LEGO Technic pendulum clock that can run accurately for more than a year

I came across this interesting YouTube video by Dillon Sharlet that showcases a pendulum clock that’s been running for more than a year, and more recently, it’s starting to stop unexpectedly. He documents this video to tear apart his build to investigate which parts have worn out over time, but before that, gives a brief description of how it works and a closer look at the clock escapement design and mechanism.

The only part that doesn’t seem to be made from LEGO is the weight which he describes as large washers slide into a 13 stud beam with 11 studs worth of washers weighing 560 grams (1.23 lbs)

While the video does not say much more, I did a bit of sleuthing and found that Dillon Sharlet built this initial model circa 2017 as it’s documented on his website (and this video). From the looks of it, he’s already been tinkering on getting a working model even prior to that. His inspiration was to build a truly practical clock out of LEGO and have it run on its own for more than 24 hours. The early version had a rudimentary clock face but focused the escapement mechanism but we can see that its current iteration below, it now looks a lot more polished with a dash of neo future vibes with the hourly markers minute hands in highlights in red and white technic axle connector parts.

2017 version of the clock design

Like most pendulum clocks, the mechanism works simply by raising the weight to a higher level and allowing gravity to do its work. With the new version shared in the video, it exceeded the 24-hour initial goal of rewinding and now will only need it done every three days or so that’s more than 72 hours. He says that it’s accurate to within a few seconds per day, or about 1 minute of drift after running for two weeks straight, according to Dillon. It uses a Galileo escapement for efficiency and built in a different configuration to accommodate to LEGO part and design constraints.

He goes on to explain the video briefly on each section and the kind of movement it takes or is impacted within the yearly cycle.

The major damage that he found is on the cheese slopes that move in lockstep with the technic gears.

It seems that the ABS plastic has worn off, well, one could imagine that after 31.5 million bumps in a year, it would definitely be worn out. He did find other damages as well, so it’s just worth watching the full video.

If you’re truly interested in all the bits and details, he’s documented the earlier version here, and yes, if you’re asking for instructions (albeit it’s the mechanism for the earlier model), it’s available in Lego Digital Designer (.lxf) file format for you to open up and discover described at the end of his article.

It never ceases to amaze me how much of these LEGO basic elements can create so much intricate and somewhat accurate mechanism that has practical uses, though some may say its an overengineered result just to tell time – I say it’s pretty darned cool indeed that the precise calculations needed to build this to a level of accuracy can be achieved with the skills and knowledge of the LEGO Technic system.

2 comments on “LEGO Technic pendulum clock that can run accurately for more than a year

  1. David Dickson

    Very interesting. I love this kind of stuff. One thought about the observed wear on parts. Lubrucant. Plenty of options for lubricants that are safe for ABS. Petrolium Jelly works well. Only a very thin film of any lubricant is needed. Don’t over do it.

  2. Robert Cailliau

    The bushing that broke into four parts probably did so for reasons related to the design: it needs to provide a lot of friction with little material.  Bushings are continually stressed just by sitting on an axle, they may break because the stressed parts are also influenced by UV light, ozone and so forth.  In over 30 years of hoarding & sorting parts, the ones that broke were bushings.
    The wear on the pallet faces is of course due to the small friction-slip of the teeth against them, not a bump (the word used in some comments).  Harrison’s grasshopper escape does not have any slip between pallets and teeth, but is too large for your clock (it also does have friction in the bearings of course, no miracles).
    A very fine and ingenous compact ratchet for winding!  It does stop the power during winding, you could consider a Huygens maintaining chain, it would not be difficult to add:
    Amazing that it runs three days on 560g.

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