Finally Breaking 100 BESS—Thoughts & Feedback Welcome

[Rob Babcock]

My bud is an avid hunter. He loved the polished skinner I sharpened last year. Said it slid through two deer effortlessly.
In the book “knife Deburring “, the late Vadim had meat processing plants evaluate what type of edge cut better, toothy or refined. Refined won easily. The cutters stated they were able to be more precise with their cuts, it caused less fatigue and the knives stayed sharp longer.
Does anyone know of any other scientific tests on the two edges, smooth vs toothy?

Not at all scientific but as a chef I have always preferred a polished edge for virtually all applications. My own knives are all finished on a 10k Chocera and stropped with 1/8 micron CBN on kangaroo leather of StroppyStuff 0.25 micron diamond on 'roo or nanocloth.

As I like to tell people, your final sharpness starts at your first stone.

Absolutely true! Most of the actual sharpening is done on the arato, it's mostly polished from there. If you don't have a shaving sharp edge off the arato (once deburred, natch) you're not ready to move on.

 

[jeffbird]

My bud is an avid hunter. He loved the polished skinner I sharpened last year. Said it slid through two deer effortlessly.
In the book “knife Deburring “, the late Vadim had meat processing plants evaluate what type of edge worked better for butchering, toothy or refined. Refined won… The cutters stated they were able to be more precise with their cuts, it caused less fatigue and the knives stayed sharp longer.
Does anyone know of any other scientific tests on the two edges, smooth vs toothy?

Cutting wild game hides, especially wild pigs that roll in mud, is different than cutting chilled meat. As I mentioned above, I use very refined edges on my kitchen knives. Try both edges for yourself on some game hides. I’ve tried every finish imaginable on a whole lot of deer and pigs, well into the many 100’s.
fwiw - I had this same discussion with Phil Wilson years ago about which edge to use on the game hides with his knives and he came to the same conclusion with his rope cutting tests.

 

[Wowbagger]

My bud is an avid hunter. He loved the polished skinner I sharpened last year. Said it slid through two deer effortlessly.
In the book “knife Deburring “, the late Vadim had meat processing plants evaluate what type of edge worked better for butchering, toothy or refined. Refined won… The cutters stated they were able to be more precise with their cuts, it caused less fatigue and the knives stayed sharp longer.
Does anyone know of any other scientific tests on the two edges, smooth vs toothy?

The Science Of Sharp has proved refined edges are stronger than toothy because the edge suports it's self along the length where toothy is like weak little independent shapes that can fold or not when stressed . Perhaps I didn't explain that as well as he does but that's the jist of it. It isn't theory he is looking at the edges on a few micron scale along the edges.

 

[Wowbagger]

. . . anyway.
I had another experience today with a toothy edge picking up and holding material from the work .
vs cutting the exact same material with a polished edge. Both were basic , basic Case SS blade alloy .

Everyday I cut "rope" off of machines in packing crates . The rope is made of brown paper that is twisted into cords to use as tyedowns .
On the same machine I went to cut one rope (all ~6mm diameter), this one was double and I knew all I had to do was cut one of the strands and then pull it out of the machine. I went to slide the blade between the two in preparation to put force into the knife to cut the cord. Just the act of sliding the blade between the cords cut one of them in two . My mouth fell open . I knew it was going to be easy but didn't expect that .

The knife was a Case Trapper (Celtic knot etched bone # 083 for those who care ) . Crazy thin / reprofiled (guessing the bevels are 10 deg per side with a very minimal secondary edge ; just enough to allow it to hold up to this type of work . . . previously I was showiing off cutting monster size wire ties and kind of beat up the edge so recently I had touched it up on the Edge Pro with just the Norton 8000 yellow stone going a little more obtuse . . . still had all that "Stressed" steel on the edge though . . . hmmm cuts like a freeking monster so I guess I won't get too worked up about the stressed steel at this juncture .

Right near it I needed to cut another cord .
I used my Case Sowbelly Spay blade in same steel . The edge was stock sharpening angles from Case but , as with nearly every Case factory edge , I had taken off the rolled jagged apex , I used one of my Sharpmaker medium (brown) triangle rods free hand / hand held just enough to get the bur off then ran the Fine and Ultra Fine just enough to produce an arm hair shaving edge so I could fool around with the knife at work until I make time to put a real Edge Pro edge on it.

