Quality Control

Matt de Clercq

Matt de Clercq

Well-Known Member
Is there a place knife makers can send their knives to get analyzed? For example: I send a knife to someone and they analyze it and give back information like- "the steel you are using has the potential to have have a certain level of characteristics and your knife does or does not meet these marks. To reach this materials full potential you need to..."
 
I guess you could find such a place, just include a month's pay and wait 6 weeks. If you buy from a known source, you should be able to obtain the analysis data of the heat lot your piece steel came from. If we each start with a piece Smith's O1 from the same heat lot, we should be able to obtain the same results if our HT process is identical. hope this answers the question
 
What do each of you do to test your knives? If doing a batch of same blade/material/HT what process do you use to regulate consistency and guarantee quality? How often do you test? Do you run a sample every batch (ie a sacfificial blade?) What specific tests do you do and at what point in the process?

When a maker says his blade is 59/61 RC is he saying he tested or stating that to the best of his abilities he has processed that blade in accordance with industry accepted practice that should put it there?

I ask because years of machining has shown me that some things in metal working are harder to prove out than others......and human nature always hopes for the best in something we have personally done even when data might disagree.

Perhaps Matt is asking himself some of these same questions?
 
You makes some good points smallshop. I have always assumed that if they put a range of 59-61 that it is there target and if they put a single number and say HT to a HRC of 60 that they have tested it. Or at least in my mind that's what it should be

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Forgive me if I come off as a serious buzzkill here but I have some perspective after working with such tests for most of my career; in black and white terms I would say no. Many knifemakers seek, or even come to believe in, a single test that will tell them everything they need to know about their knife quality (files, brass rods, Rockwell, bending, breaking etc…), but this is a fantasy. Any truly accurate and reliable test of a material property will only give you that one small slice of the whole picture, in order to get an idea of that entire picture you will need many more parts to the puzzle. This is because there are many more than just one steel property that needs to be balanced and blended together to make a well performing knife, and there are also more than one knife application- you can see how this picture does get pretty big and complex in short order.

General, nonspecific and somewhat subjective, tests that we can do at home give us some idea of what we like in a knife, but if we are looking to get standardized and accurate test results of material properties, that requires specialized equipment in the hands of folks who know how to use it. You could send you blade to a lab for analysis but you would probably leave some of the folks that had to do the tests scratching their head. If they are honest they will tell you that they cannot give you want you want with the sample as provided, if they see you as quick buck they may tell you exactly what you want to hear.

For example, if you sent me a knife blade to test on my Charpy impact tester to let you know how tough it was, I would have to be honest and tell you that I can’t help you. The Charpy test uses various standard samples around 10mm x 10mm x 55mm, the numbers generated by a broken knife blade would mean nothing.

There is a lot of confusion about grain size in the knifemaking community, I often hear numbers thrown out, but I never hear what standard scale that those numbers correspond to (there is more than one). I also never hear how the measurement was done, this also involves a couple of different approaches. And then tests are cited that are not associated with grain size assessment at all, which casts even more doubt on whether folks are getting any of the tests they think they are. ASTM grain size evaluation is not an easy task and requires good lab skills in both sample preparation and use of the metallograph (yes it requires one).

Even something as simple as Rockwell hardness is often the source of a quick buck by people who are giving knifemakers less than reliable information. First and foremost, proper HRC testing is the result of an average of multiple readings, so unless you have at least five dimples in your blade, you are not being given truly accurate numbers. Secondly the test needs to be done on a flat, level surface, so blade bevels are not a reliable area for testing. If you are using 10XX series, W1, W2 or other similarly shallow hardening steels, the thicker areas that will offer a reliable surface for reading will likely give different numbers than the edge would; once again when I am asked to test such a blade I am honest and tell them that the numbers are guesses at best. Likewise if somebody asked me to quantify retained austenite with my microscopes, I would have to be honest and tell them that only access to one of the local University’s crystallography equipment would give them the numbers they seek.

