Leading or Trailing Strokes

[Michael Lingard]

It’s sometimes hard to sift out the truth when so many seemingly experienced knife people can have directly opposing viewpoints on how to achieve the best edge…

Ain’t that the truth! Most of the knowledge base in the field is based on anecdote, which doesn’t mean it’s necessarily incorrect, but a lot of it has not been tested rigorously with controlled variables.[/quote]

I like how you experiment and post pictures like this Clay. It really helps sift things out. 😉

[wickededge]

Calling Clay…….

I read the entire post here. Sound like edge trailing creates a better edge (as in smoother), by using very light pressure the “burr” or slop on the bevel is minimized. Using strops this is cleaned up. Is it accurate to say the better edge comes from edge trailing?

I think more testing is in order! I’ve got a pair of identical Shun knives that I’ll use for the test. I’ll sharpening them with the exact same progression with the same number of strokes, one edge leading, the other trailing. Of course I won’t be able to strop the edge leading knife. Then I’ll need some series of tests to perform on each, so I’m open for suggestions on that 🙂 Maybe a few for sharpness and a few for durability.

-Clay

[Geocyclist]

Clay,

I would like to see some tests before/without stropping. Like you say stropping is only 1 direction. Plus it may erase the difference found between leading and trailing. I am more surprised that you didn’t have a preference after hundreds of knives.

I would suggest some “initial” sharpness test, such as phone book paper slicing, push cuts, cutting the side that’s hard to cut.

Then some durability tests, such as 100 cuts of rope then back to phone book paper.

I am curious about both initial and long term edge characteristics. Is one way more toothy and/or more durable?

Also neat to see the microscope shots too.

Finally, if there is a disadvantage to one direction, does stropping correct it?

[wickededge]

Thanks for the feedback. I actually do have a preference, edge trailing, but it too is based on anecdote. Our collective experience is really valuable, but I am always hesitant to make a solid statement about the superiority of one technique over another without really testing it as rigorously as possible. I think your plan sounds good and I’ll get started on it soon.

Clay,

I would like to see some tests before/without stropping. Like you say stropping is only 1 direction. Plus it may erase the difference found between leading and trailing. I am more surprised that you didn’t have a preference after hundreds of knives.

I would suggest some “initial” sharpness test, such as phone book paper slicing, push cuts, cutting the side that’s hard to cut.

Then some durability tests, such as 100 cuts of rope then back to phone book paper.

I am curious about both initial and long term edge characteristics. Is one way more toothy and/or more durable?

Also neat to see the microscope shots too.

Finally, if there is a disadvantage to one direction, does stropping correct it?

-Clay

[wickededge]

Geo – for the first test, what would you like to see for the finish grit? How coarse? Also, what angle?

Clay,

I would like to see some tests before/without stropping. Like you say stropping is only 1 direction. Plus it may erase the difference found between leading and trailing. I am more surprised that you didn’t have a preference after hundreds of knives.

I would suggest some “initial” sharpness test, such as phone book paper slicing, push cuts, cutting the side that’s hard to cut.

Then some durability tests, such as 100 cuts of rope then back to phone book paper.

I am curious about both initial and long term edge characteristics. Is one way more toothy and/or more durable?

Also neat to see the microscope shots too.

Finally, if there is a disadvantage to one direction, does stropping correct it?

-Clay

[Geocyclist]

Thanks Clay.

What is your opinion here? I would say for the coarseness and angle obviously keep both knives the same. After that use a “normal” angle. Where “normal” means a angle typical to the knife and application. Thinking we want to see results affected by leading/trailing and not a result of some extreme angle. For coarseness I would say 1000#. Unless you think finer is better.

I have some interesting questions about this topic, but I am very much a new-be at this.

[wickededge]

Did a little testing after prepping some samples. The first one is at 15 degrees and 1600 grit ceramic finish.

Here is a picture of the edge with edge-leading strokes:

and with edge-trailing strokes:

Both cut phone book paper cross grain fairly well though the cuts from the edge-trailing were noticeably smoother.

So far, I’ve tested the durability of the edge-leading blade by cutting strips of triple-walled cardboard, two layers thick. The edge-leading blade completed 45 24″ cuts before failing to cut the phone book paper.

