Bullet proof bra!

A US woman had a lucky escape when a burglar's bullet bounced off the metal underwire in her bra.Police in the city of Detroit said one of three intruders fired a shot when the woman looked out of her window and saw them raiding the house next door.The bullet smashed the window and hit her, but instead of causing serious injury - or worse - it was deflected off the wiring in her bra.The unnamed 57-year-old woman was taken to hospital and released the same day."It did slow the bullet down," said a police spokesman. "She sustained injuries but they're not life-threatening."Teenage gangThe woman, who lives on the west side of Detroit, had seen the youths breaking into the house next door while her neighbour was away.Police believe one of the gang saw her looking out of the window and fired at her.The suspects then drove away after the shooting.Local police Sgt Eren Stephens Bell told the Detroit News: "We need to get some bulletproof vests made from that. It is some strong wire." BBC Story

Topic by Kiteman 10 years ago  |  last reply 10 years ago


are you really bullet-proof?

What im asking is if you were to get hit by a bullet (with homemade bullet proof armor on) would you die from internal bleeding?

Question by Bullseye-proof 7 years ago  |  last reply 7 years ago


Is chain maille bullet proof?

How strong is this stuff? Is it comparable to Kevlar? Will it stop a bullet? I know it'll protect you from being stabbed, but what if someone's got a firearm? Are some mailles stronger than others? Which is the strongest?

Topic by MattGyver92 10 years ago  |  last reply 9 years ago


where can i get a bullet proof vest like the one below? Answered

Requirements for the vest: - i want it just like the one below -has the FBI label on it (optional) -has to be real and functional      thanks for your answers

Question by m5industriesinc 8 years ago  |  last reply 4 years ago


Where can I get reinforced graphene to make bullet proof aromor? Answered

Where can I get reinforced graphene for bullet proof armor? I live in McAllen Texas. I'm trying to get a type of graphene that is stronger than steel, but I'm not sure if I'm suppose to get reinforced graphene plastic or some other type, don't even know the names and differentions.

Question by Anti11 3 years ago  |  last reply 3 years ago


How to make a bullet proof armor vest at home ? Answered

Bullet proof armor vests are a very basic need for the news reporters in working in hot war zones. Being a freelance reporter, I would like to know how can one make a bullet proof armor vest by himself.

Question by muhammajunaid 9 years ago  |  last reply 1 year ago


knex armour

I made some im almost done the body is 90% bullet proof ( to my guns )

Topic by funwithfire325 11 years ago  |  last reply 10 years ago


is a steel kitchen pot bulletproof?

I am working on a completely home made armor set for sword combat.  Actually, it will be mixed with a few modern firearms such as .44 Magnum revolvers, 9mm handguns and .45 pistols.  It is better that you DON'T know what I am doing.  Trust me.  So the question, Is a steel kitchen pot bulletproof?

Question by bendog38 7 years ago  |  last reply 2 years ago


Is there anything hidden in the star ratings?

In the comments on my instructable, two people said they rated it 5/5 stars. In the info tab, the stars report 2 ratings but only 3.25 stars. How is this possible?Here is the instructable:https://www.instructables.com/id/The-ultimate-heavy-duty-stackable-bullet-proof/Thanks for your time!Mikey

Topic by Mikey D 10 years ago  |  last reply 10 years ago


Any tips on disassembling bullet camera and relocating the lens module?

Hello!  I've been reading instructables for a while and now it's time to join and post a question. I've been finding nails in my driveway and want to catch who's doing this.  I've got a 4 channel security camera on it's way and have been thinking and researching ways to hide them.  Due to the 'clean' surfaces around my home, it's going to be tough to make the 2" diameter x 6" long bullet cameras blend in (so people don't vandalize/steal them).  I've spent hours searching how to camouflage cameras, so I know the 'typical' tricks. I'm thinking about making a fake gutter extension and hiding the camera in there (so it blends into my one story house), possible installing a gable vent on my garage and pointing a camera through that, or trying to mount a camera about 20' up a nearby tree.  My favorite idea is to take apart a bullet camera and move the camera lens module, which is much smaller than the whole camera housing, to a more discreet location. I've searched for a while but can't find anyone who has done this with an IP66 outdoor style camera.  I know I'm going to lose the IR LED's around the lens, and that's ok (I'll have 3 other cameras for night vision).  I think I can point the camera through a small knot hole in my privacy fence and be able to detect who has last walked by when the nails appear.  I might make a small weather proof enclosure to protect the lens module...I think I'm a good tinker-er so this isn't the problem. Has anyone hacked apart a security camera and moved the lens module (by extending the wires) to a remote location?  I know there are small cameras for sale, I know I can hide a camera in a bird house, etc...but I like to make things.  I'm just looking for advice/tips from someone who has done this.  When I search for 'hack apart a security camera' I get a bunch of 'hacking into a security system', or 'spy on your neighbors'...I don't want to do either of those.  I have great neighbors, I live in a corner house where a lot of people/kids walk...I just want to catch them.  Once I know who's doing it, I'll move the cameras to more visible locations (to deter others from doing anything else). Thanks for any help!

