Leading or Trailing Strokes

[wickededge]

Something we need to add in is BassLakeDan’s point sharpness tester. The data from that test alone would be really useful to determine at least one point of efficacy of varying techniques. Has anyone built one yet?

-Clay

[Fred Hermann]

Ok, I have been reading this ongoing, and it’s fascinating.
But please forgive my ignorance…I thought I knew what you were talking about, until I didn’t.
Can someone please define ‘leading vs trailing’? I thought you were talking about going tip to heel or vice versa. Call me a noob, but this one has confused me.

[Michael Lingard]

Ok, I have been reading this ongoing, and it’s fascinating.
But please forgive my ignorance…I thought I knew what you were talking about, until I didn’t.
Can someone please define ‘leading vs trailing’? I thought you were talking about going tip to heel or vice versa. Call me a noob, but this one has confused me.

Think of edge leading as if you were trying to cut the medium. Edge facing the direction of movement. Edge trailing is the opposite where you drag the blade across with the ‘edge trailing’.

Hope that helps you. It’s actually a controversial topic in the sharpening community… haha;)

[Blunt Cut]

An edited post (mine) from my thread (not here) 10/31/2012 …

This 2 images are what I’ve envisioned a few months back. These are (~ 30% resemblance) my mental images that I stared at for countless hours and they still make sense today as the day I came up with them. Please hold-on to other variables (abrasive shape, steel composition/ht, etc) while we look at this simplified models.

V t/l is the velocity – blade or abrasive movement.

P is the blade normal force against the abrasive.

Av (Abrading Vector) is the cutting vector imparts torque on the blade. The edge will deflect/bend when the torque exceed the tensile strength at given edge thickness.

Burr-nana peel.

Apex deflect or roll but no burrnana.

These models should provide reasonable answer to alot of nagging questions.

ex1: ‘how come the burr seem long but blade height wasn’t shorten by the same amount?’
burr-nana peel around the apex, so blade height loss usually much less than burr length.

ex2: ‘raised burr 2 sides, deburred but didn’t apexed?’
Too much press, burr-nana peel around a blunted apex. Once burr removed, you end up with a blunted/un-apexed edge.

ex3: lip
Whenever Av too large for the apex area, abraded area will occur below the apex.

[Phil Pasteur]

Nice illustrations…and I have seen the post where you put it up originally. I still don’t follow it or see how you get your three examples. Maybe you can explain.

In any case, when using the WEPS… or even bench stones, I can’t say that I have seen anything… via edge perfomance nor micrographs to allow me to buy into your theory. I do have several bench stones that I can’t use edge leading, but obviously (to me) do produce significant edge refinement when used edge trailing. No “burnana-peel” or false burrs, that I can detect.

Would like to hear more explanation from you… and more hard evidence with Clay’s tests and photos.

Phil

[Blunt Cut]

Nice illustrations…and I have seen the post where you put it up originally. I still don’t follow it or see how you get your three examples. Maybe you can explain.

In any case, when using the WEPS… or even bench stones, I can’t say that I have seen anything… via edge perfomance nor micrographs to allow me to buy into your theory. I do have several bench stones that I can’t use edge leading, but obviously (to me) do produce significant edge refinement when used edge trailing. No “burnana-peel” or false burrs, that I can detect.

Would like to hear more explanation from you… and more hard evidence with Clay’s tests and photos.

Phil

Envision an edge cross section (a geometrical 2D triangle, where the area is the blade edge):
* Steel S requires force N to penetrate surface 1 molecule deep by an abrading fixed-plane abrasive. Lateral tensile strenght (bending) per molecular line is 0.2N.
* Start with a molecule thick apex.
* Abrading Vectors (Avt & Avl) for Edge Trail & Lead.

Burr form at the bend because the abrasive no longer able to penetrate the upward bent surface. If the sharpen stroke is super slow, so Av is mostly normal/perpendicular pressure to the surface. Then in this case, neither Trailing or Leading can create an apex thinner than 5 molecules thick.

Using this envisioned model to add more details to my Prev post:

ex1: ‘how come the burr seem long but blade height wasn’t shorten by the same amount?’
If start out with a flat-top edge, as abrading material reach the flat edge and thickness is less than the tensile/bend strength, these material will hinge/flop over the flat-top. Now you’ve the burr but far from apexed. Many beginers ran into this by feel the burr alone without looking at the edge reflection.

ex2: ‘raised burr 2 sides, deburred but didn’t apexed?’
ex1 applied to both side of bevel face

ex3: lip
Whenever Av N exceed tensile strength in area below apex, thus kept abrade more and more below where sufficient thickness to support abrasion. This problems are more applicable for advanced sharpeners.

Again, my posts don’t addressed the complete complexity picture of steel+abrasive+interaction characteristics. I merely focused simplistic edge lead or trail abrading interaction.

