Which direction do you want your "teeth"

[dafox]

 

[inferno]

teeth direction: i'd say it doesn't matter!

 

[ian]

I’m not really convinced that the teeth of the knife end up oriented in the direction of the scratch pattern. If you look at any of the crazy zoomed in pictures of edges, you just see canyons and valleys, you don’t see skyscrapers all aligned with the direction of the scratch patterns. Seems like b*llshit to me.

 

[Midsummer]

I thought you wanted them to be oriented to grab on the pull cut. But perhaps you want to vary your sharpening pattern based on the way you intend to use the knife.

I admit I am no authority.

 

[M1k3]

I’m not really convinced that the teeth of the knife end up oriented in the direction of the scratch pattern. If you look at any of the crazy zoomed in pictures of edges, you just see canyons and valleys, you don’t see skyscrapers all aligned with the direction of the scratch patterns. Seems like b*llshit to me.

I'm going to agree. There's also the movement from tip to heel at play. Don't really think the burr cares either. I would like to be proven wrong though.

Consistency in holding an angle and burr removal is still probably more important.

 

[Midsummer]

I'm going to agree. There's also the movement from tip to heel at play. Don't really think the burr cares either. I would like to be proven wrong though.

Consistency in holding an angle and burr removal is still probably more important.

I did not watch the video. Did they claim that the consistent angle and burr removal were of less importance? If that is what they claim; then they are definitely off the mark!

 

[M1k3]

I did not watch the video. Did they claim that the consistent angle and burr removal were of less importance? If that is what they claim; then they are definitely off the mark!

I don't know. I'm only fluent enough in English.

 

[inferno]

whats the best toothbrush for these teeth?

 

[MrHiggins]

I've actually wondered about this for a long time, thanks for raising the issue. Sometimes, I'll finish a knife at 6k, but then do a few super light edge-leading strokes on a 1k with the blade perpendicular to the stone, just to get a few toothy scratches in that direction. Seems to work, but so do a lot of other sharpening techniques I use...

 

[ref]

If you have a serious overbite then I would consider seeing a dentist, but sometimes these things take months to fix.

 

[Bert2368]

I suspect tooth orientation matters a LOT more for cutting hard materials such as wood and metal in cutting operation done by removing material from a kerf as CHIPS- where tooth geometry, tooth width/set vs. saw plate width, tooth rake and relief angle on backside of tips matter a great deal. Cutting soft material such as veges and protein, we are not chiseling out hard chips. What ARE we doing?

Can any point me towards a nerdy micrograph study of what the actual cutting mechanism is and what cut profile in food materials looks like/tool behaves like?

As noted by others, if a knife is shaving hair beautifully, cutting paper like a laser but refusing to immediately go through tomato skin on a draw cut? I have drawn such edges lightly over my oldest DMT diamond rod and added some "tooth". I have not noticed any major preference for the orientation of those scratches.

 

[Bert2368]

I am beginning to answer my previous question, re: What are the actual mechanisms of the cutting actions performed by sharp edges on food materials?

https://www.chefsteps.com/activities/how-knives-cut
http://physics.aps.org/featured-article-pdf/10.1103/PhysRevLett.109.244301
Chopping and slicing are fundamentally different mechanisms, just for a start...

A razor cutting hair or a nakiri being pushed vertically through a head of celery to separate the stalks from the base are chopping operations. A butcher knife being drawn across animal muscle or a gyuto slicing a tomato are slicing operations. Empirically, we learn what shape and edge treatment works best.


I know I tend to over think things but do feel that knowing related physics and materials science could help me to extrapolate what the results of changing sharpening procedures and resulting edge characteristics might be.

Larrin, are you out there?

(Edit)

A quote from second link.

As I interpret this, they found that a too smooth cutting edge leads to suppressed friction with medium being cut- And this friction is the primary mechanism of performing the desired work in shearing (for us, slicing) cuts. As a totally smooth cutting edge lacks this mechanism, the only cutting mechanism left to such an edge is the "normal" (chopping, straight downward to us) application of force, effort required goes way up- By a factor of around 10X in some of their jelly cutting tests.

We need to tune the friction (equates to roughness) of a cutting edge to the medium being sliced, ideally to a condition where the material's surface cracks under the cutting edge pretty much at the same point the cutting edge just begins to slide over it for least total effort.

Duh. You all probably knew that intuitively about a week into sharpening knives and cutting various foods in a kitchen job...

Nothing here on how best to micro shape the friction applying surface of the cutting edge (tooth shape).

Totally suppressing friction
would lead to sliding of the blade on the surface sample,
and no tangential force, thus suppressing the benefit of
shearing, as is observed with smooth cutting wires. For
any finite friction, the optimal configuration will then be
one poised at the edge of sliding just as fracture nucleation
occurs; indeed, any sliding leads to retarded fracture nu-
cleation and increases the elastic energy stored in the solid
before cutting actually starts.

 

[KingShapton]

I like a toothy edge, but I don't care about the alignment or direction of the teeth.

I like to keep things simple. sometimes you think things over, you make them unnecessarily complicated.

For me, keeping things simple is the way to go ...

Just my 2 cents ..

 

[Bert2368]

I like a toothy edge, but I don't care about the alignment or direction of the teeth.

I like to keep things simple. sometimes you think things over, you make them unnecessarily complicated.

For me, keeping things simple is the way to go ...

Just my 2 cents ..

All good principles, will surely get you through your working day.

---------

But I'm wired a little differently, so I'm looking for research on engineering surfaces for the highest coefficient of friction possible.

Tooth shape and orientation may matter, at least they do in this set of solid-solid tests where they achieved coefficients of friction up to 1.6 using microscopic diamond ridges and pyramids at 90 and 45 degree face orientation.

 

[KingShapton]

All good principles, will surely get you through your working day.

---------

But I'm wired a little differently, so I'm looking for research on engineering surfaces for the highest coefficient of friction possible.

Tooth shape and orientation may matter, at least they do in this set of solid-solid tests where they achieved coefficients of friction up to 1.6 using microscopic diamond ridges and pyramids at 90 and 45 degree face orientation.

Tests apart from kitchen knives and their use in personal use often lead to misleading results in my opinion.

a simple example: a hanging hair test is very impressive, but I (and I think that applies to most of us here) do not process hair in the kitchen.

Another example: a high finish on a very, very fine stone is great for woodworking tools, but, with a few exceptions, not good for practical use in the kitchen.

Please don't get me wrong, I understand you and your approach and I wish you every success and good results in your search for knowledge.

For me, development is going in exactly the other direction. I've been sharpening a lot of knives for a number of years and have developed a pretty good technique for myself over the years, with very good results.

Nevertheless, I recently discovered something new to me. For lack of a better term, I call it "Zen Sharpening".

I'll be opening a thread on this in the next few days anyway, but it's the exact opposite of your scientific approach. With "Zen Sharpening" I let myself go in the moment, I just feel and forget everything I have ever learned while sharpening. The more I let myself go, the better my results get. And they're getting better than I ever thought.

But that's just something I discovered for myself, in the end sharpening is a journey and this journey is different for everyone. Enjoy your journey and have fun with your discoveries and experiences.

 

[MarcelNL]

for now I'd be happy if the effects of someone removing a tooth that resisted the process pretty good (earlier today) were gone.... the article is interesting but IMO geared towards friction not cutting. Probably perhaps relevant for pushing but not likely for slicing.