This Sundial is designed for easy viewing and will work at any latitude. To set it up, please follow these pointers.
You have a base, a connector block, four feet (optional), an Hour Ring and a Latitude Ring, which also bears the gnomon.
It’s easier to get your fingers onto the bolts if you assemble the rings first, but if you want to attach the Latitude Ring to the base first for stability then go right ahead, the next two steps are interchangeable.
The connector block attaches the Hour Ring to the Latitude Ring. It should fit with the rounded corners pointing down, to allow clearance for the block over the base. Take out the bolts, being careful not to lose the captive nuts, and reassemble it with the rings in place. Looking down from on top, the morning hours should be on the left; the Wavytail logo should be underneath.
Remove the nut and bolt from the base, and slot the Latitude Ring into the base. Align the ring to your current latitude and reinsert the nut and bolt. The slots encompass most latitudes apart from a pair of small braces; if you happen to be at those latitudes then get as close as you can; it will be within 2-3º.
Take the Sundial outside (assuming it is sunny!) and place it where you’d like to have it. There are holes in the base if you want to bolt it down – you can also use the optional feet if it’s a rough surface. Press them in snugly and try to get them the same height. You can also use nuts and bolts as feet if you don’t want to permanently attach it; that way you’d also have some adjustment too.
The Sundial should point North. The gnomon (metal rod) should be pointing at the North Star, i.e. the higher side should be north. If you’re using a compass, be sure to use True North rather than Magnetic North (iPhones have an option for this in the Settings app).
To read the sundial, look at where she shadow of the gnomon lies on the white acrylic. This is your Solar Time reading. This will be different to the time on your watch, due to three main factors:
- The Equation of Time. This is where the Sun moves back and forth by +/- 15 minutes during the year. There is a graph on the side of the Latitude ring so that you can determine the correction for this.
- Where you are in your time zone makes a difference; 4 minutes for every degree of longitude.
- Daylight Savings will add an hour if it’s that time of year.
I’m in Central Texas, about halfway across the Central time zone. On June 28th, the Equation of Time was -3 minutes, and my time zone correction was -36 minutes, and we were in Daylight Savings. So when my watch read 12 noon, the Solar Time was only 10:20. When it became Solar Noon, my watch read 13:39. I’ve written more about these corrections here: https://wavytail.com/astrolabe-finding-times/
If you set it up correctly, given the limitations of the latitude adjustment, you should get within +/- 10 minutes of the actual solar time. My own sundial was reading within two minutes – I’m at about 31º latitude.
If you’re in the Southern Hemisphere, reverse North/South in these instructions. Hopefully you will be looking at the Southern version of the Hour ring, which also has the numbers reversed. Your Sundial will be pointing South, so the Sun comes up on the other side of it.
A useful app to cross check all this is Solar Time: https://apps.apple.com/us/app/solar-time/id1100646247 That’s on iPhone – I’m sure Android must have something similar.
A note about outdoor longevity – I have endeavored to make this as weather proof as possible. The 3D printed parts are made of ASA which is UV-resistant. The rest is made of acrylic and stainless steel, aside from the gnomon which is ordinary steel coated in sealant. 4mm hardware is used throughout, should you ever need to replace anything.
Below are these instructions in PDF form, if you would like to download them: