JHossom
12-28-2001, 10:48 AM
Here's my take on testing knives...
For starters, a knife is usually designed for a particular set of tasks. If it's a hunter, it needs to gut, skin, split a breastbone, maybe pop a joint out of the socket, and bone out the animal if you have nothing else to use. It might be able to cape, but caping and skinning are often at odds with blade shape requirments. In a pinch it should double as a useable survival knife, which means it might have to cut wood or rope and do some other chores, but it won't be a great survival knife nor will it chop concrete.
In my mind, the best tests are those performed by our customers who use our knives. If a customer tells me he's getting unusually good service from a blade, that's real world testing. If he's a professional hunter, I know that's REAL real world testing. If he tells me he's having trouble with the grip when his hands are bloody, that's real world testing. If he sends back the knife with a broken point or an edge with a chunk out of it and tells me that happened while he was skinning a whitetail, ...well I've stabbed a knife into the ground to clean the blade myself a couple times. Sometimes you get unlucky and hit a rock, and most hunting knives don't handle rocks well. If he tell's me the edge chipped while he was using it to quarter an elk, driving the edge through the spine with a log, I'll replace the knife and hope he buys a better tool for that chore before his next hunt. There is a point at which any edge will break and it's the knifemaker's responsibility to decide where he's willing to let that happen for the sake of better performance in the majority of a knife's tasks. Obviously you can build a knife that will never break under any conditions, but it probably won't be any fun to use or carry.
Some months ago on another forum, Rob commented that a few hundred happy customers can't be wrong, and he's right. It's arrogant to think otherwise, though Rob was blasted with a barrage of such arrogance for suggesting that customer feedback was THE critical test of a knife. (That's one reason we are here on this forum, where discussions are civil and productive.)
I have my fighters tested by the best knife fighter I know, and he's free to do anything he wants to those blades based on what he thinks are representative stresses a fighting blade might encounter. Fighters are high stress knives and are expected to deal with almost any impact, including the edge of an opponent's blade at high speed. With a fighter, catastrophic failure can mean death. A broken blade or even a broken point means you are weaponless. It's just like running out of bullets, and the knifemaker is obligated to ensure that never happens. Lots of folks build fighters, or knives that are called fighters, but a fighter has to be more than just something sleek and pointy. Even if there is just one chance in a thousand it might ever be used in a real fight, a fighter must be able to perform or it should never be called a "fighter". In my mind as a knifemaker, when you label a knife as a hunter, a fighter or a camp knife you are certifying that knife is fully capable of performing those tasks expected of such a knife. If it's just a toy, a pretend "fighter", call it something else. If you call it a fighter, test it or better still have someone who can really use a fighter test it under conditions that are fully representative of a knife fight, and expect the knife to be destroyed or at least badly dinged. And remember, in a fighter the blade is just one important feature, the handle and the knife's overall maneuverability are equally important. If you're not a trained martial artist, you have no way of accurately assessing these qualities. Once more, user feedback is often the best test.
But fighters are not combat knives; they need speed, balance and impact resistance, but don't have to deal with playing Mumblypeg in the desert or opening ammo crates. That's another set of demands and testing parameters. Combat knives are just maybe the most demanding knife designs you might encounter, and the testing needs are unique. Maybe one combat knife in a hundred will ever be used to kill. Most will be used to open crates, cut rope or open boxes, dig storage alcoves in the sides of foxholes, probe for land mines or serve as a piton while scaling a cliff. They'll be asked to cut or chop wood, rope, sheet metal, and other things we can't even think of. Short of sending a hundred or so blades into combat, the only way I know to test combat knives is to abuse them in everyway imaginable and see what it takes to break one. How much force does it take to break off the front inch or so of the blade? How much force does it take to break the blade in the middle? If you can do that without some additional leverage, like an extension pipe, the knife is probably not strong enough. It might well be necessary for the knife edge to be driven though some very thick and maybe very tough materials, so hammering the edge through some nails can be a useful test. While chopping on something, the blade might hit a rock or something else real hard; what will happen? Obviously if you hit something very hard with enough force, you will break something, usually the knife. What is the failure mode in that event? Will the blade simply chip along the edge, or will you blow a big chunk out of it. One is acceptable failure; one is not. A test I use for this is to drive a 10d nail into a board, bend it to 45 degrees, then chop straight down on it so you subject the edge to serious lateral stresses. You need to hit the nail in the lower 30-40% of its length. I've had blades do everything from bounce off (fortunately that hasn't happened again), to cutting through the nail like it wasn't there with just a tiny deformation in the shaving sharp edge to show for its troubles, to some small chips, to popping out chunks of an edge that was too fine for the steel used.