Now . . . this blade is A LOT thinner at the spine than the Trapper so keep that in mind also.
Firstly the Sowbelly Spay took MUCH more effort to cut the cord though it is a very thin blade.
And still toothy.
Secondly later I glanced at the knife laying open on the bench and saw something on the edge.
I thought : how did I get tape glue on that ? I haven't cut any thing but the dry cord since I cleaned the blade with WD .?
Turns out on closer inspection what was on the edge were paper fibers from the cord stuck in the teeth of the toothy .
That''s good right ?
I don't see that being a performance advantage .

 

[Jason B.]

The Science Of Sharp has proved refined edges are stronger than toothy because the edge suports it's self along the length where toothy is like weak little independent shapes that can fold or not when stressed . Perhaps I didn't explain that as well as he does but that's the jist of it. It isn't theory he is looking at the edges on a few micron scale along the edges.

And CATRA machines prove that toothy edge will last much longer. The science of sharp is a good read but it's not the final answer.

Toothy edges last longer because there is more surface area along the length of the edge, which creates a larger/longer cutting surface that takes longer to wear down.

 

[Gottagofishn]

Obviously there are as many opinions on refined vs toothy as there are ways to get your knife sharp. Kinda like politics, we twist the facts to fit our opinions.
I like a refined edge that can push cut in the kitchen, I reach for something toothy outside.
I can’t think of a rope I’ve ever push cut though.

 

[Jason B.]

Obviously there are as many opinions on refined vs toothy as there are ways to get your knife sharp. Kinda like politics, we twist the facts to fit our opinions.
I like a refined edge that can push cut in the kitchen, I reach for something toothy outside.
I can’t think of a rope I’ve ever push cut though.

The question of refined vs toothy in terms of pure edge retention is well documented in the industry and I've seen it in CATRA testing I've done.

There is a difference between edge retention and what type of edge is preferred in a task. It's why you sharpen a folding knife different from a kitchen knife, razor, etc. I put a 4000 grit edge on my kitchen knives and a 600 grit edge on my folders because that's what I like for the tasks those tools perform.

 

[Wowbagger]

I'll ask again :

PS : curious what edge geometry failed to hold a useful edge for skinning when polished ?
I go back to those old Cliff Stamp vids of endless carpet cutting with acute edges .

Since we are all about cutting sand paper (pig skin and sand impregnated cards ) :
This is from Dr. Larrin Thomas's testing at Knife Steel Nerds

Importance of Edge Geometry

Another important caveat before we get to the ratings are that these are for the steel only. This does not predict which knife will cut longer or be more resistant to chipping. The reason is because sharpening and edge geometry will also greatly control properties. For example, see the chart below for how much edge retention can change with edge geometry for a single steel (in this case 154CM and CPM-154). Using 10 dps sharpening (20 degrees inclusive on the chart) leads to about 5x the edge retention of 25 dps.

 

[jeffbird]

I'll ask again :

Since we are all about cutting sand paper (pig skin and sand impregnated cards ) :
This is from Dr. Larrin Thomas's testing at Knife Steel Nerds

Importance of Edge Geometry

Another important caveat before we get to the ratings are that these are for the steel only. This does not predict which knife will cut longer or be more resistant to chipping. The reason is because sharpening and edge geometry will also greatly control properties. For example, see the chart below for how much edge retention can change with edge geometry for a single steel (in this case 154CM and CPM-154). Using 10 dps sharpening (20 degrees inclusive on the chart) leads to about 5x the edge retention of 25 dps.

On the Edge Pro for the hunting knives, I use the yellow mark, which is 21 degrees.

I sharpen freehand more often than using the Edge Pro, so cannot give degrees for the freehand edges. I use the same placement on the pad of my thumb for all sharpening. So the edge is the same stone to stone and knife to knife. While I cannot give degrees for freehand, but can say the angles are the same for making comparisons on the same knives. In recent years my edges are towards the thinner side than I used in the past.