Impact toughness, overall hardness, abrasion resistance, grain size, carbide condition and dispersion etc… to measure them all I would need a lot of time (which I have spent over the years) and samples in many shapes and sizes all heat treated exactly the same as the blade in question, from the same bar of steel. I would then also give some practical tests to the blade itself and then put it all together for an overall picture of where my blademaking is at. It is a lifetime of testing and learning that gets you there, not a single test or even a series of tests. Because in the end it is not the knife that is being tested, it is you and your knowledge and skills to produce that blade that is the key.

I would say your best bet is to use the knife hard for the intended purpose and see how it measures up, that is probably the quickest way to get the overall picture.
 
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Good Job Kevin! When I saw the title of the tread, I was thinking.....Oh Boy! This is gona be a deep one, but Kevin is spot on, and I totally agree with his reply. About the only thing I can add, or perhaps rephrase, is that each individual knifemaker must decide those characteristics that are important in their knives, and develop their own means of testing to determine "where" their knives are within a given expectation.

The one great truth in knifemaking is that there are ALWAYS many variables throughout the creation process of each knife we make.....that's what makes us "Craftsmen". Honestly, if I were able to nail down each variable, every time, I'd likely quit knifemaking. I think one thing that draws many of us is the fact that those variables exist, and eventhough we know we can never overcome them all, the challenge of doing so is what drives us.

I would say your best bet is to use the knife hard for the intended purpose and see how it measures up, that is probably the quickest way to get the overall picture.
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RIGHT ON, AMEN, and any other words I can use to pound that statement home!! I envision some folks thinking "That's stupid, I don't have time to do that with my knives." Well, if you want honest answers, it's what you've gotta do. If you're looking for something to back up a claim of knife quality, nothing will do it better then YOU having confidience in your knives, and the only way to honestly achieve that is to USE what you make. It's not quick, it's not easy, and nobody else can do it for you.
 
Great stuff guys! Ed had said some of the same things Kevin just did in another thread. I quit making knives years ago because I felt the HT process was one I could not control. After reading some of Ed's comments in response to my questions I realized I had been quenching in the wrong juice. I had gotten my original info off a knife forum but it was bad info. So, starting up again this is a big area of concern to me and I want my thinking in alignment with proven technique. I realize now I'm going to have to "waste" some steel to get the answers I want. (so a smaller blade design will be forth coming:3:)

Three main points I think I'm hearing.....

1) there is no laboratory style test or tests that will tell you if you have made a quality blade.

2) Since ultimately blade performance is what matters, we should be testing how a blade performs and worry less about lab data. (possibly this will tell us much about design issues also?)

3) consistency in manufacture, heat treat, temper, etc. will narrow the chance of flaws and help "corral" some of the unknown variables that exist.

It's actually a bit of a relief to hear that real world testing is the best. I have been worried that not having a commercial HT facility would be a hindrance. I guess in the end if a blade is tough, holds an edge, does the job it was designed for, it's a good one.

I think of all the old time blades that had a great reputation and it was not due to laboratory results. We have better steel and probably more control over process but the skill of the maker even back then was the determining factor.

Okay, so what "real world" test do you like to put your blades through. And, after many tests with a given material/process over time, proving your quality, do you finally give yourself the okay to test less on that particular combo and move on to another material/process test?

Matt, hopefully this is not diverging too far from what you wanted to know. Apologies if so....

Kevin....this was no buzzkill! Just the info I was hunting.....
 
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To Mr. Cashen and Mr. Caffrey,
I have been staring at my computer for a while now trying to think of a way to express how thankful and appreciative I am for the responses. I will print this thread and hang it in my garage to remind me that I can always find time to help someone I don't even know and to remind me of what makes a good knife. Thank you

Now that I got that out of the way... I asked the question because I have made a large investment(for me) to reduce the number of variables associated with quality. I thought there may be a way for a knife steel expert to disect a knife and look at the grain size, shape and structure and tell me if I was producing the best product possible. I have researched the tests that the ABS uses to determine a quality blade but didn't know if it could be taken to another level.

Smallshop-no, this is exactly what I want to know. Thanks for asking.
 
Matt,
I can't add anything to the two excellent informative posts from Kevin & Ed on the science of your question.

What I can say, is that I sent my air hardening steel blades to Paul Bos HT because they do nothing but HT knife blades.
My blades return with those dimples in them that Kevin was talking about and a average of their findings for RC hardness.

