So i decided that when my blades come out of the temper oven i drop them point down on concrete slab from 6 feet high. So far i havent had any tips break or crack. i have put some decent holes in the concrete though. I have read often that people can overheat the tip and they snap off during use. Most of the knives i have been doing this to measure .015 at the tip. Is this a viable testing method to ensuring the tip didnt get overheated in the heat treatment. also list some of your testing methods. i figure if the tip break the knife was of poor quality and needs redone anyways. thanks
-
The BladeForums.com 2024 Traditional Knife is ready to order! See this thread for details: https://www.bladeforums.com/threads/bladeforums-2024-traditional-knife.2003187/
Price is $300 ea (shipped within CONUS). If you live outside the US, I will contact you after your order for extra shipping charges.
Order here: https://www.bladeforums.com/help/2024-traditional/ - Order as many as you like, we have plenty.
knife toughness durability tests
- Thread starter Dakota 11
- Start date
- Joined
- Jul 23, 1999
- Messages
- 1,409
I suppose that if dropping your blades on the concrete is something you want to do......but I don't think its very viable, simply because its rather unrealistic.
If anyone ever came to me with a damaged knife and told me they had intentionally dropped it that way, I would tell them that they are on their own.
I personally think that all of the "testing" you see and/or hear about, like stabbing a car hood, slashing a 55 gallon drum, or bashing a concrete block, is about like trying ice skating uphill....its counter productive to common sense, and pretty ridiculous.
A knife is a cutting tool....its not a prybar, its not a screwdriver, nor is it a can opener. The primary function of a knife is to cut, hold the edge reasonably well, be easy to resharpen for the owner (this is something that many knifemakers seem to miss), and withstand the "abuses" that it encounters while being used for its intended function.
OK, now that my rant it over, I do think its important to test the blades that you make, but it is also important to test them in a realistic manner.
Dropping a blade, point down, on the concrete isn't something that a blade would normally encounter during use...and if someone where to do it intentionally, that constitutes abuse in my opinion. I've handled and tested my fair share of blades that boasted of their ability to cut through a car hood or smash a concrete block, and without exception, none of them were even close to being what I would consider an acceptable cutting implements. In order to endure/survive that type of abuse, the edges are super obtuse, the blades overly thick and heavy, and the grinds utilized are often counter productive to a cutting tool.
What do I do? I brass rod test edges, cut test blades on real world materials like hemp rope, cardboard, or wood, (and other things that are generally considered as materials a knife would be expected to cut). Also, to this day, after 20+ years of Bladesmithing, I still take every 10th or 12th blade and destructive test it as a quality control measure.
Testing your blades, using measureable standards that are common in the knife's use, will help you much more than trying to follow those "hype standards" that are generally useless in the real world.
If anyone ever came to me with a damaged knife and told me they had intentionally dropped it that way, I would tell them that they are on their own.
I personally think that all of the "testing" you see and/or hear about, like stabbing a car hood, slashing a 55 gallon drum, or bashing a concrete block, is about like trying ice skating uphill....its counter productive to common sense, and pretty ridiculous.
A knife is a cutting tool....its not a prybar, its not a screwdriver, nor is it a can opener. The primary function of a knife is to cut, hold the edge reasonably well, be easy to resharpen for the owner (this is something that many knifemakers seem to miss), and withstand the "abuses" that it encounters while being used for its intended function.
OK, now that my rant it over, I do think its important to test the blades that you make, but it is also important to test them in a realistic manner.
Dropping a blade, point down, on the concrete isn't something that a blade would normally encounter during use...and if someone where to do it intentionally, that constitutes abuse in my opinion. I've handled and tested my fair share of blades that boasted of their ability to cut through a car hood or smash a concrete block, and without exception, none of them were even close to being what I would consider an acceptable cutting implements. In order to endure/survive that type of abuse, the edges are super obtuse, the blades overly thick and heavy, and the grinds utilized are often counter productive to a cutting tool.
What do I do? I brass rod test edges, cut test blades on real world materials like hemp rope, cardboard, or wood, (and other things that are generally considered as materials a knife would be expected to cut). Also, to this day, after 20+ years of Bladesmithing, I still take every 10th or 12th blade and destructive test it as a quality control measure.
