Finally Breaking 100 BESS—Thoughts & Feedback Welcome

garry3 said:
Clearly the 600 grit edges performed better than the 8000 grit edges....

knifesteelnerds.com

Maximizing Edge Retention - What CATRA Reveals about the Optimum Edge - Knife Steel Nerds

Thanks to Ed Schempp, Matus Kalisky, and Chin Lim for becoming Knife Steel Nerds Patreon supporters! Your support allows us to fund CATRA studies. CATRA Update 1/6/2020: I have since written more articles about CATRA looking at the effect of steel type: Part 1 and Part 2 Cutlery and Allied...
knifesteelnerds.com knifesteelnerds.com
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"Otherwise it appears that 600 grit did marginally better than 320 or 8000 grit. "

Then Larrin talks about the potential issue of the finer grit DMTs that has been presented by Science of Sharp.

Not saying that coarser edges don't last longer but I don't feel that study has concrete answers when it comes to edge refinement.
 
Wowbagger said:
I'll ask again :

Since we are all about cutting sand paper (pig skin and sand impregnated cards ) :
This is from Dr. Larrin Thomas's testing at Knife Steel Nerds

Importance of Edge Geometry

Another important caveat before we get to the ratings are that these are for the steel only. This does not predict which knife will cut longer or be more resistant to chipping. The reason is because sharpening and edge geometry will also greatly control properties. For example, see the chart below for how much edge retention can change with edge geometry for a single steel (in this case 154CM and CPM-154). Using 10 dps sharpening (20 degrees inclusive on the chart) leads to about 5x the edge retention of 25 dps.

edge-angle-vs-TCC.jpg
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garry3 said:
Clearly the 600 grit edges performed better than the 8000 grit edges....

knifesteelnerds.com

Maximizing Edge Retention - What CATRA Reveals about the Optimum Edge - Knife Steel Nerds

Thanks to Ed Schempp, Matus Kalisky, and Chin Lim for becoming Knife Steel Nerds Patreon supporters! Your support allows us to fund CATRA studies. CATRA Update 1/6/2020: I have since written more articles about CATRA looking at the effect of steel type: Part 1 and Part 2 Cutlery and Allied...
knifesteelnerds.com knifesteelnerds.com
Click to expand...

Can't believe I skipped over that, I haven't seen that data in years!

Learned a lot in that testing and met a lot of great people. Would love to do it again but with waterstones.
 
I'm only glancing here ; I have little patience with it .
Before I did that I read in the quote above "clearly 600 grit did better than 8000" . . .
I was thinking I remembered 120 did the best and it seems that was correct ~ 1000 cards cut . Misprint ?
anyway ; I tried 120 edges (or I'm thinking now Shapton Pro 220 edges , stropped or Sharpmaker Ultra Fine corner of rod lightly run on the edge after)
HATE THEM
all kinds of junk hanging in the "teeth" of the scratched up edge .
Not for me .
I'd rather sharpen more often .
 
Wowbagger said:
I'm only glancing here ; I have little patience with it .
Before I did that I read in the quote above "clearly 600 grit did better than 8000" . . .
I was thinking I remembered 120 did the best and it seems that was correct ~ 1000 cards cut . Misprint ?
anyway ; I tried 120 edges (or I'm thinking now Shapton Pro 220 edges , stropped or Sharpmaker Ultra Fine corner of rod lightly run on the edge after)
HATE THEM
all kinds of junk hanging in the "teeth" of the scratched up edge .
Not for me .
I'd rather sharpen more often .
Click to expand...

It's no misprint,

The test at 120 grit was done to kinda show me that very coarse and thin would win. The operator kept talking about a much coarser and thinner edge so we went to the factory floor where the edge was sharpened by an employee using a Norton blaze belt and deburred on a cotton buff with unknown compound. This is not an edge you can create by hand, it just won't be the same.
 