 

[garry3]

I'll ask again :

Since we are all about cutting sand paper (pig skin and sand impregnated cards ) :
This is from Dr. Larrin Thomas's testing at Knife Steel Nerds

Importance of Edge Geometry

Another important caveat before we get to the ratings are that these are for the steel only. This does not predict which knife will cut longer or be more resistant to chipping. The reason is because sharpening and edge geometry will also greatly control properties. For example, see the chart below for how much edge retention can change with edge geometry for a single steel (in this case 154CM and CPM-154). Using 10 dps sharpening (20 degrees inclusive on the chart) leads to about 5x the edge retention of 25 dps.

Clearly the 600 grit edges performed better than the 8000 grit edges....

Maximizing Edge Retention - What CATRA Reveals about the Optimum Edge - Knife Steel Nerds

Thanks to Ed Schempp, Matus Kalisky, and Chin Lim for becoming Knife Steel Nerds Patreon supporters! Your support allows us to fund CATRA studies. CATRA Update 1/6/2020: I have since written more articles about CATRA looking at the effect of steel type: Part 1 and Part 2 Cutlery and Allied...

knifesteelnerds.com

 

[garry3]

And this...



I'm not using a toothy edge on my woodworking tools and I'm not using a polished edge to process game in the field.
It's not that hard to understand.

 

[garry3]

Not at all scientific but as a chef I have always preferred a polished edge for virtually all applications. My own knives are all finished on a 10k Chocera and stropped with 1/8 micron CBN on kangaroo leather of StroppyStuff 0.25 micron diamond on 'roo or nanocloth.

Absolutely true! Most of the actual sharpening is done on the arato, it's mostly polished from there. If you don't have a shaving sharp edge off the arato (once deburred, natch) you're not ready to move on.

Do you not prefer some tooth when slicing tomatoes? I ask because the chefs I know prefer some tooth when cutting tomatoes.

I don't seem to care one way or the other but I'm just a home cook so I might only cut two or three during a meal prep.

 

[Jason B.]

Do you not prefer some tooth when slicing tomatoes? I ask because the chefs I know prefer some tooth when cutting tomatoes.

I don't seem to care one way or the other but I'm just a home cook so I might only cut two or three during a meal prep.

The question is deeper than that, and a lot will depend on the knife being used. The differences in steel, hardness and blade geometry can be huge factors in sharpening and performance.

Softer steels tend to perform better with a coarser edge while harder steels tend to perform better with finer finishes. Wusthof, henkles and Victorinox are all great kitchen knives but examples of softer stainless that perfer a coarser (thoothy) edge. Now, move over to harder and thinner Japanese style knives and that coarser edge starts creating drag in the cut. The edge wants the finer polish and maintains its "tooth" even at finer grits, thus allowing the blade to slice smoothly and precisely.

When I sharpen kitchen knives it's all about the knife and the food it was meant to cut. I sharpen a paring knife different from a chef knife and as the steel hardness varies between blades I adjust the final grit. I account for all of it to produce the edge most suited to the task.

 

[Rob Babcock]

A hard Japanese knife sharpened on water stones will still have bite even off the 10,000 grit Chocera stone. That falls through a tomato with the weight of the blade.

 

[Rob Babcock]

The question is deeper than that, and a lot will depend on the knife being used. The differences in steel, hardness and blade geometry can be huge factors in sharpening and performance.

Softer steels tend to perform better with a coarser edge while harder steels tend to perform better with finer finishes. Wusthof, henkles and Victorinox are all great kitchen knives but examples of softer stainless that perfer a coarser (thoothy) edge. Now, move over to harder and thinner Japanese style knives and that coarser edge starts creating drag in the cut. The edge wants the finer polish and maintains its "tooth" even at finer grits, thus allowing the blade to slice smoothly and precisely.

These are excellent points! I never take a German knife past 1,000 grit- they just won't hold that polish long enough to make it worthwhile. My preference for a highly polished edge stems from the fact that all my work knives are higher end Japanese.

 

[garry3]

There does seem to be a general consensus with the soft stainless used in them European knives to not bother with anything very fine.
I am also in that camp, usually finishing them on a fine or medium India. They offer lessons to be learned in burr removable and mitigation I suppose, but I find no joy in them.

