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How I use my sharpness tester to improve sharpening
#1
Let's share technicalities on the method from our own experience. Concrete examples or conceptual approach, all good.

My 2 cents on honing.
Keep honing while the sharpness score keeps improving (i.e. lowering), and stop when the reading has stopped changing.
At this point, should you continue honing - you will lose the edge sharpness you've just achieved.
At this point the right thing to do is either to change to a finer hone, or just enjoy the best attainable sharpness you've already got.

Want your edge to shave - hone it to 150 BESS, but want it to split a hair - change to a finer grit and continue honing to about 120-90 BESS, and then change again to the finest grit  and go on honing to 70-50 BESS.

The edge sharpness tester indicates those breaking points in the sharpening sequence, where you have to change to a finer grit, and not to ruin the edge by overhoning.
You know you are overhoning the edge when the BESS reading increases.
When I see this, not only I change to a finer grit, but may also take a shallower honing angle.

The scores the tester gives aren't equally informative, some are more important than others.
I've noticed again and again something special about the 90 BESS. It indicates some crucial events happening at the very edge.
For example, microbevelling improves sharpness of edges that initially had a BESS score of over 90, i.e. of an edge thicker than 0.2 micron at the apex.
But microbevelling has no effect on edges that are already in the 80-90 BESS range, unless of very hard steel.
http://knifeGrinders.com.au
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#2
That’s an excellent example of how sharpness testing can assist both the experienced and novice sharpener.  For the experienced sharpener sharpness testing can be used to fine tune an edge, or to compare the affect of various compounds at different stages of sharpening.  For a novice it shows the just what a compound is basically doing when honing.
 
Until I got a sharpness tester I had no concrete way to tell exactly what honing did as far as sharpness was concerned.  When I got a tester I did a lot of experiments like that and found the answers to lots of questions.  I don’t see how that understanding can be obtained without sharpness testing.
 
I like how you mention that you hone with one compound until the edge does not get any sharper.  Other than the usual crude methods of testing like cutting paper, (or using your tongue?????), etc., I don’t see any way to obtain that information other than with a sharpness tester.  Sharpness testing has also helped you to understand how micro beveling affects the edge.  Most importantly, you can represent your results numerically rather than the usual blurting of supposition and blind declarations of “facts” that is so common in the sharpening world. 2xthumbsup
 
Great post.  Very interesting.
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#3
Grepper, knowing your interest in toothy edges - here are my observations for paper wheels.

The best deburring sequence preserving those microserrations is:
Having set the edge on a grit #1000 stone or CBN wheel, straight to 0.5 micron diamond paste on a paper wheel at +0.4 degree.
E.g. if the edge was set at 15 degrees, hone at 15.4
2-3 passes across the paper wheel usually suffice, but if not, I continue till deburred completely.
Averaged BESS score 85.

The next best is after the grit #1000 stone or CBN, a paper wheel with 5 micron diamond paste at +0.4 angle (15.4 degrees) twice.
Averaged BESS score 101.
My USB microscope shows the microserrations look entirely intact after 0.5 micron diamonds, but smoothed out after the 5 micron.

I haven't tried that on a Tormek leather wheel, but can tell that +0.4 degree is about 3 digits on the US micro-adjust.

Compared to this "high-angle" honing, honing at the exact edge angle with 0.5 micron diamond paste doesn't deburr at all, as you could expect a priori.
And honing at the exact angle with 5 micron diamond paste twice averaged 107 BESS, deburred well, and smoothed away the teeth as I could see.
http://knifeGrinders.com.au
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#4
I have been sharpening with a 150 grit Cubitron belt on the Kally and like the results. Then I deburr with the rough side of a leather belt on the Kally with basically no compound. I did put a little bit of Tormek honing compound on it months ago but none since, so I suspect it is having little or no real impact.

Just out of curiosity, what do you think the .05 micron compound does exactly? Polish the side of the bevel? Abrade some of the burr away? Simply provide some lubrication?

Have you tried the paper wheel with no compound?

Can you post some of your microscopy images?
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#5
Abrasion on a bare paper wheel should be negligible compared to leather; to try would mean running a brand new wheel with just clear wax, it never came to my mind.
The best explanation I can think of is that the fine diamonds at a high angle and RPM should be breaking off the burr; the contact is too brief to even consider polishing.

