Alternate Edge Leading and Edge Trailing Strokes?

[Tactical Texture LLC]

I’ve seen a few topics discussing edge leading vs. edge trailing sharpening for maximum sharpness, and from what I’ve read it looks like edge leading wins out in that category.

That said, I was wondering if people alternate edge trailing and edge leading either going from grit to grit, or even using the same grit?

My thoughts are that both have benefits (time, technique, safety, overall sharpness, etc.) so would blending the two techniques improve the overall product, or would it dilute the benefits each has?

[Alan]

Alternating between stones makes it much easier (with a loupe) to see that you’ve replace the old scratches left by pervious stone with new scratches from current stone.  I make it a point to always end with light strokes edge leading.

Alan

[tcmeyer]

The issue with edge-trailing is that it tends to break bigger chunks off of the edge, but I don’t think it’s much of a factor in the higher grits.  My current strategy is to use edge-leading only with grits below 800.  With my 800/1000’s, I’ll use scrubbing strokes, but with full pressure on the down-ward stroke and light pressure with the upward stroke.  Since I went whole-hog to diamond film I’ve shelved my ceramic stones, so above 1000 it’s film only and film, like strops, don’t like edge-leading strokes, so it’s edge-trailing (upward) strokes.  With relatively straight edges, I’ve found I can still use scrubbing strokes with film – maybe lighten up on the downstroke pressure.

Because I have a neural deficit, I don’t enjoy the same eye-hand coordination with my right hand, so I usually don’t use alternating strokes (right-left-right-left, etc.).  I do groups of 10-20 strokes on one side, then an equal amount on the other side.  When I’ve finished with a particular grit, I’ll take maybe 5 alternating strokes to remove any burr before proceeding to the next grit.

If you’re asking which is preferable, I don’t think that there’s any advantage in edge-trailing from a technical aspect.  Once you’ve seen the damage that edge-trailing can do and consider how long it takes to remove that damage, I think you’ll come to a similar position.

Here’s a photo of a chunk ripped out of a edge with a trailing-edge stroke with a 100 or 200 grit stone (I forget which) which probably hadn’t been completely broken-in.  Consider the amount of work with my 400’s that was needed to remove the flaw.

A cutting tool scraping a furrow on a substrate is limited in depth by the strength of the substrate’s material in front of the cutter.  When it gets to the edge, there is a sudden drop-off in that strength and the result is as shown in the photo.  Of course, this is an extreme example of what can happen, but it emphasizes the point.

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Alan

[Tactical Texture LLC]

Thanks Tom, and you touched on a point that I missed in my OP, which was: At the higher grits.

I figure if you are trying to re-profile a blade and are hogging off a lot of metal, as long as you stop and switch to edge leading before you actually get to the weak part (the very edge), you should probably be fine with the edge trailing as it seems to be faster for me.  Going to the higher grits (800/1K), it seems more like you are refining the edge than actually creating it, which is where this technique probably shines by allowing the least possible damage to occur.

*EDIT: I just re-read my reply and realized it probably wasn’t clear.  What I meant was that I can see how doing all edge leading is important at the lower grits to minimize damage to the blade, just as Tom illustrated with his picture.  My question was that once you get to the higher grits (800/1K) are you switching to alternating strokes more as a refining/polishing technique since there is less potential for damage?

 

[tcmeyer]

For me, scrubbing strokes are simply a big time saver.  You can do twenty up-down scrubbing strokes in less time than it would take to do twenty single-direction strokes.  Since the stone never loses contact with the edge, you don’t need the care required to make subsequent strokes.  The seconds (or fractions of a second) you spend repositioning your stones for the next stroke are lost time.

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dulledge

[Tactical Texture LLC]

tcmeyer wrote:

For me, scrubbing strokes are simply a big time saver. You can do twenty up-down scrubbing strokes in less time than it would take to do twenty single-direction strokes. Since the stone never loses contact with the edge, you don’t need the care required to make subsequent strokes. The seconds (or fractions of a second) you spend repositioning your stones for the next stroke are lost time.

Won’t the scrubbing strokes (especially with the 100/200/400 grit) damage the edge?  Or are you saying that you only scrub with the higher grits?

[Gregg776]

I’m with Tom on the scrubbing technique especially if I haven’t reached the apex.  I use the sharpie technique and as long as I can see any of the sharpie mark, I run the diamond stones both directions.  A lot depends on the metallurgy and heat treating of the blade as well as the angle but a good loupe or microscope is the best way to determine actual results.  Another thing I do is to keep notes on everything I sharpen for future reference.

[tcmeyer]

Tactical Texture LLC wrote:

tcmeyer wrote:

For me, scrubbing strokes are simply a big time saver. You can do twenty up-down scrubbing strokes in less time than it would take to do twenty single-direction strokes. Since the stone never loses contact with the edge, you don’t need the care required to make subsequent strokes. The seconds (or fractions of a second) you spend repositioning your stones for the next stroke are lost time.

Won’t the scrubbing strokes (especially with the 100/200/400 grit) damage the edge? Or are you saying that you only scrub with the higher grits?

Correct.  I normally use scrubbing strokes only with higher grits.  If I’m doing a re-profile, I’ll use scrubbing strokes at lower grits, but only if I’m sure I won’t hit the apex.

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dulledge

[Mark76]

I think all that has been said above is true. In practice I usually use scrubbing strokes simply because it’s easier and faster. Only to make a burr I sometime use up-down strokes. And I vary techniques between concurrent stones if I want to be absolutely sure that I erased the scratches from the previous grit.

Molecule Polishing: my blog about sharpening with the Wicked Edge

[Author]

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