Apex Bevel Geometry cross-sectional

[BluntCut MetalWorks]

My speculation is that it increases the upward force of the abrasive but in a more narrow plane - where the abrasive had it been packed shoulder to shoulder on a level field might have spiked the pressure at the apex and rounded it over, instead the blade is supported on a bed of nails so to speak. Each one exerting more pressure individually but incapable of rounding the edge over (at similar pressure overall) due to support from the other points and the sharper let-off of pressure as the edge passes over the low spots. Or something like that....We might be saying the same thing...

Yes, some overlapped on pressure part. Hopefully my non-optimal(head-cold) brain is partially coherent...

1) Abrasives at the top of the conical (nail tip) are more thinly spread-out (stretched paper & stand vertically) and weak (due to lack of lateral support), so they get stripped away or bend-over quickly. i.e. ~ non-factor.

2) Abrasives on the conical facing slope lowered the abrading interaction angle (think: looking straight at rather than upward).

3) High pressure contact points slightly bend/dent steel surface, which lowered (in perspective of abrasive) the abrading interaction angle because steel normal (perpendicular) force of the concave (from bend/dent) steel surface is perspectively less downward.

Angle of abrading force 2) + 3) is much lower than angle from flat abrasive & steel surfaces at a given velocity. This lowered angle allows shallower cuts with less upward tear & curl (round) + high pressure cuts faster - yippeee a nice bevel face + apex.

 

[HeavyHanded]

Yes, some overlapped on pressure part. Hopefully my non-optimal(head-cold) brain is partially coherent...

1) Abrasives at the top of the conical (nail tip) are more thinly spread-out (stretched paper & stand vertically) and weak (due to lack of lateral support), so they get stripped away or bend-over quickly. i.e. ~ non-factor.

2) Abrasives on the conical facing slope lowered the abrading interaction angle (think: looking straight at rather than upward).

3) High pressure contact points slightly bend/dent steel surface, which lowered (in perspective of abrasive) the abrading interaction angle because steel normal (perpendicular) force of the concave (from bend/dent) steel surface is perspectively less downward.

Angle of abrading force 2) + 3) is much lower than angle from flat abrasive & steel surfaces at a given velocity. This lowered angle allows shallower cuts with less upward tear & curl (round) + high pressure cuts faster - yippeee a nice bevel face + apex.

What he said ^....

 

[BluntCut MetalWorks]

Apparently I'm going too deep into the theory behind 'making it sharp' however if you like to find answers for 'raised burr 2 sides, deburred but didn't apexed?' and 'how come the burr seem long but blade height wasn't shorten by the same amount?'

Or should I get back to rub it sharp, then continuing on with performance?

Let me know.

 

[HeavyHanded]

Apparently I'm going too deep into the theory behind 'making it sharp' however if you like to find answers for 'raised burr 2 sides, deburred but didn't apexed?' and 'how come the burr seem long but blade height wasn't shorten by the same amount?'

Or should I get back to rub it sharp, then continuing on with performance?

Let me know.

Need to do both at the same time. You are asking very good questions, but lacking the tools to give definitive answers you're left with performance criteria to feel it out. Add to this the bewildering array of grinding, polishing, lapping media available (not to mention the speed with which said media are applied), and the equally large choice of steels and heat treats the combination is daunting. There are (I believe) some generalities that can be drawn but beyond that it all comes down to
Consistent preparation of the edge (whoever this might be accomplished),

and cut and edge retention relative to a given prep, relative to a given steel, relative to a very specific target material, relative to a specific cutting strategy (straight pressure cut, draw with X length per Z unit of pressure, draw with X+Y length per Z - Q unit of pressure - now I'm getting dizzy).

And then of course the test needs to be repeated at least three times or at best all you've uncovered is a 'trend'.
Most of the burr and related steel integrity questions are possibly already answered in a tool and die reference guide somewhere. I do have a source for some of these and he'll be coming over next weekend to carve pumpkins with his grandchildren - I'll hijack the father in law and see what his thoughts are...

 

[BluntCut MetalWorks]

Need to do both at the same time.

'Shaping' is more accurately describe the process of making/creating the geometry. 'Sharp' is more relevant in context of cutleries but the edge-of-impact can be round/square/crater. So instead of in depth coverage on 'shaping', we can assume that any shape/geometry can be ground as envisioned/wanted by a machine from the future.

