I was inspired to create a steampunk clock a while ago after browsing through a lot of Instructables on various clocks. It started out with a somewhat vague idea of what I wanted to accomplish and it really evolved as I made it. I tried to document it as I went through the process but this is my first Instructables so it might be a bit haphazard. I had a great time making it and I hope that it can inspire someone else to make their own clock.
I've embedded a video of the clock in action if you want to check it out. The clock has been sped up so that the video isn't too long but it should give a pretty decent idea of how the clock works/ looks. I kept the lights on for the first part so that you could actually see the clock but at an angle its still pretty easy to see the LEDs. Unfortunately, the hour LEDs have some noticeable ghosting that I could debug with enough time but it isn't a very high priority for me and so it hasn't gotten done. I also have some pictures above that show a couple different angles of the clock so you have a decent idea about what you are getting into :)
I also want to thank Onyx Ibex for his Instructable LED Clock that was really the seed idea for this project. Out of the countless Instructables I looked through, his really caught my attention with its unique design blending an analog style of clock using LEDs to represent the position of the hands. I really liked the shape but it seemed a little large for what I wanted to do (my clock is only about 12" in diameter). Anyways I linked his Instructable below if you want to check it out:
Step 1: Materials
So this is a list of materials. As a disclaimer, a lot of these are specifically for what I wanted to do and it would be easy enough to make an awesome clock without them. For instance, I did everything in brass for a more steam-punk look but it could be done using some other material.
-Wood (I specifically used a Oak board I bought from a local Home Depot)
-Wood stain/polyurethane (I used a combination of stain and polyurethane that I also got from Home Depot)
-10 mm diameter brass tubing (60 * 1" = 5' )
-22 mm diameter brass tubing (12 * 1" = 1') (as a note, I got the larger brass tubing online at http://www.onlinemetals.com/)
-Brass sheet (I got this from a local hobby store)
-LEDs (I got these through Amazon but you can find them anywhere)
-Wire (I got some spools of multicolored, 22 gauge wire from Radio Shack though I would get a thinner gauge next time)
-Brass wire (uninsulated) (I had some of this on hand but you could find it at something like a beading store or online)
-14 resistors (the value of these will depend on the color of LEDs you use)
-Brass screws (I used various lengths and types for different applications but I got all of these at a Home Depot)
-Header pins (these aren't necessary but they make plugging wires into the Arduino easier)
-Gorilla Glue (I also got this at the Home Depot)
Step 2: Gear Design
I began the project by making the gears used for the hour "hands". I designed, cut, filed, sanded, and polished all of the gears by hand which took quite a while to finish the entire process, but since they are the focal of the clock, it was completely worth it. There are a couple of pictures of the process above but there may be some steps missing since I hadn't completely decided I wanted to make an Instructables when I started this project.
Step 1: Gear Template
My design process began with creating a template for the gears that contained all the features that I wanted to be uniform among the gears (everything except for the roman numerals). So I made one generic gear without any roman numeral and scanned it into the computer so that I could copy it 12 times. Then I printed off that sheet and added the roman numerals to each of the gears.
To begin the generic gear, I decided how large of a diameter I wanted for the gears, which would determine how small of a diameter the inner circle of the hours could be. Somewhat arbitrarily, I decided to make the diameter of the gears 35mm. This was a good diameter aesthetically as well as giving me enough room to cut out the roman numerals in the center. Then I made a template for the outside of the gears by drawing a 35mm circle and "cutting" out notches along the edge to create the teeth of the gear. The teeth came out to be about 4mm along the edge with a depth of 2mm.
Note: I should make a note here that I sometimes like to make copies of the drawing periodically through the process, generally after I finished some part that I liked. So once I finished the outside edge of the gear, I made a copy of the gear so that if I screwed up on the inside of the gear, it doesn't mean I have to start over completely. Even though I work in pencil, the erased lines can still sometimes be seen later when I scan the gear. Therefore, having intermediate steps make it easier to change something significant without messing up everything else. It might have something more to do with bad erasers though...
