Sundial!_________________________

Sundial Building Plans:

You may select any materials you desire to make your sundial.  
What follows is an example that uses:

* a  5" square piece of wood board
* paints and artist brush to mark the dial face
* the custom ordered "unit " data chart
* a ruler/straightedge for measuring
* common hand tools

For illustrative purposes, the following "unit " chart will be 
used to show sundial construction: (Your own calibrated chart is enclosed, 
this chart is for illustration only!)

6:30 am		.07 V
7:00 am		.18 V
8:00 am		.42 V
9:00 am		.73 V
10:00 am	.4  V
11:00 am	.2  H
12 noon		.03 H
1:00 pm	       -.14 H
2:00 pm        -.32 H
3:00 pm		.87 V
4:00 pm		.51 V
5:00 pm		.25 V
6:00 pm		.03 V

Gnomon Unit Measure = .8

Remember, the following procedure is for illustration only!  
After you read and understand it, use the numbers supplied on the chart 
you order!

First, draw a line to divide the 5" square in half, 
vertically:


Next, take the value from the "unit" chart for 6:30 am and 
multiply it by 5: (.07 x 5 = .35).  Measure up .35 inches from the left 
bottom corner of the 5" square and make a mark on the left edge.  
This is 6:30 am on the dial.


Likewise, use the values for 7:00am, 8:00am, 9:00am, and 10:00am multiplied 
by 5, and make corresponding marks on the left edge of the square.


To mark the dial for 11:00 am, multiply the chart reading by 5, and measure
from the center line to the left, along the top edge: (.2 X 5 = 1")


Likewise, use the value for noon multiplied by 5 (.03 X 5 = .15") and 
mark the top edge .15" to the left of the center line.

Notice that the value for 1:00pm and 2:00pm are preceded by a "-".  
All this means is that the points are marked to the "right" of the 
center line instead of the left. (-.14 X 5 = .6", and -.32 X 5 = 1.6", both points 
marked to the "right" of the centerline.

For the 3:00 pm mark, multiply the chart value by 5 (.87 X 5 = 4.35"), and measure 
up 4.35" from the bottom right corner of the square, on the right edge.
Likewise, for four, five, and six o'clock, multiply the chart values by 5, 
and measure up the right edge from the bottom.

Next, connect the points, one by one, to the center bottom edge (See 
illustration.)  The dial face is now laid out properly for the "illustrative 
chart".  Add numbers and designs as you wish. 

The next step is construction of the GNOMON, or "shadow caster".
From the chart, note that the ratio is  ".8".  This means that you must 
construct a right triangle with a ".8" ratio as follows:

On the material you choose to use to make the gnomon (wood, metal, plastic), 
draw a line 5 inches long.  At one end of the line, measure up 4 inches 
(5 inches X .8 = 4 inches).

Form a triangle by connecting the top of the four inch line to the other end 
of the five inch line.  

Cut out the triangle, and attach to the sundial face. (Epoxy glue works great)  
The "pointy" edge of the triangle should be attached to the "bottom edge 
center" point where all the hour lines meet.  Mount the sundial on a pedestal 
if you desire. 

Remember, the above numbers are illustrative only!  Now go back and use 
the numbers on the chart you ordered to lay out the sundial face.

If you have used your chart numbers and followed the above procedure, 
the SunDial is now ready for use!  The sundial measures "standard time" not 
"daylight savings time", so take that into account as your orient the 
sundial for time measurement..  The sundial is placed in the sun so that 
the "bottom" edge is pointed due south..  The quickest way to set it up is 
to note the correct clock time, and orient the shadow cast by the GNOMON to 
read the same time on the sundial face.  Be sure to note that daylight savings 
time is an hour later than "standard time".  For example, if it is 2:00 pm 
daylight savings time, orient the sundial so the shadow from the GNOMON falls on 
1:00 pm, as shown above.  It's as easy as that!  Sundial time is not as accurate 
day to day as a "clock", in that the orbit of the earth around the sun is 
not a perfect circle, and the speed of the orbit is not constant throughout 
the orbit.  The days of the year when sundial and clock time agree are April 16, 
June 14, September 2, and December 26. So setting up the sundial orientation on 
or close to those days will ensure the most accuracy.


Have fun with your sun dial!