3d-Printed Generator

This 12v generator is almost entirely 3d-printed! Being able to generate your own electricity feels like some kind of awesome magic, and this generator should be a good starting point - because you won't need any other of machinery that's usually required when constructing a generator, such as a drill press or lathe or what not. Safe for some standard nuts and bolts and magnets and a spool of copper wire, you really only need a 3d-printer.

The generator, with its built in gear-box, can be hand-cranked - but really it's quite ready to be attached to a wind- or water-mill.

These are the parts required. Most are 3d-printed - these are marked with a red text. Those marked in green text are standard parts you should be able to acquire from your local hardware store. Or - you could do what I did, and source them from used or discarded items. For example, I got all the bearings for this project from a used pair of roller blades, and the copper wire came from a broken microwave-oven someone had thrown out. So much stuff we throw out can easily be put to good use in other projects - I encourage everyone to reuse and recycle whenever possible. But that's a sermon for another day! Here are the parts:

3d-printed parts (red):

1. Two end-plates, with bearings
2. Five compound gears, with bearings
3. One single spur gear, with an M8 hex-nut pressed into it
4. One generator rotor, with bearings
5. One generator stator, also with bearings
6. Six stator coil-sockets
7. Washers, thirty or thereabouts

Standard hardware (green):

1. One 8mm aluminum rod. Can be 3d-printed as well.
2. Five m8 130mm bolts, one quarter-threaded, with nuts.
3. Eight neodymium magnets, 20x3 mm.
4. Six stator coil cores, to wrap the coils of the stator around.
5. Copper-wire 0.1mm
6. Crazy-glue, to fix the wound copper wire to the coil core

Those coil cores, green no. 4, I got those from aforementioned discarded roller blades. They're great for winding the copper wire around - but don't fret if you can get hold of them just like that, I included a 3d-modelled version in the tinkercad-design, so you can 3d-print them. You won't get nearly as much power from the generator with plastic cores - but in exchange it will be much easier to spin.

The above-mentioned parts are enough to build the generator, but there's in fact one component not shown that you will need to extract the generated electricity, and it's known as a 3-phase rectifier. Further details on that part later in this Instructable, but my recommendation is that you buy it on Amazon or similar - it's not expensive, and I really want this instructable to focus on the mechanical aspects of generating electricity. Thankfully, if you wish to make one yourself, other generous instructors have contributed instructables, such as this one: https://www.instructables.com/3-phase-Rectifier-6-and-12-pulse-reactifier

First off, 3d-print the parts. A desktop-sized 3d-printer will do fine, my own has a build-area of 6.5x6.5 inches and that's plenty.

The design was made in Tinkercad and you're free to download it at https://www.tinkercad.com/things/6l8Wafbcfa4 (I also link to it, in one of the steps below). You'll have to print each individual part, one by one. Open the design and click one the part you wish to print, then select the 'Export' option in the upper right corner, and activate the 'STL' file format - this is what your 3d-printer software will know how to print.

There are quite a few parts, so it will take a bit of time. You can speed up the process by printing with a large nozzle, and printing with big layer heights. I printed mine with a 0.8mm nozzle, and a layer height of 0.5mm. With those kind of settings it takes me 47 minutes to print of the end-plates, for comparison.

While the 3d-printer is doing its thing, why not check out the detailed YouTube-video I put together - I added a step dedicated to that. It's a bit more detailed than would fit into this instructable - and, although not strictly necessary, I included a brief explanation of the principles behind how the generator works, i.e. electro-magnetic induction.

Winding the coils is the part that requires the most patience. We need six coils, and with a copper wire of 0.1mm thickness we can get about 400 turns around the coil core - it'll take some time. But - given that patience - it's not very difficult to do. If you've never handled copper wire before, such a thin wire may seem brittle, but don't worry it's quite durable. Oh, if you can't get a hold of 0.1mm copper wire, don't sweat it, other widths will be fine. The thinner the wire, the more volts you'll be able to generate - but the current, the 'umph' of the generator, will be low; with thicker wire you won't get as many volts, but the current will be higher. Effectively you'll generate an equal amount of power, it's just the voltage and current that changes.

