This is a 15-minute paper sundial in two senses: it takes 15-minutes to make and is labeled to the nearest 15-minutes.  It is made of paper, but I designed the gnomon to have a three-dimensional base for greater stability, tapering to a thin top for better accuracy around noon.

The hard work was my doing the trigonometry for the three-dimensional paper-craft gnomon and writing a perl script that generates a pdf file for a particular location.  But with the script written, you should be able to print out a sundial from the generator on my website and construct it in fifteen minutes.

Ingredients and tools:
  • Two sheets of paper, ideally cardstock or some other heavy stock.
  • Scissors
  • Paper glue (I use Aleene's)
  • Printer
  • Ruler
  • Something pointy, e.g., a pen with no ink or a small screwdriver
  • Computer with internet access, PDF viewer, and printer
The script I used was based loosely on the one in my large patio/driveway analemmatic sundial Instructable.  This is a much simpler project.  The last one I assembled took 12 minutes once I had the design printed out and all the tools in place, and that's counting periodic stops to take photographs.

You can load the PDF file into a vector drawing application like Inkscape and make it fancier.  Just make sure that if you resize the dial, you resize the gnomon (the pointer) in the same proportions.  The script is open source so you can modify it as you see fit.

You can presumably trace the printout on copper sheets to make a fancier dial and gnomon.  I'd love to see it.

This would make a good classroom project at various levels, depending on how deep you get into explaining how it works.

Note: The script currently works for latitudes between 24 degrees (north or south) and 65 degrees (north or south).  (That covers all of the contiguous 48 states in the U.S., much of the populous parts of Canada and Europe, all of South Africa, much of India, etc.)  The limitations are due to the way the gnomon is designed to work both when shadows are short and when they are long, and its having a wider base.

Step 1: Enter the data

You will need the following information:
  • your zip code (if you're in the US) or latitude/longitude (this site should help)
  • your timezone
  • whether your location has daylight savings time (time change between winter and summer time).
Now go to my script's website http://analemmatic.sf.net/cgi-bin/papercraft.pl.  Enter the above information.  If you have daylight savings in your location, you will need to decide if you want your dial to show winter or summer time.  You can leave the colors as-is for a black-and-white sundial, or you can enter HTML color codes to customize.  I customized by setting the dial and hour backgrounds to C6DEFF (a light blue), the gnomon to 2B60DE (a royal blue) and the hour text to 000000 (black).  You can also choose whether you want Arabic or Roman numerals and whether you want 4 shown as "IIII" or as "IV".  If you don't want some element, like the time correction table, you can set its color to be the same as the background it's on.

