edge performance

[Scott Roush]

I've been doing these thin bladed stock removal knives lately made for the buscrafters and survivalists so I've really gotten into testing my edge performance by chopping on red oak knots and batoning, etc.

I'm just curious about how much you can reasonably ask out of even the best of heat treats on the best blades?  I'm using 0.095 15n20 tempered to 400 and with sustained hand chopping on oak (frozen!) my blades are slicing and shaving paper with the same performance before and after.. as well as popping arm hair.   But on another blade heat treated the same way.. I did some intense batoning (hitting the spine with a club) into the same oak knots and now I'm starting to lose performance.  I haven't seen any edge failure yet.. in terms of rolling over, cracking, chipping, etc... but a dulling which is expected I guess. This batonning does concentrate the force into a particular area of the blade compared to my hand chopping...

But I just want to know what the folks who really get into blade performance can reasonably expect? I guess I'm looking for a good standard.. or maybe a better way to assess the performance of my work?

[kbaknife]

Scott, I don't think I would be disappointed with the second test if you found no roll-over or chipping.
One of the beneficial aspects of the steels we normally use for forging is the ease of re-sharpenability.
How easily did it/they re-sharpen?

As an aside, I always quiz my new customers with the question, "How do you keep a knife sharp?"


answer - Don't let it get dull.

[Lin Rhea]

edited: Karl, I was pecking on the keyboard when you posted. Good morning. Gettin our first snow today.

Scott,
      It sounds like you are testing to a reasonable degree.
      A controlled test, one with a set routine of dynamics and cutting medium, is reasonable. Above that, we individually may want to increase the stress or wear on one or more of the differing features of the blade.

     For instance the ABS performance test is a reasonable test of a knife, but most of us will do more, or should I say differently, when in our own shop. In other words, you cant bend/flex them all 90 degrees.

     Another thing. What I consider reasonable for a 9-10 inch Camp Knife is different from what I count reasonable for a skinner. The expectations are different.

     There are a lot of variables, such as steel choice, edge geometry, blade lenghth, etc that the maker is supposed to consider when the knife is still on the drawing board. You ask yourself..."what do I expect from this knife?". Then you make it happen and test to see that is living up to your reasonable standard.

[Scott Roush]

Karl... these thin blades re-sharpen pretty easily with my belt sander and leather belt... I haven't really tried it on a stone.

Lin... yeah.. for my skinners I wouldn't worry about doing all this batonning and so forth.  

Do folks make camp/chopping knives with thin edges that can hold an edge through that kind of abuse?

As to edge geometry.. I'm grind it to a 10 degree scandi/flat type grind and then put a secondary 'apple seed' grind.   So it's completely flat to the secondary bevel.  For the smaller knives, I've been going all the way to the egdge.. but I figured with the chopper it was better to have the secondary bevel.

Anyway.. I guess I'm happy with the performance, but I just don't have a good standard in which to compare....

[Doug Campbell]

Sounds like your getting pretty good results and have put some thought into it Scott. Any particular reason you decided on the 15N20?

[Lin Rhea]

Scott,

There is thin enough and there is TOO thin. It's too thin or too thick when it dont suit the knife's intended use. I make them as thin as I can without getting too thin. So, if it's a Camp/Chopping knife, I use the same idea of making it as thin as possible and still withstand the abuse.

A blade that is too thin for it's intended use, will fail in the form of rolled edge, wrinkles etc.

Dulling with heavy use is not failing unless it is due to poor heat treat.

The best performing knives have several things all working together at the same time. Heat treat, geometry, and design.

[Scott Roush]

thanks folks... I will keep at it. Probably the best thing is to form my own standard and make sure I continue to live up to it.  I really need to start doing this more with my 1084 forged stuff too.  

Doug.. I already had the 15n20 from the san mai I was doing and on a whim I made a kitchen knife from it and was impressed with it's edge retention in the kitchen.  Then I was talking with a local bushcrafting/survival instructor who was talking about the value of thin bladed knives for what he does... And then I saw some of Andy Roy's at Fiddleback Forge, etc.  It also occurred to me that the little bit of stain resistance you get from the nickel might be attractive to some folks. I don't know.. it's fun for me to just quick cut out a design.. heat treat it and see how it does.  Adds a different component to my work I guess...

[Scott Roush]

so here is a chopper made from that stuff and a video showing how I tested this one..

 

 

 

[bretto]

If You haven't seen this video it's impressive. Great job Scott.

bretto

[Scott Roush]

Thanks bretto...


I forgot to mention... I reground this edge and made it more convex before shooting that video.. seemed to make a big difference in how it held up....

[Nosight]

Love the look and preformance of this knife...

Will like to see it finshed ....

Later....Buzz