The pyromanic that's in all of us makers wants to play with fire etc. :biggrin: I want the very best possible results in the hardening of these stainless steels.

I then proceed to use them for their given design or I loan them to someone that does, thats why I had some many questions for you after you told me that you are a guide & hunter. I have never hunted game animals so your input was greatly appreciated on the hunting/caping knives that I handed to you.

So if you aren't a Chef or much of a cook, hand your culinary type knives to people that are and get feedback from them.
I also loan my culinary knives to pro chefs and other home cooks like me, especially women, because their hands, wrists and arm's etc are different in size and in shape to some degree.

Real world testing is what counts my friend.
 
Well…

There may be some interpretation nuances to work out Smallshop. My main point is that there is no one test that will tell you everything you want to know, “real world” or lab, because there are too many things to consider about a quality knife. General tests we do at home can only tell us something is working but they are very poor at isolating what that is and why. This is why there is so much esoteric baggage in bladesmithing, we can observe an effect but we struggle and make assumptions or misstatements about the causes, because we lack the data from the more specialized tests.


I would say that practical testing by using the knife hard in its intended use is the quickest way to see if all the little things came together in the end product as a whole package, but the serious lab types tests are invaluable in understanding your process and adjusting it to bring all of those little things together into the final product. I have said that none of my lab equipment helps me make knives, this is because its real purpose is to help me adjust my process and methods. With the knowledge gained from the lab, I create a process, it is the process that then creates the knife, which I then subject to hard, real world use to see if it all came together in the final package. They are apples and oranges and one type of test cannot replace the other.

So:

1. There is no single lab type test that will tell if you have made a quality blade. There tests for toughness, abrasion resistance, internal conditions, hardness etc… And each one of them can tell you how you are doing in your manufacturing process in very definitive ways than more subjective tests, like hard use of the knife could hope to offer. For example, a Rockwell number can tell you if you nailed the heat treatment, but it can’t tell you if you got the edge geometry correct, just as a good feel and balance can’t tell you squat about carbide size.

2. Since blade performance is indeed what matters, and blade performance is determined by a multitude of things, such as properties that can be measured and qualified by lab tests as well as proper design that can be felt by physically using the finished knife. If we want to get basic feel for our overall quality, we can use practical field testing, if we want to get a serious understanding of what each step of our manufacturing process is doing the lab type test are the tools to do that.

3. YES! Consistency and control is the key. Once you develop a method that produces the desired results, being able duplicate it at will, every time, is the secret to it all. Knowledge and control are the tools to achieve it, and no test that could give you more insight should be ignored in that never ending quest.


If I convey just one thought from any I have typed it is that any test should not be about making a better knife, but about making you a better knifemaker. A test may tell you that one knife you made is better, but if a test gives you knowledge to be a better knifemaker, then all of your knives will be better.
 
1) there is no laboratory style test or tests that will tell you if you have made a quality blade.
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Right! There are tests that will tell you if your heading in the direction YOU want to go, but there simply is no lab test(s) that can conclusivley say "That's a quality blade", or "That one isn't any good".

2) Since ultimately blade performance is what matters, we should be testing how a blade performs and worry less about lab data. (possibly this will tell us much about design issues also?)
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I believe without even realizing it, you've sumed up much in that one sentence! I believe it's all about the "Overall Package"....while certain lab tests can point us in a general direction, intengration of design elements can either enhance or detract from the overall performance of a blade.....for example, you can have a high hardness, but if your grind geometry doesn't compliment that geometry (of vice versa) the edge can chip of "flake" during use. It's about mixing the proper "chemical" properties, with mechanical properties that compliment each other.

Believe it or not, there are a number of "knifemakers" out there who take little interest in "performance", and rely more on "bling" to sell their knives...and their customers frankly don't care about performance....only that they have the "coolest" looking knife. (yeah.....I don't get that one either, but it's out there).:)

3) consistency in manufacture, heat treat, temper, etc. will narrow the chance of flaws and help "corral" some of the unknown variables that exist.
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Again, yes! The caveate is that the "variables" can be constantly changing.....therefore we must be capable of adjusting from blade to blade that we produce. If anyone ever claims they produced the "perfect" blade, their either a lier, or simply have a very limited concept of knifemaking. As I mentioned before, the best knifemakers are the one's who constantly seek improvement, eventhough they realize and understand that they will never produce a "perfect" blade.....it's all about the race....not the finish.

