Levitating Clock
Clock Operation
Congratulations on building your levitating clock. I hope this clock gives you the pleasure of accurate time for years to come. Below are instructions for setting up and using your clock. The video below will take you through the setup.
Powering the Clock
Power is applied to the clock through the use of a USB C cable at the back face the clock. This can be connected to any 5 volt USB power supply. When power is connected it may take several minutes for the clock to begin moving. When the clock begins it will search for an available Wi-Fi signal. If none is found it will continue by moving the hands every minute. The clock will be much more accurate if it can have access to Wi-Fi as this allows it to get the current time.
Connecting the Clock to WiFi
On power up the clock searches for Wi-Fi network for which it has has credentials. If no Wi-Fi access is available the clock will immediately broadcast it's own network so that the user can provide the necessary credentials.
To set up your Wi-Fi network, follow these steps:
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Plug in the clock.
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Search for a Wi-Fi network named LevClock. This can be done using your phone or any Wi-Fi enabled device. No password is required.
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Once connected, a web page will be transmitted allowing the user to enter their Wi-Fi credentials (Wi-Fi network and password)
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The clock will then access this Wi-Fi network. For more detailed explanation of the clock working see the engineering section below.
Setting the Clock
To set the current time lift the ring from the clock base. Rotate the inner ring until the minute hand is on the current minute. Return the ring to the base. The hour hand can be set by flipping the inner gear set around the central axis. This is somewhat counterintuitive. To increase the hour, flip the gear set counterclockwise. To decrease the hour flip the gear set clockwise. Occasionally, gear set may be carried around with the minute hand. This is typical as the clock gears are wearing in. If this happens rotate the gear set counterclockwise to return to the correct time.
Engineering a Clock
One of the primary purposes of this clock is to introduce young minds to the wonders of engineering. I would like to walk you through some of the processes, tasks and tools engineers use in developing a project. I know engineering can be a mystery yet it is a wonderful and rewarding profession. One of the first things you should know is that engineers must use both sides of their brain. Your brain has a creative side. This is where new ideas and out of the box thinking originate. This side is critical for the engineer to be able to dream and create the products. But there is also an analytical side of your brain. This side is used to do the math and logical thought that help engineers answer the many question which engineers must answer during the design process.
The Concept
An engineering project typically begins with an idea. This idea is the nucleus around which the engineer will develop the project. In this case the idea was given to me. I came upon it while exploring a most fascinating website on clocks. Here is a link to that website.
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https://shiura.com/dfab/index-en.html
Engineers operate under a fairly strict code of conduct or ethics. One of those points of conduct involves giving credit for the ideas which originate from others. This gentleman from Japan has some excellent clocks which he has documented. This concept was not his idea however, and he rightfully gives credit to the original source. The design was developed in the 1940s by Leendert Prins of the Netherlands and commercialized in the Golden Hour Clock a product of Jefferson Electric. Mr. Prins’ original Patent is linked below.
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https://patentimages.storage.googleapis.com/72/c1/0a/e65d784506771c/US2642713.pdf
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Patents are one of the ways engineers and companies protect their ideas or "intellectual property".
Modeling
As I looked at the original model that was presented in the website above, I noticed some improvements that I wish to make. To be able to make these improvements I needed to model the project from scratch. This was done using a Computer Aided Design or CAD program called Onshape. This is a web-based CAD program which allows designers to develop their ideas virtually as the creative side of their brain comes up with new concepts. A CAD program it’s an excellent way to proceed with this task of fleshing out the design.
If you are interested in learning to model using a CAD program, perhaps consider Onshape. A link to a FREE Educational License is given below. The site also offers an excellent training program as well.
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https://www.onshape.com/en/education/sign-up
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A good Place to Start in the Learning Pathways is the Onshape Fundamentals – CAD lessons
Gears
The gears for this clock are interesting. They cause the hour hand to revolve once for every 12 rotations of the minute hand. Thus, there is a 12 to 1 gear ratio. This gearing must use a set of 4 gears so that the hour hand can reside on the same shaft as the minute hand.
The simplest math for this gearing is a 4:1 ratio and a 3:1 ratio since 3 x 4 = 12. When employed in this type of gearing arrangement they yield a 12:1 ratio over all. The gears used are (14 and 56) and (20 and 60). The 'center-to-center' for both of these gear sets must be the same. The diagram below shows that the gears must turn on a lower and upper axis. The distance between the center-to-center axis is determined by the number of teeth in the pinion (small gear) and the gear and the size of the teeth. To bring the axis of the two gear sets closer into alignment, the 2 pinion (small) gears are swapped. Unfortunately, this still leaves a small different in the center-to-center distances. To correct this error the size of the teeth in one set of gears are adjusted slightly. Gears can be really interesting and is one of the areas where math is needed in this project. See the document linked below for a more detailed coverage of this topic. 3D printed gears often make an excellent option for an engineering to prototype.
https://khkgears.net/new/gear_knowledge/abcs_of_gears-b/basic_gear_terminology_calculation.html
Stepper Motor
Engineers employ a variety of components to develop the products they create. These include but are not limit it to: pistons, gears, motors, sprockets, belts, fasteners, linkages etc. We’ve already discussed gears above, now let’s look at one type of motor that is useful for both the engineer and the hobbyist, stepper motors. In this project a stepper motor is used to drive the ring gear and move the minute hand. Stepper motors make small and precise steps instead of running with a continuous rotation. Each step is commanded by the controller and driven by the motor driver. This small stepper motor also uses gearing to further reduce the output speed. This motor requires 512 steps for one rotation. By counting the steps, the controller can determine exactly how far the motor has turned. For a more complete explanation of how stepper motors work, check out the video linked below.
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3D Printing
This clock is created using a 3D printer. The 3D printer is an excellent tool for the student and the engineer who want to create and manufacturer with a limited budget. I created the model which I used in Onshape and exported each part as an STL file. I then sliced the model and saving the G-Code for the printer. Here is a couple of links to an introduction to 3D printers and a typical build of a 3D printer.
Intro to 3D Printing
https://www.youtube.com/watch?v=MARPSciA2-Y
Building a 3D Printer
Programming
Engineers often use microcontrollers to make their designs more flexible and allow them to interact with their environment. The controller in this design sends the pulses to the stepper controller and times the delay before the next set of steps. In the WI-FI enabled mode, the controller connects to the internet and visits a special website which give it the current time. The controller makes calculations for the delays used to keep it running on time. The link below is a step-by-step video explanation of the code if you would like to learn more.
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If you are interested in learning more about programming and the Arduino coding environment, please visit the main page of this website.