At the blade show this year, I was asked what would happen to my handle if it was dipped in aviation fuel. At the time, I thought that was a pretty bizarre question, though it was asked by a guy who had been there and done that, so it needed to be considered. Think about this, you are on a raid and need to punch some holes in some fuel tanks to start a fire. Does the knife fall apart if you do that. How can you know if you don't dip a handle in gasoline and find out? (BTW, Micarta doesn't do well in that test, but I personally like it better than G-10 for other reasons so I continue to use it.)
There are also tests of reason that apply to combat knives. Many units have a 7" restriction on blade length, so building an 8" combat knife is probably better suited to Hollywood than Tora Bora. There is the inevitable trade-off between strength and weight. Remember, someone has to haul this hunk of steel 24/7, and a few extra ounces can be a drag after awhile. The handle has to work well with or without gloves, when wet, when bloody, and even when the hand holding it doesn't work too well like in extreme cold. The knife is not going to get a daily oiling; in fact it might never get oiled unless it's lucky enough to get wiped down with a dirty bore patch. So it's going to rust, maybe a little, maybe a lot. Which will depend on the steel you use, and there you are with a tradeoff between strength and stainless, which takes you back to how the knife is designed to begin with. Whatever steel you use, the knife has to deal with both it's strengths and weaknesses. And the finish is important. Obviously mirrors are not a great idea when you're trying to be sneaky, so the finish shouldn't reflect sunlight. All of these things are tests of reason, and don't need much testing beyond reasonable thought.
OK, this is long enough for starters. Let's hear some other ideas.....
For starters, a knife is usually designed for a particular set of tasks. If it's a hunter, it needs to gut, skin, split a breastbone, maybe pop a joint out of the socket, and bone out the animal if you have nothing else to use. It might be able to cape, but caping and skinning are often at odds with blade shape requirments. In a pinch it should double as a useable survival knife, which means it might have to cut wood or rope and do some other chores, but it won't be a great survival knife nor will it chop concrete.
In my mind, the best tests are those performed by our customers who use our knives. If a customer tells me he's getting unusually good service from a blade, that's real world testing. If he's a professional hunter, I know that's REAL real world testing. If he tells me he's having trouble with the grip when his hands are bloody, that's real world testing. If he sends back the knife with a broken point or an edge with a chunk out of it and tells me that happened while he was skinning a whitetail, ...well I've stabbed a knife into the ground to clean the blade myself a couple times. Sometimes you get unlucky and hit a rock, and most hunting knives don't handle rocks well. If he tell's me the edge chipped while he was using it to quarter an elk, driving the edge through the spine with a log, I'll replace the knife and hope he buys a better tool for that chore before his next hunt. There is a point at which any edge will break and it's the knifemaker's responsibility to decide where he's willing to let that happen for the sake of better performance in the majority of a knife's tasks. Obviously you can build a knife that will never break under any conditions, but it probably won't be any fun to use or carry.
Some months ago on another forum, Rob commented that a few hundred happy customers can't be wrong, and he's right. It's arrogant to think otherwise, though Rob was blasted with a barrage of such arrogance for suggesting that customer feedback was THE critical test of a knife. (That's one reason we are here on this forum, where discussions are civil and productive.)