My hat's off to you for asking these questions....many wouldn't. They would be too embarassed to do so. As I tell anyone who will listen, I learn something new, every single day in the shop, and over the years have learned many more ways NOT to do something, then I have "correct" ways of doing the task(s).....each of us must learn what works FOR US, and what works well for one knifemaker, does not work the same for another. There are always broad similarities that apply throughout, but it's the "tweaking" that makes each one of us different from the next.

Heck, there was a time when Kevin and I used to argue over heat treating blades.....but we both achieved our MS rating, going about it in different ways/methods, and I suspect to this day we do things differently, but that doesn't mean one is right and the other is wrong...just that we each do what works for us. In my opinon, there's not another MS that has the level of metallurgy knowledge Kevin does.....and when I have that type of question, I can general browse Kevin's posts and find what I need....if not, then I will ask him! If you EVER think you know it all, you're only foolin youself.
 
EdCaffreyMS said:
Good Job Kevin! When I saw the title of the tread, I was thinking.....Oh Boy! ...
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Ed, I find that I need balance in my life, as I believe we all do in our knife making as well. I think many folks see me as a caricature, some sort of mad scientist or soulless automaton stuck in a landscape of lab equipment and metallurgical jargon, far removed from practical knife making as a creative craft. But a metallograph cannot recreate a 15th century broadsword or a renaissance dagger, heck it can’t even help make a handle fit the hand properly. I like digging iron bearing rocks from the ground and building a clay smelter with which to turn them into steel as they did 2,000 years ago, and then bring it full circle by heat treating the resulting blade with digitally controlled salt baths.

It is the big picture that matters in the end. You can examine one centimeter of a Seurat with a magnifying glass and see nothing but how little dots of color were applied to canvas, but it is not until you back up and relax while taking in the whole thing that you see the scene he captured.

The coolest thing about knife making is that no aspect can totally replace the other. So we can make a blade that is heat treated to the maximum, so what, if it looks so awful nobody wants to be seen holding it, what have we accomplished? Or if the handle gives the user blisters within the first five minutes of use I guess we will never really know how long it will hold an edge, nobody will care to use it that long anyhow.
 
rhinoknives said:
Matt,
I can't add anything to the two excellent informative posts from Kevin & Ed on the science of your question.

What I can say, is that I sent my air hardening steel blades to Paul Bos HT because they do nothing but HT knife blades.
My blades return with those dimples in them that Kevin was talking about and a average of their findings for RC hardness.

The pyromanic that's in all of us makers wants to play with fire etc. :biggrin: I want the very best possible results in the hardening of these stainless steels.

I then proceed to use them for their given design or I loan them to someone that does, thats why I had some many questions for you after you told me that you are a guide & hunter. I have never hunted game animals so your input was greatly appreciated on the hunting/caping knives that I handed to you.

So if you aren't a Chef or much of a cook, hand your culinary type knives to people that are and get feedback from them.
I also loan my culinary knives to pro chefs and other home cooks like me, especially women, because their hands, wrists and arm's etc are different in size and in shape to some degree.

Real world testing is what counts my friend.
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Laurence, I admire how you get information and what you do with it. I have thought a lot about our conversation about HT that we had in your shop. While I may go about it differently than you I did not take your words lightly. I have decided to do my own HT because I like learning about it, the process is fun for me and I am a gristle head that has to learn the hard way sometimes:shush:
 
Matt de Clercq said:
To Mr. Cashen and Mr. Caffrey,
I have been staring at my computer for a while now trying to think of a way to express how thankful and appreciative I am for the responses. I will print this thread and hang it in my garage to remind me that I can always find time to help someone I don't even know and to remind me of what makes a good knife. Thank you

Now that I got that out of the way... I asked the question because I have made a large investment(for me) to reduce the number of variables associated with quality. I thought there may be a way for a knife steel expert to disect a knife and look at the grain size, shape and structure and tell me if I was producing the best product possible. I have researched the tests that the ABS uses to determine a quality blade but didn't know if it could be taken to another level.

