leading edge vs trailing edge sharpening

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kane22

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I searched and found some old posts on here, and a few other places. There still doesn't seem to be a clear answer though. So in my quest for the perfect edge I thought I would ask again.

From everything I've read, trailing will leave a foil/wire edge. Removing the foil edge is where I kind of get lost. I've seen some that are stropped leaving a very clean edge, and others where the carbids broke off leaving a bad edge. All pics under a microscope. Other say to take one leading edge stoke to cut off the edge.

So would leading edge be better in the long run, since you'll have less of a foil edge to worry about?

I know I'm overthinking this, but it's what I do. I use a KME, have the diamond plates, some arkansas stones, and use wet/dry sandpaper sometimes. The sandpaper actually works well for me. It seems to cut fast, and leaves a smooth nice looking edge. 1000 grit will give you a nice working edge, take it up to 2500 if you want more of a polished look.
 
It seems to depend on the type of steel. Anecdotally I find edge-leading useful to avoid large burrs on steel that tends to form them, and edge-trailing to produce the best sharpness on less burr-prone steel. This may come down to the difference between positive burr and negative burr, as discussed in Dr. Vadim Kraichuk's Knife Deburring book. (free version linked; full version available for purchase.)
 
Well, I guess I'm the heretic. I use an Edge Pro, I ink the bevel, and then go North/South with the stones until the edge is uniform front to back and then left to right. Yes, there is a burr.

Then I take a finer edged stone, re-ink the bevel and go South-South-South lightly on both sides until the burr is gone.

I think the idea of a limited shaping and light final stone save metal.
 
Imo it doesn't matter. The finishing strokes I always do edge leading. But I'm not a scientist nor have I read anything to say that one way is better than the other. My own observation though tells me edge leading for finishing.
 
Leading edge for V bevels, trailing for convex edges works for me. Very light forward on either to take off any burr.
 
Stone composition matters more than any other factor.

The harder the stone and less it sheds the more important it will be to use leading passes - a trailing pass is VERY liable to create a burr.

The softer the stone and more it sheds abrasive, the more important it will be to use a trailing pass - a leading pass is VERY liable to dub the edge.
 
Todd S's blog is the final word on this IMO. For me, it is edge trailing only once I reach the apex because from my inspections with my microscope the difference in damage to the apex from edge leading vs edge trailing is blatant. The idea of removing the burr with an edge leading pass just sends shivers down my spine, the stone will catch and tear that burr off trashing the apex. IMO the best way to remove the burr is by stropping. I have been studying this for a few years now and have not found any instance that edge leading is even as good as edge trailing let alone better.

I would link to Todd's article on edge leading vs edge trailing but his blog is so hard to navigate now I can't find it.

Keep in mind I only do guided sharpening.
 
Thanks, they seem to have changed but pasted strop part 1 is the best I find now.
 
Diemaker said:
Todd S's blog is the final word on this IMO.
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I think @ToddS has a more nuanced view on this than you ascribe. Hopefully he will clarify for himself if needed. For now here are some excerpts. In aggregate it appears he likes to use edge-leading strokes to minimize burr formation, then finish with 10 or 20 edge-trailing strokes for keenness.

https://scienceofsharp.com/2016/04/14/simple-straight-razor-honing/ said:
If you are unsure of the condition of the blade, raising a burr that you can feel using a 1k stone, as you would when sharpening a knife, is a helpful diagnostic. However, I would only do this once, as it is a waste of steel. It is important to remove this large burr with edge-leading strokes as the steel near the base off the burr will be damaged from the burr flipping side to side.

My preference is to set the bevel with high quality 1k stone such as a Naniwa or Shapton to achieve a good trade-off between abrasion rate and the size of the micro-chips in the apex. Lower quality stones will also work if edge-leading strokes are avoided. As a rule of thumb, using the 1k stone long enough to make black swarf, then ending with about 20 edge trailing strokes is sufficient. The reason for the edge trailing strokes is explained in the series of images that follow.
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https://scienceofsharp.com/2015/01/11/what-is-a-burr/ said:
In this case, the burr does not “grow” enough during one stroke (approximately a four inch stroke with less than one pound of force) to project past the ideal apex. In fact, a raised burr is never formed during typical straight razor honing with alternating, edge leading x-strokes on a hard surface.
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https://scienceofsharp.com/2015/02/09/the-pasted-strop-part-1/ said:
In summary, edge-trailing strokes can produce a keener edge than edge-leading; however, they generally result in the formation of an undesirable burr or foil.
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https://scienceofsharp.com/2014/04/16/the-honing-progression/ said:
Andy Westib October 3, 2015 at 11:40 am
Todd, are those all edge leading strokes?

scienceofsharp October 3, 2015 at 2:33 pm
Yes, all of these form foil-burrs with edge trailing strokes.
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https://scienceofsharp.com/2015/07/09/its-too-big-of-a-jump/ said:
In this article, a series of images are presented from a carbon steel straight razor blade (native bevel angle 16.5 degrees, inclusive) honed on a Shapton Pro 320. The blade was first sharpened with back-and-forth strokes with progressively smaller sets per side and then finished with 10 edge-trailing strokes after rinsing the hone.

For reference, edge views of two other blades are shown following honing on the Shapton Pro 320. The first, honed only with edge-leading strokes (alternating sides) displays a coarse, broken edge – essentially continuous, overlapping microchips. The edge width varies from about 1 micron to near flats more than 5 microns wide. The second, honed with only edge-trailing strokes (alternating sides) displays a massive foil edge burr. Beneath the burr, there is a keen, linear and chip-free edge.
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https://scienceofsharp.com/2015/02/22/the-pasted-strop-part-2/ said:
The examples in part 1 demonstrated that edge trailing (stropping) strokes on those hones leads to a reduced edge width (increased keenness) however, continued honing leads to the formation of a foil-edge burr.
Click to expand...
 