Testing your blades, using measureable standards that are common in the knife's use, will help you much more than trying to follow those "hype standards" that are generally useless in the real world.
- Joined
- May 18, 2005
- Messages
- 230
What he said /\
I have nothing near Ed's experience as a maker, but to me a knife just has to be able to perform as a knife to be conidered wothwhile. It's not a prybar, screwdriver or a cold chisel, it's a knife.
I test my day-to-day blades with the sort of tasks that they'll be expected to do 'in service'. If I can dress out a deer, whittle wood for an hour, cut a few 1" ropes and baton the blade through some chunks of firwood to split it THEN shave the hair off my arm, I reckon it'll do OK in the real world of knife use.
Can't remember the last time I had to stab a car or hack my way through a cinderblock wall with my knife....
I have nothing near Ed's experience as a maker, but to me a knife just has to be able to perform as a knife to be conidered wothwhile. It's not a prybar, screwdriver or a cold chisel, it's a knife.
I test my day-to-day blades with the sort of tasks that they'll be expected to do 'in service'. If I can dress out a deer, whittle wood for an hour, cut a few 1" ropes and baton the blade through some chunks of firwood to split it THEN shave the hair off my arm, I reckon it'll do OK in the real world of knife use.
Can't remember the last time I had to stab a car or hack my way through a cinderblock wall with my knife....
In 50 plus years of knife use I have broken one knife by dropping it. I can't begin to tell how many knives I have dropped over those same years. The biggest real life problem you have when you drop a knife is finding it.
Ed Caffrey
That has to be one of the most refreshing posts I have read in a long time! Thanks Ed.
Ed Caffrey
That has to be one of the most refreshing posts I have read in a long time! Thanks Ed.
- Joined
- Dec 25, 2004
- Messages
- 1,363
What's said above :thumbup:.
Most of the time I make kitchen knives, they need to have very thin geometry, on the weak side... I wouldn't accept any return if someone dropped them on concrete. Even some knives are so thin ground that a hit on a glass or another steel object would damage them. I test my chef's knives by chopping tree branches and cutting brass etc. They are and should be able to hold their shaving sharp edge. But when it comes to hitting the edge harder or same hardness material they are not supposed to withstand this kind of abuse. All depends on what the knife is intended to do. A hollow ground straight razor wouldnt take any abuse at all but a thick survival knife should be able to take some abuse as it is intended to be. It is all about the geometry and the type of that blade...
Most of the time I make kitchen knives, they need to have very thin geometry, on the weak side... I wouldn't accept any return if someone dropped them on concrete. Even some knives are so thin ground that a hit on a glass or another steel object would damage them. I test my chef's knives by chopping tree branches and cutting brass etc. They are and should be able to hold their shaving sharp edge. But when it comes to hitting the edge harder or same hardness material they are not supposed to withstand this kind of abuse. All depends on what the knife is intended to do. A hollow ground straight razor wouldnt take any abuse at all but a thick survival knife should be able to take some abuse as it is intended to be. It is all about the geometry and the type of that blade...
- Joined
- Sep 9, 2003
- Messages
- 2,361
A knifemaker owes it to himself and his customers to know what a blade can handle before sending it along and thus as the manufacturer of an item has a different level of testing freedom than that of the customer. The knifemaker doesn't have to worry about not getting the knife replaced after doing something stupid to it. GM (it is up to you to decide what the "G" stands for anymore) intentionally crashes cars into cement walls all the time to see how they are doing, what mental midget would then deduce that they could intentionally crash their new car into a concrete wall and expect GM to fix it??!! Yet as knifemakers we have to worry about customers mimicking our destructive testing and expecting a new knife
For the most part we have ourselves to blame for this situation and this is where my old saying applies entirely- If you do things to find out what could be wrong with your product or process and how to improve, that is called testing. If you do things just to make your stuff look good for the public, that is called marketing P.R. ...and too often hype, and the makers reap what they sow from that shameless pandering, but unfortunately so do we all. I have a couple of troublesome would be customers who are always going on about one particular hypemeister that they read too much about and want me to make blades around that ridiculous standard, without hesitation I have told them that I am particularly proud of the fact that my blades may not pass any of that garbage held up as "testing", you see I make knives.
