K'nex Clock - Accurate Timing




This k'nex clock runs entirely without the power of motors but uses a weight for energy. The escapement can work for about an hour before the weight needs to be lifted again but with some adjustments it would be easy to extend this period dramatically. The face of the clock displays the hour and minute using two separate hands that rotate independently. The timing is accurate to within a minute or so every few hours and the speed can be easily adjusted by changing the length of the pendulum. This project presented some challenges in terms of making the face and getting the hour hand to turn at exactly one twelfth of the speed of the minute hand. I hope you enjoy this instructable and have fun building.

Step 1: Assemble Base

This base was made to fit the surface my clock was on but it can be adapted to fit any surface desired

Step 2: Build Escapement

With modification, the gears can be changed to suit the speed and power you desire but this is the best formation I came up with

Step 3: Begin Adding Wheels and Rubber Bands

Just like the escapement, this is subject to modification but this way gives the clock accurate timing. Note that it is vital that the rubber bands are placed on when instructed or it will be difficult to put them on later.

Step 4: Clock Face

This is the face and time-telling hands that you will now be building. It doesn't realistically matter how they look as long as you can easily identify them.

Step 5: Secure Clock to Surface

The weight which will be later applied to the front of the clock is enough on its own to pull the clock off the surface. What you need to do is used the necessary pieces to firmly keep the back down or put a large weight on the back. These pictures are just examples of what need to be done.

Step 6: Assemble the Pendulum

The length of the pendulum can also be changed to regulate the speed of the escapement. The longer it is or the more mass on the end will make it move slower. If you decide to use a motor for the weight it should be noted that this one contains batteries for extra mass.

Step 7: Add Weight

The weight used for your clock is entirely up to you. The shape and mass is dependant on what works best. I chose a bottle for the practicality of being able to add or reduce weight by adding water. This is ideal because it means you can change it accordingly. The weight holder is also dependant on the shape of your weight meaning my design is just an example. The wheel on the top of the weight holder is necessary though as it keeps the string that it will be on in place.

Step 8: Add String

To determine the best length of the weight-holding string, measure the distance from the clock to the ground and double it. When you have this, tie a small knot in one end and place it onto the light brown piece as shown. Wind the wheel anticlockwise to ensure the string will move with the wheel. Once this is done you can thread the string under the weight and attach it how you want to the idle wheel on the right of the clock. I used a lasso to do so but it doesn't really matter how.

Step 9: Complete

Your clock is not ready for use. All you have to do is wind the weight up to the top and swing the pendulum. The pendulum is likely to take a bit of altering with regards to the orange teeth. You will need to try different combinations of height and find out which works best for a regular and constant beat. To change the time, remove the central rubber band from the wheel and manually spin the minute hand until both hands display the correct time and place the rubber band back on.

Step 10: Modifications

As an additional modification, you could replace the string with a k'nex chain so that it is possible to lift the weight without stopping the clock. This method is more effective for using a lighter weight but overall more fragile and likely to break. Lifting the weight is also frustrating as the chain is difficult to keep lined up. It would be a good thing to experiment with but I would personally keep the string.

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    47 Discussions


    3 years ago

    dos the can have to be full??


    3 years ago on Introduction

    What did you base this on? Or did you design completely yourself?

    Thanks :)


    4 years ago on Introduction

    I built it but the problem is the escapement is spinning really fast

    wezils tuts

    5 years ago on Introduction

    great clock i built it and it works. except for the fact that it stops after a while even if the weight isn't all the way down… i guess my weight isn't heavy enough even though its full of water :p . still I'm posting a review on it

    5 replies

    I'm pleased that it works but I am curious as to why it stops before the weight is on the ground. You don't suppose it's friction do you?


    well it could be friction, but i used a coores light bottle similar to the one you have and I've never opened it, so its full of liquid… it runs for 45 secs then the pendulum stops moving. what i think is happening is my weight isn't heavy enough so the escapement isn't pushing as hard as it needs to to keep the pendulum moving.


    or another possibility is that i don't have the pendulum ticker/stopper thingies in the right area (they are still on the blue rods on the pendulum of course)
    I'm going to see if that makes a difference,i'll let u know


    it could be that my bottle isn't big enough so when i do fill it 3/4 it isn't anywhere close to the amount that u have, or our fulcrum/penulum is messed up ill send pics of it. thx for help happy new year.


    I did notice when I added too much weight the rods were pulled down by the mass and created more friction. I eventually found the the bottle worked best at half to 3/4 full


    Reply 5 years ago

    I'm pretty sure I got them all in the K'Nex 'hometown carnival' set, however I cannot be 100% sure. I've been looking for new sets that are cheap and also contain gears but haven't had much luck. Hope you find some though.

    It keeps going because it gets a little push from the escapement every time it rotates. So it's actually the weight that turns the gears and the wheel which pushes the pendulum in the correct direction every time they make contact. Without the wheel at the top to push it a little bit it would just stop. I hope I've explained enough to understand


    5 years ago on Step 3

    any way to replace the wheel in the 10th pic?