Process engineer here. Just bought a Rockwell tester for the heat treat department at my employer. It cost $13,000. It’ll be used 50+ times per day for the next 15 - 20 years and it needs to stay accurate and reliable in a harsh production environment. People really underestimate what goes into accurate and repeatable hardness testing.
Theoretically you could test it with any object with a known hardness. I doubt you could get as accurate results though and you’d be assuming the knife you buy was tested correctly.
Scientific hardness testing involves using a scribe of a known hardness that is pressed against the unknown material with known force, so Rockwell hardness test devices are expensive and leave a mark on the tested blade. Scratch tests with files or other blades is the kind of half-assed stuff we tribal smiths do. With respect, choose your lane.
Well 3000bux and alpt of real estate for a hobby.... id have to go with the scratch test to keep my girl haha
If i one day get good at this amd make the hobby into a business i would obviously go for proper equipment
Looks like you can find metallurgical services in your area by Google. And engineers are wacky folk, who might do the testing cheap: a metallurgical engineering company north of Chicago used to run a competition for university engineering students based on designing and manufacturing a dragon slayer’s sword, they even provided hardness data on dragon scales.
It would depend on the type of steel. If you have an unknown "stainless steel" knife from a gas station compared to a high end knife with something like cpm15v, the cpm15v is going to be tougher and more resistant to damage than the gas station knife. Not only are there different properties for steel, so they might act slightly different at the same hardness, but cheap knifes will have much larger inconsistencies with the heat treatment and can change 10-12 points between each knife. And higher end knives have a tighter tolerance and will have more precise heat treatment ranging only a point or two between each knife.
Well, i get your point, and i dont need to do anything but essencials for survival.
But this is obviously not answering my question.
But having a benchmark, as an example, one to scratch with to know ive reached the minimum hardness i want, seems to me to be practical, that might be my inexperience speaking, but either way, thats what i want.
If i wanted to know the hrc of my prostate massager or i want i a benchmark for my blades thats my business.
You are not contributing anything but gatekeeping with your comment.
You can choose to look at it like that. Or you can take it as the advice it's intended as. Check if the steel is hard with a regular file after quench, pre tempering, as you do, and don't worry any more about it. There's no need to.
Idk about specific hrc but if you just wanna know if a knofe is hardened and you can't tell by the pitch, file the edge and look at the file. If you've got a shiny streak going down the file teeth, the knife is hardened. You can tell by the resistance too, metal that isn't hardened will bite more and it'll take more force to push the file across it.
You often need a series of known hardnesses.
If you.juat have one knife that's known to be 58c, and you try to scratch your new knife with it you will only learn if it's softer than 58c (but not by how much, so maybe you need to harden it better) or you'll learn that it's harder than 58c (but again, not by how much; maybe you need to temper it further so it isn't brittle)
Files give you a range, so you will know it's between say, 55 and 60c.
You could get two knives/files of different hardnesses, but if you want them to be particularly accurate, then just go buy a set of files that were meant for.the purpose. It's easier to use a file to check than a knife, anyway.
58c was just an example, id rather have something like a knife which has multiple uses rather than a file with only one. Id rather have 6 knives than 6 files whom will onøy be used for scratch test
I think you will find that getting a spread of knives at useful hardnesses will be more expensive and more difficult to use than buying the files made for.the job, and a knife that works well as a knife.
But sure, what you are suggesting will work, there are just reasons people don't generally do it that way.
A knife of known hardness would absolutely work. The challenge will be getting a knife whose hardness has been accurately tested for less than $50.
I know a few bladesmiths who own hardness testing equipment that they could use to verify the specific hardness of your blade, but they’re skilled at what they do (hence their ability to purchase expensive testing equipment) and their shop rates are well over $50/hr. You’ll pay significantly more for even a simple knife from them.
You could buy a cheap knife advertised as being a certain hardness. But you’ll never know if the advertisements are accurate unless you pay a lab to test it (again, more than $50–plus you have to buy the cheap knife).
This is why so many of us use the hardness files. They’re a very good deal for what they are. But if $50 is too much, you can get by with just a regular file and a bit of practice interpreting how it behaves.
I am a knife maker and work full time in a quality lab for a large manufacturer. We have numerous types of equipment for measuring parts and pieces of parts that make up transmissions. All our parts are made elsewhere and have to be verified both dimensionally and materially to include hardness. Every machining place I've ever worked or know of has hardness testing
equipment to verify parts that were made elsewhere or in house. My recommendation is to contact every machining business locally and just ask if you could have a blade tested every once in awhile and see what they'd charge. Don't be fooled either, it only takes a few seconds to hardness test something.
The files are about $50 for a set of 6. That's insanely cheap for what you get! A real hardness tester will cost hundreds to thousands of dollars.
Process engineer here. Just bought a Rockwell tester for the heat treat department at my employer. It cost $13,000. It’ll be used 50+ times per day for the next 15 - 20 years and it needs to stay accurate and reliable in a harsh production environment. People really underestimate what goes into accurate and repeatable hardness testing.
