Blades testing

BD Blades

Well-Known Member
I am very new to knife making and wanted to know how you guys test your blades for cut, edge holding ability, toughness ect. Is there some sort of unwritten standard about how many rope or carboard cuts a blade should get or some other test medium.

I know there are many variations, what the intended purpose of the knife is, the blade steel and so on. I would be interested in some genral performance guidlines. I am curently working on fixed blade hunting and utility type blades using 5160.
 
as far a cutting tests go its one of the things you can ask 4 knife makers and get 5 answers. I have heard so many different ways, ranging from cutting paper and cardboard to cutting metal rods. IMO if you are have heat treat professionally done easiest way is to test you first of every design with actual use and just check the rest with paper or whatever you preferred method is to check the edge. if you are doing HT yourself probably with less controlled conditions and experience will need to check each blade individually.

just keep in mind I am new too so take more experienced opinions over mine.
-Cameron
 
The important thing about testing is to decide the aspects of a knife that are important to you, and more so to your customers. Then develop tests for those desired properties. I also feel it is very important that a maker "tests" their knives as often as possible in real world environments linked to the knives intended uses.

For example, every hunting season, I produce a new knife for myself to use. This knife always has the latest innovations, materials, and "tweaks" that I have come up with. Many times I run into cutting situations in the field that I simply would not have thought about, nor encountered if I limited my testing to the shop.

In the shop, I use hemp rope for edge retention testing. At one time in my career, I was all about gaining performance in relationship to cutting, and I concentrated specifically on that aspect. I started with cuts on the rope, until the blade stopped shaving. At that time, it was about 30 cuts. Over time it got to a number that I hesitate to state here....and one that I was very proud of. However, when I started telling people how many cuts I could achieve, many of them would say "BS".....and I realized there was a point when I had to think.....When is "good", good enough?" And where is that line between what I can achieve, and what people would believe. I still use rope to test, but most of the time I keep the results to myself.

One test that Wayne Goddard taught me years ago was the Brass rod test. This is nothing more than flexing the cutting edge over a brass rod to determine the proper "working hardness" for a given blade. It is performed with the final edge on the blade. If the edge flexes, and stays flexed, the blade is too soft. If the edge experiences tiny chipping, then it's too hard. If the edge flexes, then comes back to "true"....you've nailed the correct working hardness for that steel, in that blade configuration, with that particular edge geometry. It's a very simple test, that will give you a wealth of information about your process.

One other very important aspect, that I feel many makers overlook, is the ability/ease for a customer to resharpen a knife. Let's face it, ANY knife blade, no matter what the material, sooner or later will need to be re-sharpened. Those makers who concentrate on specific, high Rc numbers may indeed produce a blade that will exhibit a longer lasting edge, but customers will also come to hate that type of blade, simply because it will be very difficult for the average person to sharpen. I learned this fact when I first produced a few blade of CPM-S30V. In order for that steel to hold up, the Rc hardness must be relatively high, and at that Rc level, the steel has a great deal of abrasion resistance. Long story short, customers had a terrible time trying to sharpen those blades. Most of the time I would get a phone call with from a frustrated customer, asking if they could return the knife to me for sharpening. Although those blades performed great when they were sharp, many customers told me that they hated those knives when they needed to be sharpened.

So, there are a LOT of things to consider and think about when deciding on how to test your blades. There isn't any "set" standard or tests....the trick is to decide what's important to you and your customers, then figure out repeatable ways to test for those aspects YOU deem important. The key is to use whatever tests you devise as a guideline to improve your knives. Objectively look at the results from testing, and use that information to improve those aspects that the test(s) measure.
 
Thanks Ed that is what I was looking for.

I know there are all kinds of variables and needs, I was just curious about how other people test. Rope is one of my favorites as I can get it at the hardware store and it is a good test of cutting ability. Threre was a time when I was not able to sharpen any knife to cut rope. However it is not the endall be all test for cutting as you say. I will say i just got 110 cuts on 3/4" hemp out of my 4th blade and I considered it a personal victory for me and what I am doing at this time. It was 5160 I HT myself. But,, I am new and just getting started.

Thanks Again.
 
You can use hanging rope to test the geometry of the blade. I use bottles of water. I think that even a chopper should cut one bottle even if it knocks both halves across the yard. Best that I've done is two bottles with both bottoms left standing with water in them. Not sure how much that means on it's own though but it do look impressive.

Doug
 
One out of ten or so of my blades gets tested to destruction, after the gentler tests...
You can learn a lot from a broken blade, and what it takes to break it.
 
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