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Author Topic: Why glass breakers?  (Read 16960 times)
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Ed Fowler
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« on: January 05, 2008, 04:08:17 AM »

Time and time again I read about knives having glass breakers protruding out of the back of a handle. I ask - Why?    

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Larrin
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« Reply #1 on: January 05, 2008, 04:12:06 AM »

Duh, to break glass.  Tongue Either that or to poke yourself with.
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K Salonek
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« Reply #2 on: January 05, 2008, 05:02:40 AM »

Must be a sheltered life, but I have not seen a knife with a 'glass barker' .

Are they an impact protrusion that could be used to bust out the glass of a windshield or to escape a window if one gets frogy?
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radicat
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« Reply #3 on: January 05, 2008, 06:05:08 AM »

I have a little chuckle when I see those expensive "rescue" knives with the protrusion on the butt. First of all (and I think what Ed is getting at)  the knife is not designed to stab anything without running the risk of opening your hand up with a serious cut.. Secondly, it is more likely seen in the eyes of a police officer as a skull crusher or attitude adjuster or pressure point tool. Some tout that their knife has a glass breaker made from some super-hard metal. Why? It sells.

Law enforcement hierarchy, being infected with political correctness, don't encourage carrying or learning to use knives. The feature therefore provides a convenient excuse for the officer to have a knife. Sad commentary that reminds me of Officer Barnie Fife with his two bullets safely carried in his pocket, and his gun empty.

I can only wonder why one thinks the feature is needed if the knife is worth buying without it. It probably isn't.

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Alan
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« Reply #4 on: January 05, 2008, 09:47:30 AM »

Time and time again I read about knives having glass breakers protruding out of the back of a handle. I ask - Why?
It is an interesting thing to add to a knife.
It's a handy addition to the butt end of a knife.
When going ice fishing I always check to make sure I got something to take out the window if needed.

The butt end of a knife is the correct place for such a item because thats the natural way people hit glass if they were seeking to break it.
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cfendley
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« Reply #5 on: January 05, 2008, 01:53:48 PM »

I've never tried but I would think you could just break the glass with the point of the knife. I want the but end of my knife round so it doesnt hurt my hand if I have to pound the tip into something.
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davidm
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« Reply #6 on: January 05, 2008, 04:06:06 PM »

..in case the car defroster suddenly quits and you're in a hurry!
 
or backup, if your other knife with a "skull crusher" breaks, fighting a bear. Evan Nappen might need it.  Wink
David
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jared williams
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« Reply #7 on: January 05, 2008, 09:27:41 PM »

i have a friend who is a paramedic. he carried a smith and wesson rescue knife that had a spring actauted window breaker on the butt of it. he said he had used it a number of times at outo wrecks where he needed to get to a victom but the door wouldn't open and the windows were closed. he said what he liked about the spring loaded one was that it would crack the glass like a spider web but not shatter it on the victom then he could pull the glass down in a more controlled manner. that is what he told me and it made some sense. the knife also had serrations on the blade for seat belts that he loved but no point on the knife. the knife was designed for one purpose. getting to a victom and getting them out. that was it even, the serrations were different than most. these were his opinions, hopefully it sheds a little light on the subject
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Alan
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« Reply #8 on: January 05, 2008, 10:39:42 PM »

I've never tried but I would think you could just break the glass with the point of the knife. I want the but end of my knife round so it doesnt hurt my hand if I have to pound the tip into something.
while you "might" be able to break some windows with a knife blade, it's not that easy for most people to do.
The action goes against the way people do things.

Remember good Knife design should learn from, and follow human nature.


The more natural way to try to break glass, is the same action when you want to pound hard on a door-
You dont swing you arm so that your thumb hits first
You dont punch the door with your knuckles
You bang on the door, (or punch out the window) with the fleshy part of the lower fist on the little finger side.

This is also the natural position of the butt end of a knife, and the correct spot for a glass breaker to be located.
« Last Edit: January 05, 2008, 10:42:29 PM by Alan » Logged
Jose Reyes
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« Reply #9 on: January 06, 2008, 04:23:30 AM »

I agree with cfendley's response. You don't actually need to swing at all to break a side door window, just put the tip against the glass and put some pressure on it. The windshield is another matter but from the inside you're probably better off trying to kick it out. If you have enough room to swing you can just use an icepick grip on the knife. Skull crushers are probbaly useful on a fighting knife but then you do limit it's scope of work.
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radicat
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« Reply #10 on: January 06, 2008, 04:46:37 AM »

If anyone has some junk cars sitting around that you can test these theories on, DON'T DO IT!! This is something a person should not do unless it is an emergency. It's the follow-through that gets you cut.

The spring loaded glass-breaker is the safest way to do the job. Thieves have been known to carry the spring-loaded punches meant to be used on metal.

If rescue workers and law enforcement could carry a proper knife these special purpose knives wouldn't be popular. The knives that don't have the spring-loaded feature have to be small enough to fit in the hand with the thumb on the butt, since they have no guard. Of course anything bigger would be illegal to carry, making the design subject to law not functionality.