[Josh]

During some reading (HERE on pg 18 specifically) I found some interesting documentations regarding edge leading vs edge trailing sharpening… In this paper Dr. Verhoeven is comparing razor blades (specifically on pg. 18 I think it is a straight razor):

“All of the sharpening done on the waterstones moved the blade along the stone in
the direction into the blade edge [edge leading] causing the abrasive debris to move away from the edge.
It was theorized that moving in this direction would reduce the bur size at the edge by
preventing the debris from being deposited along the edge. To see if this theory was
supported by evidence an experiment was done on the 6000 grit waterstone where the 10
4-stroke cycles were all done with the blade edge moving away-from [edge trailing] rather than into the
stone surface. The results are shown in Fig. 27. Comparing Figs 25 and 27 one sees that
moving the blade away-from the edge, as in Fig. 27, does seem to produce a significantly
larger bur than moving it into the edge, as in Fig. 25. The larger bur is also accompanied
by an increase in edge roughness, as shown in the face views.”

you will have to view the paper so you can reference the photographs… thought this was interesting.

[Gib Curry]

During some reading …..

you will have to view the paper so you can reference the photographs… thought this was interesting.

Thanks for posting this. I’ll finish reading it later today…

Is this what you read for leisure & entertainment? I do.

After watching The Woodrights Shop’s explanation & demonstration of cross-cut and rip saws I’ve been re-reading the first two chapters of Leonard Lee’s “The Complete Guide To Sharpening”.

They are “The Meaning of Sharpness” and “The Physics of Cutting Wood Fibers”

“Unless you are living in a remote area, sharpening your own knives really does not make sense. The time consumed is usually out of all proportion to the money saved, and the end result is usually of lower quality than that you could expect from even a run-of-the-mill sharpening service. This is truly one area where equipment overwhelms technique by a substantial margin. If you do not have an excellent system for holding a blade straight and rigid, you will be in trouble from the opening gun.”

Thanks for posting…

~~~~
For Now,

Gib

Φ

"Everyday edge for the bevel headed"

"Things work out best for those who make the best out of the way things work out."

[Josh]

During some reading …..

you will have to view the paper so you can reference the photographs… thought this was interesting.

Thanks for posting this. I’ll finish reading it later today…

Is this what you read for leisure & entertainment? I do.

After watching The Woodrights Shop’s explanation & demonstration of cross-cut and rip saws I’ve been re-reading the first two chapters of Leonard Lee’s “The Complete Guide To Sharpening”.

They are “The Meaning of Sharpness” and “The Physics of Cutting Wood Fibers”

“Unless you are living in a remote area, sharpening your own knives really does not make sense. The time consumed is usually out of all proportion to the money saved, and the end result is usually of lower quality than that you could expect from even a run-of-the-mill sharpening service. This is truly one area where equipment overwhelms technique by a substantial margin. If you do not have an excellent system for holding a blade straight and rigid, you will be in trouble from the opening gun.”

Thanks for posting…[/quote]
Yeah I do read this type of thing because I enjoy it! Lol

The only thing I take issue with what you quoted from the show is that I think sharpening is easy with a little practice and can be done with minimal tools… Look up cliff stamp sharpening a knife on a brick to newsprint slicing sharpness

[Gib Curry]

Yeah I do read this type of thing because I enjoy it! Lol

The only thing I take issue with what you quoted from the show is that I think sharpening is easy with a little practice and can be done with minimal tools… Look up cliff stamp sharpening a knife on a brick to newsprint slicing sharpness

I concur. But, the quote about holding the blade rigid is one of the clues that led me to the Wicked Edge.

I don’t necessarily agree with all Mr. Lee’s conclusions or opinions but his “science” is interesting and entertaining to me.

“Sharpness for a cutting tool could be defined as two surfaces meeting at a line of zero width. That might be fine theory but could result in bad practice. To be effective, a cutting tool not only has to have an edge of zero width, but the angle at which the two surfaces meet must accommodate the intended use of the tool and the material from which the tool is made.”

“Unlike wood, meat and soft vegetables have little rigidity to their structure. They are about 95% water held together with films and filaments of varying strengths. To cut them, you need an edge that will rend their fabric at very low applied pressure.”

“The skin of a tomato is sufficiently tough that it will maintain its integrity in the face of pressure from a smooth knife edge. Of course, you can only apply relatively light pressure, otherwise you tend to squash the entire tomato. You will find that a less finely finished edge, one that has many fine serrations in it from a medium-grit abrasive (400x to 1200x) will cut into the tomato much more easily because it is better designed to tear apart a film and sever fibers. Although the desirable amount of serration varies, you want a bit of tooth on any blade used for soft vegetables, meats and bread.”

Nothing new. Still interesting. (To me)….

~~~~
For Now,

Gib

Φ

"Everyday edge for the bevel headed"

"Things work out best for those who make the best out of the way things work out."

[Author]

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