So as for the really stupid testing that is so often broadcasted as loud and tall as possible for the sole purpose of making sales I couldn't agree more with Ed and his observations of the "blades" designed to do all of these non-knife things. My testing regimen is not a regular part of my public dialog, I know what my blades can do and am confident in that, I would ask if the guys who need public dog and pony show displays of what their knives can withstand may be compensating for something. It wasn't until I had a chance to discuss it on this forum recently that I mentioned that I have used the point drop method of checking my blades, so you can see how much I use it as a sales gimmick.
In defense of the point drop test , while is does not produce any quantifiable numbers or standardized results, neither do virtually any of the tests most smiths use- cutting rope, flexing on a brass rod, chopping boards, shaving arm hair etc..., it does in my opinion correlate strongly to real knife use much more that many other checks. How many of us have dropped a knife? How many of us have dropped blades on our shop floor before we even have them finished ( gosh, I guess that has never happened to any of us
)? What is the weakest area of cross section on the blade? Thus what area is a like a lightening rod when the blade is dropped? How many of us have had careless users present us with a factory made knife or a blade they got from dad that was missing a tip? I personally have reground the tip on countless factory made knives that people came to me to fix after they decided to throw them, play mumblety peg, stab it into a wood slab instead of just laying it down like any other tool, or my personal favorite, use on a philips screw
. We are conditioned by our society to abuse the tip on a knife in many impact type ways, but even if we treat that knife like our child, one day we ARE going to drop it, and Murphy's law will not allow any other part of that knife but the tip to impact first!
Now that the case can be made that it does approximate real world conditions, I would also like to make the case that it is not all that extreme. In fact I don't do it hardly that much anymore, except when demonstrating marquenching techniques, because when you get the heat treat down, it is just sort of a given that a bare blade will pass this elementary test. The concrete is the weakest link in the test, it has incredibly low impact strength compared to steel and thus takes on most of the burden (another good reason not to do it so much is all the damage to your concrete), I have also replaced the concrete with 1/2" steel plate. A far more extreme test of the tip, yet most makers think it is just fine, is to bury the tip into hardwood and snap the blade sideways to remove a divot of wood- once again, you will at one time drop that knife but you will have to consciously abuse that knife to duplicate burying the tip in wood and snapping sideways.
Now of course any of these tests are destructive in nature (as they are designed to find the breaking point), and thus are the domain of the maker alone in order to insure that anything that may happen by accident in the hands of the user will not result in disaster. Users who intentionally destructively abuse any knife need to be educated or eventually face the consequences of moronic behavior with the losses that accompany it.
For the most part we have ourselves to blame for this situation and this is where my old saying applies entirely- If you do things to find out what could be wrong with your product or process and how to improve, that is called testing. If you do things just to make your stuff look good for the public, that is called marketing P.R. ...and too often hype, and the makers reap what they sow from that shameless pandering, but unfortunately so do we all. I have a couple of troublesome would be customers who are always going on about one particular hypemeister that they read too much about and want me to make blades around that ridiculous standard, without hesitation I have told them that I am particularly proud of the fact that my blades may not pass any of that garbage held up as "testing", you see I make knives.
So as for the really stupid testing that is so often broadcasted as loud and tall as possible for the sole purpose of making sales I couldn't agree more with Ed and his observations of the "blades" designed to do all of these non-knife things. My testing regimen is not a regular part of my public dialog, I know what my blades can do and am confident in that, I would ask if the guys who need public dog and pony show displays of what their knives can withstand may be compensating for something. It wasn't until I had a chance to discuss it on this forum recently that I mentioned that I have used the point drop method of checking my blades, so you can see how much I use it as a sales gimmick.
