Blade Performance Testing

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rckendall

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Oct 26, 2006
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I've seen threads on cutting hemp rope to serve as a performance test, but can't find it now. I want to start doing something along these lines to help check myself.

I know of using the 1/4" brass rod as a H.T. test and will do that also.

Maybe I just need to learn to "search" better? Can someone help, please?

Thanks
Richard
 
Hi Richard
Im a MS in the American Bladesmith Society and have went through it.
Here is the standard test for Journeyman level
http://americanbladesmith.com/ABS_JSTest.htm
The Mastersmith level is the same with the exception of using a damascus blade of at least 300 layers
You may be refering to the rope cutting test where you can see how many slices of a given size rope on top of a bathroom scale at 20 pounds of consistant pressure. Thats a good test too and doesnt lead to destruction on the knife. Wayne Goddard is the man for this test. Here is something on it
http://users.ameritech.net/knives/edge.htm
 
Threads of this topic always spin off into directions guided by personal and political agendas. Before this one gets there, I thought I would just put my $.02 in. Please be certain of what you are testing for and what you see in the results. For example, you may be tickled with a 1084 blade that Rockwelled at 66, but did you get this number because the steel was overheated? Other test will be needed to validate the Rockwell numbers in this case. There is a danger in resting on one test as being definitive in assessing blade quality, the more cross referencing and verifying you can do the more reliable will be your data. A good amount of testing being done these days is actually marketing with more emphasis placed on impressing the public than on actually evaluating the process and end product. Then you end up with tailor made tests to specifically make one method shine. If you make very thick blades and are more interested in convincing the public of their superiority than in actually determining if you could improve them as knives, you may wish to drive the tip into a tree and then stand on the handle, it would be very impressive for marketing but virtually useless in improving your abilities to make a better cutting knife.

I guess I just wanted to point out that there is a difference between actual testing and exercises done to impress people.

I think great tests without all the equipment are actually using the blades according to how they were intended. If it is a camp knife or bowie, a good amount of time clearing a fence row would be more useful than making a pile of rope chunks. How does the handle make you hand feel after chopping for an hour? Any real problems with the edge? If it is a small knife, how well does it take an edge? How will this knife be cutting most of the time? Will it be push cuts or draw cuts? Whole different worlds there and parlor tricks can take advantage of that fact. What materials is the knife likely to encounter? Rope is but one very specific type of medium, hard cardboard is another, while wood is yet another. Skinning knives may slice soft tissue like crazy but how will they handle accidental or even intentional contact with bone? It can be counterproductive to limit yourself to just one testing medium just because it gives you the results you want to hear.
 
I am a part time maker and therefore an amateur. To me, the best test is using a knife for what it is made to do. I make a lot of hunting knives for people that hunt elk, mule deer and in New Mexico, oryx. If a knife will field dress, skin and quarter a bull elk or oryx without resharpening, it is a good knife and passes my test. When people report they have done 2 or even 3 elk, I am even happier.

I don't think anything tests a hunting knife better that hair, hide and cartilage.
 
Good thread!I do 3 basic tests after heat treat. After tempering, I clean up the blade and put a useable edge on it.
First comes the brass rod test. 5 or 6 times tells me I'm in the ballpark.
Next, 50 cuts on hemp rope. If it still shaves , good.
Last, I have an oak 4x4 I chop at for several minutes . No damage to the blade, then I continue on towards making it a knife. If its to be a hard user or military use, it gets some more chopping, twisting, etc.
All simple tests that can tell you a lot. bruce
 
WOW, I guess the sky is the limit. I guess I thought there was some standard tests that everyone considered worthy.

I am just now having my first blade heat treated and want to start some standard testing with a knife I have on-hand as a base line.

Birdog4, what size hemp rope do you use? This is a good starting point for me, as I only use knives in light duties on a regular basis.

Thanks to all
Richard
 
rckendall said:
WOW, I guess the sky is the limit.
Click to expand...
Yes, there are many ways to put your knife to the test to see how far it will go before it failed.

Try to come up with things that you can test with that you can record, that you can do again with another knife to compare.

Cutting is a good thing to test because thats what your knife is made to do.
On my next tested blade I plan to do the hemp rope cutting test like you plan.
My idea is that if this blade is going with me to work, then it would be nice to know how long it can cut the common things I cut at work before I need to sharpen it again.
Thats good smart information to know about my blade and it's heat-treatment.
The trouble is that I have never actually seen any true hemp rope sold in a store around here. So i will just have to shop around and get what there is to get.
Remember to get enough so that you can use the same rope to test other knives on.

Oh, and try to remember that some tests people have suggested on this forum will hurt a knife, so be carefull and know whats up when doing a test thats a danger.

and write down the results!
 
