent timekeepers were developed.

      Bearing this in mind, a ball clock kitchen timer is a nice idea, not aiming for high precision. “Well, does my 7min egg care about the Moon or Venus transit?” It would make me feel good if it would be cooked accordingly, but please consider the air-pressure as well. So it should have an aneroid capsula for this :-). I would still like this timer to be controlled by the balls motion and the μPC timer to track the deviation than having a ball running for show. But still, it sparked interesting comments.

      @ Bryan Cockfield: what clocks were you referring to that do not contain any escapements? Only clepsydra, hourglasses or Seiko’s Spring Drive come to my mind as watches without escapement.

      Many greetings

      1. When someone starts using terms like frictional rest escapement, I pay attention.

        My training and study from school as well as study of these clocks agrees with your insights. This form of escapement when it actually is an escapement is more of a novelty and there are many losses, friction and change in track length due to thermal expansion being the primary ones.


    4. I made a Congreve clock about 30 years ago, dust was the main factor effecting accuracy, I made a brass framed glass cover but it would need a vacuum to be effective. nice looking thing though.

  2. Great build presentation on the website with all of the parts broken out, but it is a shame that the rolling ball is cosmetic only. For a kitchen timer I’d be happy with even 30 second drift over ten minutes while I cook some pasta. I didn’t see how inaccurate the rolling ball is, but it’s not like you need millisecond precision to bake some cookies.

    1. It’s a great idea and beautifully crafted. But I wonder if the electronics are really necessary. Could one build a much longer ramp for the ball to roll down, stacked with (say) 10 seconds per level, so 6 levels per minute? “Set” the timer by where you drop the ball in. When it has traversed the entire maze, it drops through a hole to strike a bell.

      It might not be especially accurate, but would be fun to watch and listen to. :-)

  3. The quest of our era is about energy efficiency. Reciprocating mechanisms like the one in the article, or others in the comments, are not as efficient as a constant flow one. Therefore, i find, we are not far from Su Song or Philo.

  4. Hi everyone. I desined this project and thought I would give some background info on desicions taken when building it.
    First of all the original design of the escapement by JBVCreative used a weight and string and although it used the ball to trigger the escapement it was impractical to use for more than a few seconds due to the length of string required.
    I did try and use the ball bearing to trigger the electronics but it proved too difficult. Prob the best way if anyone want’s to add this is to add a magnet to the triggers. The movement of the triggers however is very tiny and you would require some precise adjustment to work well.

    Although I have not used the rolling ball mechnism as an escapment the rolling ball is synchronised to the stepper motor using by adjusting the stepper motor acceleration settings and the movement will run forever without the ball getting out of sync.

    The Congreve rolling ball clock always was a terrible time keeper even with constant mantenance. Not really sure if it can be classed as a clock as you can’t use it for timekeeping ): . Still it’s always one of my favorites.

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