Ok, I formed my opinion using Todd's photos and my observations more than his text, although his text does not conflict with my opinion much at all. If you use sharp diamond then there isn't as much damage done to the apex with the burr bending back and forth, and the burr will be smaller. I also always finish with a 4k stone before stropping so that also helps remove more of the damaged apex from the coarser stones. My observations support that there is less damage from edge trailing strokes than edge leading. To go into all of the details supporting this opinion would take quite a while with many photos.

A few thoughts. The flexing apex from the large burr is perceived damage since you can't really see it. Tearing the burr off and smearing it between the stone and bevel is observed damage, often as random scratches in the bevel when using a finer stone.
 
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FWIW...as I understand it KME recommends you finish each stone with edge leading. However they also say you only want to raise a burr the first time, with the coarsest stone/diamond. After that you don't want a burr, you're just refining the edge.

Thanks for everyone's input. I'm still not sure what's best.
 
D Diemaker I don't doubt your Matrix stones make this less of an issue in either case. Is there any reason you would not support the protocol of using bi-directional or edge leading strokes for most of the sharpening, then making the last ten or so edge trailing? I know you don't need very many strokes at each step with the Matrix stones so this doesn't make as much sense, but let's suppose someone wanted to go 250–1100–4000 and needed more strokes at each step. Are you of the opinion that even with these high quality stones the edge leading strokes will do apex damage that will not be removed with ten edge-trailing strokes?
 
Mr.Wizard said:
D Diemaker I don't doubt your Matrix stones make this less of an issue in either case. Is there any reason you would not support the protocol of using bi-directional or edge leading strokes for most of the sharpening, then making the last ten or so edge trailing? I know you don't need very many strokes at each step with the Matrix stones so this doesn't make as much sense, but let's suppose someone wanted to go 250–1100–4000 and needed more strokes at each step. Are you of the opinion that even with these high quality stones the edge leading strokes will do apex damage that will not be removed with ten edge-trailing strokes?
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I think he answered your question above, unless I'm misreading one or both of you:

For me, it is edge trailing only once I reach the apex because from my inspections with my microscope the difference in damage to the apex from edge leading vs edge trailing is blatant. The idea of removing the burr with an edge leading pass just sends shivers down my spine, the stone will catch and tear that burr off trashing the apex. IMO the best way to remove the burr is by stropping.
Click to expand...
 
Blues, I truly appreciate someone helping communication in case I'm just being obtuse. I don't think this answers my question, because as I understand him "once I reach the apex" implies making any edge leading strokes only on one stone—usually the coarsest—where the apex is first reached. In my example progression 250–1100–4000 I take this to mean that Diemaker would use only edge leadingtrailing strokes on the 1100 and 4000 Matrix stones, however many strokes it took. I would default to scrubbing strokes on every stone until the finish was even (coarser scratches crossed out), then finish with unidirectional strokes.
 
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I too am using a guided system FYI I think he was saying edge leading on the 250 and edge trailing on the 1100-4000
I believe what hes meaning, once you get you apex developed on the 250, using the 250-1100-4000 example, the 1100-4000 are for edge refinement-smoothing and polishing,at which point I would be doing edge trailing strokes only as the leading strokes are more aggressive and damaging to the refined apex.
I noticed this back when I was using sic stones , and when I went to Matrix stones it became even more apparent as they are very effective at lower pressures.
I think our own personal style of sharpening may influence this also as some tend to press harder than others. nothing is written in stone (with the exception of gritomatic's name in ink on my SIC stones.)
 
It doesn't matter if I'm using a guide or not, every stone up to the very last is done w/ a scrub.

If working high carbide or high VC steel the final passes will be a microbevel on an EF equivalent using edge leading. I normally will make a couple light passes on a hard strop but really is more of a fast way to QC the edge than to improve the quality.

Other steels get a microbevel on a finishing grade waterstone, a couple leading ones to erase the burr and some very light, easy trailing passes to refine the edge. I often won't bother to strop after that.

A hybrid finishing method for all steels is to use a diamond grit jointer stone, again with a few leading passes to eliminate the burr followed by some light trailing passes.

The finish direction should be decided by the composition of the surface, some will need a little experimenting if the characteristics aren't obvious.
 
Mr.Wizard said:
D Diemaker I don't doubt your Matrix stones make this less of an issue in either case. Is there any reason you would not support the protocol of using bi-directional or edge leading strokes for most of the sharpening, then making the last ten or so edge trailing? I know you don't need very many strokes at each step with the Matrix stones so this doesn't make as much sense, but let's suppose someone wanted to go 250–1100–4000 and needed more strokes at each step. Are you of the opinion that even with these high quality stones the edge leading strokes will do apex damage that will not be removed with ten edge-trailing strokes?
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I will try to do a better job answering these questions when I have more time but for now here goes. I find edge leading strokes are far more likely to cause microchipping, which you then need to drop down a grit or two to clean up so that is a deal killer when it happens. And since you should only need 10 strokes per 3" of blade once you have reached the apex there is no point in 10 more to clean up. This does have me curious though so I will see if I can borrow EPs set of SG stones when I drop off some parts next week. I last played with them before seeing the light about edge trailing only.
 
So what if you finish with a swirl? Do you end up with a partial burr? Here's a jeweled edge.

XvA3YsV.jpg
 
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