DIY Chinese-Style Cardboard Mechanical Clock (Partially Functional)

Welcome! As a high-school student who loves engineering, with a school year ending, I wanted to make something mechanically intricate, out of affordable material. I was quickly inspired by the idea of a mechanical clock, invented by the genius of the Dutch scientist, Christiaan Huygens in 1656. Combining this with an admiration for Chinese culture, this was a journey that created something both educational and accessible, A Chinese-style cardboard pendulum clock. Through this guide, I’ll share my process of trying to create a clock, what went right and wrong, and also a more general and centralised methodology that gives you the tools to build your version of this timeless machine properly. Join me as we make something that combines the logic of gears, with the beauty of culture, and create a cool rendition of a revolutionary object, from everyday materials!

Let's Build!

• Corrugated Cardboard
• Coloured paper (I used Red, Green, Dark green, Light blue, and Yellow, but go creative! Use whatever you want.)
• Craft Knife and scissors
• Ruler
• Weights (I used batteries and a bottle of water)
• Sketchbook or Drawing Paper and pencil (To design your clock if you want)
• Hot Glue and liquid glue
• Wooden skewers (at least 3 (you can break them in half))
• Protractor
• String (Strong)

The first step is to design a clock and its aesthetics. As I wanted the aesthetics to be inspired by Chinese culture, I quickly thought of the best symbols I would like from the culture. (Feel free to adapt it to any cultural background of your choice) 

I decided to create an ancient Chinese house to house the clock's gears. From Chinese mythology, I decided to include Chinese dragons, which used to represent an emperor's dignity and wisdom and the nation's prosperity. Using 4 of the main colours of dragons, red, yellow, green and blue, I decided to make 2 dragons at the top of the Chinese house. 

They have many symbolistic values: 

Red: Luck and good fortune,

Yellow: Wealth and social standing,

Green: New life and nature, 

Blue: Harmony and peace. 

Chinese Dragon Symbolism

Furthermore, I added yellow marks on top of red, with a jade green roof on the house. This colour scheme reflects ancient Chinese architecture and creates an aesthetically pleasing clock. As I didn’t have much time, I decided to stick with this initial idea since I had a deadline. This will allow the product to not only be a mechanical and complex one, but also a decorative piece.

With some research, I found the method these clocks work. Of course, there remain gears inside of the clock, which need to be spun to have the time be told. To spin the gears, in the olden days, without electrical motors, people used gravitational energy and weights, which were attached to a string and pulled down a wheel which was attached to gears, allowing them to spin. 

Pendulum Mechanics:

To accurately time and run the spinning of the gears at a certain constant speed, the oscillating or back-and-forth pendulum movement is incorporated, with a formula that measures the period each pendulum swing takes based on the length, given in the photos.

Escapement Mechanism:

Attached to the pendulum is the escapement mechanism, which turns the back-and-forth pendulum movement into the rotary movement of gears. A weight attached to one side of the escapement gear gives it the energy to spin, while, the escapement mechanism regulates the spinning motion, stopping at each hook, which is the thing that also makes the “tick-tock” sound. There are many types, but I'm just gonna focus on the one that is easiest to build, also known as the anchor escapement mechanism which hopefully will make my build easier. Experiment with different mechanisms! Would be very fun.

Gear Trains and Ratios

Now come the gear trains and ratios. After the regulating and constant motion of the spinning escapement gear, the entire premise of accurate timekeeping lies in the principle of gear ratios. The idea is that the difference in the teeth of connected gears can change the speed and timing of the gears. This hopefully is a good guide for understanding it.

Anyway from my understanding, the best option, is to accurately calculate the teeth necessary in the escapement wheel so that one whole revolution results in the span of 60 seconds.

• Then the minute hand would be in a 60:1 ratio with the escapement wheel.
• The hour hand would be in a 12:1 ratio with the minute hand.

Now, since big gears = big friction, dividing them to make smaller gears, while keeping the same ratio would result in the same outcome of keeping the correct time. For a better explanation: here.

My Calculations

Now, for my project, I designed a way that would function. Basically, there are three parts:

• One for the escapement wheel,
• One for the minute hand gears (MH)  
• One for the hour hand gears (HH)

Keep in mind the minute and hour hand gears need to be aligned, so that the hour and minute hands can be centred later. This works cause the rod attached to the hour hand would be hollow, allowing the minute hand rod to go through it. Keep in mind this diagram was made while creating my clock. Would have saved me a behemoth of time if I hadn't started with trial and error like a caveman smashing rocks.

Now would probably be the most impossible and difficult task of the manufacturing process. Working gears out of Cardboard. Simply peel the top thin layer of corrugated cardboard to find the "gear teeth" layer which is then cut out as a strip and glued perpendicular onto a circular flat piece of cardboard and voila, your gear is ready. The first thing I did was build a test through a 4 teeth pinion and a 20 teeth gear, according to the calculations I had made. Using wooden skewers instead of rods, I tried spinning the pinion to spin the gear, which kind of worked but kept getting stuck on the side of the small gear which had been glued on very badly by me. I tried another way, where the small pinion was just cut out of cardboard rather than using the corrugated side as well, but that was worse. Nevertheless, I had to change the calculations, making the pinions 5 instead of 4. However, it was still impossible for me to be sure that it would completely work. So, I decided to make the pinions with 10 teeth. I made the big gears first since they were much easier to create correctly. Then later, I created the small pinions with 10 teeth, which worked much better than other runs so I just decided to go with it.