I have a question about what you wrote Kevin Cashen (thanks for all your info as always). Are you saying that the standard RC testers that are used in industry are worthless? I know Bos and R.J. Martin both do an RC test on each blade and I have always found both there HT to be damn good. Are they doing test beyond doing a test on a RC hardness machine? I have been told that it must be done on the flats of a knife and that some people take multiple reading and average them. I guess what I am asking is wether or not a knife maker can get an accurate RC number for a knife. Not for marketing but for learining more about the HTing im doing and will do.
 
The rope I use is half inch manila/hemp used to bind baling twine. Ya can find the same stuff at Tractor Supply, Trader Horn or even Lowes.
Next test I plan to use is chopping deer antler.
 
I compare my knives to some good store bought, like you can see there is alot of difference in what performance means. I have 3/8 hemp and usually can get 50+ cuts and am very happy.
 
What I have on-hand for this benchmark, is an old Schrade-Walden M-15.
It is kind of pitted and not so pretty to look at, but it sharpened up really well.

If anyone has any particulars about this knife, I'd appreciate that also.

Thanks
Richard
 
BigJimSlade said:
I have a question about what you wrote Kevin Cashen (thanks for all your info as always). Are you saying that the standard RC testers that are used in industry are worthless? I know Bos and R.J. Martin both do an RC test on each blade and I have always found both there HT to be damn good. Are they doing test beyond doing a test on a RC hardness machine? I have been told that it must be done on the flats of a knife and that some people take multiple reading and average them. I guess what I am asking is wether or not a knife maker can get an accurate RC number for a knife. Not for marketing but for learining more about the HTing im doing and will do.
Click to expand...


Whoa! I am not sure how
"For example, you may be tickled with a 1084 blade that Rockwelled at 66, but did you get this number because the steel was overheated? Other test will be needed to validate the Rockwell numbers in this case.
Click to expand...
can be seen as
... saying that the standard RC testers that are used in industry are worthless?
Click to expand...
:confused: I also can't see how any particular heat treaters or makers could possibly have been targeted by any of my comments.

I do need to make myself quite clear- I Rockwell every piece of steel that goes through a heat treatment in my shop, and even some that were done in other shops; I find the test that invaluable. But it is only one test and can only tell you so much. Because it is such a great test is why I used it as an example- even the best of tests have their limitations. They have these limitations is due to specialization, as good material tests are very accurate because they manage to measure a single property at a time.

Many makers will quickly pooh, pooh, Rockwell tests because they do not tell them what they want to hear, I am not one of those makers. And this is what I was getting at in my first post -doing things to make you blades look good for the public is sales gimmicks, doing things to learn both the good and the bad about your process and product is testing.

My Rockwell tester is invaluable to me, but what does it tell me about grain size? What does it tell me about edge geometry? What does it tell me about carbide condition? What does it tell me about handle ergonomics? If I get 55HRC on a piece that should have been 62HRC what can the Rockwell tester tell me about finding out why? I have other tools that will. Relying solely on a Rockwell tester would be as limited as just cutting up rope.

I have never got a truly reliable reading on a bevel yet, a flat surface perpendicular to the penetrator is necessary. A proper finish is also important. If one is not utilizing proper soak times a reading on the ricasso will tell you nothing about the blade, and obviously differentially hardened blades are a lost cause on a Rockwell tester.

Rckendal, some “tests” are perceived as “standards” in knifemaking because of the amount of P.R. they get, but many get P.R. because that is what they were designed for, more than learning about the product and process. I personally like the tests that tell me something I didn’t want to hear about my work, it allows for improvement. Steve Hayden nailed it again in his post, I think putting blades in the hands of folks who will use it extensively for the intended purpose and then gather the feed back is the most efficient way to gather information (heck you can be making knives while a dozen of your blades are being tested), hunting knives being used by hunters is about the best practical test you are going to get. I had a friend who was a butcher, and every year around dear season he would get swamped with business, I would drop off a couple of blades with him and have him give me feed back, I learned a lot. I also still believe that the most destructive environment for any knife is in a kitchen. If a blade holds up well for 1 month in a busy kitchen, it can take just about anything!
 
Kevin, well said! Agree with every word. If you are going to make and sell a hunting knife, go hunting with it, a fillet knife, go fishing, a kitchen knife use it in your own kitchen. Try to optomize it in the shop with RC tests, ergonomics and check it out by cutting rope or cardboard but you are not going to know what you really have till you skin and elk, fillet a box of fish or use it in the kitchen. You do all those your self if you can and also put blades in the hands of hunting guides and commercial fishermen and Chef's.... Phil
 
Thanks for the clarification Kevin. I did not mean to imply you were trying to debunk Mr. Bos or Martins techniques, only that I was wondering if they were taking steps beyond the standard RC test to satisfy themselves. The statement you made gave me the impression that the RC test could not be trusted, my mistake. I agree 100% about kitchens and knives. A full 14 hour day in the kitchen doing 3 services will kill a knifes edge worse than 3 full moose.
 
rckendall said:
I've seen threads on cutting hemp rope to serve as a performance test, but can't find it now.
Click to expand...

