How tough is your edge really?

B

BostonBull

Joined
Dec 15, 2007
Messages
154
I have been reading a lot on here lately, TONS of great info! I see a lot of guys say, i cut this many ropes, or this gauge wire, or hit this many 2x4's and MY edge still cuts hair, or still push slices newspaper, or will still cut free hanging news paper hung over the blade.


Well..............
I am an Arborist. I am certified by 3 different organizations, and am a geek with all things wood and chainsaw related. I got to thinking..... When we cut different species of trees with chainsaws some dull chains a LOT faster than other species. I began to wonder if there was a standardized test of wood species and their densities?


I spoke with a well respected knife maker/sharpener on the boards here and did some research. Thats when I found the Janka hardness test. This test measures the hardness of wood. It measures the force required to embed an 11.28 mm (0.444 in) steel ball into wood to half the ball's diameter. This method leaves an indentation. It is a good measurement technique to determine the ability of a type of wood withstand denting and wear. It is also a good indicator of how resistant it is to sawing and nailing. (I pilfered this from Wikipedia) Here is a link to the USDA page about Janka tests. http://www.fpl.fs.fed.us/documnts/fplrn/fpl_rn303.pdf


I found a list of 1700+ species of wood on the Janka test scale here...... http://www.morlanwoodgifts.com/MM011.ASP?pageno=207


Here is what I am thinking. Most 2x4's are Doug Fir, Spruce, or Pine, very low density SOFT woods! How much damage is this actually doing to the blade of a knife? Its a piss poor measure of toughness in my opinion. Lets find a species on the list that rates at 2000 or higher, Apple, some hickory, dogwood, Osage Orange, etc all rate above 2000. Then let that piece dry out just like they do on the Janka tests, and then hit it with your sharpened edges. After the hitting, does it shave hair? Cut newspaper? Cut a piece of newspaper draped over the blade just by bouncing the knife?


The key here is knowing the exact species you're using. Using Latin/scientific names is the only way to go. Too many species have the same common names, and common names are misleading. If you need help identifying your species let me see the leaf and or the tree and ill key it out for you.



So lets see what your edges have!!!
 
Why would you want to chop 2x4s with a knife?

Don't know if you heard about batoning, but that isn't a good test on how tough knives are either.

Knives are meant to cut & slice things.

As an arborist, wouldn't you want to stick to axes and saws for cutting into any lumber?
 
Not me, folks on this forum use this as a test.

I see lots of the top level sharpeners here say they can hit this or that and still shave, slice paper, etc. So I figured why not standardize the test.

What would abetter test be? Slice through 1000 pages of a phone book and still shave with it?
Or........?
 
I'm confused by this thread. You're saying that instead of using an easily available spruce 2x4 to do some testing, the tester should hunt down a fresh cut piece of hickory, let it dry out, and then test the blade on that? What purpose does it serve? If guys are testing on spruce 2x4's then I would say that pretty much standardizes the test.

If I'm going to cut down a tree I'm not using a knife. Hell if I want to split logs I'm not going to use a knife. Honestly, where I live in NY, if I want to cut down a tree I'm calling an outside source to cut it down safely.
 
What I am getting at is that a lot of people use this striking a piece of wood as their test of choice to test their edges toughness. Spruce/fir/pine isn't a good wood to test it on, its not dense enough and absorbs a lot of the force being exerted. it would take 4 times as many strikes on pine, to do the same damage as on Hickory, or Osage orange. Would you rather hit a piece of wood 10 times really hard or 40 times really hard.

Point is these blades aren't being dulled or dinged up using these soft woods, and it doesn't prove anything. Put them to the test on some dense wood.

And there is no "hunting down" pick a species readily available in your area that is above 2000, and let it dry out. I can go out to a wood pile anywhere around here and find hickory, or apple.
 
What I am getting at is that a lot of people use this striking a piece of wood as their test of choice to test their edges toughness
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Well, my wife will use a knife for a screwdriver because she doesn't know any better.

Does that make it a good test for knives durability?
 
CWL said:
Well, my wife will use a knife for a screwdriver because she doesn't know any better.

