For a horizontal sundial we want the gnomon to be aligned with the South Celestial Pole so that the sun will rotate around it when we face our sundial due south.
The easiest way to get the nail into the wooden checker at this angle is to do the following. First, hammer the nail straight into the center of your wooden checker making sure not to go through the back side.
On an index card draw a line that is inclined from the bottom of the card at an angle equal to your latitude.
Hammer the nail from the side so that it begins to bend over.
Place the index card behind the bent nail, with the start of the line at the base of the nail. Continue to bend the nail over until it is at the same angle as the line you have on your index card.
Now the nail should be making an angle equal to your latitude with the base of the checker. It should look like the image above.
If the nail become loose, a little wood glue at the base should secure it.
Drill a hole in the wooden checker on the opposite side from where the nail is pointing. Make sure to drill the hole large enough so that the cord you have chosen will fit through it.
If you do this activity with a large group of young children it is often best to prepare the checkers up to this point ahead of time.
You are now ready to put on the hourlines for the sundial.
Once you have a hard copy of the image above, place your wooden checker on top of the image such that the center of the checker, where the nail hole is, is directly over the intersection of the horizontal and vertical lines. The horizontal line, marked with a six on each side, should run underneath your checker exactly across the center.
Without shifting the checker, rotate it until the head of the nail is pointing up the 12 o'clock line, as seen in the image to the left.
Holding the checker very still, make 13 pencil marks on the top face of the wood, each mark inline with the appropriate hourline. It is best to start with pencil so you can redo any mistakes.
Once you have made all of the hour marks go over them in pen and write in the appropriate numbers. Because the face of our sundial is so small, it is best to include only a few of the hour numbers, as in the image to the right.
Finish your sundial by threading the drilled hole with some cording and tie it off to the desired length.