In defense of the point drop test , while is does not produce any quantifiable numbers or standardized results, neither do virtually any of the tests most smiths use- cutting rope, flexing on a brass rod, chopping boards, shaving arm hair etc..., it does in my opinion correlate strongly to real knife use much more that many other checks. How many of us have dropped a knife? How many of us have dropped blades on our shop floor before we even have them finished ( gosh, I guess that has never happened to any of us
)? What is the weakest area of cross section on the blade? Thus what area is a like a lightening rod when the blade is dropped? How many of us have had careless users present us with a factory made knife or a blade they got from dad that was missing a tip? I personally have reground the tip on countless factory made knives that people came to me to fix after they decided to throw them, play mumblety peg, stab it into a wood slab instead of just laying it down like any other tool, or my personal favorite, use on a philips screw. We are conditioned by our society to abuse the tip on a knife in many impact type ways, but even if we treat that knife like our child, one day we ARE going to drop it, and Murphy's law will not allow any other part of that knife but the tip to impact first! Now that the case can be made that it does approximate real world conditions, I would also like to make the case that it is not all that extreme. In fact I don't do it hardly that much anymore, except when demonstrating marquenching techniques, because when you get the heat treat down, it is just sort of a given that a bare blade will pass this elementary test. The concrete is the weakest link in the test, it has incredibly low impact strength compared to steel and thus takes on most of the burden (another good reason not to do it so much is all the damage to your concrete), I have also replaced the concrete with 1/2" steel plate. A far more extreme test of the tip, yet most makers think it is just fine, is to bury the tip into hardwood and snap the blade sideways to remove a divot of wood- once again, you will at one time drop that knife but you will have to consciously abuse that knife to duplicate burying the tip in wood and snapping sideways.
Now of course any of these tests are destructive in nature (as they are designed to find the breaking point), and thus are the domain of the maker alone in order to insure that anything that may happen by accident in the hands of the user will not result in disaster. Users who intentionally destructively abuse any knife need to be educated or eventually face the consequences of moronic behavior with the losses that accompany it.
Last edited:
- Joined
- Jun 23, 2006
- Messages
- 2,413
I don't think it's unreasonable to expect a using knife to be dropping on concrete or asphalt, tip first. I've done it many times on accident working in the shop. When folks use knives every day, stuff like that happens. If someone came to me and said "I tried to break your knife and it worked" I would have trouble warrantying the break, but if they came to me and said "I was working on a ladder and the knife fell 6' down to the pavement and broke in half" I'd replace it.
- Joined
- Apr 16, 2003
- Messages
- 501
its funny but you see alot of extreme type testing.... what is a real world realistic type test..?
for myself if an outdoor knife cutts/chops through 2 nice size blocks of very dry hard wood and test the tip in it so that it doesn't bend or break in a stab..... if it maintains the edge, that outta do ..
what will a knife be cutting a majority of the time... wood, wood products, flesh ( animal ), etc.... and what is the rockwell hardness of that ? must be pretty hard as a couple of people i know need a knife with high 60's to cut stuff
chopping a 1/4inch soft iron rod is a neat test but jeez... when does that ever happen in real life... if i had to do it, i just reach in the tool box for a cold chisel rather than my edc ... wouldn't it make sense
i was asked to make a sword ... they asked me will it cut chainmail... .. test it out... .... actually i knew the answer.... no.. i've made some chainmail in the past and strapped it to a fence post.... then chopped into it full bore with a long handled hatchet... and the most that would happen is cut one ring and basically kept driving the chain into the wood and it kept coming out in decent shape..... ( butted mail ) if a hachette won't do it, then how in the world while a sword do it with a much longer cutting edge and way lighter blade..... .. i think they were a little disappointed when i told them that swords are made to cut fabric and flesh...
maybe its a good thing that hollywood and comic books have raised the bar...makes people push the product abit more?
for myself if an outdoor knife cutts/chops through 2 nice size blocks of very dry hard wood and test the tip in it so that it doesn't bend or break in a stab..... if it maintains the edge, that outta do ..
what will a knife be cutting a majority of the time... wood, wood products, flesh ( animal ), etc.... and what is the rockwell hardness of that ? must be pretty hard as a couple of people i know need a knife with high 60's to cut stuff
chopping a 1/4inch soft iron rod is a neat test but jeez... when does that ever happen in real life... if i had to do it, i just reach in the tool box for a cold chisel rather than my edc ... wouldn't it make sense
i was asked to make a sword ... they asked me will it cut chainmail... .. test it out... .... actually i knew the answer.... no.. i've made some chainmail in the past and strapped it to a fence post.... then chopped into it full bore with a long handled hatchet... and the most that would happen is cut one ring and basically kept driving the chain into the wood and it kept coming out in decent shape..... ( butted mail ) if a hachette won't do it, then how in the world while a sword do it with a much longer cutting edge and way lighter blade..... .. i think they were a little disappointed when i told them that swords are made to cut fabric and flesh...
maybe its a good thing that hollywood and comic books have raised the bar...makes people push the product abit more?