I was a water stone snob for two decades at least! While I've used belts for certain applications for at least fifteen years it was relatively recently that I learned how well they work in absolute terms. Most of the knives I do in my shop get the 120 Cubitron > A30 Trizact > stropping belt (I used to use exclusively leather but now I tend to use a felt belt doped with diamond or CBN emulsion). Such an edge does go for a long time between sharpenings although it depends on the steel, what the user is cutting upon, etc. Of course thinning the knife is almost always beneficial especially if it's been sharpened many times without being thinned.
 
Jason B. said:
It's no misprint,

The test at 120 grit was done to kinda show me that very coarse and thin would win. The operator kept talking about a much coarser and thinner edge so we went to the factory floor where the edge was sharpened by an employee using a Norton blaze belt and deburred on a cotton buff with unknown compound. This is not an edge you can create by hand, it just won't be the same.
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Stropping compound on a buffing wheel doesn't sound like a toothy edge anymore. It was probably repeatable though.
 
garry3 said:
Stropping compound on a buffing wheel doesn't sound like a toothy edge anymore. It was probably repeatable though.
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While there is a given level of Polish it's not as extreme as you might be thinking. It's quick passes to remove a burr, not to polish the steel. I dont know what combination of wheel and compound was used but it didn't really polish, kinda just cleaned off the burr leaving a very coarse and sharp edge. It's a method I'm guessing was used for a long time before they went to automated sharpening.
 
Jason B. said:
Toothy edges last longer because there is more surface area along the length of the edge, which creates a larger/longer cutting surface that takes longer to wear down.
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I speculate that it is not length or surface area but rather the volume of steel that needs to be worn off before the edge is smooth.
 
Diemaker said:
with a photo he shared in a post here about what a toothy edge looks like. Instead of a saw tooth edge where the scratches from the coarse stone meet a keen apex, it is far more likely the apex is missing having been ripped off leaving a blunt face.
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Do you happen to have the link to this? I was hearing about this recently and would be interested in taking a look.
 
Jason B. said:
While there is a given level of Polish it's not as extreme as you might be thinking. It's quick passes to remove a burr, not to polish the steel. I dont know what combination of wheel and compound was used but it didn't really polish, kinda just cleaned off the burr leaving a very coarse and sharp edge. It's a method I'm guessing was used for a long time before they went to automated sharpening.
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My own experience is that leather wheels and even belts do seem to over polish quickly when used with compound. A gentle pass or two to knock off a burr is usually fine and will leave some tooth, but I find it very easy to over polish if you have a stubborn burr that requires more attention than that. That's my anecdotal experience anyway, and I'm willing to bet that there is some combination of pressure, time, and compound used that would exacerbate things. At any rate, I am finding that I prefer felt belts for my deburring, and that I have an easier time keeping tooth on that media.
 
Diemaker said:
My BESS tester has taught me more than anything else about sharpening. I know it isn't everything but I like to quantify sharpness with a number so I can make a change to my technique and see what that does to my sharpness number. It has taught me that many of the tricks I used to make a knife sharper made it duller. Raise the angle .05 degrees for the last stone to make sure I am cleaning up the apex, WRONG! Double or triple the strokes needed, WRONG! Back up a grit because I think I should have done more strokes with it, WRONG! I would never have figured out these things were bad without the BESS tester. Right after the BESS is a really good microscope. Both have been very, very humbling.

To the op, using a motorized sharpener changes your technique considerably compared to manual sharpening, either freehand or guided, so be careful what advice you take. The change in speed makes a big difference, I think the biggest may be that coarser abrasives leave a finer finish. Perhaps my biggest suggestion would be don't bother with anything finer than 1 micron. My microscope tells me anything finer generally causes more problems than benefits, even when going to great extremes to avoid contamination, including not using leather as it is too contaminated to begin with. Same applies to felt as how do you clean it?

I really question raising your angle for the leather or felt wheels. They are soft enough that you will convex your apex anyway.
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I moved from an EP Apex to a TS Prof K03 some years ago. Love the blade table on the EP, but the rack and pinion angle adjustment system coupled with the arm mounted angle cube on the TS Prof have become indispensable to me in getting consistent results while chasing the ultimate edge. If EP ever integrated such angle adjustment features, I'd probably go back as I do prefer the blade table.