I also made the inner circle of the gear at this point. The inner circle has a diameter of 12mm and is centered on the gear. The roman numerals on all the gears are also the same fixed height between the upper and lower horizontal lines so they can be added to the template. I came up with 9mm between the lines somewhat arbitrarily and through a process of experimentation of how much room I had to work with. It became a trade off between the height of the roman numerals and the width of the space I had to work with (a couple of the gears get pretty compressed width-wise, especially 8). Once the horizontal lines are added, the gear is ready to be scanned into the computer.
Step 2: Roman Numerals
As I mentioned earlier, I took the scan of the gear template and copied 12 times (for each position of the hours "hand") in Word. That's just the program that I'm the most comfortable with manipulating images and positioning them on a sheet of paper but there isn't anything special about Word that would make it easier to use. Then make sure the image is the same size with what eventually get printed so that the size doesn't get screwed up. Finally, print off a sheet of twelve gear templates so that you can add the roman numerals to them.
Now its time to add the roman numerals to the gear template. Just add the roman numerals 1 - 12 between the horizontal bars of the gear templates, trying to space out the numeral so that it is centered on the gear. As a reference, I made all the ones ( | ) 2mm thick,. The fives ( V ) and tens ( X ) are both 7mm wide at the top (and the bottom for the tens). The line from the left to the right is 2mm thick while the other line (right to left) is only 1mm thick for both. Finally, the space between numerals is 2mm. The space does vary some for the gears with a lot of numerals to fit on them (like the eight) where the ones ( | ) might be 1.5mm thick instead of 2mm but I tried to be consistent so that they looked uniform. The most important thing is probably to just be consistent so that there is a theme to the gears (at least in my opinion).
Step 3: Center Piece
This was a feature that I later added and designed completely separately however if you would like to add this, now would be a good time. This creates a nice focal point for the clock and helps fill in the empty space in the center of the clock. I have also found it works well to provide a bit of a compass when looking at the clock for where 3, 6, 9, and 12 are (sometimes I have trouble deciphering between 7 and 8 early in the morning). For the design, I wanted to incorporate elements of the other gears but I also wanted it to look unique. Similarly to the other designs, I made a single quarter and then copied it and added the bridges to make it a comprehensive gear. For a reference, the center piece is about 40 mm in diameter even though it isn't quite circular.
Step 3: Gears
Now it's time to cut out the gears from the brass sheet. I used a jewelry saw since it is an effective way to cut out designs from the brass sheet by hand without having to get it sent out to some shop which could get expensive. And I like the idea of cutting out my own designs, though I also have some experience using jewelry equipment and access to the necessary tools. So if you want to try to cut out the gears by hand, you can continue reading this step otherwise it should be possible to cut out the design some other way (such as using a laser cutter if you use the right material). And the same applies to the center piece which can be placed and cut with the rest of the gears.
Step 1: Arrange Gears
Once all of the gears are designed and printed out on a sheet of paper, cut around each of the gears leaving a small margin around the outside edge. This is to minimize the amount of space between each of the gears when they are lined out on the brass sheet. Once they are set up on the brass sheet and none of the edges are hanging off of the sheet, tape down each "edge" of the gear so that the design won't move while you're trying to cut it out.
Step 2: Drill Holes
I used a flex shaft to drill the holes which is a jewelry tool but anything that can drill a small hole should work. Alternatively, a drill press would also make this process easier. I actually ended up getting a drill press later to drill holes through the brass tubes but it isn't necessary. It just helps keep the holes straight and gives you a little more control over their position.
The holes are necessary to cut out the inner details of the gear without having to cut through the gear somewhere. Try to center the holes on each isolated detail of the gear since the drill bit might slide a little bit on the brass. To help prevent this, I made a small dent in the brass where I wanted the holes so that the drill bit can't slide away.
