Introduction: Exploring Gears

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When you think of a machine, you probably think of something big like a washing machine, car, or bulldozer. Those big machines are made up of smaller parts called, simple machines.

There are many types of gears in lots of shapes and sizes. Today we'll be exploring spur gears which are flat in a wheel shape and can only move in a straight line positioned either horizontally or vertically.

A gear is just a wheel with teeth, sometimes called a cog. To do any work with a gear, you need to have at least two cogs with their teeth fitting into each other. Because the teeth fit together, when you turn one gear, the other one turns too!

Gears come in many different sizes, which help them do work. If you connect one big gear with a small one, you can turn the big gear slowly and it will make the little gear turn quickly. Since it takes less energy to turn the big gear slowly than it would to turn the little one quickly, you are saving energy and making work easier by using gears. The smaller gear turns two times for every one turn of the larger gear. One gear can make another one turn faster, but it can also make it turn in a different direction. When two or more gears are connected, it's called a gear train.


  • Scrap wood (We like to use pieces that are small enough that the largest gear can hangover the side so you can turn it with your finger.)
  • Pencil
  • Screws (Screws need to be shorter than the thickness of your scrap wood and the gear.)
  • Gears (3d printed, cardboard, whatever material you have on hand.)
    • The gears we are using come from this Thingiverse project called, Sam's Gears.
    • We have adapted them to work for us. If you want to resize them make sure it is done equally with each gear otherwise they won't turn together or interlock.

Step 1: Map Out the Gears

Lay the gears out onto the scrap wood.

Figure out where you want them, but remember all three cannot touch or else the gears won't move. They need to be offset for a gear train to work using a spur gear.

With the pencil make a dot or trace the inside axis circle so you don't forget where you wanted them placed.

Now you're ready to move on.

Step 2: Setting the Gears

To make securing the screw easier use the pointy end of the screw and make an indention by pushing down on the head of the screw. Just a small amount of pressure will create a tiny divot. Don't screw it in yet though!

Now that you have made the divot move the first gear into position so that the divot is clearly seen through the middle of the axis hole. Place the screw so that it catches the pilot divot and begin to screw it in. You will need a fair amount of pressure so ask for help if it's too hard or use a power drill with adult supervision.

When the first gear is secure and spins freely it's time to move on to the second gear.

Step 3: Attach the Other Gears

Place the next gear over the pencil mark you made in step one. Sometimes it will match up, other times it won't. If it doesn't, like our example doesn't, you can either retrace the axis circle or use the screw to make the divot mark on it's new location.

Reminder: The teeth on each gear need to interlock as shown. If they are too far away or even too close it can be difficult for the gears to turn easily.

When you have both gears attached test it out, do both spin?

If it's too tight or you made an accident screwing it in you can always unscrew the second gear move it's location away from the bad screw hole and try again. At this point as long as it is touching the first gear and turning that's all you need.

Once your second gear is secure and spinning follow the same steps for adding the third gear.

Reminder: The third gear cannot touch both of the other gears. If they do it will lock up and not spin. Spur gears only work on a flat plane.

Step 4: Ready Set Spin

Now that the gears are all set it's time to spin them.

This is an excellent fidget spinner and fun toy to learn how basic gears work.
Now that you've mastered this you can try to make a huge gear train or move on to other more complex gears.

This instructable was created for a "Remake Learning" event taking place at Science City on May 1st and Operation Breakthrough on May 8th 2021 in Kansas City. The Maker Studio has partnered with Make48 to bring this activity to guests in person.