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Knife Edges Under Magnification

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Mirror polished edges sharpened by myself

EDCs and users

Benchmade 710 HSSR AL

 - My EDC for years. M2 steel, sharpened a lot, used a lot too :) Visually, it is mirror polished edge. Nothing less. To give you an idea, the edge looks like this (top knife) to an unarmed eye, and actual sharpness is a match. I sharpen and touch up that knife quite often, since it's my EDC and I like keeping my blades sharp. However magnification showed something entirely different.
10 inch BDC
At this point the blade wasn't sharpened for a week. Magnification is 16x. As you can see that's nothing like mirror polished, and bear in mind that's only 16x magnification. For the statisticss, that blade was sharpened for last 2 years using strictly mouse/sandpaper method. And for last year or so finishing touch was always with 0.3 micron Al oxide abrasive film. That does produce extremely sharp edge capable of shaving truly effortlessly in both directions. Nevertheless, as you can see looks quite messy under magnification. Ok, give it some slack for not being sharpened/touched up for a week or so, but still that's not too long and I wasn't doing any extreme cutting during that week anyway.
BM 710 HSSR AL
Next step was to sharpen the knife and see if that'd make difference. Since I didn't have time that day and matter of fact till next weekend, this picture is taken a week later. I did manage to sharpen the blade during the week. So, 2 days before this picture the blade was sharpened with 5 micron SiC abrasive film and then finished on 0.3 micron AlO polishing film. Visually looked very impressive, all shiny, mirror polished edge. However... As you can see on this picture it's not that impressive when magnified 32 times. Although, still compared to previous picture you can see the edge does look smoother, despite of twice as great magnification. So, sharpening goes work ;) On this picture, convexed edge bevel is clearly visible and defined a lot better compared to previous one. For illustrative purposes convex bevel is marked with red arrows, just in case.

Scott Coock Lochsa

 - Another permanent EDC. S90V crucible steel this time. And quite unexpectedly very different result under magnification. To see what does the edge looks like for naked eye check out the Lochsa Gallery. Again, the edge is mirror polished. Looks like it at least :) As for the sharpening it was treated identically to BM 710 HSSR described above. Which is 15 and 5 micron SiC (Silicon Carbide) abrasive films and then finishing with 0.3 micron AlO tape.
Lochsa
Surprisingly, the edge looks polished under magnification as well :) Very few edges are like that, and Lochsa is one of them. As you can see on this picture the blade itself looks nicely finished, you'll see on other pictures what does satin finish look like, and the edge itself is also very smooth. For the blade I have to compliment Scott I guess, very nicely done finish. As for the edge... I said it was surprising that it looked so smooth. As far as I know S90V stainless steel from crucible, like any other stainless steel has larger grains, compared to M2 carbon steel. Which is why I was surprised to see it more polished. Obviously grains are much smaller and can't be seen under 32x magnification, but still, it's a factor that does affect polishing and at very high levels knife sharpness as well. So, at this point I have no idea why S90V looks so smooth and M2 so messed up with the same magnification, sharpened with identical abrasives and having same mirror polished look, with M2 having smaller grain.

Benchmade Nimravus HSSR

 - Another workhorse of mine. Again, as HSSR indicates it's serrated M2 steel. You can see Nimravus in it's current state on this picture. As for the use and sharpening I could say that Nimravus sees a lot less use compared to BM 710, however as usual the use is more prolonged at a time, and more importantly the cutting jobs are harsher. All that is nothing surprising, considering that Nimravus is a fixed blade. I don't carry it on me around, mainly use at home or while camping, which I don't to that often anyway.
Benchmade Nimravus
For last year sharpening is the same story, unless serious sharpening is required I just use 15 or 5 micron SiC, and then finish with 0.3 micron AlO. Nevertheless, the edge looks much smoother compared to 710. I have to say surprise again. I mean after seeing 710, Nimravus' edge came as a surprise. On this picture you see its edge with 16x magnification. And it is the same M2 steel, sharpened using the same technique, mousepad/abrasive films mentioned above, yet the result is quite different. I have no idea why. Since I have the equipment I'll be taking more pictures during the time so may be the results will be more conclusive.

Benchmade 771 CF

 - Another small Benchmade folder. Had it for few years. Not much of the use to speak of, but it has been no safe queen either. So, it's seen own share of cutting including harsh stuff. Sharpennig methods are same as above. However main difference is the steel. Which is D2 semi stainless steel. Now, D2 is a fine steel for knives when properly heat treated and used in the right type of the knife. Bob Dozier does wonders with this steel, and I have Neil Blackwood's D2 blade that can cut forever. However, if you wanna talk about large grains, then D2 is one of them :) Not that I have ever seen those large grains myself, but that's the word amongst knife crowds.
Benchmade 771 CF
Let's take a look at this picture now. Looks much smoother that the other edges doesn't it? Compared to beat-up 710 at least :) For unarmed eye this is a mirror polished edge again. Unlike 710 this one is a full convex edge. It was sharpened with mousepad/sandpaper method using 400, 600, 1000, 2000 grits first, then I switched to 15 micron SiC abrasive film, then 5 micron SiC and finally ended the whole thing with 0.3 micron AlO. Occasionally I'd strop the blade with Flitz loaded leather for quick touchups, or use the same 0.3 micron AlO film. Anyway, blade is sharp like crazy, shaves in both directions and slices through free hanging paper easily. However, this 16x magnified picture doesn't look like you're looking at the mirror polished edge, yet looks smoother than the other edges. Strange, but true. As you can see D2 large grains didn't have much effect on its looks. So, at least that is conclusive, I mean you can freely disregard grain size effects on polishing, although bear in mind those grains have very profound effect on sharpness and cutting.

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