Sun Earth Orrery

Earth-Sun Orrery

If you've ever wondered about the orbit of the earth, wanted to teach about space, or just love gears, this model is perfect for you. This orrery combines the satisfying mechanical movements with the awe-inducing movement of the earth. 

Usage:

To use this, simply turn the crank and the earth will spin and orbit accordingly. One rotation of the crank will move forward time by approximately 5 weeks, or 35 days. One year will take approximately 10.5 crank rotations.  

Assembly:

Once printed, you should have a total of 15 parts. I have divided the parts and assembly into three main sections: center, crank, and arm.

In the center section, you will have the following parts:

1. Base

2. Rotating arm

3. Fixed gear

4. Sun

To assemble the center: 

1. Thread the hole of the rotating arm through the rod of the base. Making sure that the gears on the rotating arm face downwards

2. Thead the fixed gear's hole through the rod and snap fit the 3 pins into the corresponding holes on the base

3. Finally, connect the rod and the sun by fitting the rod into the sun's hole. 

At this point, you assembly should look like this. 

Now onto the crank section!

In the crank section, you will have the following parts: 

1. Compound gear

2. Connecting gear 

3. Main gear

4. Crank

5. Handle attachment

6. Handle

To assemble the crank part: 

1. Thread the hole on the connecting gear into the axle of the main gear

2. Press the crank's square shaped hole into the corresponding extrusion on the main gear

3. Press fit the handle attachment to the handle through the crank, with the crank in between

4. At this point, your crank assembly should look like the figure on the right

5. Now, push the compound gear axle into the right hole on the base

6. Push the crank assembly with the main gear into the left hole on the base

At this point, your finished crank and center assembly should look like the following:

If this looks like your assembly congrats! You can move on to the arm section. 

In the arm section, you should have the following parts:

1. Large gear

2. Medium gear

3. Small gear

4. Rod with gear

5. Earth (design is not printed, just for illustration purposes)

To assemble the arm section: 

1. We will first letter the holes on the rotating arm from A to D.

2. Place the medium gear (12) into Hole B

3. Place the large gear (11) into Hole A

4. Place the small gear (13) into Hole C

5. Push the rod into the corresponding hole on the earth. 

6. Place the rod with the gear into Hole D

And there you have it! 

You have assembled the Sun Earth Orrery!

Happy orrerying! 

Why I made this:

I think I was scrolling youtube and found an orrery. Previously, I had no idea that it even existed and thought it was sooo cool how it just models the movement of the earth. Seeing as how it was the week's theme was space, I thought it was very fitting to model an orrery to a) learn how it works and b) get more of an understanding of earth's orbit itself. However, after 5 hours, it still wasn't done so it didn't qualify for the space theme. However, the next week's theme was gears, which this projects has a ton of. After another week of cadding, I still wasn't done... But all in all, this project was really cool and really made me think of how to model it so that the torque and gear ratios all work to make the earth's movement as accurate as possible.