Interesting video… do you destress your edge?

[Josh]

Interesting observation and theory about how the edge can get “burnt” at the factory and have an initial low sharpness/edge holding ability.

[Mikedoh]

If I’m understanding this, the overheating only goes so far? Which makes sense, compared to my former idea that the entire blade was ruined.
Also wondering, if quenching in water to cool blade in s30 is wrong, is there then a proper medium to quench in?

[Josh]

I have heard it explained that if you are grinding a blade on a belt sander, and it gets hot, you need to mist spray it, not actually dunk it in cold water as this can cause “micro-fracturing” of the edge.

This is something that the WEPS really shines at since its not powered…when I remember to, I take my 1k diamond stone and destress the edge before I begin the sharpening process. The diamonds are nice because they don’t wear when you do this, unlike water stones (which your blade can actually cut into).

When the knives from from the factory they are sharpened on powered equipment… it is only the edge that can possibly be damaged because that is what is contacting the belt and it is very thin, so it builds up heat quickly.

[Mikedoh]

So then de stressing the edge is getting rid of the damaged area by running the stone perpendicular to the knife edge?

[Josh]

exactly! only 1 or 2 passes w/ 1k is enough…

[Mikedoh]

No need for the multi de stress / sharpen as talked about in the video?
If sharpening is involved, just a cursory to 400 or 600 ? Then whittle some wood?

[cbwx34]

I do believe that making a cut into a stone is beneficial on some blades… it provides a nice clean surface to form a new edge. But, I question some of what’s in this video…

At 1:08 he shows a new knife. Notice how much metal is now gone from the knife (he also mentions around the 3:10 mark that the sharpening choil is “gone”.) I doubt he did that in his 3 destress/sharpening routines. So, why, after all that metal removal, is the edge suddenly better… and that it’s now a heat related issue? He could have (probably) cleaned up the edge from the previous use (which from his description was pretty harsh), but I would think that the heat related issues he claims would have been gone long before?

I often find that just sharpening a knife a couple of times will improve sharpness. My guess is that the knife “matches” (can’t think of a better word right now) how I sharpened it, so the 2nd, 3rd, etc. time, it will improve. He also did other things to it… thinned the entire blade for example, that would have improved it. Maybe the simpler answer is, after 7 years his sharpening ability improved? :dry: (No idea, just suggesting there’s other reasons).

So, yes, IMO, there’s some validity to cutting into a stone and providing fresh metal to sharpen will result in a better edge, but not sure I buy the reason in the video.

[Kent]

Where is the proof that they dipped the blade in water after grinding. Thats a ridiculous notion. I would imagine that would get one fired at a knife company.

I have heard reports of the s30v chipping. And it is a pain to sharpen both benchmade and ZT. It makes since that the edge could have been overheated when grinding. As it takes me 2-2.5 longer time wise to sharpen s30v compared to 440c.

[Josh]

I do believe that making a cut into a stone is beneficial on some blades… it provides a nice clean surface to form a new edge. But, I question some of what’s in this video…

At 1:08 he shows a new knife. Notice how much metal is now gone from the knife (he also mentions around the 3:10 mark that the sharpening choil is “gone”.) I doubt he did that in his 3 destress/sharpening routines. So, why, after all that metal removal, is the edge suddenly better… and that it’s now a heat related issue? He could have (probably) cleaned up the edge from the previous use (which from his description was pretty harsh), but I would think that the heat related issues he claims would have been gone long before?

I often find that just sharpening a knife a couple of times will improve sharpness. My guess is that the knife “matches” (can’t think of a better word right now) how I sharpened it, so the 2nd, 3rd, etc. time, it will improve. He also did other things to it… thinned the entire blade for example, that would have improved it. Maybe the simpler answer is, after 7 years his sharpening ability improved? :dry: (No idea, just suggesting there’s other reasons).

So, yes, IMO, there’s some validity to cutting into a stone and providing fresh metal to sharpen will result in a better edge, but not sure I buy the reason in the video.