Topic by MountainBikeOutlaw 2 years ago  |  last reply 2 years ago


Glassphemy lets you recycle and have fun smashing bottles at the same time

Glassphemy is a large clear box made by Macro Sea where people can smash their bottles for recycling. Thanks to some bullet-proof Lexan panels, others can watch the action from right behind the smash zone. It's a great way to get rid of some stress and break up bottles for reuse. GLASSPHEMY! via core77

Topic by fungus amungus 8 years ago  |  last reply 8 years ago


What do you recommend as a home DVD player for the next decade ? Answered

Last night our Panasonic DVD QUIT just as we wanted to play Swiss-Family-Robinson for the grand kids. So we had that Yamaha 6 platter player that first lost its VF display and later the player quit too the only reason its still shelved is its the audio drive for speakers installed around the room.. . What is a bullet proof player with easy to use control and HDMI output in your opinion

Question by iceng 4 years ago  |  last reply 4 years ago


How to Build combat suit? What materials are needed for bulletproofing? Cheapest materials that can be used safely? Answered

I have some designs I'm mainly looking for recommendations and references for the materials needed. Also need some advice on kinetic energy replacement for high drops and jumps. Frame material needs to be light weight and strong. Outer armor will be interchangeable. Weapons are still in development more posted later. Also all metals must be nonferrous.

Question by DaVinciStein 7 years ago  |  last reply 22 days ago


I keep getting email notifications for other members' question answers.

If I comment on someone's question in Answers, I get an email notification as if I had asked the question. Here's the last one I got: "Hi JamesRPatrick! People are answering your question! You have 1 new answers. Please do not respond to this email, the Instructables Robot already has its arms full of messages, and it might drop yours! --------------------------------------- From: JamesRPatrick Date: Dec 30, 2010. 5:18 PM Subject: https://www.instructables.com/answers/where-can-i-get-a-bullet-proof-vest-like-the-one-b/ Here. Or try this google search." This Answers topic was posted by m5industriesinc, I only commented on on it.

Topic by JamesRPatrick 8 years ago  |  last reply 8 years ago


For All the Concrete Enthusiasts at Instructables

Dr Purnell is actively seeking other researchers, engineers, scientists, designers or even sculptors and artists who also have ideas for new uses for cement.I'm not sure if anyone is interested or if someone in the community previously posted this, but I thought I might throw this out to the ingenious and innovative Instructables community. I thought some of you all might be interested.Main Page / Network Link:http://www.engineering.leeds.ac.uk/resilience/research/NACNetCementingtheFuture.shtmlLeeds engineers developing bullet proof vests from cementhttp://www.leeds.ac.uk/media/press_releases/current09/bullet.htmMight be a good way for interested Instructables folk to continue contributing on a global scale and to showcase the open-source power of the Instructables community. Plus, it might help you out if you're younger and/or looking for undergrad or graduate level resume boosting aspects for design and/or engineering programs.

Topic by MolecularMaestro 9 years ago  |  last reply 9 years ago


Good type/thickness for a clear acrylic sheet which may(will) be taking occasional impact? Answered

I've got a martial arts gym setup in my basement, and we're tight on space. There's a lot of stuff I have hanging on the walls (sword racks, training pads, weaponry, the like) and I'm looking to put up some acrylic sheets or something similar, hinging up at the ceiling, so that that stuff is protected, and more importantly, that if a sparring session gets a little wild, nobody is going to get thrown against a wall of (potentially sharp) gear.  Home Depot sells acrylic sheets, and I'm thinking I can fashion something workable to support them, but they're not super cheap, and I don't particularly want to waste money on something that will break the first time someone bumps into it. Any ideas? I'm not springing for bullet-proof glass- lemme rule that one out. TL;DR: Impact-absorbing clear plastics, sold in ~40"x~20" sheets?

Question by kytsunei 6 years ago  |  last reply 6 years ago


Too all Instructablonians: Rockin an awesome lunchbox? I wanna hear about it.

I currently don a teenie-tiny plastic brown-bag shaped lunch tote that barely fits an 8oz water bottle, sandwich, chips, and ice pack. I need something with a bit more room for food. At an impressive 5'3" and 105 lbs, I'm a growing man, and I need my fuel. But I don't want just some clearance-rack generic latest-movie/pop icon plastered lunchbox, no sir. I want an bullet-proof, high-capacity, industrial-strength lunch transportation system. Something that will make people say "Holy crap, that guy's a MAKER."  I want a lunch box that scores major cool points. Something that has character. Something that has features, like extreme insulation or something. Bottom line: it needs to be big, look cool, and last a long time. Price isn't an issue, Christmas is coming up :D So, ibles, how cool is YOUR lunchbox?

Topic by Labot2001 9 years ago  |  last reply 9 years ago


Knex War?