There is a picture above of the bottom of the brass sheet with some of the holes drilled in it as well as some empty space where some of the gears have already been cut out.
Step 3: Cut Out Gears
Then once the holes are drilled, cut out the outermost circle of the gear so that you can maneuver the saw to cut out the inner details of the gear. Just trace around the very outside and don't worry about the teeth of the gear yet. Those are easier to cut out at the end and it is too difficult to maneuver the saw blade around the large sheet of brass anyways. Make sure you tape the design down again after you have cut out the circle since you probably cut through most of the tape holding it down.
It doesn't really matter where you start on the inside details of the gear but be careful to try and keep the gear solidly on the bench pin (another jewelry tool that makes it a little easier to use the jeweler's saw) otherwise the gear tends to slip and the blade will break. To get the saw blade into the hole, just loosen one end of the saw so that the blade can slip out and thread that through the hole. Then clamp the blade back in the saw making sure that there is enough tension on the blade that it won't break.
Also I would suggest trying to be as careful as you can to follow the lines of the design so that you don't have to spend as much time cleaning up the details later on. That being said, it isn't a huge deal if something is off a little bit. One last piece of advice is that as more of the details are cut out the paper the design is printed on will sometimes tear. Just tape it down occasionally as you go so that you always know where you want to cut.
Finally, once all of the inner details have been cut out of the gear, it is time to cut out the teeth. Just pick a place to start and make you way around the gear following the lines of the design. If you are having trouble getting the sharp edges of the teeth then you can always use a file to help square off the edges. Also, to start the cut on a rounded edge can sometimes be difficult since the blade won't always stay in one place. To prevent this, I place the tip of my thumb nail just to the side of where I want to make the cut and use that to prevent the saw blade from slipping along the side of the gear. And as mentioned earlier, you might want to tape down the edges again as you go so that the design doesn't fall off or get off centered.
There are some pictures of this process above that hopefully help to reduce any confusion about how to cut out the gears but feel free to ask any questions in the comment section.
Step 4: Polishing Gears
So this is just to clean up the gears a little bit and make them look as nice as possible. You can do as much or as little on this step as you want but personally I think that the more you do the nicer it will look. And if you're going to spend the time to make this clock why not make it as nice as possible? You can also wait to do this step closer to when the gears will actually be mounted if you are afraid something will happen to them.
Step 1: Filing
To file the gears I used a set of jewelry files called micro files. Really they are just a small set of files that can fit into the crevasses of the gears. To start, remove the paper design that is taped onto the front of the gear and make sure all of the tape is off of the surface of the gear. Otherwise when you try to file the gear down the paper will just get caught on the teeth of the file and tear or the tape will prevent the file from gripping the brass.
Next smooth out some of the edges that might not follow the lines of the design. So if an edge of the gear isn't quite as rounded as you wanted, just take a little bit off both of the sides. If it should be straight and it isn't then try to take just a little off where it sticks out. But be careful of being overzealous because you can make things worse by taking too much off and you can always take more off but you can't add anything back onto it.
Step 2: Sanding
The reason to sand the gears is to help make the metal shinier and to remove any imperfections or scratches in the metal. The idea is to start with a coarser sand paper to get rid of any of the scratches or imperfections in the metal and then gradually work your way down to a finer sand paper that will give the metal a bright and reflective look (somewhat).
So start with a coarse sand paper. It shouldn't matter too much how coarse it is but i used a 220 grit sand paper to begin with. Something along those lines that can at least take a little bit off the top of the gear should work to remove the scratches that are inevitably on your gears. The higher the grit you start with, though, the more work it might be to remove any scratches but its really a matter of preference. With whatever sand paper you start with, try to sand in a single direction so that the lines created by the sand paper are all parallel. That way you can alternate directions and it will help remove all of the surface imperfections. The amount you sand is also based on how many scratches are on your gear and how much you care about the scratches. Just try to make sure you completely sand both sides of the gear before you move on to the next grit.