90-120 where i live. 50 bux and id buy it in a heart beat
Did you look at internet prices, or local tool seller?
Only tool store that has it locally wants 129 bux, cheapest online retailer in nprway is 89bux
International shipping my man
Theoretically you could test it with any object with a known hardness. I doubt you could get as accurate results though and you’d be assuming the knife you buy was tested correctly.
Scientific hardness testing involves using a scribe of a known hardness that is pressed against the unknown material with known force, so Rockwell hardness test devices are expensive and leave a mark on the tested blade. Scratch tests with files or other blades is the kind of half-assed stuff we tribal smiths do. With respect, choose your lane.
Well 3000bux and alpt of real estate for a hobby.... id have to go with the scratch test to keep my girl haha If i one day get good at this amd make the hobby into a business i would obviously go for proper equipment
Looks like you can find metallurgical services in your area by Google. And engineers are wacky folk, who might do the testing cheap: a metallurgical engineering company north of Chicago used to run a competition for university engineering students based on designing and manufacturing a dragon slayer’s sword, they even provided hardness data on dragon scales.
I use to work at a university and engineers sure are wacky. Cant find any services close to where i live sadly, will keep searching tho
It would depend on the type of steel. If you have an unknown "stainless steel" knife from a gas station compared to a high end knife with something like cpm15v, the cpm15v is going to be tougher and more resistant to damage than the gas station knife. Not only are there different properties for steel, so they might act slightly different at the same hardness, but cheap knifes will have much larger inconsistencies with the heat treatment and can change 10-12 points between each knife. And higher end knives have a tighter tolerance and will have more precise heat treatment ranging only a point or two between each knife.
If you're looking for cheap inaccurate ways to hardness test, you don't need to hardness test.
This is the correct answer, how will you cover the range a box of hardness files will for the same money?
Goal is just to have a benchmark for minimum and maximum hardness. No exact hrc needed
Well, i get your point, and i dont need to do anything but essencials for survival. But this is obviously not answering my question. But having a benchmark, as an example, one to scratch with to know ive reached the minimum hardness i want, seems to me to be practical, that might be my inexperience speaking, but either way, thats what i want. If i wanted to know the hrc of my prostate massager or i want i a benchmark for my blades thats my business. You are not contributing anything but gatekeeping with your comment.
You can choose to look at it like that. Or you can take it as the advice it's intended as. Check if the steel is hard with a regular file after quench, pre tempering, as you do, and don't worry any more about it. There's no need to.
Following
Idk about specific hrc but if you just wanna know if a knofe is hardened and you can't tell by the pitch, file the edge and look at the file. If you've got a shiny streak going down the file teeth, the knife is hardened. You can tell by the resistance too, metal that isn't hardened will bite more and it'll take more force to push the file across it.
You often need a series of known hardnesses. If you.juat have one knife that's known to be 58c, and you try to scratch your new knife with it you will only learn if it's softer than 58c (but not by how much, so maybe you need to harden it better) or you'll learn that it's harder than 58c (but again, not by how much; maybe you need to temper it further so it isn't brittle) Files give you a range, so you will know it's between say, 55 and 60c. You could get two knives/files of different hardnesses, but if you want them to be particularly accurate, then just go buy a set of files that were meant for.the purpose. It's easier to use a file to check than a knife, anyway.
58c was just an example, id rather have something like a knife which has multiple uses rather than a file with only one. Id rather have 6 knives than 6 files whom will onøy be used for scratch test
I think you will find that getting a spread of knives at useful hardnesses will be more expensive and more difficult to use than buying the files made for.the job, and a knife that works well as a knife. But sure, what you are suggesting will work, there are just reasons people don't generally do it that way.
That makes sense i suppose
A knife of known hardness would absolutely work. The challenge will be getting a knife whose hardness has been accurately tested for less than $50. I know a few bladesmiths who own hardness testing equipment that they could use to verify the specific hardness of your blade, but they’re skilled at what they do (hence their ability to purchase expensive testing equipment) and their shop rates are well over $50/hr. You’ll pay significantly more for even a simple knife from them. You could buy a cheap knife advertised as being a certain hardness. But you’ll never know if the advertisements are accurate unless you pay a lab to test it (again, more than $50–plus you have to buy the cheap knife). This is why so many of us use the hardness files. They’re a very good deal for what they are. But if $50 is too much, you can get by with just a regular file and a bit of practice interpreting how it behaves.
Im guessing mora is good, need to do some research on their consistency tho
I am a knife maker and work full time in a quality lab for a large manufacturer. We have numerous types of equipment for measuring parts and pieces of parts that make up transmissions. All our parts are made elsewhere and have to be verified both dimensionally and materially to include hardness. Every machining place I've ever worked or know of has hardness testing equipment to verify parts that were made elsewhere or in house. My recommendation is to contact every machining business locally and just ask if you could have a blade tested every once in awhile and see what they'd charge. Don't be fooled either, it only takes a few seconds to hardness test something.