Anyway- I say all that to provide background on the equipment I'm using. K03 with axicube, my preferred finishing stones lately have been the PDT premium metallic bonded diamonds (although I would not use them with softer steels). Most often I am setting a bevel with an atoma 140, then finishing on the PDT 550 as most of my sharpening volume is EDC knives and I prefer a "toothy polished" edge. For stropping, I have landed on balsa as my favorite media, and find that diamond compound of .5 um or under tends to yield the best results for me.

In process itself, I find that I get the best repeatable results by raising angle .5° for one deburring pass per side on my finishing stone. Then I drop back down to the original angle and do just a few increasingly lighter passes to back sharpen a bit. One pass per side at weight of stone, followed by a couple passes per side, barely maintaining stone contact. All of this edge leading, by the way. From there, I strop on the balsa with diamond compound, obviously switching to edge trailing. Just a few passes per side, weight of the strop only. Never got around to buying a BESS tester, but I have found that with this equipment and process, my results land between easily hair whittling to hair splitting on contact, every time. I'm sure there's BESS variance there, but not sure how much.
 
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choochaw104 said:
I find that I get the best repeatable results by raising angle .5° for one deburring pass per side on my finishing stone.
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I used to do this too, until I discovered it raised my BESS score around 40+ grams. Even .1 or .2 degrees is enough to screw up the apex, often even with a strop. I think it is from increased point loading.
 
Diemaker said:
I used to do this too, until I discovered it raised my BESS score around 40+ grams. Even .1 or .2 degrees is enough to screw up the apex, often even with a strop. I think it is from increased point loading.
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Have you seen anything under the microscope that suggests this? If it is the case that it is point loading, then I gotta think there is a certain sweet spot to hit, or a stropping technique that can correct it. I've really been reluctant to part with the $200 something dollars for a BESS tester, but now I'm morbidly curious if I would see the same with my edges.

ETA: now that I mull it over more, this also brings up questions about BESS scores vs practical use. Raising angle prioritizes removing the primary burr. Even if that diminishes BESS scores, in theory, it could lead to a better edge. How certain are you that your techniques are not in fact creating a very microscopic wire burr that would improve BESS scores at the expense of real world performance? Have you developed practical cut tests to account for this?

Somewhat unrelated follow-up question: how much influence does primary geometry have on BESS results? For instance, I can sharpen my axes to a hair splitting edge as well, but would the overall BTE thickness greatly skew the results up into the 200 range or something?
 
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choochaw104 said:
Have you seen anything under the microscope that suggests this? If it is the case that it is point loading, then I gotta think there is a certain sweet spot to hit, or a stropping technique that can correct it. I've really been reluctant to part with the $200 something dollars for a BESS tester, but now I'm morbidly curious if I would see the same with my edges.

ETA: now that I mull it over more, this also brings up questions about BESS scores vs practical use. Raising angle prioritizes removing the primary burr. Even if that diminishes BESS scores, in theory, it could lead to a better edge. How certain are you that your techniques are not in fact creating a very microscopic wire burr that would improve BESS scores at the expense of real world performance? Have you developed practical cut tests to account for this?

Somewhat unrelated follow-up question: how much influence does primary geometry have on BESS results? For instance, I can sharpen my axes to a hair splitting edge as well, but would the overall BTE thickness greatly skew the results up into the 200 range or something?
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Not really due to the narrow band of focus and viewing angle constraints. I think the apex is incredibly fragile and very easily damaged, and there is a lot that will damage it that we don't think much of. The more you try to refine it the more of an issue this is, but still critical to BESS scores even with an 80 micron stone. If you are actively trying to improve your sharpening, a BESS tester is very important to further your knowledge. Most of my use of it is to see what I am doing to my knife with the current stone, not so much what the ultimate sharpness is at the end.

I can see burrs down to .0005" so I don't think I am leaving wire burrs on my edges, but do know what you are talking about. I don't do any test cuts but do inspect for it after a BESS test to see if I can find any damage from cutting the filament.

