It is a simple idea. An Awesome idea actually. Take a piece of PVC pipe and turn it into an LED light.
Since the LED's run on only 12 volts and are already waterproof it would make a great all purpose light. It would be waterproof and since it uses low voltage even if its damaged it would not be a threat to safety. You can't get a shock from 12 volts. It would be very bright but not produce much heat, be energy efficient, shock and impact resistant, and could be used both in a car and at home, indoors, outdoors, anywhere. You could use it in the rain, in the snow, even in your pool. Use it to change tires or as an emergency signal. A great concept. But as usual it proved to be a little more involved than I anticipated.
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Step 1: Doing It the Hard Way
In the answers section someone recently asked about cutting a bottle in half the long way. They wanted to bisect it. I asked them if they were one of those people who always does things the hard way. Reason I asked is because sometimes I seem to go in that direction also. Take for example cutting a pipe. Yep, I did it lengthwise. How else do you get a half pipe? Turns out its a bit difficult to do. Cutting something round on a square saw takes effort and skill. The best way is to draw a line and then try to follow the line. You can end up with a spiral cut if your line is off or if you roll the pipe at all when its in the saw. If you ever want to try doing this for some reason, cutting a pipe in half lengthwise, try to follow the lettering on the pipe when you make your line. Its pretty close to straight.
PVC cuts pretty easily on most saws. But it can melt if the blade is not sharp enough. It makes lots of PVC dust which picks up a static charge and sticks to everything. It's a mess to work with. It's like really bad dandruff, it ends up all over you.
Another interesting thing about cutting pipe. When you make a cut it's never at 90 degrees unless its at the bottom or top of the curve because those are the only points that are flat to the table. So if you slice off a piece on the edge the angle it will have will not be 90 degrees. Cutting round material definitely adds a degree of difficulty to things.
I Think the biggest problem I had though is that this is a prototype, the first one I tried doing this way. Any time you try something new there is going to be a learning curve. Once you figure things out it gets better. Going from concept to finished product is often a challenge and this was no exception.
Step 2: The LED's
The LED's that I am using are put together in a strip that is held together with double stick tape. There are 5 LED's to each unit and they are coated with a plastic to seal them so they are waterproof. I can get units with 6 LED's but the best price break at the moment is for 5. Adding one more LED almost doubles the cost. These particular units are designed for use in light up signs. Older signs on buildings can be retrofitted with them also so they use less power and are not effected by the weather. They don't flicker when it gets cold and dampness does not bother them either.
So, the next problem I ran into is that flat LED's don't really stick well to curved pipe. You only get contact at the edges. In addition the curve of the pipe causes them to project their light inwards. So I needed to have something in the pipe to mount the LED's to. Essentially I had to fill in the pipe with something so I could mount the LED modules. Nothing is ever easy.
Step 3: Filling the Pipe
The solution I came up with was to cut another strip of pipe to fill in the bottom of the half pipe. Sand the top of the insert down so its flat and not curved to give a flat surface to mount the LED's to. Fortunately I had another half pipe, the other half.
I also cut some strips to glue to the edge to give me a wider lip and to act as a fill in and help hold the LED units in place.
Just a simple thing, cut a strip, glue it in place. Nope. Turns out pipe glue doesn't work to good for this. You have to work fast because your gluing a large area. But then rather than sticking, parts slide around. You have to spread the glue, stick it together and clamp it before the glue skins over. Guess what, when you try to clamp it the parts squirm around, more like they were slimmed. And then of course there is the little problem of using flat faced clamps on a curved surface. It took me a number of tries before I found a way to sort of do it. And no there are no pictures because my hands were totally coated with glue by the time I got it done.
After it finally dried I had to sand down the edges of the pipe to get a smooth surface. Belt sanders work great for this, that is until the PVC dust builds up under the sanding belt and it starts to wander all over. Sanding PVC makes nice white dust to add to the static cling. And you have to be really careful not to get it to hot while sanding otherwise it melts to the sanding belt.