Once your done with that, move on to the next grit that is a little bit higher (I used a 320 next) and try to align the direction you sand perpendicular to the previous direction you sanded. Once again sand both sides completely then move on to the next highest grit, alternating the direction you are sanding.
Overall, I used 220 -> 320 -> 400 -> 600 -> 1000 girt sand paper. You probably don't need that many different grits but that can act as a general guideline of what range you might want to use. Something around 200-300 to begin and end around 800-1000. Then once you're done sanding, put aside the gears being careful not to scratch them up. I just wrapped mine up in tissue making sure there was a layer of tissue between every gear (by folding the tissue a couple of times).
Step 5: Brass Tubes
Now that the gears are almost complete it's time to cut the brass tubing down to size. This will give you a better idea of the overall size you want for the clock and is really when it starts to all come together. I would suggest you double check the diameter of the brass tubing you are planning to use for the hours to make sure that it is wide enough to be outside of the inner cutout of the gear but within the outside diameter of the gear. I had some trouble with the first set of tubes I cut because they had too small of a diameter and you could see the tube so I ended up ordering another foot of tubing and re-cutting them. There is a difference between the outer and the inner diameter of the tube so be careful when ordering them.
Step 1: Mark the Tubes
The first step is to mark along the length of the tubes where you want to cut them. That way you get tubes that are all the same size or at least relatively close. Each tube is only an inch long so if you want to take a ruler and just mark every inch with a sharpie that would work. You may want to mark multiple places so that you can get a straight cut through the tube. Since the tubes have to lay flat against the wood on one side, at least one of the cuts needs to be relatively flat. Both need to be for the hour tubes so that the gears can be mounted to them with a strong connection.
Step 2: Cut the Tubes
So there are two ways to cut the tubes and both have their advantages. One is to use a pipe cutter and the other is to use the jeweler's saw. I ended up using both because I was trying to cut some of the pipe in my dorm room where I didn't have the room or equipment needed for the second method. Later when I was cutting the pipe for the hours I used the jeweler's saw so that I could get a better cut but either way will work, though I would suggest cutting the hours pipes with the jeweler's saw. And, of course, I'm sure there is a more efficient way to do this but this was what I did given my access to tools.
Pipe Cutter: The pipe cutter is nice because is will, hopefully, give consistent cuts that are fairly flat. Another advantage of the pipe cutter is that it is a lot less work to cut 72 one inch lengths of pipe using it rather than the jeweler's saw. The major drawback from the pipe cutter is that it tended to bend the ends of the lengths of pipe inwards slightly. This is because the brass used for the pipe is a fairly thin and will bend under the pressure of the pipe cutter. The result isn't always particularly noticeable but it is there on most of the minutes so I used the best cut for the edge of the pipe that can be seen and the other is face down against the wood.
Jeweler's Saw: The other method I used was just cutting the pipe by hand. I felt like I could get a slightly better cut using the jeweler's saw which was important for attaching the gears to the hours. You need a good even plane and as much surface area as possible to glue the gears to the edge of the hour pipes. As mentioned before, it is a lot of work sawing through 72 lengths of pipe with the jewelry saw as well as difficult to line up the cuts so that they're flat. It is very easy to begin to saw through the pipe at a slight angle and any correction in the angle of the blade while you are cutting the pipe will create a very uneven cut. You will also screw up two lengths of pipe with every bad cut and so it can be costly and time consuming to make mistakes.
Step 3: Drill the Holes
In order to attach the lengths of pipe to the clock, I drilled two holes into each length and used brass wire to thread them onto the clock. These are only necessary if you want to attach the pipes the same way.
I took a small slip of paper, maybe half an inch wide, and taped it so that it would fit tightly around the outside of the tube. On this I marked two dots where the holes should go. I placed mine directly across from each other for the small tubes and slightly less than 180° for the larger tubes so that the wire could exit the tube perpendicularly to the hole. Then I sat down for a couple of hours with a drill press...