Print both pages of the PDF file, ideally on heavy paper, e.g., card stock.
i made it,gave the right co-ordinates,made a right gnomon pointed it at north it was 3 it gave 5!
1. Did you check to make sure the gnomon's angle was the same as your latitude after you attached it? A photo directly from the side might help to diagnose this.<br><br>2. How did you check for north?
1.yes i checked the gnomon right<br><br>2.i have a compass
1. Did you correct the compass reading for the magnetic deviation at your location?<br><br>2. Did you correct for daylight savings if needed?
1.yes<br><br>2. i don't have day light saving
Unlike widely believed wisdom, the deviation of the compass reading and the true north is not minute at all, and, instead, may be quite considerable. For example, in Vancouver, B.C.. it is 17 degrees (!) If one uses the compass without the magnetic deviation adjustment, the error in the sundial reading will be more than 1 hour! You can check the deviation for your area at the US National Geophysical Data Centre. Try for your location and you may be surprised: <br>http://www.ngdc.noaa.gov/geomag-web/#declination
<p>lol regarding magnetic deviation; did I hear a rumor that magnetic north has moved and is now somewhere over Russia?</p>
Can you give me your time zone, latitude and longitude (feel free to round off to the nearest half degree for privacy) and I can experiment a little?
<p>Is it possible to have a sundial using concentric circles, to indicate Month and curved or stepped time lines to indicate corrected time based on time of year. So a person could look where the gnomon touches based on time of year? From what little I have come to understand, I would think the curve would follow some sinusoidal curve with max &amp; mins, instead of +1 &amp; -1 being variable based on time of year, from +/-15 to +/-6 minutes, so a double sinusoid? Sounds like a possible programming change, or even fairly accurate with only the bimonthly changes plotted step wise. The concentric circles drawn into the blank area could indicate Month.<br><br>I guess it would depend on how the conversion to PDF worked; and I'm completely unfamiliar with that. I believe I've seen sundials that do something like that.</p>
<p>98 x 102 cm sattelit dish</p>
<p>can I resize the clock? I am thinking to use in a </p><p>dish satellite</p><p> What should I get attention?</p>
You can load the pdf file into Inkscape or Adobe Illustrator and resize. Just make sure all the parts are resized proportionally.
Sooooooooo Cool! <br>
Bummer - I wanted to use this at a scout camp this weekend, but the perl file isn't working. I have tried to load the file on my own server using the source code - but can't get it to work there either :(
I just went to the link, put in my zip code, changed nothing else, and everything worked. I was using Chrome on WinXP.
The equation of time is the difference between apparent solar time and mean solar time. This depends neither on latitude nor longitude I think. There is Ann additional adjustment based longitude difference from the official central longitude of the time zone, but that's taken into account when generating the shoal.
If I understand it correctly, the equasion of the time does depend on the location. The one calculated by your app dosn't seem to take this into consideration. For example, for Vancouver, B.C., the zero time adjustments (0 min) happen on about Oct. 7 and Nov. 30 only, and not on Apr. 15 and Sep. 1 as the app says. Am I not getting something right?
Here's a picture of the one I built from your directions. I used an over-turned ceramic planter base, with the hours cut using a dremel tool. Then I used a piece of found wire (from a street-sweeper) as the gnomen and glued it to the base using a kneadable putty that was out-door-proof. I used the angle guide and the software to create one for the zip-code of the person I made it for. Nice instructable and nice program. Thanks! -- Dauphin1974
well my latitude&acute;s out of your range... but hey, great job anyway!! love sundials
Too far from equator or too close to equator? :-)
too close :(<br>4 degrees aprox<br>i already have a sundial generated in a website, but you locate the edges of your home and it generates a sundial to put in your window (really nice). but for some reason i like too much this kind of sundials i found them more attractive.
I looked up gnomon on dictionary.com, because it's a new one on me, and I wanted to know how to pronouce it. Apparently, the g is silent and it is pronounced like a Jamacan man saying No man: &quot;No mon. every little ting gonna be alright.&quot;
Yeah, the g is silent. For a visual pun, you can put a picture of a gnome on the gnomon. Sorry, couldn't resist that.
By the way, there is an undocumented feature in the script. When you click on &quot;Go&quot; in the script, you get sent to this very long URL, a part of which says something like &quot;num=roman&quot; or &quot;num=arabic&quot;. Change that part of the URL to &quot;num=now&quot;, and you might be amused by the result.
change it to cardinal<br>
Now, now, now, now, now, now, now, that was a dirty little secret!<br>Now....
Very cool!
Yet, another question...<br><br>Does size matter on this?<br>Could I size the dial down, let's say 50%. <br>Would that effect the time?<br><br>Could I make one that you could wear around your wrist?<br>Kinda like a joke...Caveman watch?
If you scale it, just scale both the dial and the gnomon equally. (And of course, don't squeeze it down in one direction and stretch it in the other.) Actually, nothing really bad will happen if you scale the dial and gnomon differently, except that the sizing in the script is designed to work well with the different shadow lengths in summer and winter (if I got the trig right).<br><br>Do post a picture if you make a copper one.
Oh, one other thing...<br><br>Your link to your script.<br>http://analemmatic.sf.net/cgi-bin/papercraft.pl<br>Is bringing me somewhere else.<br><br>I had to cut and copy the link in a new browser window.<br>You may want to fix that!
Just did, thanks for pointing it out.
GREAT! <br>I do have a piece of copper here. <br>I may have to give it a try!<br><br>Love the sundial generator!<br>Great job.
Unfortunately, horizontal sundials of this design don't work this close to the equator. A different design is needed.
Longitude: -38.522186<br>Erro: Latitude must be between 24 and 60 degrees (north or south).<br><br>And now?
What was your latitude?
In google maps: Fortaleza, Brazil -3.718394, -38.543395

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