In my initial design I had planned on putting a plastic diffuser to cover the light so after sanding it I made a little recess channel for the diffuser to fit into. I cut this in with a router. Just a tiny thin indent. The plan was to then seal it with another strip of PVC on top.
To finish the pipe I glued on end caps and when dry cut them down to match the pipe. Then sanded it all down and routed the end caps for the diffuser.
Step 4: The Diffuser
The diffuser material I used is the stuff that is used in regular light fixtures. You can buy it in sheets at most hardware stores. It can be cut with a table saw. It is a little difficult to work with because it tends to chip easily. I already have another material in mind to try using for this in the future. I don't like how delicate this diffuser material is and want something that is less likely to break. But this is a prototype.
Step 5: Adding the LED's
Once the pipe body was ready I started putting in the LED's. A new problem showed up right away and that was the fact that the connecting wires were to long and there was not enough room for them if I wanted to space the LED modules close together. Again with doing things the hard way. If I wanted to fit the most modules possible into the pipe I would have to shorten the wires. This meant cutting them and soldering them back together. What a PAIN. It was tedious and delicate work. In addition I now had to insulate them good enough to make them waterproof. If I just used electrical tape it would not be good enough a seal to be waterproof. I tried a special rubber insulation first but it was to bulky. What I ended up getting was a liquid electrical tape that paints on and forms a water tight seal. It is also more flexible. I got the red color just because.
I used the double stick tape to initially mount the modules. After they were all in place and the wires done I dribbled glue onto the tabs to glue them in place. The modules are PVC so the pipe glue worked perfect.
Next step was to fold up and glue down the wires. I used hot melt glue for this. It also served to make everything waterproof. Throughout this process I kept testing the lights to make sure I didn't disconnect any of them. It was nice that they all kept lighting up after the abuse I put them through.
By the way there are 90 LED's in this light. Eighteen modules with 5 LED's each.
And if your counting there were 36 wires to cut, shorten, solder and insulate.
Step 6: The Cord
I planned on using regular lamp cord to power it but when I priced it at the hardware store it was 49 cents a foot. A ten foot cord would cost me 5 dollars. But silly as it seams the cheap extension cords they had actually cost less. I bought a 12 foot extension cord for less than 3 dollars. Cut the ends off and I had my power cord. Drill a hole in the end. Solder and insulate and it was done. With the knot and the glue it is unlikely to pull out. Once everything is dry and the fumes gone I will work some silicone into the hole to seal it.
Since this is only 12 volts the connecting end is a special female adapter that matches with standard (wall wart) power adapters.
I did not put an on off switch on the pipe. Instead I have a special remote control unit at the end of the cord. It is an RF unit and besides turning the lights on and off it can also dim them. There is a 50% and 25% preset and 100% full bright plus two up and down buttons that will vary it from full bright to almost not on. And the controller also has a bunch of modes that will flash the lights along with a button for speeding up and slowing down. Pretty slick little unit. It is also possible to skip the control unit and just plug it into the 12 volt supply. But then you only have full bright and these are almost to bright without a dimmer. I also have a small in line mechanical dimmer I can use instead of the fancy one.
For power I am using a standard 120 to 12 volt power adapter. They can be from anything as long as they have a high enough amperage rating for the number of LED's. This one is rated at 2 amps and it is just enough to handle the power draw. With the lights turned on full the unit gets pretty warm but not hot. At a dimmed setting it does not even get warm. To power it from a car there is an adapter that fits the lighter socket of the car and plugs into the cord. No voltage adjustment needed.