I've never been saving microscope images systematically as the sharpness tester was giving me the answers I needed; but after reading your interesting posts on this forum I will
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#6
What do you mean when you say “fine diamonds at a high angle and RPM should be breaking off the burr”?
 
Specifically, what do you mean by “breaking off the burr”?
 
My thinking is that a 0.5 micron particle is extremely miniscule.  Also the amount of abrasive particles in compound is very small and what little there is, is distributed throughout the compound.  It’s a lot like a very poorly manufactured abrasive belt with very few, randomly placed abrasive particles that are poorly adhered to the belt substrate.
 
I just try to imagine exactly what impact that has on the burr.  While I have no proof, I would suspect that it acts like any other fine abrasive and may remove a minute amount of steel.  Basically, just continuing the sharpening process at a very fine level.
 
This may very well abrade away some of the burr, and because it is such a fine abrasive, create less burr than is abraded away.  I do know that very fine abrasives like that will remove very fine scratches, polish the bevel and further smooth the edge even if only a very small amount.
 
Obviously, unless you have created a really big, mean, nasty and tough burr it can be removed by repeated bending back and forth until it fractures off using a plane leather strop and doing it by hand.  But that can take more time than I like so I use the Kally @ 1750 RPM – (about 1800 ft/min) belt speed.  That said, I don’t really understand how the moving belt impacts burr removal compared to just bending it back and forth.  I’m still trying to figure out exactly what that means.
 
Anyway, that’s my thinking when I ask, what do you mean when you say “fine diamonds at a high angle and RPM should be breaking off the burr”?
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#7
Diamonds concentration in the pastes is 10% to 50%, depending on the brand.

This particular paper wheel has got 3 vials of diamond paste rubbed into it, 20 grams each, since I started using it. There should be some depth of concentrated crystals in the outer paper layer.
As far as my imagination goes, at a higher than the edge angle it impacts the base of the burr next to the apex, breaking it off. Alternating the blade sides, it usually takes 3 passes per side across the wheel, sometimes more. With 0.5 micron diamonds, I cannot see any polish to the apex with the USB microscope after that.
I tend to agree with you that there should be a lesser burr left behind, unless we underestimate deburring effect of a compressible substrate - on a paper wheel it may be closer to stropping than honing.
Its deburring effect may be similar to that of high-angle pasted stropping done by straight razor users.
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#8
(10-29-2017, 01:05 AM)KnifeGrinders Wrote: This particular paper wheel has got 3 vials of diamond paste rubbed into it, 20 grams each, since I started using it. There should be some depth of concentrated crystals in the outer paper layer.
As far as my imagination goes, at a higher than the edge angle it impacts the base of the burr next to the apex, breaking it off. Alternating the blade sides, it usually takes 3 passes per side across the wheel, sometimes more. With 0.5 micron diamonds, I cannot see any polish to the apex with the USB microscope after that.
I tend to agree with you that there should be a lesser burr left behind, unless we underestimate deburring effect of a compressible substrate - on a paper wheel it may be closer to stropping than honing.
Its deburring effect may be similar to that of high-angle pasted stropping done by straight razor users.

Yes!  I, underestimatED the de burring effect of a compressible substrate - on a paper wheel it is closer to stropping than honing.  My opinion.

Do any of you have experience with using wheels made from MDF?

Rupert
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#9
Have you ever cut anything?

No offence intended at all. To be honest, I was Thrilled at the beginning!
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#10
Rupert sharpened his first knife when I was just beginning to toddle Smile
Or was that a question about practicality of that sharp edges? I love Ken's likening of the science of sharp we pursue here with auto-racing industry, Ken said: "Numerous automotive innovations which began in auto racing would have seemed like overkill for driving the family sedan at fifty miles per hour. Today many of those innovations have become part of everyday family auto technology... I can see these advancements gradually filter into everyday sharpening. "

People who tried MDF wheels mention scratches, MDF is not suitable for fine honing.
Unlike the pressed paper, MDF surface is pockmarked (microscopically), trapping abrasive particles into larger conglomerates; as these break and form again you get random scratches on the finish.
Another argument against MDF and pro paper is the paperwheel compressibility: use of a compressible substrate helps to avoid formation of the burr that is produced by edge-trailing honing on a hard substrate.
http://knifeGrinders.com.au
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