The last two pictures are close ups of the clock that hopefully show how the wire is threaded through the tubes. It difficult be seen from the front, but there is a hole in the wood where each tube sits that the wire is threaded down into and then an LED is added so that the wire can't be pulled through again. There are pictures above and I will go into more detail later.
Note: You can also wait to drill the holes for the hour tubes until you have mounted the gears on top of the tube. This will make it more difficult to drill the hole but it will be easier to line up where you want the holes to go instead of doing it upside down when mounting the gears.
Step 6: Wood Base
Now it is time to create the wood (or any material) base on which the tubes will be mounted. I decided to use oak but anything would work. One difficulty I faced, however, was that I couldn't fine/ wasn't willing to pay for a board that was wide enough to fit the entire circle of the base on so I was forced to cut two half circles from the board and glue them together. If done properly, the divide can be almost seamless.
Step 1: Cut the Circle
Shown above is two pictures of the oak board before it was cut where I made sure that I aesthetically had enough of a margin between the minutes and the edge of the circle. The overall circle is 290 mm in diameter and I just cut two half circles using a jig saw. Aesthetically, I tried to choose an interesting grain for both halves that could plausibly blend together seamlessly when they were combined. After the cut, the two halves didn't quite turn out the same so I just sanded the larger side down until the edges were pretty close together while maintaining the overall curve of the circle. I also decided to add a beveled edge to the outside of the circle so it isn't quite as harsh.
Step 2: Complete the Circle
Once the edges are close to being even, use some wood glue and a clamp or two to create a complete circle for the base. When the glue is finished drying, use sandpaper to finish smoothing out the edges of the circle. You can also sand down the crack between the two halves on the face of the clock to help make the line almost invisible.
Another feature that I added was two small mechanical fasteners between the two halves as a safety precaution. Just a small strip of metal that bridges the two halves and hopefully help hold the circle together. These went on the back of the clock (as seen in the above picture). The center piece also helps strengthen the two halves as well as creating a focal point for the clock.
Step 3: Drill Baby, Drill
If you weren't sick of drilling holes yet, here come 72+ more holes :) I began the process by defining a radius at which I wanted the tubes to be located at. Due to the diameter of the smaller holes, the radius for the minutes was already set so I only had to choose where the hours would go in relation. As a reference, I placed the hours on a radius of 80 mm from the center and the minutes at a radius of 110 mm. Then I marked the center of each hole. The hours were just 12 evenly spaced holes but the minutes have a more complicated layout. Every five minutes is marked by a tube that juts out slightly. I chose this style so that it was actually possible to read the time as well as giving the circle of minute tubes a vaguely gear shaped outline. So each 5 minutes, or every minute tube radially equivalent to the hour tube, is offset by 5 mm (or by half of the diameter of the tube) from the normal radius. The other four tubes between each of these is placed on the minute's radius. I would highly recommend that you make layout the tubes on top of these marks to make sure that everything will line up.
Optionally, you can also create holes for LEDs under the center piece. For my clock, I made these holes slanted so that the LED doesn't shine directly into your eyes when you look at the clock and also give a better sense of the depth to the clock when it is seen in the dark. The center piece itself was also suppose to help diffuse the light and create a back light effect but it doesn't work very well for that purpose due to the design but I still like it. My holes are setup diagonally so they are in the center of each quadrant. This is approximately 15 mm from the center on the front (narrower on the back). You may also want to drill smaller holes in order to mount the center piece, though these don't need to go all the way through the wood.