You are asking very good questions, but lacking the tools to give definitive answers you're left with performance criteria to feel it out. Add to this the bewildering array of grinding, polishing, lapping media available (not to mention the speed with which said media are applied), and the equally large choice of steels and heat treats the combination is daunting. There are (I believe) some generalities that can be drawn but beyond that it all comes down to
Consistent preparation of the edge (whoever this might be accomplished)

Exactly why we want a consistent 'shaping' way adapts to moving parameters. Consistent = take skills = versatility/adaptability. Recipes = mostly restricted within formulaic techniques parameters.

and cut and edge retention relative to a given prep, relative to a given steel, relative to a very specific target material, relative to a specific cutting strategy (straight pressure cut, draw with X length per Z unit of pressure, draw with X+Y length per Z - Q unit of pressure - now I'm getting dizzy).

Right, performance is integral reflecting the interaction environment + parameters (lol - sounds like my fuzzy brain speak). I left Z (3rd physical dimension) out to contained the interaction physics to a more manageable set. Sure, for a complete picture, we need to add Z - later.

And then of course the test needs to be repeated at least three times or at best all you've uncovered is a 'trend'.

Bingo! If we can come up with a consistent way to shape a target geometry for a reasonable environment+parameters, every body in the world can contribute with data points. After extremes/biases data points are removed, we would easily spot 'trend' - yes, go for the low hanging fruits.

Most of the burr and related steel integrity questions are possibly already answered in a tool and die reference guide somewhere. I do have a source for some of these and he'll be coming over next weekend to carve pumpkins with his grandchildren - I'll hijack the father in law and see what his thoughts are...

Roasted pumpkin seeds conversation, right

 

[HeavyHanded]

OK, this is about to get picture-heavy. Disclaimer, I really flew thru this - haven't taken a very close look at the images but did make some observations as I went. I have also never taken a close look at this topic.

First, I only used Aus8 on the India stone, and only used it edge-leading. Here's the reason - I was able to more or less completely remove the burr edge leading except for a few small bits hanging out in the low points. As I implied in an earlier post, complete removal of the burr generally involves some form of loose abrasive/lapping action, or the use of an extremely fine fixed abrasive. In the range of an India stone the abrasive is fixed in a block with fixed highs and lows - there is no way to get the abrasive highs and lows to match perfectly from side to side or pass to pass, therefore there will always be low points that have some unsupported steel left over from the last grinding pass, the high points will be relatively burr free. The resulting 'burr' will be very fragmented and feathery and (in my experience) need some form of post-grind finishing to completely de-burr. It is possible to get it down where it will not catch on a cotton ball, shave differently from side to side, catch on newsprint etc, stand only in very small patches when backdragged on wood - undetectable to the naked eye but just visible at 10-15x with strong lighting - not a problem. This is not unique to the India stone, but applies to virtually all firmly fixed abrasive media whether used edge leading or edge trailing (IMHO). Tools such as a waterstone or SiC stone are a bit different in that they shed a bit of loose abrasive that can accomodate itself to the existing grind texture in the steel and hit those low spots - without which some form of conformable media (or submicron fixed abrasive) will be needed. In any event the burrs I'm speaking of are not readily visible at 40, 160, 640, or 1600, but I could find them by shifting my light source at 15x.

Anyway, I attempted to do some edge trailing on the Aus8 steel on the India stone - marked the bevel with a Sharpie and swithched sides/pass - by the time the Sharpie was gone (approx 10-12 passes) a burr had formed that was impossible to reduce or remove (though it was extremely small - still much larger than the tattered micro remnants from the edge leading test. I didn't bother with images as I felt the prep hadn't made it past the starting line.

These are the images with scale for 160, 640, and 1600 - the gouge is a very deep scratch from me correcting the uneven factory bevels with an 80 grit stone:

Related - I took images of a Mora Classic that had been sharpened edge leading on a fine Norton Crystalon and finished off with a 500 grit silicon carbide jointer stone, resin bonded - bothe edge trailing and edge leading. This stone is relatively 'soft' - sheds some abrasive and binder as it goes - and can be used to deburr fairly completely. Since the current discussion has come to the differences btwn edge leading and edge trailing I thought I'd include these images as well. Should be noted there was very little difference in how well these edges performed for a handful of cut tests (crossgrain newsprint, arm hair, cardboard). Interesting note - the edge trailing appear to show some unsupported metal on the high points in the grind structure, edge leading appear to show unsupported metal in the low points (including the Aus8 India images). Part of this might be the inclusive angle on the Mora is only 23 degrees or so opposed to the 28 the Aus8 is set at.

