Introduction: Emergency Vehicle Escape Keychain

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Car accidents. Yikes!
The best way to avoid being in an accident is to use safe driving techniques and always pay attention to where you are going and to other cars around you. However, despite your best efforts you are not in control of other drivers and sometimes accidents happen. Bummer.
There are options available on the market for vehicle escape devices which will help you out in case of an emergency, however a few of the models I have seen are designed to be placed under your seat or in the glove compartment. What these products do not address is that the location of these devices are often inaccessible after an accident or are thrown around the vehicle during impact.

This project will outline a design for a post-accident escape device which will never be further than your steering column. In the case of an emergency, use your good judgement to get yourself to safety.
Be smart and ensure your vehicle is equipped with all necessary safety gear such as tire repair, cones, and road flares. This project is part of a complete car survival kit.
Construct at your own risk.

statement of design:
The design consists of has a small blade located in a narrow channel designed to cut your seat belt should it become jammed, there is also a shard of ceramic which can be used to break your driver's side window allowing you to escape your vehicle if the door has become compromised. An LED can also be fitted allowing you some light if it's dark. The entire device has a non-slip grip made from a waterproof material and can be attached to your car key ring.
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Enough talk, lets make something!

Step 1: Materials

  • spark plug
  • plastic (credit) card
  • 2-part epoxy (or other strong adhesive, must be able to bind metal to plastic)
  • permanent marker
  • hobby knife with 'snapable' blade
  • masking tape
  • sandpaper (I used 3 types: 120 grit for wood, 120 grit waterproof emery cloth, and a stiff hobby board sander)
  • hammer
  • vice grips (grips or clamps)
  • drill (with metal bit)

Knives are serious business. Be safe, and use responsibly.
Spark plug shards are also serious business, use goggles and gloves.

Step 2: Snap Your Blade

Grab your hobby knife and extend out the blade exposing a few sections. I measured off 2 section with a total length of about 1cm (1/4"), depending on the desired size of your cutter and the type of knife you use yours may look different. The size of the cutting blade will dictate how large your device will be.

Once the blade is extended to the desired length lock the blade in place (seriously, lock that bad-boy down). Place a small piece of masking tape over the exposed blade and press down on an angle on the exposed portion. If done correctly the blade should snap along the scribe, the masking tape prevents the snapped blade from flying out and stabbing you in the face (because we've all been there).

Step 3: Cut Card to Shape

Next, use your marker and creative license (you have your license, right?) to design the shape of your belt cutter and channel opening. Since you'll be covering the plastic card you can draw willy-nilly to find that perfect shape. I chose a minimalist design but you could go for whatever shape and size you wanted.
Position the small blade you just snapped over your design to ensure that you have enough room on the card. I recommend maybe going a little larger than you need as sanding the plastic is easy, the metal not so much.

Once you are satisfied with your design cut the card into two blanks, mine measure 2cm x 5.3cm (0.8" x 2") each. Use your hobby knife to carefully rough out the inner channel, this channel is what will guide the seat belt to the blade.

Step 4: Add in an LED

Depending on your size and design you can include an LED to your belt cutter.
I had an old bike lock key that had a small LED in the handle, the battery was small and just managed to fit on the cut plastic. Find a good spot and carefully position your LED and battery.

Step 5: Light Sanding

Give your cut plastic shapes a rough sanding to take off any burrs and sharp corners. It's easy to get into the tight spots before it's assembled, but don't go too crazy sanding as the final sanding comes after we glue the two halves together.
The only place that needs some roughing is the inside faces of the halves being glued, this roughing allows a stronger bond between these two glossy surfaces.

Step 6: Glue

Squeeze out some 2 part epoxy onto some scrap and mix it up. Apply a thin coat of epoxy on one half, gently position the blade and LED assembly, add an extra dab of glue to the other side of the LED and blade then close the halves.

Next cut a few strips of waterproof sandpaper the rough shape of your plastic card, apply another thin coat of epoxy to the underside of the sandpaper strips and cover the outside of joined halves.

Clamp. wait. trim excess with hobby knife and sand all edges smooth.
By waiting until now to do a more thorough sanding you'll even edges on both sides and have a smooth top and bottom.

A word on epoxy:
As with most glue a good rule to follow is "less is more". This means that adding huge gobs of glue does not equate to a better bond. Most epoxy is stronger than the components being glued, using too much will result in a sticky mess with no added strength. Be smart, use enough to adequately cover the area you are working on, when you clamp it together some glue will ooze out but not so much as to glue the clamps to your project.