Hey guys! Sharir1701 here and, as most of you guys that knew me back when I was still around probably know, I've lost most of my interest in Knex. I do, however still come on the site ever so often to browse, comment and so on. I've noticed during my past couple of visits that there seems to be a "war", so to speak, raging on between some members of the community, regarding the effect of bulldozing a gun with rubber bands, as well as "how good" is the NAR. In this forum I am assuming you all have basic knowledge in Knex gun technology, are familiar with the stated guns and have a little bit of background in mechanical engineering. Moving on. You might know my opinion about the subject already, but I would like to state it once more as well as explain it better, so perhaps some people that disagree with me could understand my point of view. BUT, before I do that, I can't help but feel guilty for tossing the long burning logs into a small fire. About a month or two ago, in one of my visits, I posted a comment on one of Red's topics (or 'ibles, strike me dead for my memory) about my quite specific opinion about each and every one of the three guns in question in the said topic, the ZKAR, the NAR and the TR8. I said a few things about rubber bands and brute force vs. complexion and efficiency, and I may have started something unintentionally. That argument has been around since, if I recall correctly, 2009, but it hasn't been brought up again in a while. I feel like I made that happen and then I enraged a few more people by saying that "efficiency and good design beats brute force any day" (or something like that...). I'm not taking credit for starting this thing again, but rather I'm apologizing for sparking up an old and possibly pointless argument. Nonetheless, I will now explain my opinion on the subject and hopefully nobody gets mad at me for doing so, but if you have a valid counter argument, please state it below in an understandable and polite way. Thank you. If so, then, what is this whole thing even about? The "KI Crew", as I like to call them, have been very proud of their NAR and TR-n series guns for a few years now. The TR series I'll admit is very good, but I don't accept the "add as many rubber bands as possible" argument. Now, the NAR, personally, I dislike the gun. I have had nothing but bad range tests with it in the 3 times throughout the past 4 years that I've built it, and I've heard similar results from several people and some close friends. I highly doubt I was doing something wrong all THREE times, so don't bother to bring that up, please. The NAR is a gun designed for nothing else but being capable of withstanding great amounts of force and shooting a single round "the strongest a pin gun can shoot". How? Very simple - make a massively dense and very shock-proof body and then just add as many rubber bands as you can before your hands start bleeding. Now, let me explain, I'm saying 2 points here. First, the NAR is nothing special, just a strong structure with a simple connector barrel and a reinforced pin. We've seen it before, people. The claim that it's a good gun simply because you can put on as many bands as you want, pretty much, is, in my eyes, invalid. So I can make a bomb and just put as much explosives on it as I can afford, surely it'll be better than an atomic bomb... WRONG. It won't. Theoretically, even if it makes a bigger bang, it takes so much effort and it is so non-elegant that it loses it's point within itself. (Do not take this metaphor out of hand! You know what I mean). Second, and more importantly, I'm claiming that even if my first claim is wrong, if you look at the technical side of things you'll see that the very premise that adding more and more rubber bands to a gun will make it much stronger, is wrong in it's origins. I'm sure we all know this, but let me remind us all the physics of how a basic pin gun works. When the potential energy stored in the strained rubber bands, and rested on the cocked pin, is released, it accelerates the pin. The pin then proceeds to gain speed and it reaches three main milestones:  The initial strike of the bullet (The pin is already accelerated and is just touching the bullet, but the bullet is still). The point of equality, as I've dubbed it before (Just a few tiny fractions of a second after the initial strike, at this point the pin is ever so slightly slower than it was in the initial strike, but the bullet is now travelling at an equal speed as the pin, with a tiny gap between the two, meaning they aren't actually touching at this point) And finally, "the crash" (the bullet has left the barrel, the pin is at it's highest speed and is the most energetic as it pointlessly crashes into the back of the barrel losing and wasting all of it's remaining energy). In a world where you could use 100% of the acceleration of the pin and transfer it all into the bullet, adding more bands would indeed make a much stronger gun. BUT, that is impossible, in fact, it's no where near that. To put it all into a short sentence, the bullet accelerates and fires with a fraction of the energy released during the shot and to a certain limit, it is almost exactly the same amount of energy after a certain point. So, let's talk Maths. There is a direct correlation between the number of rubber bands on a gun and the amount of acceleration (and force) in the pin when fired. The pin's acceleration as a function of the number of rubber bands on the gun is in the order of magnitude of y=x. That's true, and that is where the misguided claim in question comes from. However, if we take a look at the graph of a bullet's acceleration as a function of the number of rubber bands on the gun, we can conclude, according to the above explanation, that the function is in the order of magnitude of y=sqrt(x). That means that up to a certain pivot, which I claim is, on average, around the 2-3 rubber band mark, adding more rubber bands does in fact produce a drastically stronger shot, but past that point, adding more rubber bands adds more brute force, yes, but it makes the shot stronger only just slightly, and by an increasingly smaller amount the more bands you put on it. BUT, and this is the big BUUT, the graph of the force required to cock the gun as a function of the number of bands on the gun is, again, in an order of magnitude of y=x. In conclusion, up to a certain, quite low point, adding more rubber bands will give you a drastically stronger shot without stressing the gun too much and without making the pull incredibly hard. However, past that point, adding more rubber bands adds an insignificant amount of power to the gun while introducing a whole lot more difficulty in operating it, resulting in an overall, worse gun. That is why I claim that a gun built around the sole concept of being capable to handle a lot of rubber bands is a nice concept, but is much worse than a gun built around efficiency (meaning you try to invest as much of the potential energy of the pin into the bullet by making a more efficient layout and a smarter usage of the forces in play). If you got this far, thank you for reading my article, and I hope this will put an end to this silly argument, but knowing how people's feelings work and how male ego and testosterone works, I bet it's far from it. Happy Knexing everybody ;)

Topic by Sharir1701 5 years ago  |  last reply 5 years ago


[newsletter] Light Sabers, Plasma Globe Tricks, Wall-E Robot...

