How to make lightsabers for LARP fighting for about 20 USD.
In this Instructable, I will (try to) show you how to build a very cheap lightsaber, with which you can duel your friends or make great night time shows. However, this will not be a step-by-step recipe; rather than that, I hope to inspire somebody else to make something similar.
Note: If you have any questions, notes or whatever, ask! I will gladly answer you. Also, I am not from English-speaking country, so should you spot a mistake, tell me please.
Of course, you can buy a lot of toy “lightsabers” on the internet. But they have two basic problems – either they are really expensive (those look great, but I don’t want to spend 200 USD on one sword; but you can really fight with those) or you can buy those cheap ones (they look decent, but they are made from plastic and are only made for light effect, e.g. you can’t fight with those).
I designed my lightsabers to be cheap (under 20 USD per piece), but at the same time strong enough to survive very hard LARP duel – meaning you can hit a block of steel and nothing will happen to them! Also I should note, that I created this design for night time fighting. This means that while they look great in dark (I think), at daytime they are just ugly wooden swords. You can spend more money to make them look like Star Wars lightsabers, but I had limited budget. And lastly, the blade is not retractable - this is, I believe, even not mechanically possible.
Step 1: Basic Construction
The saber consists of 3 basic parts:
The blade itself, which is a piece of hard wood, preferably oak, covered in a few layers of cloth tape (to reduce the shock from impacts & prevent the wood from splintering) and finally covered in a few layers of transparent foil, to make it at least a little bit waterproof and to further reduce shocks from impacts. The blade's main purpose is to house and protect 4 LED strips, which provide the light effect.
The guard, which protects your hands and at the same time houses the electronics. It is just a plank cut down to size with a big hole in the middle.
The electronics - the most expensive and also I believe the hardest part. In the sake of brevity, I will expect that you have at least basic soldering and electronic skills. If somebody would want more detailed description, message me and I will make it. The core of this sword is about 4 x 0.8 metres of 3528 LED strips. You can get them really cheap from Ebay, about 5 USD per 5 meters without power supply, which we don´t need. Then we also utilize two lithium 18650 batteries and a boost converter. Optionally you can also include a switch and a fuse, to protect from short circuits and battery overdischarges.
Step 2: Building the Blade
The core of the blade is a 30 x 30 mm block of hard wood, about 1 meter long. You will need to machine this, but first make sure it will withstand the shocks from fighting – simply hit a block of concrete or steel with it a few times and if it will not break, you have the right piece.
Now about that machining I've just spoken – in order to protect the LED strips, you have to make 4 small grooves in the block (see the picture to understand). Your LED strip must be hidden in this groove enough to protect the SMD LEDs, but it can't be too deep, otherwise the angle of radiance will be too small. For 3528 LED strip, I've made grooves 3 mm deep and 10 mm wide. I also recommend rounding the edges, because otherwise the sharp part will wear out really fast.
For this machining, you can either use a router, a stationary drill with routing bit or you can ask your local carpenter to do that for you.
You also have to decide on the overall length of the blade and the grip. I recommend maximal sword length of 100 cm, 80 of which being the blade and the rest the grip.
User Experience: 100 cm is a pretty long and heavy sword; also, if you want to make your sword two-handed, make the handle longer than 20 cm. So if you are not a skilled swordsman, make your sword shorter (90 cm in total) and give more space to the handle (25 cm).
After you are finished with machining the wood, its time to glue the LED strips (you need to cut your strip into 4 pieces). They usually have adhesive tape on the back, but this adhesive is weak, and we need a strong connection. So we will use every tinkerer's best weapon - hot glue gun. Simply remove the adhesive cover and then glue the strip itself into the grooves. I recommend gluing it in sequences of 10 cm, don't try to glue the entire strip (80 cm) at once.
Next, we need to cover the exposed areas of the wood block with cloth tape. The cloth tape should slightly protect the wood from impacts and also prevent it from splintering.
The last step is wrapping the whole blade assembly with transparent wrapping foil. This will make the blade at least a little bit waterproof and furthermore protect the wood. I used 10 layers of this foil and then heated it with hot air gun, which will seal it. And this foil also diffuses the light from the LEDs.
When you are finished, you need to connect the LED strips together, because you will cover their ends during the next chapter (cross-guard assembly). For this, refer to the electronics chapter.
Optionally, I recommend gluing some soft foam on the point of the blade, just in case you accidentally stab someone.