Here are the steps to wind the coils. Each step corresponds to an image above:

1. Hold one of the six 3d-printed coil-sockets, and ...
2. ... push one of the coil cores through it. Shown here is a metal core - a 3d-printed one will do just as well, there's a 3d-model in the tinkercad-design I link to.
3. Fix the coil onto a bolt and add a masking-taped metal washer to the end of it, and fix the assembly into a vice. The washer ensures the copper wire won't wind beyond the core, and the masking tape makes it easy to remove the washer after winding. Leave a few inches of copper exposed, so you'll later on have a bit of loose wire to connect to.
4. For every 50 turns, apply crazy-glue to the windings, to fix them in place. You'll probably want to write down the number of turns you've arrived at, it's easy to loose count.
5. After 400 turns, pull out a few inches of wire and fix that in place, then apply crazy glue to the coil and leave to dry for a spell. Then return and remove the washer from the coil. The masking-tape should make that easy, although some force must be applied.

That's it - but for just one coil! Repeat five more times. Practice makes perfect - just take your good time and don't rush it. And don't sweat it if you accidentally wind a few more or less turns, for this application it's not a perfect science - the generator will generate power even if five coils have 400 turns and one has, say, 420.

Winding the coils was the hardest part. Now that's done, we can connect them together.

Referring to image (1), you'll see how five coils have been placed into the stator. If you inspect the coil you'll see a flange on the side of it; this effectively 'clicks' into the stator body. Push it firmly into the stator and it should be fixed in position, and you can turn the stator over and it should look like image (2).

Now let's connect the coils together. We'll connect them in three pairs, or 'phases', to make the generator in fact a so-called 3-phase alternating current generator. Connecting the coils like this makes for a much more efficient generator. It's a two-step process, as shown in image (3) and (4). First, in image (3), I demonstrate how to connect the coils in pairs. Leave one end wire of one the coils exposed, and connect the other end-wire to one of the end wires of the coil opposite. Then connect three exposed wire together, leaving just 3 wires exposed.

However: 'connecting' those wires isn't just a matter of twisting them together, as you normally would regular electrical wire. Rather, copper wire is coated in a varnish that acts as insulation. Think of the varnish as the plastic coating on regular wire, only much thinner. Because it's so much thinner we can wind a lot of wire close together - but just as we do with plastic coating on regular wire, we need to get rid of this insulation to connect the wires. It's thankfully very easy to burn the coating off the copper wire, as the lighter in image (5) shows. Having melted most of the varnish off the tip of an end wire, we can sandpaper - as shown in image (6) - the remaining stuff away. The silvery wire beneath the varnish should appear, and that's the conductive wire you can twist around other similarly exposed wires to make a good connection.

Having connected first the coils in phases, and then connected three end wires together, you have effectively made the stator of a 3-phase generator! If you have a soldering iron, it's recommended to solder the connections. Makes them much sturdier.

Next up, the rotor. As the name indicates, this part rotates - and with this generator it holds the magnets that rotate against the stator, generating the electricity. The ultra-brief and very simplistic explanation for this is that the changing magnetics force of the magnets push the electrons in the copper wire back and forth, in that process creating a current of electricity.

The 3d-printed rotor, as shown in images, holds the magnets in place solely by way of its design. Just like the coils, the magnets 'click' into place into the designated slots. It takes just a bit of force to push the magnet in, and it should stay there. And in the end you'll get a rotor that resembles that on image (3).

BUT there is one important requirement you must follow, as shown in image (3) - the magnets must be inserted in reverse polarity order. Meaning, every magnet with a magnetic North facing outwards should have as its neighbor a magnet with its South-pole facing outwards. How to tell? It's easy - insert the first magnet into the rotor, you don't need to care which way it turns. Then put another magnet close to it: if that second magnet is immediately attracted to the first magnet, that means they have the same polarity and you must turn magnet number two over, and try to put it close to the first one again. You should feel the magnetic forces of the two magnets repel each other - that's how you know you got the direction right. Then you can go ahead and insert the magnet into the neighboring slot. Repeat all the way around, and you have your finished rotor!