First set is edge trailing:

Next are edge leading - same stone:

And to add a bit more to the mix, here's the same edge stropped with loose abrasive from the same 500 grit stone applied to a sheet on newspaper wrapped around the same stone.

The apex line appears to be much more unified - less trace of any unsupported steel.

Finally, the same edge stropped with white compound on newspaper - a bit more unified still. Not as big a visual improvement over the previous as one might think, tho a noticeable improvement in how well it tree-topped leg hair:

One thing I notice is that edge trailing on a firm stone seems to make the apex less uniform than going edge leading. Other thing is that stropping (at least with an abrasive) even on a surface as firm as a single sheet of paper wrapped around a stone, results in a large increase in apex uniformity.

 

[wouldestous]

what im getting from this is that i need to get better at maintaining consistent angles while sharpening. (i freehand on stones, dont have a guided rig or a strop).
still, this satisfies that geeky part of my nature. thanks!

 

[BluntCut MetalWorks]

OK, this is about to get picture-heavy. Disclaimer, I really flew thru this - haven't taken a very close look at the images but did make some observations as I went. I have also never taken a close look at this topic.

:thumbup:HeavyHanded:thumbup:

Anyway, I attempted to do some edge trailing on the Aus8 steel on the India stone - marked the bevel with a Sharpie and swithched sides/pass - by the time the Sharpie was gone (approx 10-12 passes) a burr had formed that was impossible to reduce or remove (though it was extremely small - still much larger than the tattered micro remnants from the edge leading test. I didn't bother with images as I felt the prep hadn't made it past the starting line.

If we are keep carrying this burr along finer grit progression, can we know exactly when this edge would be free of burr? Iffy at best. I just re-read John D. Verhoeven's reseach and extracted burr finding
*****
link
Experiments on Knife Sharpening
John D. Verhoeven, Emeritus Professor, Department of Materials Science and Engineering
Iowa State University, Ames, IA, September 2004
Page 22

All of the sharpening done on the waterstones moved the blade along the stone in
the direction into the blade edge 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 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.
*****

Peformance is what we are chasing after. To me, burr is a sympton that can easily detected and removed but the cause of burr formation may already compromised the resultant edge.

A lip (in this context) = where edge thickness below the apex is not progressingly the same or thicker going toward bevel shoulder.

A lip can roll easily because there isn't as much metal supporting the edge, quickly degrade the performance. Whereas there more metal supporting metal for the cliff/slope geometry, therefore stronger -> perform better.

 

[HeavyHanded]

Good observations.

Couple thoughts to add - because the edge leading had no post grind finishing its impossible to tell if the 'lip' architecture you highlight mightn't be present but concealed under some loose metal. That is, the highlights from your three 'lip' details are not consistent along the length of the bevel. They appear to wind over and presumably shift to the backside where they are no longer visible from the front. This could easily be present but not obvious on all the samples and would actually make sense - not surprising one might have micron swaying back and forth along the line of the theoretical perfectly straight apex as viewed edge on. Along this line of thinking ---
Additionally, among those samples there are a number of highlight areas that progress along the upper edge of a grind ridge and do not dim or fade as they link to the highlight on the apex - bridging the low point on the lip - yet its doubtful the bevel thickness or focal depth could accommodate such a combination of seemingly opposite characteristics. There are also some darker low areas that proceed straight to the apex with no change even where they should be climbing the lip and coming back into a highlight region. There's a reason most serious studies of edge geometry do not rely on optical microscopes, even metallurgical ones - preferring the SEM even at modest magnification levels. Controlling for the lighting becomes very tricky at higher magnification.

That said, even if there is a swaying of the apex to one side or the other at this scale, I cannot find any evidence this leads to a weaker edge in use. My stropped machetes and hatchets amaze me at their cutting performance and ability to keep cutting well even after much abuse, all of them stropped either on a waterstone or abrasive impregnated paper.


