- Joined
- Nov 26, 2001
- Messages
- 1,375
Reading most knife magazines, both here in Italy and american ones, I've been disconcerted at the approximation reached by some knife "testing" methods I've seen.
We all know what the so called "scientific method" is: repatability of a process, direct connection between method and results.
I've seen all knds of tests performed on various knives, from splitting a nail in two, to piercing some steel sheet, to cutting various things, from carrots to free hanging manila rope, all followed by the writer's feelings on how a given knife performed.
Mind well: the writer's feelings are important, a sa knife is not something working alone, but a tool which will be heldd by a hand, so how the tool feels in the hand is important, but it's not necessarily an index of the tool performance.
Even more: it gives us no way to confront a given knife with another...
Which is the diameter of the split nail?
Which steel it's made of?
Does all the nails used, even if they are of the same diameter and steel come from the same production run?
How was the knife used to split the nail?
Without all these information, it's impossible to use any of the information gathered by putting the knife under such grievous abuse for anything useful. We just wasted time and spoiled an otherwise perfect knife.
Even a process apparently constant, such as buying 100 nails and using them to test two knives by splitting them putting the blade on the nail and then using a hammer to pound on the blade's spine are indeed extremely erratic and unpredictable.
The hammer could hit the blade at any angle, putting the edge under severe torque, over the obvious stress of cutting a nail.
The blade could very well chip or dent because of this, and we would be convinced that the blade is soft because the edge bent while cutting a simple nail, or too hard because it chipped.
Even cutting a 2" free hanging manila rope may seem a quite objective testing method. It isn't so. The way the edge is ground, the final sharpening grit and, more than anything else, the cutter's skill, will do an enormous difference, so even this method says pretty nothing. It just demonstrates that THAT specific knife, held by THAT specific guy, could cut THAT specific piece of manila rope. Hardly of any use at all. It doesn't say nothing about ay other knife, or how the average knife will perform in the hands of the average person or how it will cut any other material.
So.
What methods we could employ to obtain data from our testing which can be compared with those obtained by other people, testing other knives?
Well, first and foremost the methods must all be the same, otherwise we'll be comparing apples with oranges...
How can we devise testing methods that can satisfy these requirements?
Well, it's fairly simple: forces, materials, angles and such must be as constant as possible.
For example: we could test edge sturdyness by cutting the same wood nail, made of mild iron (so that steel alloy is no more a problem) by cerating a small die which will carry the nail and hold the blade perfectly vertical on it, and letting a constant, given weight fall from a given height on the blade, and seeing how many blows are needed to cut the nail completely, which damage the blade underwent, measuring its depth and width as we do in a Rockwell hardness test, or increase the weight till the blade chops the nail cleanly and noting the various damages done to the edge by the various weights.
This is just an example.
Yes, it requires building a little device.
Yes it can't be done in an impromptu way while playing with your new knife in the backyard, but it gives significant, repeatable, constant results that can serve to give an objective evaluation of the knife and that will allow, over time, to build a valuable database of knife performance.
We all know what the so called "scientific method" is: repatability of a process, direct connection between method and results.
I've seen all knds of tests performed on various knives, from splitting a nail in two, to piercing some steel sheet, to cutting various things, from carrots to free hanging manila rope, all followed by the writer's feelings on how a given knife performed.
Mind well: the writer's feelings are important, a sa knife is not something working alone, but a tool which will be heldd by a hand, so how the tool feels in the hand is important, but it's not necessarily an index of the tool performance.
Even more: it gives us no way to confront a given knife with another...
Which is the diameter of the split nail?
Which steel it's made of?
Does all the nails used, even if they are of the same diameter and steel come from the same production run?
How was the knife used to split the nail?
Without all these information, it's impossible to use any of the information gathered by putting the knife under such grievous abuse for anything useful. We just wasted time and spoiled an otherwise perfect knife.
Even a process apparently constant, such as buying 100 nails and using them to test two knives by splitting them putting the blade on the nail and then using a hammer to pound on the blade's spine are indeed extremely erratic and unpredictable.
The hammer could hit the blade at any angle, putting the edge under severe torque, over the obvious stress of cutting a nail.
The blade could very well chip or dent because of this, and we would be convinced that the blade is soft because the edge bent while cutting a simple nail, or too hard because it chipped.
Even cutting a 2" free hanging manila rope may seem a quite objective testing method. It isn't so. The way the edge is ground, the final sharpening grit and, more than anything else, the cutter's skill, will do an enormous difference, so even this method says pretty nothing. It just demonstrates that THAT specific knife, held by THAT specific guy, could cut THAT specific piece of manila rope. Hardly of any use at all. It doesn't say nothing about ay other knife, or how the average knife will perform in the hands of the average person or how it will cut any other material.
So.
What methods we could employ to obtain data from our testing which can be compared with those obtained by other people, testing other knives?
Well, first and foremost the methods must all be the same, otherwise we'll be comparing apples with oranges...
How can we devise testing methods that can satisfy these requirements?
Well, it's fairly simple: forces, materials, angles and such must be as constant as possible.
For example: we could test edge sturdyness by cutting the same wood nail, made of mild iron (so that steel alloy is no more a problem) by cerating a small die which will carry the nail and hold the blade perfectly vertical on it, and letting a constant, given weight fall from a given height on the blade, and seeing how many blows are needed to cut the nail completely, which damage the blade underwent, measuring its depth and width as we do in a Rockwell hardness test, or increase the weight till the blade chops the nail cleanly and noting the various damages done to the edge by the various weights.
This is just an example.
Yes, it requires building a little device.
Yes it can't be done in an impromptu way while playing with your new knife in the backyard, but it gives significant, repeatable, constant results that can serve to give an objective evaluation of the knife and that will allow, over time, to build a valuable database of knife performance.