The three things that matter in photography of edges

[EOU]

Okay, here they come Cyrano. Two knives, each rolled at two locations. First location rolled approx. 250 points and second location approx. 350 points. As you can see we we have reduced the surface polish on one of the knives in an experiment to see if it photographs better.

For those just joining in, Cyrano is going to see if he can photograph the rolled edge portion of these knives using his digital microscope.

                                                          

[Larrin]

How do you know for sure that the edge is rolling and not wearing?

[Bud]

I can help here I think Larrin. Eou uses their SET unit to roll the edges. If you need more particulars than that then just start reading here http://bessex.com/forum/showthread.php?tid=322

[grepper]

From my experience edges dull because they roll, not wear away.  Of course if you are cutting sandpaper or some other substance that could actually remove steel it could be an exception, but in almost all cases rolling or other edge deformation is the cause of dulling.  Even in the very rare case where edge wear might occur, edge rolling would would most likely account for the majority of dulling.
 
As an example, if a knife is sharpened to say, 150, it will be duller after chopping vegetables on a wood cutting board.  You can’t sharpen a knife using broccoli or wood because sharpening requires removing (wearing away) steel.  In the same way, broccoli or even potatoes won’t wear away the edge.  The edge dulls because it rolls.

[grepper]

Mr. Cyrano, you said, "I've found Dino-Lite's embedded EDOF algorithm is good, and usually yields results comparable to stacking in Photoshop." 

I have a couple of questions:

Does the Dino-Lite produce a stacked image automatically or does it simply automatically produce a bunch of focus bracketed images that then require stacking in post processing with it's software the same as you would do in PS?

How many images is the focus bracketing?

[Larrin]

I'm very confused; the results thus far are correlating with wear resistance not with strength. Rolling of edges is a strength and geometry test. Higher strength and heavier geometry resist rolling. Vanadium carbides do not improve resistance to rolling, they improve resistance to wear.

[grepper]

What results are you referring to?

[EOU]

Thanks Bud for pointing Larrin in the right direction. Yes it is confusing Larrin and since your membership began well after the original edge rolling thread began we're happy to give you the Cliff's Notes recap here.  This whole project is a spin off of a question that was asked a year ago "why are burrs so malleable?". The writer was simply asking why the steel that forms the burr appears to have much different attributes than the steel it emanates from and particularly with regard to ductility. As the discussion progressed the question was extended to finished edges as well. Then the discussion was extended further to ask whether or not HRC hardness levels above a certain level are contributing to any added resistance to edge rolling. Then blade/edge geometry and steel type entered the fray.

Preliminarily, early tests indicate that there are other or additional factors at work here with regard to very thin edges and that they do not seem to adhere necessarily to conventional wisdom. That's what we are testing for. Don't put anything you glean from these reports in the bank just yet though. There may be many variables at work here that we are not yet aware of and that includes our test processes. We and our test partners are just banking data at this time, we'll try to draw conclusions later.

[Larrin]

What results are you referring to?

I'm referring to these posts:
http://www.bessex.com/forum/showthread.php?tid=324
http://www.bessex.com/forum/showthread.php?tid=326

There are also specific mechanisms described with three "Phases" including "elastic deformation," "elasto-plastic transition," and "plastic deformation," along with specific ranges of edge impacts where those different phases will take place.

[grepper]

I could be laboring under delusion, but I don’t think those studies in any way indicate the possibility that the measured dulling is caused by wearing of the edge.   Rather, it is simply comparing how “wear resistant” steel formulations compare to regular steel as far as resistance to rolling is concerned.

As far as I know, and that’s not a claim to fame,  , it requires work and abrasives to wear away or abrade steel.  While edge wear may occur in some very specific situations, most all of the dulling we see in every day knives is caused by rolling which is what the SET tests for.  I suppose in some cases the edge could be bashed, mashed, mutilated, mangled or generally deforming causing the edge to be brutally stove-in, but for the most part dulling is caused simply by rolling.  At least that’s my take on why knives get dull.