Here is the edge-leading blade after cutting the cardboard:

For both blades, I used very consistent, VERY light strokes once the bevels were set and I started working up the grits. I’ll complete the durability testing of the edge-trailing knife as soon as we get through the rest of the shipping frenzy.

Attachments:

• 1600-Leading.jpg
• 1600-Trailing.jpg
• 1600-Leading-after-45-cuts.jpg

-Clay

[Geocyclist]

Thanks Clay, nice photos. Please expand on your explanation.

Here is what I see, but not sure I am interpreting the photos correctly.

The edge trailing edge looks much crisper. However, the edge leading edge looks “dark” . Is this the edge of the just lighting in the photo.

Looks like the edge is nearly gone after cutting cardboard.

[wickededge]

I’m trying to understand it as well, but it looks like there is some folding or blunting of the edge with the edge-leading blade. I was careful to use very light pressure, so I don’t think it’s coming from heavy handedness. I’ll have to redo that blade and triple check my angles etc… to rule out any inconsistency of the sharpening angle. The edge does look fairly well obliterated after the cardboard, but I’ll want to repeat that process to verify.

-Clay

[cbwx34]

Nice pics!!!

Another factor you might consider is to have someone else do the sharpening… I’m thinking maybe someone who is familiar with the WE, but doesn’t have a lot of experience on it… might show a different perspective. The sharpener is a factor in the equation after all….

He or she also could not tell you which is which ahead of time… help eliminate a potential bias…

Just a thought! 🙂

[wickededge]

Nice pics!!!

Another factor you might consider is to have someone else do the sharpening… I’m thinking maybe someone who is familiar with the WE, but doesn’t have a lot of experience on it… might show a different perspective. The sharpener is a factor in the equation after all….

He or she also could not tell you which is which ahead of time… help eliminate a potential bias…

Just a thought! 🙂

Are you volunteering? 🙂

-Clay

[cbwx34]

No… (I actually was going to put that in the post). 🙂 I’m thinking someone that may not be biased one way or the other (I think I might be, although I try and keep an open mind)… one reason I thought someone relatively new to sharpening might be a good candidate.

[Phil Pasteur]

No… (I actually was going to put that in the post). 🙂 I’m thinking someone that may not be biased one way or the other (I think I might be, although I try and keep an open mind)… one reason I thought someone relatively new to sharpening might be a good candidate.

I would think that consistency would be critical in drawing any conclusions. Someone with less experiece may not be able to provide that.

I am curious though. Clay is doing this to answer a question posed. I think he is trying to be unbiased until he has some evidence one way or another. Of course there might possibly be sub-concious biases at work. I just don’t think that this is very likely.

I would guess that a double blind test where the person sharpening did not know the orientation of the blade including placebo blades, or where we would just throw out a random number of blades and photgraph the others.. would be the best way to go… Of course we would need many operators so we could make this statistically sound…:evil:
🙂

Not sure how to design that … or if it would be worth the effort.

Phil

[Gary Crumb]

…placebo blades…
Phil

Interesting concept…:lol:

[Geocyclist]

Very good discussion going on.

I think this can easily be 2 separate studies –

1. is to use an expert operator (Clay) and only one operator to remove the human influence as much as possible to concentrate on leading vs. trailing, as shown by Clay. True any other operator could have different results. This can be repeated by other operators for comparison.

2. A 2nd study to show the affect the human influence, different operators would need everything else constant but the operator. Same blade, same WE, have the blade set in the vice by the administrator each time. I think (haven’t tested) the #1 human influence is pressure that creates different results. Also speed, length of stroke etc.

In the end it I think it is hard to remove the human element from sharpening, at least for a controlled experiment, without being able to measure and control critical variables such as pressure.

I searched the web on this one a while and found more questions than answers. I did like this post here.

Key points I picked up were:

• Some people talk about the edge getting duller as they progress through stones
• May be due to “snow plow” effect of the blade rolling on edge leading instead of cutting the steel
• Edge trailing will polish more

Do both leading and trailing on coarse stones
Finish on fine stones with trailing only
Strop

I am now wondering if this is what Clay’s photo of edge leading is showing, a rolled or deformed edge? I am very curious to see how this knife does in the same sharpness tests.

[Author]

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