Good observations Curtis… My answer to your first question (why is it suddenly better) I would say that it depends upon 1. how damaged the edge was at the factory (in terms of depth from the edge to the spine” and 2. how many times it was sharpened over those 7 years. These are two variables that we don’t know… Cliff could have removed a bunch of steel during those sharpenings or not much. Anyway, that is his theory and it makes sense, but I would like to see some metallurgical data that shows heat treated steel can be damaged w/ only heat.

I have heard that it takes not just heat but also TIME to damage temper… don’t know how true this is? I will probably be able to speak w/ a metallurgist tomorrow so I will def. ask :side:

[Josh]

Where is the proof that they dipped the blade in water after grinding. Thats a ridiculous notion. I would imagine that would get one fired at a knife company.

I have heard reports of the s30v chipping. And it is a pain to sharpen both benchmade and ZT. It makes since that the edge could have been overheated when grinding. As it takes me 2-2.5 longer time wise to sharpen s30v compared to 440c.

While I don’t have any proof at this point =) Think about it… dunking your blade in a bucket of water while using it (post heat treat) with a belt sander is a pretty common practice, otherwise you WILL over heat it if you are doing any serious amount of metal removal or reprofiling (which you would be to put the final edge on it post heat treat). It may or may not be the case, but is an interesting theory none the less.

[Kent]

While I don’t have any proof at this point =) Think about it… dunking your blade in a bucket of water while using it (post heat treat) with a belt sander is a pretty common practice, otherwise you WILL over heat it if you are doing any serious amount of metal removal or reprofiling (which you would be to put the final edge on it post heat treat). It may or may not be the case, but is an interesting theory none the less.

I took a relook at the you tube video of Bark river knives shop tour. The showed the employees dipping the knives in water while putting the edge on then. :blush:

But while searching, the act of destreesing a knife is usually a heat treat process called “normalizing”. Where a forged blade is softened to allow the initial grinding to take place. What he is doing isnt de stressing the edge, as the original edge metal is long gone. How can u de stresss something that isnt there

It would be interesting to see the results of a Rockwell hardness test of the new edge. Maybe the initial heat treat wasnt done properly on the first batch of knives. Or they surfaced hardened the knife edge in properly but the initial heat treatment was correct and the countless sharpenings made it past the surface harding.

[Josh]

Yeah 😉 He isn’t referring to normalizing, which is a step just prior to heat treating. What Cliff is referring to is this. When you use your knife the edge gets dented bent, and chipped with the various peaks and valleys (i.e. micro-serrations) basically suffering the damage. When you strop, “steel,” or even lightly sharpen your knife, it weakens your edge due to the metal at the very edge being bent back and forth. Destressing would be removing the weak metal by cutting 90 degrees into a sharpening stone to remove the damage before actually sharpening to put a clean, fresh edge on it that is stronger. This is how the theory goes anyway :side: Makes sense to me as it is commonly accepted that metal weakens the more it is bent.

[Eamon Mc Gowan]

Think about it… dunking your blade in a bucket of water while using it (post heat treat) with a belt sander is a pretty common practice, otherwise you WILL over heat it if you are doing any serious amount of metal removal or reprofiling (which you would be to put the final edge on it post heat treat). [/quote]

Please excuse my ignorance? When grinding a knife how hot is to hot? I’ve heard if you can still hold the blade it never got hot enough? I’ve had it pretty hot as I pull away from the pass but it drops rapidly in the next two seconds. But never hot enough that you just could not touch it?
What do you guys think? Thank you,
Eamon

[Carl Sauer]

I keep pretty detailed sharping records even though most of the knives I sharpen are pretty low quality.
One thing I noticed is that sometimes for a particular knife the first few sharping’s turn out marginal at best. Each time I sharpen it, the better the edge becomes.

Early on I thought it was the WEPS learning curve. I was just getting better at using the tool. But it still happens after many knives and many incredible first edges. I then thought maybe it was the steel. But if it was the steel should not the edge remain marginal on every sharping? Something else must be the happening.