 

[Diemaker]

I finish my Henkels well beyond 5 micron stones and they hold their edge fine, 10 dps with a 15 dps mini bevel. Granted, I only cut on polyethylene mats and never hit bones or hard things knives are no good at cutting. Wood is far too abrasive to use as a cutting surface.

 

[Wowbagger]

tomatoes

Oh now there I can write a novella :

It's all about geometry (see Carter Cutlery YouTube : Western vs Japanese kitchen knives ).
My knive's geometry (and edges ) are set to slip into the skin on the very , very side (as if cutting the tiniest slice off imaginable) of a past ripe tomato and hang there slipping into the skin just from the weight of a very light knife . ( I had a few photos of that here in the past . . . but . . . alas . . .)
so
here again I MUCH prefer polished.

An extreme example of the very opposite is an inexpensive folding pocket Fruit Tester's Knife I bought a decade ago that had such OBTUSE edge geometry it would not slice / cut in half a hot dog bun but would just keep crushing in on the soft crust of the bread even when sharpened tooth on the factory edge.

Western kitchen knives do the same thing on tomatoes ; fail to penetrate the skin because the edge is sitting in a "hamock" of skin .
It seems every Western kitchen knife MUST be capable of cutting through bones (and so is incapable of cutting anything else).

I reprofiled the folding fruit tester's knife to about 11 or 12 degrees per side and , polished the edge . . .
It will now easily and precisely slice hot dog buns all day .
(bread knife ? ANY knife is a "bread knife" with some decent / appropriate edge geometry .)

I just pulled out my perfectly lovely bread knife (which I never use) to have a look at the geometry :
about 1mm at the spine
sabor ground with ~10 bevel grind with edge bevels about a degree or so more obtuse
wavy serrated of course.
I was just wondering if it was like so many serrateds and single bevel / chisel grind . Nope double bevel.

EVERY BODY GETS ALL EXCITED ABOUT SERRATED
when
WHAT IS DOING THE CUTTING IS THE EXTREME EDGE GEOMETRY
e.g. my brand new MIRACLE Spyderco Chaparral with serrated edge ; you know the one . . . Gray FRN , XHP . . . I got so exited with all the Hype I bought one (love Chaps and love XHP ; why not right ?)

I stand by what I said : it is a good cutter because it has an even more acute edge than the standard Chaps = a single bevel edge is a so MUCH more accute edge .
Not some magical serratedness .
I still prefer cutting most every thing with my standard , old time , original , peal ply Carbon Fiber Chaparral that I reprfiled the crap out of ( and polished) .

any day .

but back to the tomatoes (and apples and . . .) no need for serrated or toothy for tomatoes . . . polished and acute . . . acute and polished
mic dropped
BOOM .

 

[garry3]

My thoughts on wood cutting boards and butcher blocks......

 

[Wowbagger]

I'm not using a toothy edge on my woodworking tools and I'm not using a polished edge to process game in the field.
It's not that hard to understand.

I've been mulling this for a day or two.
No doubt you are right .

FOR ME
AND GETTING BACK TO CUTTING FILAMENT which is what the thread is originally , roughly , about .

I enjoy cutting stuff . It isn't a chore to get through as quickly as possible .
Polished edges are more interesting than toothy edges :
more fun for me
the way they look
the way they slide more controllably through the work
they cut with less effort

Edges , on my knives , set at about 1.8 mm at the spine or less , about 12 degrees per side and 0.010 inch behind the edge cuts about everything I need to cut (unless I go even more acute for cutting rubber products at work with lube on the blade and on the work (ooooh sounds like skinning doesn't it) .
anyway
The former includes kitchen knives AND knives that do the hardest cutting job I do which is cutting quadruple wall cardboard (which puts the most force into the blade to handle joint of anythinng I do).

I enjoy sharpening . . .
Toothy edges are MUCH easier to sharpen
they stay sharp(ish) longer (~)

So I get to sharpen less ! ? ! ?
so I don't GET to sharpen as often ! ? ! ?
so I don't GET to sharpen as long (meditation periods will now be LIMITED ! ? ! ?

And I have so many knives I rarely sharpen as it is . . .
THIS TOTALLY SUCKS !

FOR ME .