Sign-up for our newsletter here. June 12, 2008 Welcome back! RoboGames starts tomorrow. If you can't make it this year, then you better enter our Robot Contest in the next couple weeks. The grand prize is a trip to RoboGames 2009! Winners have been announced for the Park Tool Bike Month. See who won! Check out these cool Instructables! Cheap Custom Lightsaber Build your own Battle-Ready Lightsaber! Use a good light source, and build it for cheap! posted by Ricardoaraujo on Jun 3, 2008 Turn a Cruise Full of Old People into a Death Defying Adventure In the immortal words of former Gov. Jesse Ventura, sometimes you gotta defy death in order to enjoy life. posted by iwasthinkingaboutsoup on Jun 9, 2008 Animate with light Learn how to make your own snazzy light-animations on the cheap for a music video or any other project! posted by buenoben on Jun 10, 2008 Wall-E Robot The movie comes out in a couple weeks, but you can start building your own Wall-E right now! posted by 4mem8 on Jun 6, 2008 Electroforming an Iris Seed Pod Commonly referred to as "dipping" in metal, this technique can make organic items permanent for jewelry. posted by MaggieJs on Jun 9, 2008 How to rejuvenate a box fan Many box fans are tossed just because they're too dirty. Here's how to clean one up for a few more years of use. posted by jgodsey on Jun 8, 2008 Ping Pong Ball Lights Sometimes you really need the diffuse glow of dozens of ping pong balls with Christmas lights in them. posted by advancedMischief on Jun 8, 2008 The ultimate, heavy duty, stackable, bullet proof, extreme saw horses! OK, maybe not quite bullet proof, but everything else is accurate. posted by Mikey D on Jun 1, 2008 Make your own tote bag from recycled plastic bags With a little time and creativity you can make some pretty cool stuff from all those plastic bags like this big tote bag. posted by user669 on Apr 8, 2008 Light Bar Ambient Lighting Add a bit of a colorful glow anywhere you want with a little bit of work and some inexpensive parts. posted by QuackMasterDan on Jun 9, 2008 Cable car Know someone who has trouble with stairs? A powered lift can help them move around more easily. posted by Mockfish on Jun 8, 2008 Win amazing LED POV kits! What have you done for robots lately? Winners to be announced next week. Make a High Voltage Supply in 5 Minutes Learn how to get up to 1,000 volts in just a few minutes. Be careful with this one! posted by Biotele on Jun 8, 2008 Creating, cutting and printing your own woodblock Learn the basic process for buying tools, cutting a woodblock, inking and then printing with it. posted by rbanks on Jun 6, 2008 Amazing plasma globe tricks! Just touching a plasma globe can get boring, so check out these new tricks. posted by highvoltage2000 on Jun 7, 2008 Plastic Bag Rug! This rug is pretty easy to make, looks really cool, and costs almost nothing! posted by denona on Jun 11, 2008 Leather Bracelets from Recycled Belts Make up to three custom leather bracelets from an old leather belt! posted by fungus amungus on Jun 6, 2008 Now go make something awesome, and I'll see you next week! - Eric

Topic by fungus amungus 10 years ago  |  last reply 10 years ago


KWR1 V.1 + "The More Bands, the Better" Myth

The KWR1 (K’NEX War Ready gun #1 Version #1) V.1 came out of my idea to build an entirely “mod-able” slingshot sniper weapon that you could rely upon in any outdoor K’NEX war (hence the name). You could make this gun longer; you could make this gun shorter. You could add a nonadjustable stock; you could make the stock longer, you can do practically anything to this gun (other than change the mechanism and the handle position).   Features: Good range: 60 ft. (1 band) – 100 ft. (5 bands, 45 degree angle) Can shoot: Oodammo (1 band: 60 ft.), Large K’NEX wheel (5 bands: 30 ft.), Small K’NEX wheel (5 bands: over 80 ft.), Lego bricks (5 bands: 50 ft.), NERF darts (5 bands: 50 ft.), and size #117 bands as a RBG (30 – 40 ft.) 10 point adjustable stock (see pictures 8 -11) with “Stock lock” (see pictures 13 - 15, 17) Totally customizable Safety (see pictures 15 - 16) Cheek rest (see picture 9) Not too piece consuming   Now, with all of that out of the way, I want to talk about ammo sizes and the “the more bands, the better” myth. So to do that, let’s look at the stats (shooting with three size #117 bands):   Red Connecter Ammunition: No rod attached: 62 ft. Green rod attached: 55 ft. 4 in. White rod attached (oodammo): 42 ft. Blue rod attached: 35 ft. 5 in. Yellow rod attached: 40 - 45 ft. Red rod attached: (got caught in the bands) Grey rod attached: (got caught in the bands)   Grey Connecter Ammunition: No rod attached: 64 ft. 9 in. Green rod attached: 59ft. 4 in. White rod attached: 50 ft. Blue rod attached: (got caught in bands) Yellow rod attached: 40 ft. Red rod attached: (got caught in bands) Grey rod attached: (got caught in bands) As you can see, the larger the round got, the lower the range you would receive. I think that this is a direct proof that bigger bullets are not necessarily good ammunition. For example, the ZKAR uses yellow rods? Might it get better range if it shot blue rods? Now, admittedly, the instances may be different with different guns, but I highly doubt it.   Conclusion: Stick with ammo sizes between blue rods and white rods (including both the blue rod and the white rod).     Now I want to talk a little about the “the more bands, the better” myth.   I took the KWR1 out to my backyard, grabbed some oodammo (growing in our garden, mind you), and commenced shooting from a prone position. Then I got this idea… what if I was to shoot with only 1 band, and not all 5? So I started to do that, leaving the bullets where the fell after having been shot. Then I decided to go back to shooting with 5 bands, to see how much better the range would be. So I fired a couple rounds… and got no better range than I did when I shot with only 1 band. I did this a couple more times, and found it to be true.   There is a myth (myth = a traditional story) pervading instructables that you will always get better range with more bands. Now, it is my personal opinion that if a gun can’t get 50 ft. with two bands, it’s no good, but that is irrelevant.   Conclusion: More bands does not necessarily mean better range.     Now, I am not stating these subjects as fact, for that would seem arrogant and presumptuous, but I do believe they are, to some extent, true.   -The Red Book of Westmarch