I have my fighters tested by the best knife fighter I know, and he's free to do anything he wants to those blades based on what he thinks are representative stresses a fighting blade might encounter. Fighters are high stress knives and are expected to deal with almost any impact, including the edge of an opponent's blade at high speed. With a fighter, catastrophic failure can mean death. A broken blade or even a broken point means you are weaponless. It's just like running out of bullets, and the knifemaker is obligated to ensure that never happens. Lots of folks build fighters, or knives that are called fighters, but a fighter has to be more than just something sleek and pointy. Even if there is just one chance in a thousand it might ever be used in a real fight, a fighter must be able to perform or it should never be called a "fighter". In my mind as a knifemaker, when you label a knife as a hunter, a fighter or a camp knife you are certifying that knife is fully capable of performing those tasks expected of such a knife. If it's just a toy, a pretend "fighter", call it something else. If you call it a fighter, test it or better still have someone who can really use a fighter test it under conditions that are fully representative of a knife fight, and expect the knife to be destroyed or at least badly dinged. And remember, in a fighter the blade is just one important feature, the handle and the knife's overall maneuverability are equally important. If you're not a trained martial artist, you have no way of accurately assessing these qualities. Once more, user feedback is often the best test.
But fighters are not combat knives; they need speed, balance and impact resistance, but don't have to deal with playing Mumblypeg in the desert or opening ammo crates. That's another set of demands and testing parameters. Combat knives are just maybe the most demanding knife designs you might encounter, and the testing needs are unique. Maybe one combat knife in a hundred will ever be used to kill. Most will be used to open crates, cut rope or open boxes, dig storage alcoves in the sides of foxholes, probe for land mines or serve as a piton while scaling a cliff. They'll be asked to cut or chop wood, rope, sheet metal, and other things we can't even think of. Short of sending a hundred or so blades into combat, the only way I know to test combat knives is to abuse them in everyway imaginable and see what it takes to break one. How much force does it take to break off the front inch or so of the blade? How much force does it take to break the blade in the middle? If you can do that without some additional leverage, like an extension pipe, the knife is probably not strong enough. It might well be necessary for the knife edge to be driven though some very thick and maybe very tough materials, so hammering the edge through some nails can be a useful test. While chopping on something, the blade might hit a rock or something else real hard; what will happen? Obviously if you hit something very hard with enough force, you will break something, usually the knife. What is the failure mode in that event? Will the blade simply chip along the edge, or will you blow a big chunk out of it. One is acceptable failure; one is not. A test I use for this is to drive a 10d nail into a board, bend it to 45 degrees, then chop straight down on it so you subject the edge to serious lateral stresses. You need to hit the nail in the lower 30-40% of its length. I've had blades do everything from bounce off (fortunately that hasn't happened again), to cutting through the nail like it wasn't there with just a tiny deformation in the shaving sharp edge to show for its troubles, to some small chips, to popping out chunks of an edge that was too fine for the steel used.
At the blade show this year, I was asked what would happen to my handle if it was dipped in aviation fuel. At the time, I thought that was a pretty bizarre question, though it was asked by a guy who had been there and done that, so it needed to be considered. Think about this, you are on a raid and need to punch some holes in some fuel tanks to start a fire. Does the knife fall apart if you do that. How can you know if you don't dip a handle in gasoline and find out? (BTW, Micarta doesn't do well in that test, but I personally like it better than G-10 for other reasons so I continue to use it.)
There are also tests of reason that apply to combat knives. Many units have a 7" restriction on blade length, so building an 8" combat knife is probably better suited to Hollywood than Tora Bora. There is the inevitable trade-off between strength and weight. Remember, someone has to haul this hunk of steel 24/7, and a few extra ounces can be a drag after awhile. The handle has to work well with or without gloves, when wet, when bloody, and even when the hand holding it doesn't work too well like in extreme cold. The knife is not going to get a daily oiling; in fact it might never get oiled unless it's lucky enough to get wiped down with a dirty bore patch. So it's going to rust, maybe a little, maybe a lot. Which will depend on the steel you use, and there you are with a tradeoff between strength and stainless, which takes you back to how the knife is designed to begin with. Whatever steel you use, the knife has to deal with both it's strengths and weaknesses. And the finish is important. Obviously mirrors are not a great idea when you're trying to be sneaky, so the finish shouldn't reflect sunlight. All of these things are tests of reason, and don't need much testing beyond reasonable thought.
OK, this is long enough for starters. Let's hear some other ideas.....