Smallshop-no, this is exactly what I want to know. Thanks for asking.
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Matt, unfortunately there are no simple answers. No wait, strike that, it is great that there are no simple answers, it is what makes knifemaking a life long adventure in which we can always grow and discover more! :1:

I thought the same thing about the ABS standards and when I got my Master stamp almost 20 years ago I wanted to know if there was a “next level” and that is when I started collecting the equipment to do the exact testing you describe and all I have every day is more questions. I just had a friend in my shop last Friday and told him how much I love my job because I had just once again changed many of the ways I do it. I have no recipe for making knives, I have an ever changing process that I fine tune more every day, and will for the rest of my life, or it wouldn’t be worth doing. A one time test at an outside lab couldn't help me in that, I had to make it my own life pursuit.

There are as many different definitions of what a good knife is as there are people using them, if you try to make just one and call it THE knife, you just traded a universe of possibilities for a dead end. So of course there is a “next level”, there will always be, and that is the magic of it. The proper tests, in the lab or in the field, will take you to the next level, so you can take your knives anywhere you want to.

Ironically the reason I have time to post in this thread today is that I am heat treating. As I type this my high temp salts are coming up to temp in the background while I wait.:3:
 
Thanks for all the input guys! I just realized there is a goldmine of info in the "sticky" that Kevin put there. I'll try to read up a bit before I ask redundant questions. This is a real good thread though. I appreciate the wisdom.

felix1.jpg

Sorry Kevin.....I couldn't resist.
 
Matt de Clercq said:
Laurence, I admire how you get information and what you do with it. I have thought a lot about our conversation about HT that we had in your shop. While I may go about it differently than you I did not take your words lightly. I have decided to do my own HT because I like learning about it, the process is fun for me and I am a gristle head that has to learn the hard way sometimes:shush:
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Matt,
That'a the beauty of knife making, We can all go at it from our perspectives, learn along the way, share our information to help each other improve and all produce excellent working knives.

Somewhere, someday my wife and I will have a place on some land where I can build an outside forge and go at it Blacksmith style! I already have a 12" piece of railroad tie to make a simple anvil out of.

I want to learn how to forge and HT the way it's done by color of the flame & steel.

This has been a excellent and informative thread and thank you for asking your questions and to all that contribute.
 
hi, i am a newbie knife maker. near the end of year two. but i have been making and fixin stuff for 40 years, thank goodness concepts are mobile.
JMHO
trying to control quality is like herding kittens. you work your butt off and very little to show for it. what works is quality assurance and the key to that is figuring out what works for a certain step, and trying to do it the same way every time. once you figure out what works you can reduce the number of things you have to buy.
both Ed and Kevin brought up variables. the easiest way to deal with variables is eliminate them. some things that work for me:
all steel is same name brand, and I buy big enough pieces to get at least 12 knives a piece.
quench oil is an industry standard, i keep it at the same temp for each heat treat adventure. I found sanding belts that work for me and my style of grinding, another variable down. same would apply to adhesive, finish, drill bits.....
this is the way we do things at the office. we forge the part that drives your front wheels and the part that fits into the transaxle. i have been there over ten years, over 100 million parts(drive axles for 25 million cars), no customer returns linked to our process.
 
You can tell that Scott has the industrial experience that he does, he immediately identified the threat of unknown variables to consistent quality, and he immediately zeroed in on two of the areas of greatest vulnerability to variable blindsides in knifemaking despite his short time making; I suspect he will do well with the wisdom he already possesses. It is no coincidence that I cite those same two areas as the basis for the quickest path to consistent success for any beginner. We must be in control of the process to shape the metal so that is all up to us, but there are two moments in the entire process that are critical and we are not in control as much as the variables are. The first is when we pick up a bar of steel and decide, for whatever reason, to use it for a knife, and the second is when we plunge a carefully heated blade shaped piece of steel below the surface of a liquid and hope it comes out a knife.