Topic by The Red Book of Westmarch 5 years ago  |  last reply 5 years ago


Perfecting DIY dog boot? (Any cobbler gurus out there?)

Hi, I have a dog who I adopted off the street who has a stub for a paw. The padding on his stub is deformed and since he has not toes/claw he is always getting this stub cut up when he runs around (just barely more than a year old and runs around like a nut). He is a real sweetheart and a big lug at the same time (100lbs) which has made it a bit more of a challenge. (I tried to put the photos inline with the post but when i tried to publish the whole post was blank so I just attached them). Design Issues Sleeve/leg durability To resolve this problem I have been trying to make a shoe that will #1 Actually stay on snugly and #2 Last more than a few weeks. It has been an evolution starting off with bought doggie “booties” which were pretty much worthless, to a old indestructible (until now) hiking sock + “shoe goo” to a sewn nylon sleeve thingy + shoe goo. This is the best we have been able to come up with as he destroys (since he is so active), I was going to go to the dump to see if I could get some used airbag material as I had made a dog bed cover from the stuff before (previous dog who was hell bent on digging through her rubber foam bed) and it was friggin bullet proof. Keeping it on So the shoe goo + nylon sock is the closes we have come so far, the sock/sleeve part kind of works because it allows us to “strap it on” above his hock so it doesn’t slip down/off, that worked great when we were using a softer material but this more durable nylon stuff (from an old suit travel bag) seriously rubs around his hock, I am guess I will try some sort of padding (shoe insole?) around the inside where we strap it on, bulky but just using a thick sock to provide a protection wasn’t enough. I’m not in the US (or a western country) at the moment so I haven’t been able to get my hands on proper Velcro and the Velcro I managed to get he has decimated (I think mostly due to crappy Velcro but also again his just scraping up against just about everything) so I was going to try a belt of sorts but am hoping someone has a better idea. Durable Sole that Stays on Shoe goo is the best we have come up with so far for a sole as everything else I tried just didn’t work (tried rubber pipe stopper thingy, Ear Bulb Syringe, modified mini-plunger) either because they didn’t fit how he walks on that foot (can’t describe it but a ball type shape is needed) or they were too hard to affix to a sleeve in a way that they would stay. The best version we have come up with so far has involved the afore mentioned nylon sleeve (durability) with shoe goo smeared in layers on the end. This has been workable but the shoe goo doesn’t stick to the material as well as I would like and is starting to come off after about 2 months. As with the other issues, any suggestions would be appreciated!

Topic by gaikokujinkyofusho 5 years ago  |  last reply 3 years ago


"Knex War?" (The Math Bit)