Step 3: Building the Cross-guard
Thankfully, this is the easiest step. You only need a big plank and a big drill bit. The size is determined by the electronic components, because they will be glued onto one side. So I recommend that you lay all of your components on a piece of paper, mark their position and then create guard as small as possible.
To put it onto the blade assembly, simply drill big enough hole in the middle. Then add multiple layers of cloth tape on the place on the blade where you are planning to glue the guard. Then force the blade thru the hole you drilled previously, add liberal amounts of glue of your choice (I have chosen hot glue, but my assembly was a little bit special).
Note 1: I haven't had wide enough plank, so I was forced to screw to planks together. In the end it proved to be better, because the screws allowed me to squeeze the guard really tight around the blade.
Note 2: Yes, I know that the lightsabers in Star Wars didn't had cross-guards, but because we want to fight with those, guard is very important, as it protects your fingers! (and in this case, also your electronics).
Step 4: Assembling the Electronics
And now the hardest part. Your LED strips's maximal voltage is 12 V, and it starts to light up at about 8 V. The current consumption depends on the voltage (Ohm's law), but it is approximately 1.5 A at 12 V. So, we need to provide some source of energy - the best choice is surely batteries.
But there is a big problem - battery voltage. Even those funny 1.5 V batteries are not always 1.5 V. When they are new, they can have about 1.7 V, when they are depleted, they can have about 1.2 V. We don't want floating voltage - imagine that on the start of a duel, your sword is very bright and on the end, it is very dim. Isn't that dumb?
You can theoretically power this device with AA batteries, but you will need a lot of them - about 8, but remember what I said about battery voltage? When you insert 8 new AA batteries, their total voltage will be about 8 * 1.7 = 13.6, which could destroy your LEDs! And also they won't work long - 1.5 A in not much, but for those small batteries it is a lot. So I recommend using lithium 18650 batteries - they are used in high power torches, RC toys etc. Their nominal voltage is 3.7 V, but again - when they are full, they have about 4.2 V, when fully depleted, they have about 3.5 V. So how to solve this?
The solution is a small circuit called boost converter. It basically takes lower voltage and transforms it into higher one. In our case, we will use it to boost our batteries to 12 V, so we will have a constant brightness. Just use a DMM (digital multimeter) and turn that knob on the blue potentiometer until you get 12 V at the output.
User Experience: When you set the boost converter to 12 V, it is unnecessarily bright and it consumes a lot of current. You don't need to dazzle everybody around, so I recommend that you set the converter to 10 V - at this point, it is bright enough, but not too bright.
See the schematics in the pictures to learn how to connect everything together. The optional parts include:
- switch - you probably want to switch your saber on and off. The connection is really simple
- low voltage alarm - lithium batteries don't like it when you overdischarge them, and this handy thing will warn you when their voltage is too low.
Step 5: Where to Get the Electronic Parts?
Note 1: I am not affiliated or endorsed by any of those sellers. I just bought those.
- Batteries - you can get really cheap fake ultrafire batteries from China. Two of those will power it for about 2 minutes - I used those, since one duel in usually not longer that that. If you want, get a real ones (Samsung, Panasonic), they should be able to power it for about and hour. My batteries.
- Battery holder - you need to somehow fix the batteries onto the guard. Holders.
- Chargers - if you do not have Lithium charger, this circuit works fine and is cheap as hell. Charger.
- Converter - if you use only two batteries in series, you need a boost converter. If you use 3 batteries in series, you need buck-boost converter. Boost converter.
- LED strips - if you want only one color, then use 3528 strip. If you want RGB, buy 5050 RGB strip. Do not buy 3528 RGB strips! I used those. (configured as Blue, 3528, non-waterproof)
Note 2: If you want to increase the action time, the first thing I would do is buy higher quality batteries. If you want to further increase capacity, then use 3 batteries in series and buck-boost converter.
Step 6: Final Notes
It took me about 4 hours to build one lightsaber, but I was doing that for the first time. We really fought with those, and the effect is great for this price, I think.
Of course, the blades are still very hard, so you can't hit your enemy with full power, but you can cross you sword with enemys with full power. Try to not hurt yourself (I am not responsible for that).
Also, when gluing the electronic to the guard, use very strong glue (preferably epoxy or a LOT of hot glue), because on our first fight, the battery holders had loosen up. And don't forget to solder the wires really thoroughly, otherwise the solder point can break.
If you are wondering what are those strips of white clothing in the battery holders - they serve as simple battery ejectors, because otherwise it is very hard to get the battery out of the holder.
And finally - if you have any questions, notes, or grammar corrections, I will gladly answer them! Also, should you build this, then please let me know how it worked out.