Now to the fun part - assembling the generator. The very first step is to press the bearings into the 3d-printed parts. It's a deliberately tight fit, so you may want to put a vice to good use here. Don't worry if you don't have a vice; you can hammer the bearings into place, just make sure to put a piece of wood or a washer on top of it so you don't hammer on the bearing directly. Also hammer an M8 hex-nut into the spur gear - that's the one that sets the other gears into motion.

Remember, you can always refer to the tinkercad-model if you need to see where the parts go. Here's the order of assembly:

1. Slide 2washers onto 2 M8x130mm quarter threaded bolts and insert them through the center holes of one of the two end-plates.
2. Add 5 washers to the bolts and then add the stator, with the coils facing away from the end-plate.
3. Now's a good time to add the aluminum rod, or the 3d-printed version if you opted to print one instead.
4. Add one single washer and then the rotor, as shown.
5. Here comes the gears. Add 3 washers to one of the bolts, and then one of the compound gears. It's the first to engage with the rotor.
6. Add 6 washers to the other bolt, then a compound gear to that.
7. Keep adding gears, with a single washer between them. The more gears we add, the faster the rotor will spin, and more electricity will be generated. Sadly we can't keep adding gears, because the more we add the harder it will be to spin them, so it's a bit of a trade-off.
8. The last gear, the single spur gear, must be rotated onto the bolt. The bolts must be quarter-threaded for a reason: where the thread stops is where the gear will engage with the others and make the rotor spin. If the bolt was fully threaded, the spur gear would continuously tighten and the gears wouldn't be able to stay apart. So that works to our advantage - but you also won't be able to rotate the spur gear all the way to its engagement point with the neighboring compound gear, as they rub against each other. Not a problem; simply rotate the bolt instead, until the spur gears meshes into place.
9. Add two final washers and then the second end-plate. Push the aluminum or 3d-printed rod into place, and fixate the end-plate with hex nuts, two on each bolt. You mustn't tighten the nuts fully, though, there should be a tiny bit of space to allow the bolts to turn.
10. Last step - add 3 bolts to the bottom of the end-plates, to stabilize the generator.

That's it - the generator is complete. It should end up looking like image (11).

That's you functioning generator - time to put it to use. To set the gears in motion you apply a wrench to the bolt where you rolled the single spur gear on to, the one with the hex nut pressed into it. The direction of rotation is away from the generator, as shown in the image above.

As the gears engage, the rotor will spin quite fast! In fact, the gearbox on this generator has a so-called 64:1 gear ratio, i.e. when the first spur gear spins just one time, the rotor will spin 64 times!

The generator delivers 3 phases of AC, alternating current. However, you will probably want to convert that AC into direct current, DC, that you can use to power lights or charge your phone or similar. So this is where that 'rectifier' that I spoke of in the 'Supplies'-step comes in. So far in this Instructable we haven't dabbled in electronics, a whole different ball-game. So, I recommend you purchase one; it's just a few dollars on Amazon or similar. I can, at least, demonstrate how to connect it to the generator - see the image above for reference. The 3 loose copper wires from the generator goes to the 3 poles of the rectifier, which offers a plus- and minus-pole to run DC-powered devices such as fans, or chargers, or similar.

Here's the detailed video of yours truly putting the generator together - hopefully useful if you feel stuck at any point. I divided it into chapters, so you can skip straight to the part where you may need a helping hand.

And here's the tinkercad-design. If you don't know tinkercad, why it's the most simple and useful way to ever get started with 3d-design, and you can produce your own parts from the very most basic stuff to utterly advanced items.

And best of all, you can adapt any design to your own liking. Maybe you have some standard parts lying around, that you'd like to use instead of those I used myself. Then it's just a matter of copying the design into your own tinkercad-account and adapting it to your own liking.