This would also be a good time to drill holes for the screws that will act as anchors when the wire is threaded through the holes later. Mark these holes on the back of the clock somewhere in between the hour tubes and the offset minute tubes. The exact placement isn't critical. I would also suggest you drill pilot holes for screws in the back of clock so you can hang it when you are finished. I used three inch-long screws on the outside rim of the clock and strung a wire between two of them. The third was to create a plane on which I could rest the clock right-side up on a table without damaging any of the LED leads. I placed one on the bottom, radially out from 6, and the other two radially out from 2 and 10. I also drilled pilot holes for screws to mount the Arduino to the back of the clock. There was just enough room for it above the holes for the center piece and within the radius of the hours. Just look at the mounting holes on the Arduino and mark where they line up on the wood. Finally, I used four screws to mount a standard 9 V battery to the back of the clock, underneath the center piece and within the hour's radius. I just marked two holes below a 9 V battery, one above, and one to the side so that the screws would hold the battery in place. There is a picture that shows all of these screws in place after the clock was wired up.
Caution: these holes should not go all the way through wood base otherwise you will have random holes in your clock.
For the most part, the drill bit you use should create a hole that is sized perfectly for the LED to fit into but not slide all the way through the hole. It would be prudent to drill some holes into scrap wood to make sure you have the right size to fit your LEDs. This bit is only for the minute, hour, and center piece holes. The other holes should be sized appropriately for the screws you are planning to use for these and don't need to go all the way through the base so don't get too trigger happy...
Step 4: Stain
Here I used a combination of wood stain and polyurethane mostly out of laziness. I wanted the polyurethane coat to help keep the rich color of the stain over the years and give it that slight sheen. Not much to say here. Just follow the instructions and apply as many coats as you need until you achieve the color you want. I went with a darker stain that would contrast nicely against the brass but is still light enough that the grain of the wood can be seen but this is a completely aesthetic choice. Once again I would recommend that you use a scrap piece of wood to test the color first since the color you get won't be exactly the same as the color on the can.
Step 7: Mount the Gears
It is time to mount the gears to their respective tubes. Initially, I tried to solder the two pieces together but it was more trouble than it was worth. Or at least I didn't have any luck with it. I ended up using Gorilla Glue for this after looking around on the internet for a good, easy way to attach brass to brass. I think this is the weakest part of the entire piece but it has stayed together so far through three moves and some slightly less than gentle handling.
To prep the surfaces, try to make sure the rim of the tube is flat as possible to maximize the surface area between the tube and the gear so you can get a strong bond. Then you can wet both surfaces and apply some Gorilla Glue on the rim. I sat the side of the gear you want to see when it is mounted upside down on a table and tried to center the tube onto the back of the gear. Make sure you remember that the tube will be flipped over when it is dried. In other words, make sure the holes you drilled into the tube earlier will line up correctly when it is flipped over. Alternatively, you could wait to drill the holes until you mounted the gear, however, the tube can't lie flat on its side and can make the process more difficult, as mentioned earlier. You can also always re-drill holes if necessary (I had to do this for one of the tubes that I accidentally flipped the orientation of the holes).
Once the tubes are aligned, make sure to put pressure on the top of the tubes to get a good bond. I set my tubes up in sets of four and used a very heavy, hardback book to weigh them down. Just be careful to not move the tube as you set the book down on top of it.
After they are finished drying, I would make sure the bond is reasonably strong. I half-heatedly tried to pull the gear off of the tube but I was honestly too afraid to pull very hard. But it reassured me that the gear wouldn't just fall off randomly because gravity was too strong for it.
Step 8: Fasten the Tubes
This is the step where things really start to pull together and this project starts to actually look like a clock. Before this point, people had a lot of trouble imagining what I was trying to do. I used brass wire to "sew" the tubes onto the clock but it would probably be a better idea to use something that is still strong but not conductive such as fishing line. Or at least add insulation to the wire where it is close to touching the leads of the LEDs.
Step 1: Test the Holes
It would be a good idea to see if you can fit whatever material you chose through the hole as well as the LED before you get started. I ended up having to cut small channels or notches in the sides of the holes to help guide the wire where I wanted it to go as well fit with the LED. I just used a small jeweler's file for this (from the same set I used earlier on the gears).