Hey guy! Sharir1701 here and I just want to start off by saying that I'm not back into Knex warfare, but I have something to show you. About a year and a half ago, I posted this forum topic. There I explained why, in my opinion, just adding more rubber bands to a gun will not actually produce an overall better gun (past a certain, low point). I'm not getting back into that discussion, but I simply wanted to share something regarding that. Don't ask me how or why (I don't know, myself), but a few days ago I suddenly remembered that old assumption I made. Being a perfectionist, I hate leaving things unfinished or unexplained (particularly math and physics related inquiries). Back when I posted that topic, I had little to no formal Physics knowledge, and the beginnings of an understanding in mathematics. Now, I have a much broader understanding, much more knowledge, and an ability to explain and evaluate what I once couldn't. Anyway, what I'm trying to say is, back then, I didn't have the tools to prove my claims. I firmly believed in them, but I couldn't confirm them. It's nothing complicated, but, like I said, just something I'd like to share. I also want to point out that, although I personally don't enjoy spending days upon days perfecting a little plastic mechanism for firing (mostly) non-aerodynamic plastic projectiles, anymore, there still is a warm spot in my heart for the craft I once loved. More to the point - this is a small article just showing something I did in a few minutes the other day, that helps me to better understand how a Knex gun works. I hope that in writing this, more people that are still building guns, will think about more accurately calculating certain things about their guns to help improve their performance and hopefully produce more efficient guns. The final note I have is that I'm about to show you equations, all of which can be plugged with real, measurable numbers, to calculate to a high degree of accuracy, the forces at play. This means you can actually calculate the most efficient layout for a gun, and also that in designing your next, you will be able to use these equations, and many others, to find optimal solutions to your problems. So, what's all this fuss about? Well, basically, I just proved with a few, painfully easy equations that my conjecture about the forces in a gun, working on the pin, is true. I'll just get to it: First, Hooke's Law states that the force necessary to change the length of a spring or a (tense) rubber band is F=K*dX, where F is the force, dX is the distance you want to change, and K is a constant number, that each rubber band (or spring) has. You can quite easily measure both of these. For rubber bands connected parallel to each other (assuming they are the same type of rubber band, which ever is your chosen standard), this equation becomes F=K*dX*N, where N is the number of rubber bands used. dX and K are both constant in the regards of the pull of a pin on a standard Knex pin gun. Therefor, the amount of force required to cock a pin (pull it back to it's full length) is linearly correlated to the number of bands you put on your gun. Next, if we examine Newton's equation of work and energy, W=dE=F*dX, where W is the work, dE is the change in energy in your system (input from an external force, i.e. your hand), F is the force applied along a length of movement, and dX is that length. Let us define the base position of the pin (not cocked, minimum tension on the rubber bands, fully in the barrel, etc.) as having 0 energy. This then means that the work applied to the pin by cocking it is equal to all the potential energy it has. From this, plugging in the force, we get Ep=K*(dX)^2*N. Let us assume a perfect world, where we neglect the effects of friction and air resistance, and assume all the momentum of the pin is transferred into the bullet as it fires (I will briefly mention in the end, why everything we're neglecting here just strengthens my claim in reality, but let's continue for now). After being released (in other words, shot), the maximum velocity the pin reaches right before the end of it's journey can be found using the equation for kinetic energy Ek=1/2*M*(Vmax)^2, using the fact that (again, neglecting energy wasted as heat due to friction) the energy is conserved, as no external force is working on the system, which then means that Ep,start=Ek,end => K*(dX)^2*N=1/2*M*(Vmax)^2 => Vmax = sqrt(2*K*(dX)^2/M) * sqrt(N). The first sqrt term in the final equation is all one big constant (again, K is the ratio associated with the rubber band, dX is the distance the pin travels, and M is the mass of the pin), meaning we can conclude that (C for constant) Vmax=C*sqrt(N). Finally, force applied by a moving, massive object can be calculated using Newton's second law, F=dP/dT (P is the pin's momentum, T is the time it takes for the pin to go from velocity Vmax to 0, transferring all it's energy into the gun and the bullet, but as I said, let us assume all of it goes into the bullet), or F=M*dV/dT (M, mass of the pin, dV is the difference in velocity, Vmax-0, which is simply Vmax. This is because P=M*V, which means dP=M*dV, ignoring relativity). So, F=M*C/dT*sqrt(N). The time varies slightly, but insignificantly, so let us assume it is a constant. So that's it. The force exerted by the pin on the bullet is some constant (calculatable, as mentioned and as shown), times the sqrt of N, the number of rubber bands on the gun. So there you go. Just a little something I did out of the blue the other day and thought I would share a proof of my conjecture from what feels like eons ago. I hope you enjoyed. Finally, I would like to tell you guys, perhaps as a little tease, since I'm not sure if I will ever upload it, but I have made 1 more gun after I stopped posting. I have already slightly teased about it in my user info. I guess I'll tell you guys what it is if I'm already posting something here again :) Possibly my most enjoyable, most well received, and quite innovative gun of all time? The REMPAR-2. I built the REMPAR-3 (I was also going to call it S5 when I thought about posting it). In a brief summary, it's a pump action, chambering (or bolt action as I and many others falsely used to call it), magazine fed rifle, that's only 5 layers thick all over, except one tiny area where it's 8 layers thick (1.5 extra on either side), as a reinforcement, not necessary if you use less rubber bands. Oh, actually, there's another small necessary area where it's 7 layers thick, but it's tiny and doesn't make the gun look bulky at all, and who cares. Plus, the one is around the pump, which looks quite natural, and the other is "disguised" as a detachable sight (not really detachable) that also looks fine. It also looked fairly good for a gun that I made, it used (if I remember correctly) a grand total of 0 broken pieces, which is a big accomplishment for me (the mag has some broken white rods, but fuck off), and it worked flawlessly, reaching ranges over 80ft and being able to go at 2-4 rounds per second, depending on your skill level with it. In other words, I could shoot 4rps; My girlfriend, with no experience or practice, could do 2rps, which says something about the gun's comfortability and ease of use in my opinion. It shot blue rods up to an accuracy of about 5x5cm (2x2in) over 30ft, which is amazing for a Knex gun, and it was truly super comfortable. It wasn't even long at all, which is saying a lot, looking at some other people's attempts at 5-wide pump actions (I may also be guilty of an attempt several years ago). Being quite short and only 5 wide, it is also quite light. I'm sorry, I just really liked this gun, I think it was truly my best creation ever (of course, the S3 is by far the most innovative gun I've made, but it's mostly a concept gun, not meant for real effectiveness). I may post it in the future, but I'll make no promises. I suppose I won't leave you guys completely hanging and take a picture of it. Oh yes, there's also a neat, fun little thing I did, originally because I saw no other option, but then I actually really loved it. I'm talking about the mag-lock. It locks automatically (there's a band on it, but it ripped a long time ago, so...) and the mag cannot fall out. Then you pull on it with your middle finger, similar to a trigger, and the mag just drops right out. Love it :)