Speaking from experience, here is what you do to break a window. First of all, it is good to know that a knife will  fit in the hand with the blade toward the heel ( as though were going to stab cockroach on the kitchen table). Second, breaking glass that is not of the safety type will cut your arm off when you run your hand and knife through it. So hit it with something besides your elbow (which can be used on auto glass if protected).

As for vehicles, it ain't a complicated thing.
Stand to the side, of the subject window, facing away from it (not toward it). Give it a back-stab with the
knife and you're in. Some of the older vehicles have glass that just cracks, rather than shatter. So, you have to whittle it out of the way. It will cut you badly if you touch it without gloves. And, you'll be asking "Now why did I do that?" It's also a good idea to "not" be supporting your weight with a windshield when you bust it. Same with ice. I read some foreign survival stuff that is interesting. In Europe, a lot of the lakes that are fished in the winter, have rapid changes in the water level due to power plant operations. A person may go out on the ice safely when the water is up, but when it drops, you're out on a ledge with a hole in it. 
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Alan
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« Reply #11 on: January 06, 2008, 09:02:04 AM »

Once while out in a field with some beers, my friends and I found a car that was left in the woods to rot away.
The odd thing was, all the windows of this junker were in great shape.

Well when drunken young men come in close contact to that type of temptation,....

I learned that the side windows bust like "Pow!" and they are just gone.
Windshields on the other hand are a different story.

Side windows must be made of a different type of glass, because they bust all the way out easy and safe.
Heck, it's a wounder more dont get busted all the time from hitting things.
The windshield tended to spider crack on me.
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Ed Fowler
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« Reply #12 on: January 06, 2008, 04:16:53 PM »

Excellent discussion! I do not believe there is much that has not been covered. This is the kind of discussion that should happen when any great new and improved knife design comes on stage.
In my opinion, a knife is at its best when it is a knife, an honest simple knife that is made with knowledge of the functions it may be needed to work at and the one using her knows her well. Anything we add to her will detract from function. As Larrin noted the glass breaker is something to poke yourself with.

I have yet to find any attribute to add to a knife blade that would not detract from a knife's job as I see it. The gimmicks sell a lot of knives, when I see some new great deviation from an honest knife I wonder how much it detracts from honest function and how much it may cost the man who buys it - should he ever be in a position to really need a knife.

"Special Purpose" knives attract a lot of attention and some learn how to use them, all too many carry them and believe they are prepared until the jackpot, then they find out different. The old boy scout knife was truly an honest all purpose knife, not supreme as a knife, but it could open bottles, cans, punch holes in leather work as a screw driver and some pull corks but there was no way it could replace the sheath knife when a real knife was needed.

Should one need to break a side window on an automobile, simply holding the tip against the glass with a reverse grip and tapping the handle butt with a rock, night stick, black jack or revolver and the glass shatters with precision, just like the spring loaded glass breaker.

In an emergency a back swing works also, thumb over the butt,  be sure and wear gloves because the momentum of your swing can carry your arm into the glass.

I believe that poor quality knives (the kind that can be easily abused) led to the development of gimmicks (glass breakers) to overcome weak tips.

 Thanks to all that have contributed!
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Alan
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« Reply #13 on: January 06, 2008, 05:30:20 PM »

I tend to believe that there is room in any person's knife design for new ways of thinking, new ways of use.

While I have never given much thought to a "glass breaker" I do spend a lot of time out on frozen lakes in my truck as I go icefishing, and I can see the point of designing a knife with such a glass breaker on it.

Once while out on Battle Lake at my brothers the wind was so strong it opened up a 6 foot wide crack that all us guys had to drive a mile around. 
Had it been dark at the time?...nasty!

If I were to actually design a knife that was aimed at the ice fisherman, (like a Fillet with a soft rubber handle) I can see now how a a good strong glass breaker mounted on the butt end would be a smart idea.
 
The trick to designing my own glass breaker would be - "How to test it?"
Im not really sure how I would be able to test different designs against each other without getting ahold of several thousand $ worth of car windshields?

But the concept for designing one is sound.
« Last Edit: January 06, 2008, 05:32:58 PM by Alan » Logged
Harold Locke
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« Reply #14 on: January 06, 2008, 05:55:18 PM »

I wanted to get my 2 cents into this thread before it's completed. For an automotive rescue blade and glass breaker I feel that a a 3" handle with a 2" to 2.5" blade with a razor sharp gut hook with some serrations behind it would do the job best for sliceing seatbelts without injuring the victim with a spring loaded punch in the rear of the handle.

As far as specialty knives go, I have friends out here in CA that know of my intrest in knives and they are looking for custom makers that make heavy duty a horsemans folding knife. They feel it should have a strong hoof pick for cleaning the hoof on the trail, a very strong main blade for cutting off the harness quickly in the event of a snag and wreck. I also have run across some right and left handed hoof knives for nail triming and have wondered if that could be used for the main blade. The horsemen out here are generally of some wealth and want art as well as extreme functionality. This kind of work is beyond my ken but I thought I would get the idea out there. I have found some knives being made like that but they are coming out of china.

Harold Locke
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