Sundial: Make your own for free

Created by Liza 2010-08-11 07:24:51
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Sun clocks are the first scientific invention. Sun clocks kick-started time counting. Sun clocks are called Sundials. Sun clocks are simple. The first sun dials where simple sticks stuck in the ground.

Sun clocks evolved into today’s digital precision clocks. However, telling the time with sundials, using just the sun and the shadow, works to the day just fine. There are many different sun dial designs. This article shows you how to make horizontal sundial. This design can be used to build a big horizontal sun dial or a pocket sundial.

Here is what you will need: A surface where to draw your sun dial design, (this can be a piece of paper, a piece of wood, or it can be designed on the floor). You will also need, a scientific calculator, a protractor (yes, that is the tool to measure degrees), a world map with latitude and longitude (you can find that online) and a compass if you have one.

If you follow the instructions step by step you can not go wrong.

Step One: Draw a half circle, on a piece of paper, with your protractor. Make three markings. One on the right end side (180 degrees) of the half circle. The other on the upper (90 degrees), and one on the left end side of the half circle (0 degrees). Mark the left mark as
6 am, the upper mark as 12 o’clock, and the left side as 6 pm.

Step two: Time varies on every part of the world.Your sundial has to be fitted for the place where you live. Use the world map to figure out the latitude of your location.

Step three: What you need to do is to fill in the hours in your sundial. You already know where 6 am, 12 pm and 6 pm is now you need to figure out the other hours.
You will need this equation: L sin x H tan.

L is equal to latitude. (look up your latitude in the map, let’s say you live at 40 degrees latitude)

H means hour degree. This is simple, just multiply the hour you are working out times 15, for example 1 hour times 15 equals 15 H.

So, in this case,
L sin x H tan
40 sin x 15 tan

Now use your scientific calculator.

Put in 40 then press sin in your calculator, then multiply by 15 and press tan. Now press 2nd function and press tan again. That will be the result.

This is very easy to do with a scientific calculator.

So.. 40 sin x 15 tan (2nd function tan) is 9.77252615 degrees The result for 1 hour is 9.7 degrees.

Step four: Using the protractor, set it over your half circle and mark 9.7 degree from 12 o’clock to the right. That will be your hour one (1).

Step five: Repeat step three for all the times. Using the same equation figure out the hour degree for every time. Then mark on your design.

Step six: Transfer your half circle sun dial to the surface you want to use your sun dial. The surface can be on the floor, or it can be small to fit your pocket. The 12 o’clock should be pointed North.

Step seven: Use a stick, a nail or your own body (if you transferred the design on the floor) to cast a shadow on your sun dial.

Important: The object that is casting a shadow should be pointed North and bent in a Northerly direction 40 degrees. The object casting a shadow will not work if it is 90 degrees from the ground pointing into the sky. It should be 40 degree.

Step eight: Point the 12 o’clock of your sun dial North.

Step nine: Use a normal clock to see if the hours agree with your sun dial. If they do not, then do the math again.
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Comments / Add a comment
dick Bolt
I am making one using a wide mouth (International) Sat TV dish.
Face up & using same mounting brackets holding to 6X6 on ground.
added 2010-11-13 22:30:34
I hope the future to share this good work
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