Edge Durability

zachattack

zachattack

Joined
May 5, 2012
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210
So I have a question about edge durability. If two of the same knives were sharpened at the same angel and used in the same way to cut the same thing for an X amount of time one had a hair splitting edge with a morror polish and the other with an edge that was just hair shaving sharp with out a mirror polish witch one would last longer and why? Would the mirror edge roll or dull easyer being that it is thiner on the very apex or how does that all work? If you could also say what you prefer and why that would be great too. I'm sorry if this is a dumb question but I am just getting into sharpening and tring to find the perfect edge for everything or most things.
 
Depends on the angle one uses, what steel and how you cut it ie push cutting or a sawing push and pull motion, if all else is the same such as geometry etc.

At low angles certain steels will have the carbides tear out, others can maintain low angles very well, others cant. Others do well with coarse edges because of things such as vanadium carbides being exposed.

Have a look here:

http://www.hypefreeblades.com/files/schneiden.pdf

See those giant white blocks, those can chip out at very low angles rather then rolling. However, at a higher angle and courser finish exposing those giant white blocks can give you very good cutting edge for a sawing motion.

It is all give and take and what you do for a living.

For me. High finish push cutting is for woodwork. Lower grit finish is for everyday things.
 
Wow thank you very much that actually helped a lot you seem to know quite a bit about this stuff thanks again
 
zachattack said:
Wow thank you very much that actually helped a lot you seem to know quite a bit about this stuff thanks again
Click to expand...

Thanks, but I only know through experimentation on my knives and reading. There are a lot of people that know more then me.
 
My experience with different steels, blade profiles, and edge thicknesses is pretty much the same as Marthinus'. I work in a warehouse and most of the cutting I do at work and around my house is draw or saw cutting. I don't have any need for push cutting since I don't use my knives for food prep or anything else where that would be necessary. I've found that a knife like my Emerson mini-CQC15 with old school 154CM and an edge off the Sharpmaker fine stones works better for me than a highly polished edge (UF rods and a strop) on something like S30V, M390, or ZDP189. I get a quicker cut with less effort, and a faster edge return when I have to touch it up.

No knife is best at everything. You just have to decide what your everyday cutting tasks consist of in most cases and try to meet those needs. Keep other blades around that are suited for different cutting tasks that don't come up often in your everyday use.
 
These gents above know what they're talking about. Reminds me that a very sharp, highly-polished mirrored edge won't easily cut through the skin of a tomato.
You need a bit of a roughness to the edge for best kitchen work. And according to the fellow who invented and sells the Edge Pro Sharpener, the best steak knives are regular cheap paring knives that have intentionally been slightly dulled. Perhaps a similar form of logic, but unsure. Someone can help me out here.
 
A coarser edge will slice longer than a polished edge, if both start at the same sharpness. There is a test for just what you've asked. Check out CATRA edge retention and cutting ability testing. Comparing results from different sources is tricky because you need to know several variables, but that test will answer your question.
 
Sonny, I sharpen toward a more coarse edge around 320 grit and it will shave arm hair and cut cardboard, rope and such for a long time. While not utilizing the top high end cutlery steels. (154-cm). I'm not so sure if the original poster is meaning the same by edge durability and edge retention. i.e. cuts a long time or resists rolling or chipping. A thicker edge angle 16-17* and sharpened to 300 grit will be durable yet will not give lighting cutting preformance. So, thru trial and testing one decides what degree they like taking their blade to. DM
 
More and more I break it down into draw cutting, combination cutting (draw and press) and press cutting. For hard use short blade I prefer a coarse edge, sometimes very coarse. For EDU it's something in the medium range, and for shaving or chopping I try to shoot for a finer smoother edge. Machetes, hatchets, axes get a higher polish than my pocket knives. I also believe longevity is a function of this selection too - a coarse edge tends to last a lot longer draw cutting, and a finer edge lasts longer when chopping. Most of this is probably related to the amount of pressure exerted on the apex - chopping with a rough edge requires noticeably more energy, as does draw cutting with a fine edge on many materials. As David Martin says, trial and error is the only way to get a feel for this.
 
Thank you everyone for all the info it has helped me understand it all very well. I'm super stoked about the feedback I'm getting.
 
Sonnydaze said:
These gents above know what they're talking about. Reminds me that a very sharp, highly-polished mirrored edge won't easily cut through the skin of a tomato.
You need a bit of a roughness to the edge for best kitchen work. And according to the fellow who invented and sells the Edge Pro Sharpener, the best steak knives are regular cheap paring knives that have intentionally been slightly dulled. Perhaps a similar form of logic, but unsure. Someone can help me out here.
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Might be true for the average housewife with a dull kitchen knife that lacks cutting technique but for the professional with a $200 Gyuto I would would say that's not all correct.

Instead of talking I'll just post the video, this is a highly polished edge when done correctly.
[video=youtube;GTHD2J2za6Y]http://www.youtube.com/watch?nomobile=1&v=GTHD2J2za6Y[/video]
 
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I'll second that. Nothing I've seen leads me to believe a polished edge should have trouble with a tomato. There are ways to improperly polish an edge that leads to an edge that will shave arm hair but not slice a tomato. This also is a highly polished edge:

http://www.youtube.com/watch?v=2P4ZCawMN8c
 
knifenut1013 said:
Might be true for the average housewife with a dull kitchen knife that lacks cutting technique but for the professional with a $200 Gyuto I would would say that's not all correct.

Instead of talking I'll just post the video, this is a highly polished edge when done correctly.
[video=youtube;GTHD2J2za6Y]http://www.youtube.com/watch?nomobile=1&v=GTHD2J2za6Y[/video]
Click to expand...

Man, that's an awful lot of draw just to get through a tomato! You know I'm Kiddin:)


I hear what you are saying, I keep one of my chef's knives to where it can do a straight up presscut through a tomato without catching. Not that I use it for that...But seriously, there's a huge gulf between the average housewife's block and a 200 dollar Gyuto. I'm willing to bet if you took a look at a dozen commercial kitchens outside of a sushi bar, you'd be lucky to find a knife among them that can press cut a tomato, and then only on the day when the sharpening service swaps out the lot. It definitely takes more time and effort to create and maintain that kind of edge, and I'm not even sure the soft Chinese stainless of most low-end kitchen cutlery will hold that edge for any length of time once achieved.
 
And that's probably some of the confusion, "kitchen knife" can be interpreted in many ways from visualizing a J.A. Henkles or something a little better like a Takeda.

Yeah, I probably could have worded that one better but that's why I posted the video :)
 
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