Step 7: Adding the Diffuser and Sealing It Up
In order to make it waterproof the idea was to sandwich the diffuser in a small channel with a sealing strip put on top of it. More strips of pipe. I tried gluing the first one and then realized that the curve in the strips would prevent the glue from sealing all the way across. SO it was back to the sander to turn curved strips into flat strips. And once again trying to glue this stuff is a nightmare. It's not fun to work with. I thought about drilling small holes and using toothpicks for alignment but I was worried it would be to fragile to hold up to that. If I make a few more of these (and it is likely I will) I am going to make a gluing rig to hold things together so the glue can set.
The end result of the gluing was not pretty. The strips did seal but they had a lot of overlap that had to be trimmed and the pipe surface was pretty dirty. Functionally it appeared to have worked. Now I need to make it look good.
Step 8: Making It Pretty
The first tool brought into play was the router again. I used it to trim off the overlap. I have to say I was rather impressed at how well it worked. In fact of all the different power tools I used on the PVC I think the router worked the best. Normally using a router with wood you have to be careful of it catching on the grain and taking off. Since the PVC has no grain it doesn't do that and it makes it possible to use very fine control.
After the router came hand files, and then sand paper and then finer sand paper. PVC sands different than wood. The scratches left by a coarser sand paper tend to stay visible so I would advise to use finer grits right from the beginning.
Once everything is smoothed down and the dirt is gone it's time for the last step. Usually you would paint or put a finish on a wood item at this point but PVC doesn't need protection from the elements. So what you do now is take pipe cleaner and, working in sections, use it to melt the surface of the pipe and wipe it with a paper towel and let it dry. This seals up all the little scratches and gives the pipe a nice finished appearance and feel. It's like it was polished. What I found works best is to use the applicator and wet a section down. Wait a few seconds and do it a second time and then immediately wet the paper towel with more cleaner and wipe the pipe. It should glide across the surface. If it feels sticky put more cleaner on the paper towel. Wipe it again until it glides over the surface without sticking and then let it dry without touching it. The plastic will be soft and tacky for several minutes until all the solvent evaporates out of it. Then it will feel smooth and polished and will look it also. Once you have done this you don't need to do anything else to the PVC.
So, now it is sealed, waterproof AND looks good too. Also it should be tough as nails since it is all welded together and is basically one piece.
Step 9: Bright Enough to Attract Bugs, and Kittens Chasing Bugs. Also Some Stats.
I put the light outside at night to try and get some pictures of how well it works. That's actually hard to do because the camera adjusts its exposure to fit the light. So dim and bright both look the same. But very shortly after being on it started drawing bugs to it. Must be working good to pull them away from the overhead yard light. And it was set at 50% power. Then the kitten showed up, drawn to the bugs that were drawn to the light. It made for some very interesting pictures.
For those of you who like statistics:
Total length of pipe segment is 33 1/2 inches. 90 individual LED's in 18 12 volt modules all fit into a 1 1/2 inch PVC pipe.
The LED's have an expected life span of 50,000 hours. which is 5.7 years of continuous operation.
At full power it draws 1.5 amps according to my meter or 18 watts so its an 18 watt LED light.
At 50 % power setting it draws .75 amps which is 9 watts which is exactly 50 % --- Amazing.
At 25% power setting it draws .36 amps which is 4.3 Watts --- pretty close to 25 %
At the lowest setting it draws .07 Amps which is less than 1 watt (.84) which is less than many night lights.
At full power the power adapter does get warm as it's pushing its max limit. The light itself does generate some heat at full power so it does get warm after an hour of operation but not hot. It stays comfortable to hold in your hand with no need to switch hands because of heat.
At 50 % power the light stays cool to the touch as well as the adapter.
As a prototype it worked out pretty good. I have some ideas for improvements so the next one will be better.
I even considered skipping the plastic diffuser and just filling the entire half pipe with resin. That would make it near indestructible but if I did that you would not be able to run it at full power because the LED's would not be able to disperse the heat. Anyway, it's a fun and educational project with a good result, even if it did take me a bit more effort than I thought it would. It's a nice light.
If you are interested in my source of LED's I have published another Instructable about buying LED's
You can find it here
I hope it helps you.