I have no idea at what grit value a burr could be removed by backhoning on a hard stone, but my experience is that it might not be possible. I do believe one can polish an already clean edge by backhoning on a very fine stone, but a quick check of some of the straight razor forums will make one very dubious of this technique - at least on a firmly fixed abrasive (tho even they would not consider a blade shave ready until it had been stropped). My guess though, is that if I were to take this edge up to a fine Spyderco ceramic I could polish backhoning on an EF. Not sure if this is where the discussion leads tho. As a side note Verhoeven did no cut tests - anyone familiar with most varieties of waterstones will be rather emphatic re the benefits of finishing with some edge trailing.

To my way of thinking, the burr is a constant companion to grinding, like the recoil is to a bullet discharge. It is tied inextricably to the act of removing steel from itself, at least at moderate grit values. You progress to a level where the abrasive is so small, it removes so little metal per particle that the structure of the steel itself will not distort when cut edge leading, or when edge trailing the particle itself is no longer rigidly fixed and therefore can roll or slide as it cuts the metal and distortion at the grind site is reduced/eliminated this way.

There are characteristics of abrasives, underlying surface, and mobility of abrasive on said underlying surface that all add up to whether one is better off edge leading, edge trailing, stropping on a finishing media. I can say that there is a huge difference between the stropped edge and the unstropped edge in pretty much every case - I notice no loss of longevity but a large improvement in cutting performance, even when done with 220 grit SIC compound following the coarse side of combination stone. Then again, I haven't used every grinding/polishing method out there.

Too many variables.

 

[BluntCut MetalWorks]

It isn't about strop vs non-strop.

For two edges with same apex thickness/radius but different geometry. I conjected that the one with the 'lip' (micro hollow/concave bevel below apex) won't be as strong as the one without 'lip'. I made grinding surfaces with abrasives sizes from 12microns to 0.1micron, so I can use edge-leading stroke to create an apex thinner than a razor. Without scientific instruments & softwares, I settle for morning shaves - many time dry shaves - to test the edge sharpness and durability. I can easily shave with this edge(endura vg10) for a couple weeks. In contrast, after a dry shave a standard straight razor or stropped endura-vg10 lost its glide-smooth cutting edge.

IMO, burr is a partially/incomplete abraded metal, can be submicron in size. Instead of your 'recoil' analogy, I think burr as 'smoke & fragment' that gunk up the barrel

Too many variables.

Yes.

Even Prof Verhoeven hand-waved '.. All of the sharpening done on the waterstones moved the blade along the stone in the direction into the blade edge causing the abrasive debris to move away from the edge..'. Oh darn, it's up to us to come up with a better explanation.

 

[HeavyHanded]

For two edges with same apex thickness/radius but different geometry. I conjected that the one with the 'lip' (micro hollow/concave bevel below apex) won't be as strong as the one without 'lip'. I made grinding surfaces with abrasives sizes from 12microns to 0.1micron, so I can use edge-leading stroke to create an apex thinner than a razor. Without scientific instruments & softwares, I settle for morning shaves - many time dry shaves - to test the edge sharpness and durability. I can easily shave with this edge(endura vg10) for a couple weeks. In contrast, after a dry shave a standard straight razor or stropped endura-vg10 lost its glide-smooth cutting edge.

I find this curious - I have kept my face reasonably smooth for a week at a time dry shaving at work using a variety of knives tho I generally carry carbon steel, all finished by stropping similar to the edges done for the pics. And while I have little to compare it to, as mentioned the performance I get from my choppers - all stropped and presumably sporting a lip if any of my edges do - exceed my expectations, esp when I use them on very hard wood (seasoned American beech).

 

[BluntCut MetalWorks]

I find this curious - I have kept my face reasonably smooth for a week at a time dry shaving at work using a variety of knives tho I generally carry carbon steel, all finished by stropping similar to the edges done for the pics. And while I have little to compare it to, as mentioned the performance I get from my choppers - all stropped and presumably sporting a lip if any of my edges do - exceed my expectations, esp when I use them on very hard wood (seasoned American beech).

