Capricorn: Dec.22-Jan.29 The Sundial Primer
created by Carl Sabanski
Capricorn: Dec.22-Jan.29

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Cycloid Polar Sundial Kit

Cycloid Polar Sundial:  a variation of the standard polar sundial in which the gnomon has a cycloid shape, with the result that the hour lines are equally spaced.

The cycloid polar sundial is a very cool sundial. Because of the special shape that the gnomon takes on, a cycloid, the hour lines on the dial plate are equally space. Just like the polar sundial this sundial is universal and will work anywhere in the world.

The cycloid is a very interesting shape and you can visit The Sundial Primer to find out how it is created.

Figure 1 shows the Kit that you will use to make your own cycloid polar sundial. Just print it out on card stock or glue it on to cardboard. Cut it out very carefully with scissors. Follow the few simple instructions and you're done. You can construct a couple of cardboard right angled triangles that can be glued to the gnomon and the dial plate at the centre of the sundial. This will help to hold the gnomon in a vertical position. Styrofoam triangles would work well too. The joint line on the dial plate should be reinforced by gluing a strip of cardboard on the back.

Figure 1: Cycloid Polar Sundial Kit

Figure 1: Cycloid Polar Sundial Kit (CAD)

We have made up two kits so that you can build a cycloid polar sundial for the Northern or Southern Hemisphere. All you need are scissors, cardboard, glue and tape. The sundial is a lot of fun to make and would be a great science project. If you would like to download a PDF file of the "Cycloid Polar Sundial Kit" just open the door that works for you. 

Cycloid Polar Sundial Kit - Northern Hemisphere Cycloid Polar Sundial Kit - Southern Hemisphere
Northern Hemisphere Southern Hemisphere

When you have completed the sundial all you have to do is set up and it will tell you solar time. This sundial is set up the same way as a polar sundial.

Here's what the sundial will look like once you have finished making it. This one is located in the Northern Hemisphere and positioned for a latitude of 50. It is important to note that the gnomon lies in the equatorial plane. As a result the sun spends half the year above the gnomon's plane and the other half below. This is illustrated by the position of the shadows.

Cycloid Polar Sundial - Northern Hemisphere - June - 4:00 P.M.

Northern Hemisphere - June - 4:00 P.M.

Cycloid Polar Sundial - Northern Hemisphere - December - 11:30 A.M.

Northern Hemisphere - December - 11:30 A.M.

Happy Dialling!