I have never done a rope cutting test myself yet.
I have seen on a few DVDs by Ed Fowler where he cuts some rope and he just cuts the rope in a very normal manner.

I remember that some rope is so thick that you can un-twist the three sections and then only have to cut one section.

I think I remember that Cliff Stamp suggested that you be very carefull what you have under the rope that you are cutting. If you have the wrong cutting board it can mess up the results of the test. I think most people suggest a plastic cutting board under the rope.

I also remember a story of a cutting test where a scale of some type was placed under the rope to be able to learn the amount of down-force the knife will need to cut the rope.

My guess is that you sharpen the knife in a normal manner, then count the number of cuts you can do before the blade gets dull.
Then resharpen the knife edge again, and cut some more rope and count again the numbver of cuts.

Perhaps if you do this a few times you can start to understand where the knife starts to get dull. And this average number of cuts should help you compare this knife to others in the future that get the very same test..

I think you are darn smart to start thinking about testing your knives, because cutting is what the knife is designed to do after all. Therefore the cutting test is about the most important test you can do on a knife to learn what type of knife it is.
 
Yes, knives are made to cut, and therefore cutting tests can help. But what does each test really tell you? in a way a cutting test is just as specialized as any other test.
In a rope cutting test say, Knife A cuts 50 times and Knife B cuts 30 times through the same rope. all you have shown is that knife A cuts more of that rope, it doesn't tell you what else it will cut, nor does it tell you WHY knife A cut more. Too often I have seen people say that the rope cut test proves one steel is better, or one heat treat is better. Bunk. Knife A may actually be a poorer heat treat that has a better edge geometry, Knife B may still have decarb on the edge. There are many factors in getting a knife to cut, which one made the difference? did two or three combine to make a difference?

I remember back in one of the Knives Annuals, there was a series of cutting tests done on four blades made form wire rope. they were testing blades with different wire counts, from a blade that was just welded to one that was welded and folded several times to get the wire count up. The test was pushing the blades through 2x4's at an angle. the first knife performed better than expected, the second one had been ground too thin, and the edge rolled. The authors statement stuck in my mind. it was something like "I thought I had the edge right, I didn't but the steel knew" a small difference in the edge geometry may be too small for us to notice a difference, but it will make a difference in cutting.

Please understand that I am not running down teststing, or even a type of test, I just want to know what is actually being tested, and what that information means.

Ken Nelson
 
One type of cutting test Im not sure actually tests the cutting edge is chopping some sections of firewood.

There are many video clips on YouTube I have been watching as of late , where the knife maker is able to shave hair, then pound it in some firewood. The blade splits the fire wood, and then we see that the edge still shaves hair.

But is this chopping of firewood really testing the cutting edge?
Im not too sure it is because it would seem to me that the wood can be also getting split by the pure shape of the sides of the knife.
It might be true that chopping firewood does not cause that much harm to the cutting edge on a convex grind knife blade.
But I would agree that chopping firewood is a good way to test the spine of a blade, to see how it works and how it stands up to this type of stress.
The handle can also be well tested by cutting firewood because once the blade gets stuck you may have to twist and bang on the handle to get the blade free.

Cutting rope is a good test because you can use the same rope on many knives over the years. It's also something that many people can copy as we all more or less have a chance to get some of that very same size and type rope. This would allow in a limited way, a chance to compare knives to see how you are doing compared to other knives.

Cutting things like leather is hard to reproduce again later on, as it's only going to show you how it cut this one section of leather due to the fact that leather can change in thickness, and stiffness so easy.

Cutting newspaper is another way for many people to have a common item that each can test against to see if this blade can compare to that blade.
 
BigJimSlade said:
... A full 14 hour day in the kitchen doing 3 services will kill a knifes edge worse than 3 full moose.
Click to expand...

Amen, I have found that steels and heat treatments that will keep a knife going strong for months in the field will be sorely tested in hours in a kitchen. Cutting surfaces can tear on things but then after all the chopping an dicing the blade will often get used to slide the food sideways into a pan... ouch! Frozen things, the acids in the foods, contact with other instruments, careless washing techniques etc... Not to mention real use, not sittin on a shlef while owners fantasize about surviving with their knife, but every day, hard "I don't care because it is just a knife and I need to get this dish prepared" type of use!
 
Isn't this why we have kitchen knives, and hunting knives, and not one knife?

I'm very interested in how you all bevel and/or heat-treat different blades for different purposes. I dare say that's at the core of why this whole topic is so intriguing.
 
The guidelines I described at the top of the thread only give me a redlight/green light as whether to continue on and finish a blade.
Any number of things can go wrong during a heat treat and it doesn't make sense to finish a knife if you know it isn't gonna hold an edge or chiop out.
As said above, field testing is the best answer but you aren't gonna send each knife you build out for 30 days testing before sale.
 
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