- Joined
- Sep 9, 2003
- Messages
- 2,361
As knifemakers we go on an awful lot about quantifiable standards for our knives and yet rarely examine that concept in enough depth to keep it from being one of the largest stumbling blocks in our business.
As tools knives are rather open to subjective evaluation since everybody will use them a little differently. No two people will have the same definition of sharp, and a hunter will be using a blade very differently than a fisherman or chef. Thus I believe we can never eliminate general knife testing that give no hard quantifiable numbers and standards. We will always need to evaluate how the knife feels overall, or how it will perform in a number of different hands and varying situations. So I use very specific tests to evaluate my process and materials, and then more general human based tests to evaluate the knife as a whole. Neither can stand alone. To believe that one test can tell it all is not only unrealistic, it is naïve.
But in exploring those two realms the contrasts between the two have made it clear to me how confused we are about what is truly quantifiable and what is subjective. The slightest introduction of just one or two variables in a test will instantly shift it from quantifiable to highly subjective, and the VAST majority of testing done by knifemakers falls into the later category despite all of the claims to the contrary.
Standardized, objective tests tend to work with absolutes. After all how do you provide concrete numbers on something if you have all kinds of middle ground or shades of included? Lets take the above point drop test for example. This is highly subjective, after all what is it we are measuring? We can say the tip or the steel, but there is another material involved- the concrete. A real quantifiable test of the tip would involve a drop from a set distance for the total mass of the blade into a totally immovable surface, e.g. hardened steel, so that it would not be a matter of whether the tip would be damaged, but a simple measure of the level of damage that would invariably occur. But of course as soon as any of the dimensions of the next tip varied in the slightest the numbers would be meaningless.
Rope cutting is one of my personal pet peeves due to how easily and widely accepted it is as standardized or quantifiable in any way. The slightest deviation in pressure, speed, angle of attack, etc from one cut to the next make any qualitative assumption based upon number of cuts patently absurd. The blade materials itself can be manipulated in such a way to produce deceptively impressive results for this specific test yet rather disappointing on a wider array of applications. This one should be easy to spot as subjective, yet I am disappointed how many really sharp people see it as a measurable standard.
We have discussed ad nauseum here about how unrealistic any maker is in thinking that flexing the blade or any portion of it is at all a quantifiable test of heat treat or useful hardness, when cross section is the far great factor being measured and no uniform standard of exact pressure applied/thickness is considered. Tugging on blades in a vice is more a Rorschach test of the tugger than anything in the blade if you are looking to generate any numbers on a specific property. And attempting to glean such using props like torque wrenches, while they at least measure something only give you what a calculator and the blade dimensions could have were it fully hardened or fully annealed.
These and so many others while quite valid (well, some are) in assessing the subjective qualities we look for in a knife or its performance are not standardized tests capable of measuring properties in any truly objective or comparable way. When industry had to set minimum standards by which things could be made to perform in a consistent and reliable way they developed very exacting tests to do so. Unfortunately most knifemakers do not have the resources, or even access to the resources, to gather that type of specific data. So instead we have had to rely on our more subjective approaches, which is fine until we come to believe that it is more than it is.
One standardized test actually capable of giving solid numbers that many makers have access to is hardness Rockwell. Yet have too much oil on the elevator screw, irregularities in the sample surface, or even grit on the anvil platform and your numbers are voided by variables. As touchy as this sounds the Rockwell hardness test is so common because of how well it can overcome human error and the variables it can introduce, and yet it is often dismissed due to the unfortunate frequency with which it has been presented as the entire picture instead of just one valuable piece to a much larger puzzle.
One can gather Rockwell and Charpy impact numbers on their steel at every step of the process, have detailed chemistry and images of the microstructure along with data on abrasion resistance and still not be able to tell you squat on how the final knife will cut, handle or perform in the hand. And we see everyday the tragic confusion that occurs when knifemakers assume they can quantify specific material properties by tests of subjective general use (realistic or not).
If it were just a wrench we could measure the tensile strength and overall hardness and call it good. But the knife is one of mankinds most personalized tools, thus we can never eliminate subjective general testing for the indefinable qualities we look for and how each human hand will use it. But specific properties most often cannot be reliably measured by such means and many problems arise in thinking otherwise.