Step 2: LEDs
At this point you should have decided what color of LEDs you want to use for the minutes, hours, and center piece. I chose yellow for the minutes, red for the hours, and yellow for the center piece because I thought the pallet nicely complemented the brass and the wood. I choose a different color for the minutes and the hours to help distinguish between the two but in retrospect I'm not sure it is necessary (the orange and the red look pretty similar anyways).
Regardless of the color, you probably want to frost your LEDs to help diffuse the light. That way, the LEDs are not quite as harsh if you look directly into one of the tubes. I believe it also helps to make the inside of the tube glow. To get this effect, I just took a medium grit sandpaper and roughened the LED until it is a cloudy white instead of clear. It would also probably be a good idea to check if the LEDs work while you can easily replace them.
Step 3: Hours
You can start wherever you like, but I started with the hour tubes. These are probably the easiest to get started with since you can secure one at a time rather than in larger sets. I started by inserting all of the anchor screws into the holes you drilled for them earlier. Leave just a little space between the head of the screw and the wood base so you can wrap wire around it. Then take a length of wire (or your desired material) and secure one end of it to the anchor. For the wire I just wrapped it under the head of the screw two or three times. Thread this through its respective hole and out the other end and pull through all of the slack.
Here you get to chose the orientation of your clock based on which hour tube you decide to mount. Here I am going to assume you started with the 12 tube and will be working clockwise. Thread the wire through the clockwise hole in the tube (hole pointing towards 1) from the inside to the outside and pull through all the slack. You should end up with a length of wire coming out of the clockwise hole of 12 and the base covering up the hole for the LED. Then thread the length of wire through the counterclockwise hole of 1 and through the LED hole. Once you pull through all the slack, you should end up with a short amount of wire exposed between the base of 12 and 1 with both of the tubes covering their LED holes (though it probably won't be centered yet). Try to center the bases of 12 and 1 around their LED hole and take the wire and wrap it around the anchor post of 1 such that there is no slack.
Then it is a matter of repeating the above process for the rest of the hour tubes. I would suggest you try to pull on the wire enough that there is absolutely no slack otherwise you will be able to move the hour tubes around after they have been fastened. While a little bit of slack isn't a problem, it allows the tubes to move and screws up the spacing of the clock.
Note: It can also be difficult to work on since it needs to be propped up while you work on it and flipped back and forth fairly often. Just try to find something tall enough that can support it on both sides and be careful that it doesn't slip off.
Step 4: Minutes
The minutes are more difficult since I fastened them as sets of five tubes rather than individually. It is a very similar process except that for the minutes between the five minute marks, I used an LED to anchor the wire.
Start the same way as the hours by securing one end of a fairly long length of wire (you probably need more than you would think) to the respective anchor post. Pull the wire up through the LED hole and through the clockwise hole of the tube. Then thread that through the next minute tube and down through the LED hole. Here is where the pattern diverges. Thread the wire back up through the LED hole and through the clockwise hole without pulling through all the slack. There should be a loop of wire on the bottom of the clock. Take one of the LEDs you want to use for the minutes and insert it into the hole where the loop of wire is. Orient the LED so that the flat side is facing out from the center of the clock. Then you can pull through the slack so that the wire is looped through the two legs of the LED and the LED can't be pulled out. This is where it would probably be a good idea to add some insulation between the wire and the legs of the LED before you pull through all the slack if you are using a conductive material.
Continue this process for the next three tubes and fasten the end of the wire to the anchor post of the tube marking the five minute tick like you did for the hours. You should end up with four LEDs that are tied to the clock with wire and two offset holes that are unfilled but you can still put an LED in it. Repeat this process until all the minute tubes are securely attached to the face of the clock. Some of my tubes are able to wiggle around a little along the axis of the wire, however they do not move towards or away from their neighbors.
