A Pocket Sundial From a Broken Pocket Watch!
by JGJMatt in Workshop > Metalworking
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A Pocket Sundial From a Broken Pocket Watch!
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Hello fellow makers,
A while ago I bought a box full of old pocket watch spares on marketplace to re-purpose them into something else as I couldn't bare the thought of letting these beautiful 100+ year old pieces end up on some landfill.
In a previous Instructable I showed you how to "Transform an Old Broken Pocket Watch Into a Beautiful Trinket!" with some of the original parts of the watch and epoxy.
This time around I'd like to tackle a functional sundial, which by the way the maths behind it was a lot more complicated than I first imagined... Luckily we have a whole internet full of helpful information!
Let's get making...
What You Will Need
To replicate this Instructable you will need the following:
- An old broken pocket watch
- For the faceplate we need a flat piece of brass to engrave the sundial on, I used a one of the spare pocket watch back covers for this.
- Soldering iron
- Solder
- Metal polishing compound
Optional:
- A Dremel
- Brass bristle bit
- Felt polishing pads
- Liquid polish
*As an Amazon Associate I receive a small percentage from sales made through provided links at no cost to you, this helps fund future projects.
Sundial Basics
What is a sundial?
A sundial is the earliest type of timekeeping device, which indicates the time of day by the position of the shadow of some object exposed to the sun’s rays.
As the day progresses, the sun moves across the sky, causing the shadow of the object to move and indicating the passage of time.
The first device for indicating the time of day was probably the gnomon, dating from about 3500 BCE.
It consisted of a vertical stick or pillar, and the length of the shadow it cast gave an indication of the time of day.
If you would like to read up more on sundials and their history head over to Britannica
The Old Pocket Watch
First thing we need to do is to get rid of years and years worth of grime buildup on the old pocket watch.
The easiest way to get rid of all the stubborn grime is to soak the case in normal spirit vinegar for an hour or two, I just left it in there as I was busy with the sundial face. This might seem unnecessary as we will be polishing it later on but this gets rid of all the dirt in those tight corners that a cloth would never be able to reach.
After soaking make sure to rinse the watch thoroughly in clean water to get rid of any left over vinegar, any residue that might be left on the watch after soaking in the vinegar will disappear when we buff it with the compounding later on.
Design Your Sundial
Now we are going to need to design our sundial.
When I started this projects I didn't realise just how much math has to go into making the sundial functional for your area, I went in thinking it was going to look like the textbook store bought sundial that looks like a normal clock with a stick in the middle!!?
Boy was I wrong..
Luckily for us there are sites like this one Sundial Calculator that lets us simply select our location on the map and it does all the hard work for us.
My sundial is made for South Africa that is 27 degrees latitude and in the southern hemisphere.
After selecting your location on the map it will give the results as shown above, you can then go ahead and download the example as an SVG file straight from the site to use in your design.
Attached below is the SVG file for my sundial, you can use it and simply adjust the hour positions to the ones shown for your location.
Downloads
Getting the Design Onto the Pocket Watch
Now we need to get the design of our sundial onto the "watch face", this step will depend on what you have available to use.
I used my home built CNC machine to engrave the design onto the brass plate, as this is a non ferrous metal it is easy to engrave with inexpensive small desktop CNC's.
To hold the piece in place to engrave I stick painters tape on the work bed of the machine as well as on the back of the work piece, this allows me to stick the work piece onto the bed using CA "super glue" and easily peel it off when done.
If you don't have access to a CNC here are a few other options:
- Sticker and salt water etching.
In my Instructable "Turn an Old Saw Blade Into a Kamagata" I show how you can get a beautiful etching with a lasercut/Cricut sticker followed by salt water electroetching.
- Photoresist with acid etching.
In my Instructable "This Is the Way... Hand-forged & Etched Ring" I use photoresist film that is usually used in PCB manufacturing to acid etch a design into metal. the design can be hand drawn and doesn't require any other machines just the photoresist film and our good old sun to expose it.
- Hand painting the face.
Now this is probably my favourite but I'm not nearly talented enough, you can hand paint the design onto the face of the sundial, note that this will need to be done after soldering on the gnomon to avoid heat damage to the paint.
The Gnomon
The gnomon is the centre piece that looks like a sail, this casts the shadow onto our sundial to indicate the time.
We use the measurements given by the site in Step 4 to design the gnomon you can get creative with this as much as you like as it is quite a prominent piece of the sundial. The most important thing is to stick to the dimensions and angle given by this as it will determine the accuracy of your sundial.
I cut mine out of a 1mm thick piece of brass plate on my CNC.
Next we need to solder the gnomon onto the face of our sundial.
For this I used normal tin solder (the same as used with electronic soldering) as it is readily available and easy to adjust if something goes wrong....my first attempt was VERY skew!
Simply heat the gnomon with a soldering iron or heat gun (holding onto it with tweezers) and melt a small bead of solder onto the bottom edge of it.
Now position it onto the sunface dial making sure of the true north/south position as shown in Step 4, heat the entire face until the solder melts and the the gnomon is affixed.
Bring Out That Shine
With the sundial face completed it's time to make it shine.
Using a fine compounding block on a cloth wheel I polished each component separately, for the hard to reach nooks and crannies I used my Dremel with felt pads and the same fine compounding block.
I finished it off with a liquid hand polish on a soft cloth as the compounding blocks tend to leave a hazy effect that the liquid polish takes care of.
To make the engraving on the sundial stand out more I used a black permanent marker and coloured in all of the engraved areas and left it for a few minutes to dry completely.
After the marker has dried you can used a slightly damp cloth stretched over the tip of your finger to wipe away the excess marker. Use an old cloth as it will be stained.
Instead of the marker you can also use thin paint/nail polish to fill in the engraving but personally this is a lot more work and the results are not always perfect.
Assembling Your Pocket Sundial
Now for the last step, assembling your pocket sundial.
I first needed to enlarge the middle piece of the pocket watch body slightly with a deburring tool as my sundial face had rounded edges and it didn't close properly but if you are using a flat brass plate this will not be necessary.
Further assembly couldn't be any easier you simply have to screw on the front bezel and back plate.
And finally you can clip in the bow (I swapped mine for a slightly bigger one than the original) and attach the crown, unfortunately the old watch I started with no longer had it's original crown as the repairers usually remove it with the clock movement so I replaced it with a beautiful ruby fuchsite bead held it place with some 2-part epoxy glue.
Enjoy!
I hope you guys find this Instructable useful and if you have any questions please feel free to leave me a message or comment bellow.
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Happy making!
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