Topic by Sharir1701 4 years ago  |  last reply 4 years ago


Advanced Helmet

Advanced Helmet By: Arseny Ratnikov I want to create a helmet that looks like a sci fi helmet (mass effect, titanfall, halo, etc.) and that; **Want to make cool helmet, need help with having multiple camera feed output to multiple screens** * Protects my head (able to decrease force from impact by significant degree) * Can filter the air I breath (does not need to be super extreme filter, just filter out general junk, the better the filter the more pleased I am, but if it becomes too bulky/expensive then it is unnecessary)(Optional/Most Likely) * Has a HUD with my vitals on it. I would wear some sensors, such as HR monitor to have some cool biofeedback, maybe also include other information.(option) * Maybe even have it be a digital display where there are cameras on the front and maye back of the helmet that then are displayed on the interior screen, where I have voice commands setup for some different things. * Have the helmet be as sound proof as possible and have microphones where my ears would be, then inside the helmet speakers, so that I can modify the noise around me to be how I want it to be. I understand this would be rather difficult (at least including all of the bullets) and that it could even be a touch silly. Yet, I find this a rather intriguing pursuit and think it will help contribute to becoming a cyborg. Any tips would be greatly appreciated as I don't really know where to start for this. I can imagine a lot of the work might be done on an arduino, but I simply don't know the feasibility of modifying noises of the world around you and having the cameras on the helmet. So here's a little prioritization sheet I worked out, it is not exactly in order, and maybe you all have some suggestions on what might be more critical to design and functionality. Prioritization 1. Functionality a. Head protection a1. Padding/Inertia dampener a2. Sturdy/solid b. Control of phone through bluetooth b1. In helmet speakers b2. In helmet microphone b3. Voice control c. Control of other systems such as screens c1. Voice control of screens c2. Screen modification c3. Screen HUD and other functions (maybe GPS map, time, etc.) d. Camera view d1. Camera live to screen with little to no latency d1a. 360 degree view compressed to 180 degree screen (maybe) d2. Computer control of camera feed d2a. Visuals, different HUDs e. Sound modulation e1. Sound cancelling e2. Sound reproduction at low to no latency e3. Sound modification e3a. Changing pitch e3b. Change decibel levels e3c. Change relative level of external sounds f. The HUD f1. Display of vitals f1a. Heart rate, oxygenation, etc. (Requires some monitor) f2. Display of time and other running interests f3. Display of current location on google maps/GPS system g. Air Filtration g1. Filtration of air, relatively high quality g2. Seal on head or seal over mouth and nose or full body suit that connects to helmet h. Extra Features 2. Style a. Look good b. Look like popular sci-fi media c. Does not interfere with functionality and accents functionality How should I do this? I am planning on using some old phone screens if I can for the screen part and multiple cameras. I plan on using a raspberry computing system (might need multiple) to modulate the output from the cameras. How could I make multiple camera outputs lay onto multiple screens that looks good at three to five inches from the eyes? Also how can I make the raspberry pi control my phone and computer via voice, or at least change a screens properties? Thanks

Topic by ArsenyR 1 year ago  |  last reply 1 year ago


Tempered glass screen protectors - understand and beware!

