Thin Behind the Edge

[curreel]

Excuse this basic question.

When we speak of a knife being 'thin behind the edge', where is this 'thin' measured? Is it directly - at the top (spine side) of/ just above - the edge bevel itself?

If it is, what of wide bevel knives (such as Hado)?

Apologies again; no doubt this forum has more worthy issues to concern itself with!

Thanks in advance

 

[ethompson]

I think of “behind the edge” as the area from the cutting bevel up 5mm as measured perpendicular to the edge. And then I think of the area just above that as “above the edge”

 

[Jovidah]

For me it means the area right above the edge, so the first couple of milimeters. Though you could debate whether 1mm above the edge is more important or 5mm above the edge; I honestly don't know. But the general idea is that the thickness of the knife near the edge has far more influence on cutting performance than the thickness of the spine - which used to get a lot of attention (and is often measured by retailers) but is not particularly informative in regards to cutting performance.

So for example a Wüsthof and a Yoshikane are actually not all that dissimilar in spine thicknesses, but they cut wildly different, because the Wüsthof is fat near the edge, while the Yoshikane is ground very thin near the edge.

 

[Benuser]

I would measure at the shoulder, if any. Above the bevel. The area from there to 1cm (3/8") upwards is what I would call behind the edge, whose thickness determines the knife's performance. With a chef's knife or gyuto used with a lot of board contact, I aim for 0.2mm thickness above the edge, 0.5mm at 5mm more towards the spine and 1mm at 10mm. Just meant as a rule of thumb, and easily remembered.

 

[Rangen]

Excuse this basic question.

When we speak of a knife being 'thin behind the edge', where is this 'thin' measured? Is it directly - at the top (spine side) of/ just above - the edge bevel itself?

If it is, what of wide bevel knives (such as Hado)?

Apologies again; no doubt this forum has more worthy issues to concern itself with!

Thanks in advance

It is an excellent question, with more of an "I know it when I see it" answer than a precise answer from most. It's also a question that goes to the heart of what we do and like.

I am still sorting out my answers as to what "thin" means. I have been using 10mm behind the edge as a reference point, but that's only because it's a clear demarcation on my calipers. There are people here who like knives to be really thin behind the edge, which would be <1.25mm at 10mm behind. Some speak of being able to flex the edge with a fingernail, and want the knife, or at least the tip, to "ghost through" onions and peppers and the like.

My preferences are more like 1.40mm thickness at 10mm behind the edge, with some weight to the knife.

 

[Bensbites]

I have started measuring the thickness of the knives I make or thin at various increments, then I can plot the pictures and understand how thickness impacts performance

 

[Delat]

I don’t personally use the term “thin behind the edge” because there’s no general consensus for the definition as you can see from the responses so far.

For my own science experiment I’ve been measuring immediately behind the cutting bevel (i.e. at the shoulder) and up to 10mm at the midpoint of the blade. Here’s a snapshot of my in-progress spreadsheet. Where I have multiple entries like a “.1”, etc, is where I’ve done some thinning.

I’m sure my measurements lack both precision and accuracy, but measurements definitely cluster around the way certain groups of knives feel to me. For example the Myojin, Yoshikane, and Birgersson have a similar light effortless feel through food - what I personally consider to be laser or near-laser performance. The Kamon has more of a midweight feel, requiring a bit more effort but bringing a certain robustness overall. When I decide to start thinning a knife, I generally shoot for the Myojin/Yoshikane measurements.

 

[HumbleHomeCook]

Excuse this basic question.

When we speak of a knife being 'thin behind the edge', where is this 'thin' measured? Is it directly - at the top (spine side) of/ just above - the edge bevel itself?

If it is, what of wide bevel knives (such as Hado)?

Apologies again; no doubt this forum has more worthy issues to concern itself with!

Thanks in advance

No bad questions here friend. That's what this forum is all about!

 

[ethompson]

In fact this is one of the most important questions of all!

 

[curreel]

Many thanks for all the posts which were helpful and informative. And a happy new year to one and all.

 

[mengwong]

In fact this is one of the most important questions of all!

See:

The Rule

Any knife which carries convexity into the edge and easily passes the nail-flex test is thin enough to be an elite performer for kitchen tasks.

 

[Just a DK]

For me its bee about the feel of a knife…

Kinda hard to describe but the yoshi kind of became my standard…but the feel of below is similar (top to bottom Yoshikane SKD, Komorembi, TxK). TxK feeling the thinnest.

And then there is msicard doing his thing…

 

[Just a DK]

Lined the msicard, txk, yoshi to see a better comparison.

 

[Ben.G.]

I would measure at the shoulder, if any. Above the bevel. The area from there to 1cm (3/8") upwards is what I would call behind the edge, whose thickness determines the knife's performance. With a chef's knife or gyuto used with a lot of board contact, I aim for 0.2mm thickness above the edge, 0.5mm at 5mm more towards the spine and 1mm at 10mm. Just meant as a rule of thumb, and easily remembered.