Sorry, no surprise here, it's inline with my expectation of an expert sharpener

I will try to get my abrading interaction model done so we can get past this edge-shaping part.

edit:
a) My edges are quite messy from impatience unsteady hands. So as the rest of the worlds, not too many can get the edge as nice & clean yours under a microscrope. I am just a tinkerer with plenty of curiousities.
b) Please look at the Verhoeven's research fig 37 & 38 SEM edge-view on pg 30, those look like lips too me. And just from stropped alone because they were sharpened by true-hone (edge-leading into wheels).

 

[ainokea]

I'm a Noobie (whatever)I'd like a good, solid, simple answer on Knife Burrs. Having said that, amateur home cooking-sharp my own knives using the Work Sharp WKTS sharpener, should I be concerned about "Burrs"? After the sharpening I wash the knife with soap and water and wipe it dry. So...if Burrs are still attached to the edge, and I slice and dice, and feed the family with that food, are there repercussions eating that food if it's contaminated with Knife Burrs?

 

[BluntCut MetalWorks]

I'm a Noobie (whatever)I'd like a good, solid, simple answer on Knife Burrs. Having said that, amateur home cooking-sharp my own knives using the Work Sharp WKTS sharpener, should I be concerned about "Burrs"? After the sharpening I wash the knife with soap and water and wipe it dry. So...if Burrs are still attached to the edge, and I slice and dice, and feed the family with that food, are there repercussions eating that food if it's contaminated with Knife Burrs?

I wouldn't even worry about burr, unless burr of size 1mm or larger. Even so, our stomach acids (HCl, KCl, NaCl) probably will dissolve most small metal with large expose surfaces. There are plenty of metal filing in cereal - yumm just a source of iron.

Nevertheless, even better just to remove those burr/wire:
1) scrape your knife edge start at 10* scrape and rise until about 90* to a pieace of plastic or a piece of wood - the idea is to bent/roll burrs or wire over to 1side.
2) use gentle edge-leading strokes into the finest spare belt - not connected in the machine - until you feel (with fingers) that rolled burrs/wire are gone. Repeat 1) bent remnant burrs/wire to the opposite side. do 2) again. repeat with less pressure each time (would take more than 1 or 2 times do completely clean up burr/wire).

Note: Power grinder belt/wheel moves abrasives at high velocity, so abrading interaction is different than hand-power sharpening. Usually the burr is smaller with high-velociy abrasives because the abrading vector is more parrallel to bevel surface. Of course there is collision momentum too

 

[ainokea]

Thanks for the information, it puts my concerns at ease.

 

[HeavyHanded]

Sorry, no surprise here, it's inline with my expectation of an expert sharpener

I will try to get my abrading interaction model done so we can get past this edge-shaping part.

edit:
a) My edges are quite messy from impatience unsteady hands. So as the rest of the worlds, not too many can get the edge as nice & clean yours under a microscrope. I am just a tinkerer with plenty of curiousities.
b) Please look at the Verhoeven's research fig 37 & 38 SEM edge-view on pg 30, those look like lips too me. And just from stropped alone because they were sharpened by true-hone (edge-leading into wheels).

Took another look at Verhoevens paper and the images you refer to appear to show a blush just shy of the apex on both sides(?). Not sure what to make of this - still having a hard time with the 'lip' theory - will have to take images of two sides in the exact same spot and see what's up.

Have to say it again, for ultimate clean edge preparation and not me sawing away on 320-500 grit stones, look into the methods for sharpening microtome blades - any tool capable of slicing off samples as thin as 3u have got to be at the pinnacle of refinement. Perhaps not for ultimate geometry in general, but for clean apex preparation.

 

[BluntCut MetalWorks]

Took another look at Verhoevens paper and the images you refer to appear to show a blush just shy of the apex on both sides(?). Not sure what to make of this - still having a hard time with the 'lip' theory - will have to take images of two sides in the exact same spot and see what's up.

Have to say it again, for ultimate clean edge preparation and not me sawing away on 320-500 grit stones, look into the methods for sharpening microtome blades - any tool capable of slicing off samples as thin as 3u have got to be at the pinnacle of refinement. Perhaps not for ultimate geometry in general, but for clean apex preparation.

Apexes of those razors are swollen/dented, also with face up/down you can see the apex is brighter due to more light reflected back because of the apex area is more like a cylindrical than a triangular rod.

