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View Full Version : Sharpening stroke - edge trailing vs edge leading



bluntcut
10-09-2012, 12:31 AM
I just posted this msg in my 'Apex Bevel Geometry' thread in another forum. It could be a fun read, so I copied-post here:

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I spent considerable amount of time on the physics & visualization of sharpening grind interaction -> I gave up (more like deferred) for now, since who the heck want to read this dissertation anyway (ok, maybe a few of ya).

Alright then, booted myself back to Keep-Simple principle.

Sharpening stroke direction - edge trailing or edge leading or combination? I found a while back (re-invented the wheel - only sharpmaker is the purist) that edge leading stroke worked better than trailing/stropping stroke. Here is an easy experiment you can easily replicate.

Setup
http://imageshack.us/a/img7/2493/strokesetup20121008.jpg

Used DMT 6EF to de-burred: Used light pressure strop strokes for edge-trailing sample. Used light pressure edge-leading strokes for edge-leading sample.

Results
http://imageshack.us/a/img253/5933/strokedirection20121008.jpg

I don't have a SEM & SW (to construct field depth) to give a good edge/apex facing view. Just to show that 'Edge-leading 90* deburred' edge is clean and thinner than 'Edge-trailing'. I am not going to blah about variables this & that at play.
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Eamon Burke
10-09-2012, 12:34 AM
Can you do this with a stone, and not a diamond plate? I'd be interested to see the difference.

This is really cool.

bluntcut
10-09-2012, 12:50 AM
Can you do this with a stone, and not a diamond plate? I'd be interested to see the difference.

This is really cool.

[Waterstones]
Clean:
trailing - edge a bit less jagged.
leading - same results.

Slightly muddy:
trailing - less burr, tiny convex, less teared
leading - less burr, apex not as thin. However change stroke angle to 30*, to get corrected apex thinness.


I conducted quite a few experiments with this stroke direction, using abrasive (fixed, embeded & loose/lap) from 165microns down to 0.1 micron (oh, can't bring myself to get those pricey 0.025um polydia yet).

ajhuff
10-09-2012, 10:06 AM
Pretty cool. Thanks.

-AJ

pitonboy
10-09-2012, 11:46 AM
This is great work and invaluable to those of us who like to know what the big manipulations while sharpening actually translate to at the very cutting edge of things (i.e. the really obsessive-compulsive types)

Sarge
10-09-2012, 11:50 AM
So what your saying edge trailing produces nice results a bit nicer than edge leading in your findings?

I've been thinking this myself as I recently altered the way I deburr and found I get a sharper final result but I don't have a nice of retention and have decided to return to my old way and enjoy the better retention i got when I used edge trailing strokes to deburr.

bluntcut
10-09-2012, 11:52 AM
So what your saying edge trailing produces nice results a bit nicer than edge leading in your findings?

I've been thinking this myself as I recently altered the way I deburr and found I get a sharper final result but I don't have a nice of retention and have decided to return to my old way and enjoy the better retention i got when I used edge trailing strokes to deburr.
The other way. Edge-leading produces nicer/cleaner edge than edge-trailing.

Zwiefel
10-09-2012, 11:56 AM
The other way. Edge-leading produces nicer/cleaner edge than edge-trailing.

But it probably removes more material? (I would guess that the difference would take decades to have any meaningful effect.)

Dave Martell
10-09-2012, 12:00 PM
Some thing that comes to mind....Edge trailing leaves the burr folded outwards (away from the edge) and shows better whereas edge leading pushes/folds the burr over to the opposite side and doesn't show well. It's been my experience that if both edges are stropped lightly (on both sides) edge trailing they will look the same with regards to burr formation. I will say that creating an edge on belts by edge leading does produce a slightly smaller burr than edge trailing.

bluntcut
10-09-2012, 12:12 PM
This is great work and invaluable to those of us who like to know what the big manipulations while sharpening actually translate to at the very cutting edge of things (i.e. the really obsessive-compulsive types)

A short story. A year ago I was on a mission to teach sharpening skills to my cousins (in SE Asia). 'Doh' turned out that I didn't know much, hence I lurked & learned alot from here, other forums, google-fu, etc... All roads lead to knife performance (skipped the 'look' aspect for now). I created this thread to share with others and hopefully it's skills forming. http://www.bladeforums.com/forums/showthread.php/992879-Apex-Bevel-Geometry-cross-sectional?p=11375171#post11375171. Rec read: newest posts first, if interesting then go to 1st post. I prefer practicality over knuttiness.

bluntcut
10-09-2012, 12:41 PM
Some thing that comes to mind....Edge trailing leaves the burr folded outwards (away from the edge) and shows better whereas edge leading pushes/folds the burr over to the opposite side and doesn't show well. It's been my experience that if both edges are stropped lightly (on both sides) edge trailing they will look the same with regards to burr formation. I will say that creating an edge on belts by edge leading does produce a slightly smaller burr than edge trailing.

Good insights :doublethumbsup:

Continuing with my non-pro speak... High velocity abrasives (belt, wheel, disc) is more complicated because effective grit & momentum vectors can easily exceed steel properties. Analogy - high pressure water can cut steel. However the final resultant impact is the same for moving or static abrasive: which is away from the apex for edge-trailing, and 'into' bevel for edge-leading.

btw - my language skills is sub-par, so please over-look dull (or so sure or if construe as un-respectful) statements :O

keithsaltydog
10-09-2012, 02:25 PM
Edge trailing when sharpening on whetstones certainly works.

Burr removal on the stones I've seen some Japanese sharpeners use edge lead & others use edge trail,of coarse burr removal is a very lite touch.