Step 7: Drill Keychain Hole

After sanding allow the epoxy to completely set (maybe an hour, maybe overnight depending on the type of epoxy used), then you can start drilling the hole to hang your belt cutter from your key chain.

You will need to use a drill with a bit specifically designed for metal, if you use a wood bit you run the risk of damage to your tools, this project, and yourself. Slap on your safety goggles and slowly start drilling.
The reason we're using a metal bit is because we're going to drill through the metal blade inside. Start small with a pilot hole, then change to a large bit and drill again to enlarge the opening.

Step 8: Smash That Spark Plug

We're now going to break our spark plug to obtain a shard from the ceramic insulator.
For safety sake treat ceramic like glass, it splinters and shatters when broken. These slivers can fly everywhere and can embed themselves into your skin if you are not careful.
Wear goggles and gloves!! this is not an option, you are putting your juicy eyeballs in peril.

Put the spark plug inside an old sock to prevent splinters flying when impacted, then take it outside and smack it a couple of times with a hammer, it took me about 3 solid swings to break the ceramic apart. Carefully turn the sock inside out and empty out the broken pieces, select a shard that is small enough to fit on your project.
Ceramic shards have sharp sides which can cut fingers, carefully file down the sharp edges of your shard. Sanding down the sharp edges of ceramics using regular wood sandpaper isn't going to work that well, try using emery cloth instead.
Once the edges are smoothed out mix up some more epoxy and put a dab on the ceramic shard, then place the shard onto the end of your belt cutter.

Through some post-published field tests it's been determined that a smooth rounded surface does not work as well as an exposed edge. Your edge does not need to be as sharp as a razor, so you can sand off the hard edge so it doesn't cut you. I have also discovered that the shard size can be very small, half the size of your fingernail would work. Check out the video in step 10.

there's been some discussion in the comments section regarding the composition of spark plug insulators.
My research has uncovered that insulators can be (and are) manufactured from both ceramic and porcelain. The insulator tip at the bottom of the plug is almost always made from ceramic.
Checking the definition of porcelain it says that it is a type of ceramic, though with a Moh scale rating lower than just ceramic due to the added minerals. This makes porcelain a poor choice for this project, make sure you check before you start smashing.

In any case the idea of this is that we are looking for a ceramic shard to shatter the glass. If you are unsure of the composition of your spark plug insulator you can either use the insulator tip (located at the end of the spark plug) or simply find another source of ceramic. There's a few household ceramics that come to mind, however carrying around a shard from your toilet is kinda gross.

Step 9: Science, Limitations, and Further Reading

Some Science:
The Moh scale measures the hardness of a mineral and it's ability to scratch a softer mineral. On the Moh scale diamond is the hardest at 10, ceramics measure around 9, glass is close to 6.5, and talc is at the bottom with 1. Using this scale we can see that ceramic is harder than glass, which is why a small shard of ceramic can damage glass. If you want to know more about the hardness of minerals why not read all about the Moh scale.
Through ceramic is much harder than glass there are some limitations

Laminated glass:
Laminated glass is glass which has been sandwiched with layers of plastic to allow the windshield to retain it's shape after an impact and prevent it from showering you with shattered glass. You can try to chip the windscreen and shatter it with the ceramic shard and kick out the glass once shattered, but your better option is just to use the driver's side window as they are not usually laminated.

Thick Glass.
If you have bullet-proofed your minivan windows to avoid suburban assassination, or if you are riding in the Pope-mobile this will not work.

Plastic Windows.
Some custom cars and older vehicles use plastic composite windows, it will not work for these types of windows.

Step 10: Action!

Not content to let science and other internet videos make my point for me, I went to the auto wreckers and managed to talk my way onto the site.

The owner was skeptical to the reasons why I was there and asked one of his workers to show me a car I could test it on. While walking along the aisles of cars I asked my escort if he'd heard about ceramics working on breaking windows. Judging by the look he gave me it was like asking a sailor if he'd ever seen water. His exact words were "it's the oldest trick in the book.".

To complete the breaking action there needs to be impact, simply applying pressure to the surface of the glass will not work.
Check out the video below where I toss a shard at the window, the force used was less than what you'd use to clap your hands together.

Step 11: Final Thoughts

You now have a small device which, in the event of a complete wreck, is able to cut your belt, smash your window, and light your escape!

Happy making :)

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