The angle does have an effect on BESS numbers but I haven't tested it enough to say. My main focus is usually how to best sharpen around 15 dps as I am generally testing products or ideas for products.
 
choochaw104 said:
My own experience is that leather wheels and even belts do seem to over polish quickly when used with compound. A gentle pass or two to knock off a burr is usually fine and will leave some tooth, but I find it very easy to over polish if you have a stubborn burr that requires more attention than that. That's my anecdotal experience anyway, and I'm willing to bet that there is some combination of pressure, time, and compound used that would exacerbate things. At any rate, I am finding that I prefer felt belts for my deburring, and that I have an easier time keeping tooth on that media.
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That is my experience as well. I used a leather belt for many years and it's faster and more "reliable" as means of deburring but it's very easy to strip all of the 'bite' off the edge. Generally now I use a felt belt doped with whatever emulsion I have on hand (which is usually 4 micron CBN from ENZO, but occasionally 2 or 4 micron ENZO diamond). It takes an extra pass or two sometimes and on occasion even a pass on a hand strop. My goal is to not sell burrs to the customer but neither do I want to give them an edge with no bite.

Apropos of nothing, that's the biggest practical difference between belt sharpening and using water stones, aside from speed of course. You can finish a knife on stones all the way to a mirror polish off a 10k Chocera and it will still have bite whereas a 600 Trizact > leather wheel will leave no bite at all unless you're very very careful not to overpolish. I love a polished edge but only if it's from water stones.
 
Rob Babcock said:
That is my experience as well. I used a leather belt for many years and it's faster and more "reliable" as means of deburring but it's very easy to strip all of the 'bite' off the edge. Generally now I use a felt belt doped with whatever emulsion I have on hand (which is usually 4 micron CBN from ENZO, but occasionally 2 or 4 micron ENZO diamond). It takes an extra pass or two sometimes and on occasion even a pass on a hand strop. My goal is to not sell burrs to the customer but neither do I want to give them an edge with no bite.

Apropos of nothing, that's the biggest practical difference between belt sharpening and using water stones, aside from speed of course. You can finish a knife on stones all the way to a mirror polish off a 10k Chocera and it will still have bite whereas a 600 Trizact > leather wheel will leave no bite at all unless you're very very careful not to overpolish. I love a polished edge but only if it's from water stones.
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Recently I have been experimenting with edge leading belt sharpening, and find that it is raising a much smaller burr that is much easier to remove. I have not built out or bought a dedicated edge leading machine yet, but I'm thinking that might be my next step. Trizact a30 is always my token finishing belt, and it works very well edge leading. Minimal stropping on felt belts and you have a really great edge with great tooth. I don't even remember what compound I'm using at the moment, I believe .5um diamond spray.

It's funny, I think the amount of bite or tooth is pretty relative sometimes. In the culinary knife world, people are satisfied with bite off of very high grit polishing stones, whereas for EDC pocket knives, it can seem to be lacking tooth and initiate cuts poorly the higher you go. I think the thinner geometries are really forgiving in that the ultimate thinness just initiates cuts well, no matter the level of polish. Stone hardness and binder material matter too, I find. Even very fine diamond plates will still have more feeling of toothy bite than a comparable grit alumina ceramic, for instance. Like you, I tend to prefer a higher grit finish for my kitchen cutlery, but when I move to my pocket knives I start to really hate anything much above 600 grit and a light stropping with fine fine diamond compound.
 
choochaw104 said:
Stone hardness and binder material matter too, I find. Even very fine diamond plates will still have more feeling of toothy bite than a comparable grit alumina ceramic, for instance.
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I think this is because the harder bond, and abrasives, microchip the apex more, which I suspect is where your toothiness is coming from. Bond hardness should decrease as the abrasives become smaller, at least according to my observations.
 
Size, shape and hardness of the abrasive all play a role as well as the friability of the stone.

Henk Bos touched on it in Grinding And Honing part 1

As did Science of sharp on diamond plates showing how a coarser diamond plate can act finer than smaller diamond abrasives.
scienceofsharp.com

The Diamond Plate Progression

In The Honing Progression entry, an example of apex geometry refinement during honing with Shapton glass stones was presented. A slow, but linear improvement in sharpness and keenness was observed…
scienceofsharp.com scienceofsharp.com
 
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