I avoided microtome and other specialty instruments because blade material usually highly specialized (composition, ht, etc). For metallic blades, sharpening usually employs circular glass plate/disc, where the blade interact with abrasives both edge-lead & edge-trail per cycle with more lateral than perpendicular motion. For friable blades (brittle crystalized), one could use edge-trailing to nick/knock material away. All in all, as long as the apex pass the sample tolerance, all is good. Which mean the apex doesn't has to be a perfect thin plane nor strenght & toughness way past the requirement. Glass/diamond blades for nano sampling, sharpening mostly will be using fracture or lattice/crystal grow/deposit.

As for SiC stones, I agree, edge-leading would prematurely wear out stones with high friability abrasive and could even change the result because of excess smaller SiC abrasives now act as lapping agent.

btw - please keep in mind, I always sound sure on many things (including stuff I barely know or wag ) but I'll be quick to admit & adopt the right stuff.

 

[HeavyHanded]

Apexes of those razors are swollen/dented, also with face up/down you can see the apex is brighter due to more light reflected back because of the apex area is more like a cylindrical than a triangular rod.

I avoided microtome and other specialty instruments because blade material usually highly specialized (composition, ht, etc). For metallic blades, sharpening usually employs circular glass plate/disc, where the blade interact with abrasives both edge-lead & edge-trail per cycle with more lateral than perpendicular motion. For friable blades (brittle crystalized), one could use edge-trailing to nick/knock material away. All in all, as long as the apex pass the sample tolerance, all is good. Which mean the apex doesn't has to be a perfect thin plane nor strenght & toughness way past the requirement. Glass/diamond blades for nano sampling, sharpening mostly will be using fracture or lattice/crystal grow/deposit.

As for SiC stones, I agree, edge-leading would prematurely wear out stones with high friability abrasive and could even change the result because of excess smaller SiC abrasives now act as lapping agent.

btw - please keep in mind, I always sound sure on many things (including stuff I barely know or wag ) but I'll be quick to admit & adopt the right stuff.

They (microtome platter) also have grooves cut into surface to further break up any patterns that might result in burring. I suspect there may be something to the abrasives piling up on the leading faces of these recesses. When stropping on hardwood I find it helps to scuff the surface with a rasp periodically - gives the abrasive something to catch on. Otherwise it eventually polishes the wood to a fine luster and lapping action all but stops. Still don't know how stropping could create an indent/low spot just shy of the apex, but the dynamics of an abrasive on a conformable surface probably are very complex - could easily be pressure spike for whatever reason, or just a change in reflectance.

I hope I sound sure of very little when it comes to sharpening and cutting - I know what is working when it works, and what I can duplicate, not much more. Until recently I dismissed 'steeling' as nothing more than creative burr manufacturing - couldn't have been more wrong. And before that I harbored incorrect assumptions about edge trailing on waterstones, before that - elements of stropping, microbevels, convex edges, use of oil....

 

[BluntCut MetalWorks]

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.

ex4: edge goes dull by sitting around
(ok this is a maybe answer but it sounds good) Av (trailing) abraded the metal but stretched the bond structure, which will contracted/settled back to a lower energy state.

ex5: edge gets sharper by sitting around
(ok this is a maybe answer but it sounds good) Av (leading) compressed the bond structure, which will relax back to a lower energy state, which make the apex more pointy.

 

[BluntCut MetalWorks]

Edge-leading conjectures against reality? perhaps it's best seen/apply in a sharpening video.

I'm thinking about create a video (mostly actions since my voice doesn't record well and hopefully under 30 minutes) edge-lead sharpening a Spyderco Endura vg10 using abrasive

Stones: AlOx, SiC, Water/alumina, Ceramic, Diamond
Miscs: spine of a ceramic knife, ceramic coffee cup, red clay flower pot, w&d SiC sandpaper, granite rock

Rapid loop through each abrasive, each time the same knife will be forced dull by gentle slice into a rock. Test when ready - 5 slices to newsprint/catalog-paper at 20-45* cross grain determines pass/fail sharpness for each attempt. multiple torns = fail.

Endura vg-10 is known to have tough burr, let's see how this test turn out.

Anyone - Interested/thoughts/suggestions?