As tools knives are rather open to subjective evaluation since everybody will use them a little differently. No two people will have the same definition of sharp, and a hunter will be using a blade very differently than a fisherman or chef. Thus I believe we can never eliminate general knife testing that give no hard quantifiable numbers and standards. We will always need to evaluate how the knife feels overall, or how it will perform in a number of different hands and varying situations. So I use very specific tests to evaluate my process and materials, and then more general human based tests to evaluate the knife as a whole. Neither can stand alone. To believe that one test can tell it all is not only unrealistic, it is naïve.
But in exploring those two realms the contrasts between the two have made it clear to me how confused we are about what is truly quantifiable and what is subjective. The slightest introduction of just one or two variables in a test will instantly shift it from quantifiable to highly subjective, and the VAST majority of testing done by knifemakers falls into the later category despite all of the claims to the contrary.
Standardized, objective tests tend to work with absolutes. After all how do you provide concrete numbers on something if you have all kinds of middle ground or shades of included? Lets take the above point drop test for example. This is highly subjective, after all what is it we are measuring? We can say the tip or the steel, but there is another material involved- the concrete. A real quantifiable test of the tip would involve a drop from a set distance for the total mass of the blade into a totally immovable surface, e.g. hardened steel, so that it would not be a matter of whether the tip would be damaged, but a simple measure of the level of damage that would invariably occur. But of course as soon as any of the dimensions of the next tip varied in the slightest the numbers would be meaningless.
Rope cutting is one of my personal pet peeves due to how easily and widely accepted it is as standardized or quantifiable in any way. The slightest deviation in pressure, speed, angle of attack, etc from one cut to the next make any qualitative assumption based upon number of cuts patently absurd. The blade materials itself can be manipulated in such a way to produce deceptively impressive results for this specific test yet rather disappointing on a wider array of applications. This one should be easy to spot as subjective, yet I am disappointed how many really sharp people see it as a measurable standard.
We have discussed ad nauseum here about how unrealistic any maker is in thinking that flexing the blade or any portion of it is at all a quantifiable test of heat treat or useful hardness, when cross section is the far great factor being measured and no uniform standard of exact pressure applied/thickness is considered. Tugging on blades in a vice is more a Rorschach test of the tugger than anything in the blade if you are looking to generate any numbers on a specific property. And attempting to glean such using props like torque wrenches, while they at least measure something only give you what a calculator and the blade dimensions could have were it fully hardened or fully annealed.
These and so many others while quite valid (well, some are) in assessing the subjective qualities we look for in a knife or its performance are not standardized tests capable of measuring properties in any truly objective or comparable way. When industry had to set minimum standards by which things could be made to perform in a consistent and reliable way they developed very exacting tests to do so. Unfortunately most knifemakers do not have the resources, or even access to the resources, to gather that type of specific data. So instead we have had to rely on our more subjective approaches, which is fine until we come to believe that it is more than it is.
One standardized test actually capable of giving solid numbers that many makers have access to is hardness Rockwell. Yet have too much oil on the elevator screw, irregularities in the sample surface, or even grit on the anvil platform and your numbers are voided by variables. As touchy as this sounds the Rockwell hardness test is so common because of how well it can overcome human error and the variables it can introduce, and yet it is often dismissed due to the unfortunate frequency with which it has been presented as the entire picture instead of just one valuable piece to a much larger puzzle.
One can gather Rockwell and Charpy impact numbers on their steel at every step of the process, have detailed chemistry and images of the microstructure along with data on abrasion resistance and still not be able to tell you squat on how the final knife will cut, handle or perform in the hand. And we see everyday the tragic confusion that occurs when knifemakers assume they can quantify specific material properties by tests of subjective general use (realistic or not).
If it were just a wrench we could measure the tensile strength and overall hardness and call it good. But the knife is one of mankinds most personalized tools, thus we can never eliminate subjective general testing for the indefinable qualities we look for and how each human hand will use it. But specific properties most often cannot be reliably measured by such means and many problems arise in thinking otherwise.
- Joined
- Dec 13, 2006
- Messages
- 2,415
I cut some paper, some rope and if I dont like the knife it becomes a test piece. I will try to drill though a 2x4 to test the tip, and bend until it breaks to test the HT. I probable screw up more than every 10-12 blades so I get opportunities to test.