I don’t personally use the term “thin behind the edge” because there’s no general consensus for the definition as you can see from the responses so far.

For my own science experiment I’ve been measuring immediately behind the cutting bevel (i.e. at the shoulder) and up to 10mm at the midpoint of the blade. Here’s a snapshot of my in-progress spreadsheet. Where I have multiple entries like a “.1”, etc, is where I’ve done some thinning.

I’m sure my measurements lack both precision and accuracy, but measurements definitely cluster around the way certain groups of knives feel to me. For example the Myojin, Yoshikane, and Birgersson have a similar light effortless feel through food - what I personally consider to be laser or near-laser performance. The Kamon has more of a midweight feel, requiring a bit more effort but bringing a certain robustness overall. When I decide to start thinning a knife, I generally shoot for the Myojin/Yoshikane measurements.

View attachment 290422

I enjoy using measurements to compare knives, but I like those measurements to be well-defined. You both reference 10mm and 5mm behind the edge, but where exactly is “above the edge”, “at the shoulder” or “BTE”? It could be 0.5mm behind the edge or 1.5mm behind the edge. The difference between 1mm and 2mm is 100%.

I just wish we could agree on an exact location of BTE thickness for the sake of consistency.

 

[M1k3]

I enjoy using measurements to compare knives, but I like those measurements to be well-defined. You both reference 10mm and 5mm behind the edge, but where exactly is “above the edge”, “at the shoulder” or “BTE”? It could be 0.5mm behind the edge or 1.5mm behind the edge. The difference between 1mm and 2mm is 100%.

I just wish we could agree on an exact location of BTE thickness for the sake of consistency.

5mm and 10mm up from the cutting edge.

 

[Benuser]

With an edge of 1mm, the difference in thickness would be 0.1mm at 5mm and 10mm. I gave the figures as a rule of thumb. If there is any need for consistency, it's by an individual user comparing the effect of his thinning. In that case it makes sense to always measure in the same way.

 

[Delat]

I enjoy using measurements to compare knives, but I like those measurements to be well-defined. You both reference 10mm and 5mm behind the edge, but where exactly is “above the edge”, “at the shoulder” or “BTE”? It could be 0.5mm behind the edge or 1.5mm behind the edge. The difference between 1mm and 2mm is 100%.

I just wish we could agree on an exact location of BTE thickness for the sake of consistency.

In my chart above, BTE is literally “behind the edge” and means where the cutting edge bevel ends and transitions to the blade road, usually with a distinct shoulder unless you round it off. It’s definitely less than 1mm and you could probably use some high school trig to calculate exactly how high it is based off the bevel angle (which I show in the chart).

 

[blokey]

Choil shot also don’t represent acutal thinness in some cases, here’s the Sugimoto I got, choil doesn’t look like much, but the edge is actually nail flexing and cuts extremely well

 

[Just a DK]

Not sure if Nail Flexing Edge, equates to thin BTE that contributes to the feeling of "ghosting" through food, especially in that initial cut... Unfortunately the thought for me here is not measured like others on here, but as with everything re. knives for me its about the feel and look... not really a measurable distance.

I guess for me thin BTE meant how long that feel of the initial cut lasts before meeting resistance, so i guess that distance of thin BTE is kinda different for all knives.

for certain tasks (slaw, making thin pickels, kolrabi) the longer that initial feeling lasts helps me guide the knife to make the thinnest cut possible (at least it feels that way..).

 

[Delat]

Not sure if Nail Flexing Edge, equates to thin BTE that contributes to the feeling of "ghosting" through food, especially in that initial cut...

No, definitely not. A knife can be “nail flexing” in the last 1-2mm before the edge, but if it’s thick at the 5-10mm point then it won’t “ghost” through food.

There’s trade offs for thinness though, and people prioritize different things.

 

[Benuser]

Choil shot also don’t represent acutal thinness in some cases, here’s the Sugimoto I got, choil doesn’t look like much, but the edge is actually nail flexing and cuts extremely well
View attachment 290683

Abrupt thickening at the heel, I guess?

 

[blokey]

Abrupt thickening at the heel, I guess?

Probably, same with the Kagayaki

 

[Ben.G.]

In my chart above, BTE is literally “behind the edge” and means where the cutting edge bevel ends and transitions to the blade road, usually with a distinct shoulder unless you round it off. It’s definitely less than 1mm and you could probably use some high school trig to calculate exactly how high it is based off the bevel angle (which I show in the chart).

“Definitely less than 1mm” is the number that I was looking for. It’s still not exact, but better than saying, “literally behind the edge.” I don’t think trigonometry is necessary to establish a reference point.

 

[Ktag]

Forgive me for asking a stupid question… I am a noob … I don’t understand the photos. I hope you don’t mind explaining that to me? Tia