Like I said most knives that I have fall in the budget price category. Most people I know don’t use quality knives. If it’s good enough for Ron Propiel, it’s good enough for them. Other than my own knives, I rarely get high quality knives to sharpen. Low quality knives can still get razor sharp but just don’t stay that way for long.

I had a knife that I got from my junk box, a Farberware Chef knife. It was a dull as a board. I wanted to use it to practice the speed techniques as discussed in another tread. I started with the 80 grit stones and followed the progression to 600 grit. Eight minutes later I still had a pretty dull knife. Better but it was in no way acceptable.

OK I’m not doing something right. I did it again and got the same result; a little better but not good. It would not cut printer paper cleanly. Now one more time – same result (is this the definition of insanity – doing the same thing over and over and expecting a different result?). Now I’m thinking the knife is junk but still I should have gotten better results. I then decided to go for it and do a proper WEPS sharping. After about half an hour down to 1000 and strops, it was getting better but still struggled through printer paper. It was a lot better but nothing to write home about. I did get a burr on the course stones which accounted for most of the sharping time. The burr was weak and hard to get, but it was there. It must be the type of steel I thought and was ready to give up. The knife was just trash. Then I decided, after seeing this tread, to take a few minutes on the belt sander to see what I could do. I didn’t want to spend too much more time on this knife, but I wanted to see what would happen if I ground it down further. I had nothing to lose.

I used 80, 40 and 9 micron belts and in less than 10 minutes the knife would glide through phone book paper! I have other records of knives I started on the belt sander that were fair and after a sharping on the WEPS razor sharp. The reverse of what happened here. It’s not the tool; something else is going on. It may be the way the knife is made; maybe the way it was heat treated or the way it was sharpened at the factory that affected the steel. I think I see more of this and it may be more pronounced given the kind of knives I get to work with.

I’m not a metallurgist just a hobbyist so I don’t know. What I see lends weight to the theory that the steel at the edge is inferior to the steel further in whatever the reason. It’s a matter of how far you have to go to get to the ‘good stuff’. I must not have gone deep enough with the WEPS but must have been close. Maybe another sharping would have gotten me there. I also know for some really cheapo knives there isn’t any good stuff.

For some knives distressing the blade may have value. I have in my records where I did several passes with a file to clean up a really rough edge and the results have been very good. I can’t say that distressing caused the good final result but it sure didn’t hurt. Distressing may help in some cases get to that good steel quicker. I would not distress a blade as a matter of course, however, especially on a good knife. But it may be something to try if you are not getting the results you think you should be getting.

[cbwx34]

Yeah 😉 He isn’t referring to normalizing, which is a step just prior to heat treating. What Cliff is referring to is this. When you use your knife the edge gets dented bent, and chipped with the various peaks and valleys (i.e. micro-serrations) basically suffering the damage. When you strop, “steel,” or even lightly sharpen your knife, it weakens your edge due to the metal at the very edge being bent back and forth. Destressing would be removing the weak metal by cutting 90 degrees into a sharpening stone to remove the damage before actually sharpening to put a clean, fresh edge on it that is stronger. This is how the theory goes anyway :side: Makes sense to me as it is commonly accepted that metal weakens the more it is bent.

Maybe instead of “destressing” simply “cleaning up” the edge, might be a better description.

Think about it… dunking your blade in a bucket of water while using it (post heat treat) with a belt sander is a pretty common practice, otherwise you WILL over heat it if you are doing any serious amount of metal removal or reprofiling (which you would be to put the final edge on it post heat treat).

Please excuse my ignorance? When grinding a knife how hot is to hot? I’ve heard if you can still hold the blade it never got hot enough? I’ve had it pretty hot as I pull away from the pass but it drops rapidly in the next two seconds. But never hot enough that you just could not touch it?
What do you guys think? Thank you,
Eamon[/quote]

If I do something major on a belt sander, my approach is to use water to keep the blade cool, not to cool it off once it gets hot. If you make several passes, you can feel heat build up in the blade, and eventually it won’t “pull heat” from the area being worked. So, I try to keep it cool and avoid the blade getting hot (or even very warm) in the first place.

[Author]

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