What Is A Servo Clock? Make Your Own Dancing Art Clock

Have you ever thought about what new tricks the clock in your home can do besides telling time? Ordinary quartz clocks always feel like they lack some warmth after looking at them for a long time, while the smart clocks on the market are all the same. Recently, I discovered a particularly interesting thing in the maker circle - aservoclock. It turns theservo, a part originally used on robots, into the core of driving the clock hands. It not only retains the mechanical beauty, but also can realize various creative timekeeping methods through programming. Today, as someone who has experienced this, I will talk to you about how to play with theservoclock from scratch.

What’s so special about the servo clock?

The hands of ordinary clocks are driven by quartz oscillators, and they move erratically, and they cannot be controlled by themselves. The servo clock is different. It uses the kind of servo in the robot joint. You can accurately control the pointer to any angle. what does that mean? This means that you can make the hands of the clock dance on the hour, or let the second hand slide across the dial at a constant speed. The smoothness is particularly charming.

The first time I saw a clock made by someone using a servo at Station B, I was immediately amazed. The three servos are stacked together, each driving the hour, minute and second hands. The second hand does not jump, but sweeps smoothly like a high-end mechanical watch. What’s even more magical is that at the hour, the pointer will rotate first and then point to the correct position, which is full of a sense of ritual. This kind of clock is no longer just a tool to tell time, but has become a piece of art at home.

What do you need to prepare to make a servo clock?

If you want to make a servo clock, you must first prepare these things. The first is the steering gear. It is recommended to use this kind of metal gear, which has high torque and is not easy to shake. Three are needed to control the hour, minute and second hands respectively. Then there is the main control board. Uno is the most suitable for getting started, and there are plenty of information on simple programming. You also need a clock module, which is recommended. It has temperature compensation, and the error will only be one or two minutes a year.

In addition to these core components, you will also need some auxiliary materials. For example, laser-cut acrylic dials, or 3D-printed pointer connectors. Breadboard and Dupont wire are used to test the circuit, and then soldered and fixed after debugging. Don’t forget to prepare a beautiful shell. There are many open source design drawings online that can be downloaded directly. A set of basic materials costs only about 200 yuan, which is much cheaper than buying a ready-made creative clock.

How to achieve accurate travel time with steering gear clock

In order for the clock to keep accurate time, we must first solve the problem of time source. This is what the clock module does. It has a crystal oscillator inside, and it can continue to keep time by relying on a button battery even if the power is cut off. Each time it is started, the current year, month, day, hour, minute, and second will be read from the module. Then you need to convert these time data into the angle of rotation of the servo.

Here’s a little tip. The rotation range of the servo is usually 0 to 180 degrees, while a circle on the dial is 360 degrees. So we need to do conversions: for example, the second hand should move 6 degrees per second, but the servo can only turn 180 degrees. Then we can make the second hand go from 0 degrees to 180 degrees from 0 to 30 seconds, and then from 180 degrees back to 0 degrees from 30 to 60 seconds. The hour and minute hands have similar logic, but the linkage relationship between them must be considered.

How to design the mechanical structure of a clock

The mechanical structure is where the steering gear clock most tests your hands-on ability. The three servos must be stacked one on top of the other, and their output shafts must be on the same axis. You can use a metal bracket to fix the servo into a tower shape. The bottom one is responsible for the hour hand, the middle is the minute hand, and the top is the second hand. A pointer connector must be installed on the steering wheel of each steering gear. This connector must be designed to be adjustable to facilitate calibration of the zero point position.

The choice of pointers is also particular. Because the steering gear torque is limited, the pointer cannot be too heavy. It is best to use lightweight plastic sheets or thin aluminum sheets. The second hand is the longest, but the lightest; the hour hand is the shortest, but can be a little heavier. When installing, make sure there is no fighting between the pointers and leave enough space. When debugging, first use a program to turn each servo to 90 degrees, and then manually align the pointer with the 12 o'clock direction and fix it.

Is programming control difficult?

Don’t panic when you hear the word programming. The control code of the servo clock is actually quite simple. Using the Servo library, you can activate the servo with just a few lines of code. The core logic is: read time → calculate angle → write angle. For example, to make the second hand move, first read the current seconds, multiply by 6 to get the theoretical angle, and then use the map function to map it to the actual travel range of the servo.

Let me give you a simple example framework: initialize the servo and clock module in void setup(); update the time every second in void loop(), call three functions to calculate the angle of hours, minutes and seconds, and then use servo.write() to turn the servo. Remember to add a judgment to avoid servo jitter caused by frequent writing. The pointer position may not be accurate at first, don't worry, just add a calibration value to the code to fine-tune it.

How to make the servo clock more creative

After the basic functions are implemented, you can start to use your imagination. You can have the clock automatically dim the hands at night to avoid disturbing your sleep. Or connect a temperature and humidity sensor and use an LED light ring on the edge of the dial to display environmental data. One of the coolest works I have ever seen is a dial made into a city map, with the hour hand pointing to different areas to represent different times.

There are also many ways to play with the exterior design. Use old records to make the dial and take a retro route; use transparent acrylic and RGB light strips to take a technological route; you can even carve a hollow dial out of wood to make the hands faintly visible. There are many open source projects on the Internet for reference. For example, "Clock" uses swing instead of rotation, and "Word Clock" uses lighted words to display time. They are all variations of servo clocks.

After reading this, are you itching to give it a try? What do you most want to make the servo clock look like? Retro, industrial or minimalist? You are welcome to post your creative sketches in the comment area. If you like it more, I can share the full set of codes and drawings! Remember to follow me, I will update the steering wheel clock pit avoidance guide next week to tell you which detours are unnecessary.