Building A Mechanical Counter Out Of Scrap Wood

Watching [Matthias Wandel] fabricate this mechanical counter from scrap wood is just fascinating. He likens the mechanism to the counters you would find on decades-old cassette tape players.

You may recognize the quality of [Matthias’] work. We’ve seen several pieces, but his binary adder is still one of our favorites. This project gives us a very clear view of the development and fabrication process. He even posted a detailed guide if you want to build your own.

He started by prototyping a mechanism to increment and decrement the counter. With that proven design he started laying out the rest of the gears. These were cut from plywood scraps he had from other projects. Notice the small gears seen above which are missing parts of some teeth. Those sections were removed using a drill press with a Forstner bit. The missing teeth cause the next digit over to increment more slowly, resulting in a 1/10 ratio. This part of the design is demonstrated about three minutes into the video after the break.

22 thoughts on “Building A Mechanical Counter Out Of Scrap Wood

  1. The gears that have some teeth cut down aren’t a 1:10 reducer but a 1:2 reducer. From what I remember it’s because the wheel that causes the 1:10 reduction has two teeth on it but you only want to flip the 10s counter once when it completes its revolution.

    1. It breaks my head trying to apply this mechanism to time instead of straight counts.

      Minutes should be straightforward, just gotta tweak the gear ratios to make the ten minute have only 6 steps instead of 10.

      I have no idea how I would do hours though. The easiest thing I can think of is have a two gears linked together 1:1 (or one double wide) and just have 12 (or 24) steps around. It just sucks that the tens hour gear needs to carry at different points at different times.

      Alternatively, you could redefine the day to have 10- 100 minute hours, and his design is a great clock. You just need some mechanism to increment it every 86.4 seconds or so.

      1. For hours you do need a 12-position wheel, yes. You could either number it 1-12, or number it 1,2,3,4,5,6,7,8,9,0,1,2 and put “carry” triggers after 9 and the second 2. Probably simplest just to make a single 1-12 indicator.

        (Note that if you use the two-wheel setup, you also need to keep track of the fact that it’s 1-12, not 0-11! There are only 9 hours, not 10, that are prefixed with “0”.)

  2. Extremely methodic and well made video, bravo. I like the part where the parts are enormous to really understand what’s going on in the small mechanical counters.

    Next do a 3D printed mechanical counter!

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