This step turned out to be more annoying than creating the gears, as it was very easy to create the escapement wheel and attach the toothpicks, but it was difficult to create a working anchor escapement. I kept making versions that would hit the other rods while trying to spin. Just trial and error worked for me, you could try experimenting with other mechanisms, which I couldn't since my time was running out. I also made the pendulum. Instead of just one piece, I divided it into a long stick and the curved part at the bottom. I put a used battery for weights in the bottom pieces of the pendulum, and to glue them together, I simply added paper coating on top of the cardboard, aesthetics and function, two birds with one stone. Then I also ensured the pendulum's period swinging calculations were correct, which thankfully it was. I quickly created a system for the weights as well, just a cardboard spool, attached it to a heavy object and finished it. Then, I tried to figure out a proper escape mechanism. Also known as the Graham pallet, my decision to an anchor escapement cost me a lot of time, as even though I used geometrically calculated things from a trusted source, it still did not work. Eventually, I tried another mechanism, following one of Gallelio's original ones, which sadly did not work. Therefore, for this instructable, as I was trying again, 5 hours away from the deadline for the tournament, decided to leave it be and focus on only the gears moving and the aesthetics. Perhaps looking back, the choice of using pegs, or making such a random-sized escapement wheel was not smart and required more careful consideration. Here is an example which I came across afterwards, which may help give you a better insight into making the anchor escapement.

Now, after an upsetting inability to do the pendulum or the escapement, I focused on gear placements. I quickly started by adding the escapement wheel, for later and the first pinion and then added the second too. I secured the parts with additional support cardboard from the sides too. This shows the versatile nature of cardboard, which is a less malleable Play-Doh in my opinion. I decided to shorten the size of the clock and have four things attached (2 10 teeth pinions, 1 50 teeth gear and the escapement wheel) This took forever because of my lack of experience in creating gear chains, please let me know how to do it efficiently in the comments, if you have any idea. A tip is to spin the gears next to each other before committing and flipping it to see if it works with the other side of the corrugated cardboard, which is what I have to do sometimes. Also, use supports hot glued to the structure and uphold the skewer rods straight. Nevertheless, I pushed through after countless errors and finally, I can rest in peace after the aesthetics of this product.

Now everything will look professional. To hide all the intricate yet dirty mechanics of the clock, we'll be using coloured paper. Now I wish I could find my glue stick but since I had like 1 hour left until the deadline ended, I had to speedrun and use a hot glue gun (Not recommended burns your fingers). Now, for my clock, I simply collaged paper, following whatever it said on the plan. I made some changes to speed up the process but that was it. I added some supports, looking back I should have added more since it almost broke, so yeah.

Alright, now polishing time. I started by creating the dragons, this was done way before, looking back I should have done them after the function was done. Simply create a body structure underneath with cardboard and hot glue and then just start cutting out parts from paper, which would be attached on top. I just decided to follow my sketches and not spend any time changing my decisions. You can change this to whatever symbolism you would like! Then attach it to the clock according to the thing you made.

Now it's just a matter of making sure everything is correct and in the right place/cleaning up any weird parts of the clock.

Really helpful links in my peregrination:

Gear Ratios

Cardboard Clock

Documented Process of Making a Clock

Escapement Mechanism

Another well-explained video

Escapement inner workings

Book: How Things Work by Theodore Gray 

Some other things I found, which may help:

https://www.woodenclocks.co.uk/clock-41/

https://cdn.hackaday.io/files/1638147008618176/SP1_Build_Notes_2019_Mar.pdf

https://bluepapertech.com/clock-repair/calculating-a-clocks-ideal-pendulum-period-the-sequel/

https://bluepapertech.com/clock-repair/clock-repair-101-making-sense-of-the-time-gears/

https://uwoodcraft.com/how-mechanical-pendulum-clocks-work/

https://www.youtube.com/watch?v=L0juTu66uqk 

I feel like the most fun part of this entire experience was sitting there and trying to figure it out through a caveman mindset, but here are some more links to guide your journey which I found along the way too. I would encourage you to use other complex escapement mechanisms, more complex and more interesting, and share them on Instructables too! Also, Chinese culture is just one of the many, you could be creative in your journey and put in elements from other cultures or even hobbies which you like. You could even try to create a cool design and invert it, which also gives you a dark mode version of your clock, a cool choice, in my opinion, as you can see in the attached images. This was just a dip in the river of the world of mechanical clocks, which has so much more to explore, offer and innovate upon. Hopefully, you enjoyed reading my first instructable! I might make more, but I'm not sure as I'm soon reaching Class 11, we'll see how it goes. I might finish this project for real if I get the chance, not for now since my hands are full of blisters but we'll see. Here's my rushed entry to the Paper and Cardboard contest!

PS: I thought it was due a day before, kinda stupid. Oh well.

Thank you!