As a maker I think destructive testing is important to see the limit of what your blades can do, but, really do not reflect how well a knife is made. There are so many other important factors which will be part of every days such as blade shape and geometry that are more important than being able to open a 55 gallon drum.
I did not read all of kevins post prior to mine, I would like to address the rope cutting issue. Although there are alot of variables I feel I do get some good information on how well by blades are performing. Many times making the same knife serveral times you get a feel for the knife and what its capable of. Since they are all handmade they are subject to significant differences, cutting tests are one way to recognize these differences and determine if adjustments are needed.
The tests also allow me to set goal for a new blade, if its a chopper I expect it to chop at least as well as my other choppers. Same with a slicer, I need to cut some paper and rope to see how it compares to my other knifes. I do keep some for myself and have kept one of the best drop point slicers that I have made and I will cut some rope with those at the same time to compare.
I have also purchased some knives to compare to commercial products.
Not all testing must be absolute, we make tests every day and form opinoins on how products perform based on our experience. You dont need a QA/QC plan with set goals and determinations to determine if you like Starbucks more than Dunkin Donuts.
As a maker I think destructive testing is important to see the limit of what your blades can do, but, really do not reflect how well a knife is made. There are so many other important factors which will be part of every days such as blade shape and geometry that are more important than being able to open a 55 gallon drum.
I did not read all of kevins post prior to mine, I would like to address the rope cutting issue. Although there are alot of variables I feel I do get some good information on how well by blades are performing. Many times making the same knife serveral times you get a feel for the knife and what its capable of. Since they are all handmade they are subject to significant differences, cutting tests are one way to recognize these differences and determine if adjustments are needed.
The tests also allow me to set goal for a new blade, if its a chopper I expect it to chop at least as well as my other choppers. Same with a slicer, I need to cut some paper and rope to see how it compares to my other knifes. I do keep some for myself and have kept one of the best drop point slicers that I have made and I will cut some rope with those at the same time to compare.
I have also purchased some knives to compare to commercial products.
Not all testing must be absolute, we make tests every day and form opinoins on how products perform based on our experience. You dont need a QA/QC plan with set goals and determinations to determine if you like Starbucks more than Dunkin Donuts.
Last edited:
- Joined
- May 4, 2009
- Messages
- 1,036
Quality is the foundation of the custom knifemaker/bladesmith. I work in a tool and die shop, and I am fortunate to have full use of a rockwell tester that is calibrated and certified every 3 months. So if I tell a customer his blade is 58 Rc. then you can bet the farm it is 58 Rc. This also let's me know if my oven needs adjusting. It breaks my heart to see a maker slide a file across a blade and say " Yeah that's 58-60" I guess for some people it's o.k. to rely on Nicholsons Q.C. guy. I guess my point is, any testing is fine as long as it proves quality for the intended use. I make fine cutting tools for field dressing if that's what the customer wants. I guess if a customer called and needed a pry-bar that would also defend him against angry car doors then I would make the best tool for that job that I can.
Jason B Stout
Jason B Stout
Nathan the Machinist
KnifeMaker / Machinist / Evil Genius
Moderator
Knifemaker / Craftsman / Service Provider
- Joined
- Feb 13, 2007
- Messages
- 17,493
I find it depressing how a lot of knife knuts emphasize the herculean toughness of a knife, yet completely miss the cutting ability and edge retention aspects.
I put a lot of effort in developing HT and geometry that optimize the cutting ability and edge retention in a knife - then the new owner shows it off to his friends "look, see, it is real hard metal - look how deep I can scratch this steel pipe!" (true story)
I put a lot of effort in developing HT and geometry that optimize the cutting ability and edge retention in a knife - then the new owner shows it off to his friends "look, see, it is real hard metal - look how deep I can scratch this steel pipe!" (true story)
Having had a knife jump/fall out of my pocket, bounce, open, and land point first on the floor of a commercial freezer, I'd say the drop test is valid enough. The tip of that knife broke from a pocket height drop onto cold (~15 F) concrete. I dont think its at all unreasonable to expect a kitchen knife tip to remain intact after a fall to a tile floor. The last couple of knives I've made were drop tested on the concrete driveway and the tips survived. Having never done this test, the first one surprised me. By the second, I kind of expected it to survive. Weight makes a big difference, and both were very light.
