A sundial is a device that uses the position of the sun to determine the time. A stick is positioned vertically, called a gnomon, so that it projects its shadow on a pre-marked surface; as the sun "moves" across the sky, the shadow moves too. You can easily verify this phenomenon by putting a rudimentary sundial in the garden consisting of a stick and a handful of small stones. There are many simple projects that help children understand this concept. If you want something more complex, you can build a permanent sundial in the garden or yard. After taking some measurements and doing some carpentry work, your creation will mark the time precisely.
Steps
Method 1 of 3: Build a Rudimentary Sundial with Sticks and Stones
Step 1. Gather the tools
This extremely simple sundial is a perfect device for explaining the basic phenomenon with very little planning. Everything you need is in the garden or courtyard. You need to get a straight stick (about 60 cm long), a handful of stones and a wristwatch or a mobile phone that shows the time.
Step 2. Find a sunny spot to plant the stick
Look for a spot that stays in the sun all day and push one end of the stick into the grass or dirt. If you live in the northern hemisphere, tilt the pole slightly north, do the opposite if you live in the southern one.
- If you don't have a surface of grass or soft soil available, you can improvise.
- Fill a small bucket with sand or gravel and stick the pole in the center.
Step 3. Start at 7:00 am
If you want to complete the sundial in one day, you must start construction in the morning, once the sun has fully risen; when hit by the sun's rays, the stick casts its shadow. Use a rock to mark where the shadow falls on the ground.
Step 4. Go back to check the stick every hour
Set an alarm and keep an eye on the clock to be able to update the sundial at any precise time. Return to the device at 8:00 am and use another rock to indicate where the shadow of the stick is. Repeat the same procedure at 9:00 am, 10:00 am, and so on.
- If you want to be very precise, use a piece of chalk and write the exact time on each stone you place on the ground.
- The shadow moves in a clockwise direction.
Step 5. Continue in this way until sunset
Go back to the sundial at any time and mark the position of the shadow with a stone until there is no more sunlight. By the end of the day you should have completed the project. As long as the sun is shining in the sky, you can use this simple device to know the time.
Method 2 of 3: Making a Simple Sundial for Kids
Step 1. Gather the material
This simple sundial is a perfect summer project for kids. The tools required are basic, you probably have everything you need at home. You need to get some crayons or markers, a paper plate, a sharp pencil, thumbtacks, a ruler and a straight plastic straw.
Step 2. Start preparing the dish around 11:30
Get the child to start working on the project just before noon on a sunny, cloudless day. Take the sharp pencil, push it through the center of the paper plate and then pull out the pencil, so that there is a hole in the middle of the plate.
- Write the number 12 on the far edge of the plate using a crayon or marker; the number represents 12:00 or noon.
- Use a ruler to draw a straight line from the number 12 to the hole you made in the center.
Step 3. Get a compass to identify north
In advanced sundials the "straw" (ie the gnomon) must be slightly inclined and, specifically, must point in the direction of the nearest celestial pole which is parallel to the axis of the Earth. This means that people living in the northern hemisphere must tilt the straw towards the north pole, while those living in the southern hemisphere must point it towards the south.
- Use a compass to find north (or south, depending on where you are).
- Make sure you bend the straw slightly in the correct direction so that the sundial is more accurate.
Step 4. Take the dish outside
Leave the house just before noon and place the dish in an area that is exposed to the sun all day. Insert the straw into the central hole and let it hang a little north (or south, depending on your geographic location). At 12 o'clock sharp rotate the plate so that the shadow of the straw overlaps the line you drew.
- The device resembles a clock face with the shadow hand pointing to 12:00.
- Since you are only measuring the hours of the day, the plate looks like a clock showing only twelve hours.
- Stick a few thumbtacks into the plate to secure it to the ground.
Step 5. After an hour, return to the sundial
When 1pm strikes, go to the plate and check the position of the straw shade. Write the number 1 (i.e. 1:00 pm) at the far edge of the plate, right where the shadow falls. Set an alarm to return to the device every precise hour and keep marking the position of the shadow on the circumference of the plate.
- The shadow moves clockwise.
- Analyze the dynamics of the shadow with the child; ask him in which direction he thinks he will move.
- Tell him what happens as the shadow moves across the dial.
Step 6. Repeat the procedure until sunset
Keep tracing the hours on the plate every 60 minutes until there is no more sunlight. Have the baby go back to the sundial on the next sunny day and ask him to tell you the hours based on the position of the shadow. This simple device lets you know the time on every sunny day.