Sun Tzu could have said “Know thy steel…” and not been any less correct. The more you know about your material, the more in control of it you can be, that is just basic, irrefutable, common sense. The second you pick up a piece of steel to make a knife you can either be in control by knowing the chemistry and condition of it, or saddle yourself with countless unknown factors throughout the process of making it and the entire using life of the knife. The main character in the movie “The Matrix” gains the ultimate control over his reality when he no longer sees the outer façade but actually sees the code that all objects in that reality are written in. If I had my way, aspiring bladesmiths would be like Neo when it comes to steel. The words “1095”, “O-1” or “15n20” would be meaningless and all they would see, or care about, is- .90%C, 1.00%Mn, .5%Cr, .50%W… etc… When I get requests for heat treating advice, the first thing I want to know is the chemistry, not if it is 1075 or L6, just the actual chemistry; that is all I need and the name that AISI, or some supplier, gave to it is meaningless in determining its behavior. Despite the name, each batch will have a slightly different chemistry and thus behave slightly different from the last; that becomes irrelevant if you know the chemistry.

There is one heat treating operation that looms tall over all others in our hopes and fears of making a knife. Hardening is the make it or break it moment (sometimes literally) in knife creation, it is the trial by fire of any blade, and we sweat through the process because it is the one part that we cannot see the results with our eyes. We have to have faith that a million things occurred correctly inside that steel; that is why the vast majority of knifemaking questions I get are about that single operation. We are the masters of heat, and apply as we will to the blade, we can regulate and adjust to get just the right temperature for any amount of time, but once that blade hits the surface of the quench it is out of our hands. There are countless things that have to occur just right in a matter of seconds or less, to be honest it is not only out of our control it is beyond our ability to control. At this point we are turning the process of making our knife over to a container of liquid. You could get a great blade, identical to your last, or you could get warping, cracking, staining, scaling, soft spots, mixed microstructures, etc… When you think about this you may realize why I am so adamant about getting the most reliable and consistent quenchant you can. If I farmed my heat treatment out (bear with me and use your imagination), you can bet I would find the best guys in the business, at least as good as I am at making the rest of the blade, in a sense that is exactly what we are doing in those few seconds below the oil. I could only trust a serious professional to take over for me at such a critical moment.

For years now I have held these two bits of advice above all others for an aspiring knifemaker to achieve consistent control over their process and quality, for the reasons given but also for the level of difficulty bladesmiths have in accepting these two basic concepts. There are those who find the challenge of overcoming mysteries with every knife part of the charm, that’s fine I’m not knocking that, but this thread topic was established by the original poster as taking consistency in quality control to the next level and this is my best advice to get on that path at ground level.
 
"There is one heat treating operation that looms tall over all others in our hopes and fears of making a knife. Hardening is the make it or break it moment (sometimes literally) in knife creation, it is the trial by fire of any blade, and we sweat through the process because it is the one part that we cannot see the results with our eyes."

I doubt this could be stated any better. And hearing it from a seasoned maker removes some of the angst caused by my inexperience. That "not knowing" feeling is kind of horrible and exciting all at the same time. I made 6 exact knives about 8 years ago. 4 came out nice 1 cracked and 1 didn't get hard. I was busy running a job shop at the time and was lean on time to enjoy "discovery".(On top of getting lousy HT advise) The two failures created a "how do you know the other 4 are really okay" resonance in my head.....even though 8 years later the folks using them still like them. I got disgusted with my seeming lack of control and not having time to test and gave up......


This entire thread is an amazing blend of fact/experience/philosophy. This is THE one area I doubt my ability. The thoughts you guys have been sharing are an absolute tonic to doubts and fears.

I do follow different guys on here because their thinking makes sense to me. I often don't comment but read what they share. Scott is one of those guys. I know he hasn't been making knives forever but he is scientific and analytical and has been getting great results on his stuff.

I have a heat treat furnace showing up this week (hopefully). This thread is preparing me for our first dance.......:biggrin:

Thank you all again...Very much!
 
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I had a pitching coach tell me that I had to be the master of my domain by controlling what is possible for me to control. I can't control the crowd, the other team, my team or the umpire, just me. This bit relates to everything in life. I'm glad my knife making isn't a team sport. :biggrin:

He also said- piss poor preparation precedes piss poor performance- another one of life's facts

Thanks again for sharing your experience!
 
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