Step 9: Wiring
At this point you can insert the rest of the LEDs into their respective holes, orienting them the same way as the others. In order to wire up 76 LEDs that need to be individually controlled, I used a wiring scheme called charlieplexing. This allowed me to use the limited pins of an Arduino Uno for this project at the expense of some more complicated wiring. If I redid the wiring, I might consider using shift registers instead as a slightly more elegant solution. Because this Instructables is getting a little long, I'm going to leave some of the details out of this section, however I will recommend some great resources. I also posted quite a few pictures that hopefully add some clarity despite the tangle of wires.
This Instructables gives good general information about charlieplexing and how it works. It walks through the basic scheme using smaller circuits that are easier to trace what is going on by hand.
Once you are comfortable with the basics of charlieplexing, you can use Onyx Ibex's Instructable to help guide you through the wiring for your clock. His Instructables provides another example of charlieplexing in a very similar application to this project, however, he uses 24 hours instead of 12 and has an extra ring for seconds.
Step 1: Hours
I would start with the hours since it is the same pattern but a little bit simpler than the minutes. Just try to be careful with all of your connections so that you don't accidentally short something. You can always go back and fix it but it can be difficult to track down bugs like that later on. Also be sure to choose you resistor values based on the color of LED you are using since different colors have slightly different requirements.
I posted a roughly drawn diagram that I used to help me wrap my head around charlieplexing the hours. I also had some notes on there that I used to debug the circuit while I was testing it. As you can see, only 4 pins are necessary to drive 12 LEDs so you can connect the inner leads of the hour LEDs in four sets of three. The rest of the wiring follows the charlieplexing scheme.
Step 2: Minutes
This can follow the instructions in the second Instructables above. The LEDs can be grouped in nine sets of eight for a total of 72 LEDs. Since you only need 60, the minutes are broken up into seven sets of eight and one group of four LEDs. Connect the inner leads of the minute LEDs in this setup and wire the remaining leads based on the charlieplexing scheme.
Step 3: Center Piece
This should be easy if all you want is the LEDs to always be on. These LEDs can just be wired in parallel and use the digital output and GND pins of the Arduino. You could also connect them individually or with charlieplexing if you want to use them to indicate AM / PM or something similar. Regardless, this should hopefully be straightforward.
Step 4: Testing
This can become quite tedious but it is necessary. I just used the 5V and GND pins of the Arduino to manually stimulate the pins that will be controlled by the Arduino since for charlieplexing one pin goes high ( 5 V ) and another low ( 0 V = GND ) and the rest should be in a high impedance or high-z state ( basically disconnected ). Just make sure that each combination of inputs produces the correct output. Also be conscientious if you used a conductive material to fasten the tubes that a signal could be shorted over that wire as well as from incorrect wiring. If an LED refuses to turn on, test to make sure that the LED wasn't burned out somehow. I would just suggest that you be methodical in your approach and perhaps even take notes.
I also made an Excel sheet that color codes which pins should be high, low, and high-z for the minutes. This might be useful for debugging as well as coding in the next step.
Step 10: Code
This is the final step. In my code, I continuously increment through the minutes and hours in order and use a delay function between minutes. I will attach my code for reference, however this is not the best way to keep track of time since the internal clock on the Arduino does not keep perfect time. As you can see in the code, my delay is not 60,000 ms as you would expect ( 60,000 ms = 1 minute ), it is 59956 ms. This keeps fairly accurate time but will slowly become a little fast and will need to be reset. This is also not a magic number since each Arduino board will have very slight differences in hardware that can effect the timers. Another slight issue is that the clock is hard-coded to reset to 12:00 if it loses power and I currently have no way to adjust the time. This could be a simple as adding a single button to increase the time one minute when it is pressed however I have not implemented it.
If you would like to keep perfect time, there are breakout boards that you could purchase for the Arduino that will keep track of the time properly as well as the date. This would require some extra wiring as well as coding but there are resources to walk you through it. Below is a link to a board sold by Sparkfun, a good online source for everything Arduino.
If you have any questions, feel free to ask in the comments and I will attempt to answer them.