Method 3 of 3: Constructing an Advanced Sundial
Step 1. Cut a 50cm diameter disc from a 2cm thick piece of plywood
This circle represents the sundial dial and you need to coat both sides of it with primer. As the adhesive dries, think about the final look you want to give the device. You should choose the style in which to draw the numbers, such as Roman, Arabic and so on.
- Choose the color you want to use and, if you like, draw a design or illustration to apply on the front face of the disc.
- Do a few different drafts until you have the final design established.
Step 2. Draw the final image on a large circular piece of paper
You must use this sheet as a stencil to transfer the design or decorative pattern onto the plywood, then make a drawing to scale. At this point, you need to enter the numbers on the image, which requires a series of precise measurements. To do this, you need a ruler and a protractor.
- Start by writing the number 12 at the top of the circle, as if it were a clock face.
- Find the center of the circle and, using a ruler, draw a precise line from the number 12 to the center itself.
Step 3. Use a protractor to measure exactly 15 ° to the right
At this point write the number 1 and use the line again to draw a line that joins it in the center. Keep writing the numbers so that they are 15 ° apart from each other by moving clockwise; for this purpose, use the protractor. The twelfth point should be diametrically opposite to the first, the one you have already marked with the number 12, and together they mark noon and midnight.
- Continue dividing the circumference by resuming the numbering from 1 until you reach the number 12 you wrote at the beginning. At this point, you have drawn all the numbers correctly on the card.
- To have an accurate sundial it is necessary to represent all 24 hours. When the season changes, the position of the Earth in relation to the Sun changes. In summer, the days are longer, while in winter they are shorter.
- On some summer days there are more than 12 hours of daylight.
Step 4. Transfer the design to the wooden disc
Use the paper template as if it were a stencil, so that the lines and numbers exactly coincide with the previous measurements. Use paint markers to write the numbers on the wood, as the work is full of small details. These types of markers are better than permanent ones, because they are more resistant to climatic agents.
Step 5. Get a gnomon
This is the sundial element that casts its own shadow. To make this you should use a piece of threaded tube about 5-8 cm long and with a diameter of 1.5 cm. Make the gnomon slightly larger in diameter than the tube and improvise a conical tip.
- The length of the tube and the tip of the gnomon should not exceed 7-8 cm in all.
- Paint the gnomon the color of your choice, this way you also protect it from rust.
Step 6. Prepare a pole to mount the sundial on
The supporting structure must support the dial, that is the wooden disc; you need a 10x10x20cm pressed wooden post that has been treated to withstand the elements. Make sure it is perfectly straight and has no large gaps. To properly install the sundial, the top of the pole must be cut at a precise angle.
- To get this angle, subtract the value of the latitude you live at from the number 90.
- For example, if your city is located at 40 ° north latitude, you should draw a 50 ° angle to the 10x10 cm section.
Step 7. Cut the tip of the pole respecting the angle you calculated
Using a carpenter's square, draw a line 6 inches from the top of the stick that represents the base of the corner. Use a protractor to measure the width and then make the cut with a table saw.
- Find the center of the sundial dial in which to drill a hole.
- Make sure you can secure the dial to the pole with an 8mm hex head screw to make sure everything fits together perfectly.
Step 8. Dig a hole for the post
Find a sunny spot in the garden to plant the pole, but make sure it is not traversed by electrical wires or underground pipes. Place the pole in the hole and check that it is no higher than 1.5m above the ground when perfectly straight. Use the compass to check that it faces north and check that it is perfectly vertical using a carpenter's level.
- Fix the post to the ground permanently by pouring concrete into the hole and allowing it to settle.
- Wait a few days before mounting the dial to allow the concrete to dry completely.
Step 9. Connect the sundial to the pole
To do this, use an 8mm diameter and 5cm long hex head screw. Tighten it just enough to join the two elements but not too much, so you can turn the dial effortlessly; put a flange directly above the dial.
- You should be able to see the screw head through the center hole in the flange.
- With your right hand, screw the gnomon tube to the flange, while holding the flange still with your left hand.
Step 10. Rotate the dial so that the 6:00 am and 6:00 pm lines are horizontal
Align the gnomon so that these lines appear to form a single straight segment running through the center. Make sure the noon line crosses the center perfectly.
Step 11. Set the time and fix the gnomon
You must set the time during the legal period to get accurate readings. Hold the flange with your left hand and use your right to rotate the dial. Check the current time and keep turning the sundial until the shadow of the gnomon points to the same. Use the pencil to mark where the four flange screws are and then remove this element.
- Fully tighten the hex screw without moving the dial.
- Drill four holes at the position of the four screws and attach the flange to the sundial.
- Finally, screw the gnomon.