Does that make it a good test for knives durability?
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Not talking about a knives durability. I am talking about the independent manufacturers, and the top level sharpening guys here on the forum. They use striking a piece of wood and then shaving with that same EDGE as their base test to prove they have a method that is superior to others.

Aren't most survival knives (Esee, Busse, Kabar) made strong enough to be struck through a piece of wood and still be able to retain their sharp edges?
 
Not looking for arguments, I am just looking to standardize abuse tests for edge retention that we can all relate to and replicate.
 
Ask the American Bladesmith Society. It's their test.

I'm not sure what would happen if a blade were used on apple, hickory, etc. I do have the opinion that cutting normal wood (pine, holly, whatever I have in my back yard) in general is not that tough a test for a hardened steel edge. I went through a 4x4 with a $10 machete and it would still shave hair off my arm.

Some species are worse than others, and I've heard of some that pull a lot of minerals up in the water and are quite abrasive on saws. I don't have any of these in my yard, so they are not "normal" to me.
 
Well let me start by saying this, I cannot tell a lie....

I chopped down the cherry tree, using my Mini-grip, and let me tell you, it was still hair popping sharp :D :rolleyes:



Disclaimer- This was done under the influence of some pretty good pain pills....
 
I believe the best test of an edge is doing whatever you typically do with the knife...and see how it holds up.

I (and apparently a few others) do not chop lumber with my EDC blade...so that would be a poor test for an edge for me (and apparently a few others).

I appreciate that some people might want to standardize a test for their edges...but do not assume that your standard and the standards of others will always agree.

I think the mistake being made is attempting to invent a protocol to "standardize abuse tests for edge retention that we can all relate to and replicate". Asking others to do anything involving "abuse" with their knives is pretty questionable....
 
unit said:
I believe the best test of an edge is doing whatever you typically do with the knife...and see how it holds up.

I (and apparently a few others) do not chop lumber with my EDC blade...so that would be a poor test for an edge for me (and apparently a few others).

I appreciate that some people might want to standardize a test for their edges...but do not assume that your standard and the standards of others will always agree.

I think the mistake being made is attempting to invent a protocol to "standardize abuse tests for edge retention that we can all relate to and replicate". Asking others to do anything involving "abuse" with their knives is pretty questionable....
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not asking anyone to do anything. Loads of people on here, all higly regarded makers and sharpeners already use this style of testing as a "proof" of edge retention. Why not use a dense wood, instead of a piece of soft pillowy wood?
 
me2 said:
Some species are worse than others, and I've heard of some that pull a lot of minerals up in the water and are quite abrasive on saws. I don't have any of these in my yard, so they are not "normal" to me.
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This is what I am talking about. certain trees abilities to take in different minerals than others, and the way their cells develop, and align themselves determine their density and strength.
 
BostonBull said:
Not looking for arguments, I am just looking to standardize abuse tests for edge retention that we can all relate to and replicate.
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To the OP, your proposed testing seems far more suited to woodworking and/or wood cutting tools and not knives. Sounds like a great test for an axe, plane, or wood chisel, not so much for my Kershaw Leek... just sayin'
 
See if you can find Wayne Goddards The Wonder of Knifemaking. It's in paper back and I found mine at the local B&N. It has a "choppomatic" in it that does what you are talking about, w/r to standardizing the test. He uses some Micarta, Mahogany, and another material I can't remember. The choppomatic is just a lever on a pivot with the blades clamped in place. The blades are dropped a known distance, and he has it set up to add weights for comparing different edge profiles while weight is held constant. He uses it to test cutting (chopping) efficiency of different edge profiles, but one could change things a little and use it for edge impact comarisons.

Out of curiosity BostonBull, did you ever run across a book by Anglo Prak on structural uses of wood? He was one of my professors and I was just curious if his book is widely read/recommended.
 
Maybe make a post about this in the Wilderness & Survival forum. That's where most of us who chop on wood hand out. :thumbup:
 
Why would you want to chop 2x4s with a knife?

Man, I gotta go along with this 100%. Knives are a cutting tool- period. I've seen first hand, people using a Damascus knife to pry open a paint can lid and snap the tip off a $200 plus blade. I find that totally rediculous but, short of giving an a new owner of a blade and IQ test, I guess you just shake your head and shut up because it's their investment.:confused::confused:
 
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