How to Build a Sundial

What You'll Need
Flat surface
Balsa wood
Carpenters level

Although a sundial is no longer the most practical or accurate way to tell time, one of them can make an interesting conversation when placed in a garden or in your back yard. And, if built and placed accurately, and if the sun is shining, your sundial should be able to indicate a fairly accurate time of day. If you are going to add one of these ancient time instruments to your landscaping, you will certainly want it to be functional. You can build a sundial that is both interesting and functional by following the directions below. But keep in mind that you will need to pay particular attention to details and be precise in your measurements, placement and marking. Draw hour lines at the correct angle according to latitude lines. Be sure when you are drawing these lines that you use an accurate compass and protractor.

Step 1 – Determine your Home's Latitude

Finding the latitude of your home will be simple to achieve if you use a map that has latitude and longitude lines marked on it. Once you have gained access to a map like this, locate your home to determine its latitude.

Step 2 – Calculate Sunday Hour Placement

You'll need a sundial hour line calculator to figure the correct placement of hours for your sundial's latitude. The use of one of  these calculators is essential, and if you don't have one and don't know where to get one, find an online calculator vendor.

Step 3 – Create and Mark Hour Lines

Use a piece of card stock on which to draw hour lines. These lines and angles can be determined accurately by using the hour line calculator, a compass, and a straightedge. Your baseline will be set at 6 a.m. and 6 p.m. Mark the appropriate hours on each of your sundial's hour lines.

Step 4 – Build your Gnomon

Use balsa wood to build the sundial triangle, called gnomon, that indicates time by casting its shadow. The shape of the gnoman should be an equilateral triangle. The location for angle degree on the gnomon should be the latitude degree you found for your home on your latitude map. On the sundial line marked as 12:00, tape or glue the gnoman to secure it.

Step 5 – Choose a Place for your Sundial

Now that you have your gnomon and hour lines put together, you'll need to find a flat surface where the sun will shine on your sundial. That is, it should not be placed in a location where buildings, tree limbs and such will shade it from the sun. You'll need to be sure the surface is truly flat, so use your carpenters level to ensure this.   

Step 6 – Situate your Sundial

Using a magnetic compass, position your sundial with its back side facing north. You can confirm correct placement by comparing your sundial time with your watch time. For best results use daylight standard time. Read the sundial time by the alignment of its bottom edge shadow which should line up with the hour line that is closer to your local time.