I recently had the joy of needing a new screen protector for my mobile after being dumb enough to drop it on gravel. The hard cover took all the impact but the film protector on the screen was scratched badly. Was old and partially worn anyway so I decided to upgrade to a Tempered Glass screen protector. Being somewhere rural I had no chance to get one in a shop so I ordered online. With no intention of advertising for some sellers, I collected a few links so you can check what I am talking about: Item1 Item2 Item3 Item4 Item5 Item6 So, what is my concern with these? They all can be found on amazon and other online services as well as on local markets... As I said I ordered a glass screen protector. If you check these listings and even some of the packing you will notice they all have a thing in common - being shatter proof and of 9H hardness. I also love this video showing how to remove and fix a glass screen protector! The last time I checked glass had one very distinct feature: It is hard and before it really bends it breaks - unless you use fibre optics of fibre glass cloth... What is my concern and warning here? Pretty simple: Stay away from expensive scams! Some claim their screen protector is only 0.25mm thick, even the 0.2mm one I measured was over 0.5mm with the glue... The hardness of 9H refers to the so called Moh's hardness - look it up on Wikipedia if you like. That means these tempered glass protectors would have a similr hardness than a diamond, or at least close to it. Problem is that they are made from plastic to start with and not glass at all. They claims that the screen protector is flexible because it is so thin - again a fake! Even the thinnest tempered glass will shatter if you bend it enough, not so these plastic ones. If you think I am making all this up try to use a really sharp knife or deburring tool and cut the thin sides of one of these protectors. All the ones I tested could be cut quite easy - and I though glass can't be cut with a kinfe... A nice website showing that the scratch resistance is far from the claims can be found here. And a video showing how a real glass screen protector sounds and breaks can be found here. So is it really all bad and should I avoid getting one? Not really if it is only for the added protection. To be clear here, and without the intention to blame any of the above sellers, some protectors actually do have a top layer made from glass and you can hear it as in the above video - it sound solid and not like plastic if you tap it with something hard. Another factor is the simple fact that plastic absorbs impact much better than glass. So where a real glass screen protector might shatter and crack like in the above video, the fake ones might one get a nasty dint or scratch. But you should be aware and clear about what you get and what to expect from it. These glass imitations are made from a strong polycarbonate plastic, similar to the stuff used for bullet and explosion proof "glas" windows - if you every watched the Mythbusters you have seen the big sheets I mean. The top layer of these things is specially treated to repell water, oil and dirt, it also gives the surface the good scratch resistance. The technique is nothing new, camera lenses, plastic sheets and the clear covers you see over the timetable at your bus stop all use it. The new thing is to intentionally mislable a product to make the consumer think it is glass ;) What is the real difference for the user? Check this video. Here a guy performs a drop test with a real glass screen protector. Thing is once the protector breaks the screen itself is broken too but until then it was not too bad. Here it is demonstrated how a real glass screen protector reacts to certain types of abuse - one of the reason I decided on glass. Compared to the plastic counterfeits just the sound on the glass is worth it, but I think the hacksaw was best. Another video from XDA gives a bit more info on how the glass is made - if you can't seeing a phone being abused then don't watch the drop tests at the end ;) Glass with these hardness levels and types of surface protection will give the user a long and worry free use of the phone. The plastic fakes will perform at a similar level for some time but will show signs of wear long before even the top coat of the glass one fails. Both types have their uses and if the fakes would be labeled correctly the user would actually benefit from that. On bigger screens like a tablet I would actually prefer the plastic ones to prevent damage once it needs replacing. On a mobile used in less than perfect conditions I would also go for plastic as it usually is a bit thinner and will fit better within quality hard covers. But when it comes to real abuse like using with dirty fingers most of the time or mostly outdoors where a lot of dust and fine sand can be involved I always go for glass. If you paid attention to the surface treatment then you already realised that the plastic and the glass are in the same region, making them quite scratch resistant. Still fine sand or metal dust will scratch it.... The difference is in the hardness of the actual material that was covered with the oleophobic film. Glass will not give in any way, where plastic is much softer - so not to be confused with the surface hardness! This mean that sharp and point object will easier penetrate the plastic than the glass, something to be considered if you often ecounter harsh use. In terms of actual protection we need to differenciate between surface quality and actual screen damage. After all when badly scratched we can replace the protector but if the display got damaged we are back to square one. The surface hardness was already covered so let's move on to the screen itself. In some of the above videos you can see the abuse a screen might see in normal conditions, and if we would not drop our phones so often repair shops would not be at every corner LOL I have done quite a few screen repairs, mostly for friends and work mates that did not want to pay the hefty extras in a repair shop. From there I got the stories on how it happened and in almost all cases the screen cracked when the phone landed on the corners. In one case the screen and glass protector failed, including the actual display when the phone was dropped out of a 4WD and landed screen first onto a rock. A glass protector will spread the (direct onto the face) impact force onto a much larger area, where a plastic one will produce a dint onto the actual screen much sooner. So again glass wins in terms of actually protecting your expensive screen. But be aware that all this is useless if the phone lands on the corners!! Let me explain: Both the top glass on your screen and the screen protector have a thin layer of "glue". This acts like a shock absorber, so unless an impact goes deep enough so the pressure on the actual screen is too much only the protector should fail. But the screen itself is a tight fit into the frame of the phone, so all side and corner impacts go directly into the glass. As the rest of the glass has no way to give or go the stresses will crack the screen. How should I treat my phone with the new screen protector? Exactly the same way you would without it of course. But if you don't have a proper cover that offers protection of the corners you should invest in one. Having a quality protector and a good case does not mean your phone can be used as a football, see it as an added insurance in case something does go wrong. For obvious reason it can also pay off to have a spare at hand, if something bad happens that requires replacement of the protector you won't be left with an unprotected screen ;) Last but not least, double it up: For people that already know their screen will see a fair bit of abuse in term of scratches it is a good idea to put an extra film protector onto the glass one. Once it is too scratched you peel it off and replace it, while the glass protector gives you the actual protection for your screen. Corning Willow glass As time of wrinting Corning Willow glass is the only "flexible" glass on the market, unless stated with your flexible screen protector you can assume it will be just plastic. I did not list it above as this high tech material is mainly reserved for displays and at least to my knowledge is not available for screen protectors, although I will stand corrected as I have to assume some big players use it for their protectors. The material is actually a sandwich where an ultra thin sheet of glass stis bewteen two layers of durable coating, read it up on their website it is quite interesting. It won't reach the strength of their famous Gorilla glass so without an outer plastic that has the additional oleophobic coating it won't provide the strenght of real tempered glass protectors. Some phones like the Galaxy Round and the fleixble HTC phones use it for example.

Topic by Downunder35m 3 years ago  |  last reply 5 months ago