How is the tip of a center punch much different than the tip of a knife?

I'd be cautious about using keys or a knife blade. You'd have to hit keys awfully hard into the window - with a risk of hurting your hand as well. I'd be worried that a knife blade would tend to skate across the smooth surface of the window glass.

You need an impact tool:
* Center punch.
* Impact end of the AK-47 knife.
* A small hammer, where one end of the hammer anvil comes down to a cone (e.g. a small rock hammer).

Pete

As for the science part, i'm not really sure. I guess the little cone is more effective because it concentrates the force more effectively.

But from experians, sharp things are not created equilly. So i have the same suggestion as Martin. Try it out and see the diffrence yourself.

It doesn't bend or break off and it doesn't slip and skip across the surface of the glass and then stick in your leg.

The tempered safety glass used in vehicle side windows is engineered to withstand large force spread over wide areas, but is easily defeated by even moderate force applied to a pinpoint area. I have seen side windows broken in by rocks, hammers and knife butts, but it always takes MUCH more force than you would expect. I've even watched a guy in a fit of road rage punch through a side window, but I think it was a very lucky shot and he broke several bones in his hand. Conversely, I've seen cops beat on windows with their nightsticks and do nothing more than fracture their wrist, and suspects locked in patrol cars kick at windows with no effect.

The problem with using a knife blade is that you're holding it on the handle, far behind its center of mass and fulcrum point, which makes it impossible to control once the tip meets the smooth resistance of the glass. This translates into the blade twisting in your hand and the force is deflected off the glass, and as NobodySpecial notes, possibly into your leg. You would be better off using the butt-end of the knife, but you would need to use a lot of force.

With a punch you can hold it so only an inch or so extends beyond your grip. Because you are gripping the punch on the inside of its center of mass and fulcrum point, the punch doesn't deflect and the direction of force is perpendicular to the glass. The conical tip then concentrates that force to a pinpoint area, making it easier to break the tempered glass than the wider knife butt.

Robert your question has made me think of my own situation.

I keep a Res-Q-Me on the steering column of both my work and personal vehicles, they are cheap and it just makes good sence to me. My knives and multi-tool are all located at the sides of my waist, not easy to access when sitting in the drivers seat.

On my work truck key-ring I have a red Fox 40 whistle, it is there to help me tell this key ring from my 3 others (work, personal, youth organization) and to add some colour to my keys in case I drop them in the bush/snow. In 7 years I have never used this whistle as a whistle, maybe I should replace it with a bright coloured Res-Q-Me for use on other vehicles when I am outside of my vehicle? I do carry a second whistle but it is sealed (therefore not as accessable) in my PSK. Thoughts?

Mike

I mentioned on a similar thread that it is not always about self rescue.
If you are at an accident scene one of these small tools on the windshield visor or key chain might save somebody else.
Sometimes you break windows to get into cars instead of out of them.

Mike, you know that as soon as you get rid of the whistle you will start wanting it.

By chance I went to the main ETS page today and found the answer to my window punch/whistle problem there.

Doug has recently posted a story about 3 college students who perished when trapped inside a submerged car.

Shown was a resque tool called the Houdini Automotive Escape Tool which combines a window punch, seatbelt cutter, whistle and LED flashlight all in one small unit, sounds just like what I was looking for.

Now I just have to find a source in Canada.

Mike

Anyone know of any follow-up reports on exactly what may have happened there? Apparently a couple of them had time to at least dial their cell phones...

Sound like they would have had plenty of time , if they had known what to do and if they had a way to break the windows, or even presence of mind to roll down the windows before the electrical system shorted out.


It just shows the importance of playing these scenarios out in your head, seatbelts, windows, children , out, at least it will give you some idea of what to do and possibly prevent panic.