Mirror edges

Bill DeShivs said:
I'm quite sure I understand sharpening. I have been doing it for 45 years.
Blade loss- when the two bevels apex there is blade loss. Sheesh--how could there not be?
Check out the Gesswein ruby stones. They will cut your steel just fine, and leave a polish that is extremely bright. I use it to sharpen gravers.
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I'm very confused by what you mean by "blade loss" then. Do you mean the "loss" of blade material by sharpening? Then yes, any time you sharpening, you are "losing" blade steel. However, I'm not shortening the life of the blade, since I'm not removing height (i.e. edge to spine dimension) nor length (tang to tip) rather I am removing width (side to side dimension). This improves the edge geometry and allows the knife to cut better.

Ruby stones look pretty much the same as Japanese waterstones. Ruby (Al2O3Cr) is an aluminum oxide. Shapton has stones that go up to 30,000 grit which is roughly equivalent to half a micron. I use diamond pastes/sprays as I find them more economical than using the extremely high grit waterstones.

On the other hand, I can't seem to find any good reference for the grit sizes for the Gesswein ruby stones you mention. If they can offer a stone that matches a Shapton 30,000 at a lower price, they might be worth taking a look--I'm skeptical, however, that they would offer any real advantages over a high quality waterstone.
 
HwangJino said:
Can I see a video of this? I would be very very impressed!
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I can pull it off with a shearing cut - holding the edge at an angle to the paper towel, but using only one spot on the edge (no draw). I cannot quite get to reliably pushcut with the edge perpendicular to the cut path. Depends a lot on the brand as well - the cheap stuff is very difficult.
 
Bill DeShivs said:
I'm quite sure I understand sharpening. I have been doing it for 45 years.
Blade loss- when the two bevels apex there is blade loss. Sheesh--how could there not be?
Check out the Gesswein ruby stones. They will cut your steel just fine, and leave a polish that is extremely bright. I use it to sharpen gravers.
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Well Cynic has most of this covered but im going to add a couple points.

A lot of things have changed in the knife/sharpening world in the past 45 years.

Ruby will not cut modern powdered steels , it just cant , its softer than the vanadium carbides present in modern powdered steels.

And finally I'm leerie of any stone that only defines abrasiveness as "medium" and "fine"...
 
HeavyHanded said:
I can pull it off with a shearing cut - holding the edge at an angle to the paper towel, but using only one spot on the edge (no draw). I cannot quite get to reliably pushcut with the edge perpendicular to the cut path. Depends a lot on the brand as well - the cheap stuff is very difficult.
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Amazing. Even my sharpest knife has trouble going through paper towels . Though I can get clean cuts if I cut on board lol
 
HwangJino said:
Amazing. Even my sharpest knife has trouble going through paper towels . Though I can get clean cuts if I cut on board lol
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The key is a thin clean apex. I don't find paper towels difficult, though tissues and toilet paper can sometimes cause problems.
 
HwangJino said:
Amazing. Even my sharpest knife has trouble going through paper towels . Though I can get clean cuts if I cut on board lol
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Uh oh, sounds like I might have to attempt a video? My acid test of all around "good edge" is if it can swat freehanging paper towel using only the belly of the blade with a very shallow swipe, no tip. Passing that, I slice into a paper towel and pull the towel toward me with the edge at about 20 degrees to the surface of the paper towel, contact at one point - this is what I mean by a "shearing" cut. If the cut side falls away cleanly, I'll take the whole thing, twist it into a "rope" and lightly draw the edge across, noting how far it penetrates and how fast it catches initially. This part is pretty subjective, but if it passes the first two tests and fails at this one, the edge likely won't last long. This type of edge tends not to whittle a hair, but will generally tree-top my leg hairs and is certain to bite on most materials while being acute enough to press cut well - my best balancing act.
 
Cynic2701 said:
The key is a thin clean apex. I don't find paper towels difficult, though tissues and toilet paper can sometimes cause problems.
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Yep , Paper Towel is not typically a problem , but push cutting Tissue is a whole different challenge.
 
Richard sent me a video of his knife slicing through newspaper freehanging, I can do that too, meed to make a video.

He kind of stabs it, bounces newspaper and slices through.

I think only a few of us can achieve that level of sharpness and even fewer can get sharper.

I have spent time carefully sharpening my knives perfectly and will top hair, but IMO its not worth the time spent, while if I just spend 30 seconds its still extremely sharp.

it seems EXTREME sharp is not useful for everyday, but useful for showing off haha, which is fun too.

my new kitayama stone is fantastic btw, much better mirror than last 8000 grit.
 
HwangJino said:
Richard sent me a video of his knife slicing through newspaper freehanging, I can do that too, meed to make a video.

He kind of stabs it, bounces newspaper and slices through.

I think only a few of us can achieve that level of sharpness and even fewer can get sharper.

I have spent time carefully sharpening my knives perfectly and will top hair, but IMO its not worth the time spent, while if I just spend 30 seconds its still extremely sharp.

it seems EXTREME sharp is not useful for everyday, but useful for showing off haha, which is fun too.

my new kitayama stone is fantastic btw, much better mirror than last 8000 grit.
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Have seen that video and have imitated it with one knife. It had to be ground very thin at the back bevel and apexed very thin with a touch of tooth to it. Not my norm! I describe approx a 4k JWS edge and that's right in my comfort zone.
 
HwangJino said:
Richard sent me a video of his knife slicing through newspaper freehanging, I can do that too, meed to make a video.

He kind of stabs it, bounces newspaper and slices through.

I think only a few of us can achieve that level of sharpness and even fewer can get sharper.

I have spent time carefully sharpening my knives perfectly and will top hair, but IMO its not worth the time spent, while if I just spend 30 seconds its still extremely sharp.

it seems EXTREME sharp is not useful for everyday, but useful for showing off haha, which is fun too.

my new kitayama stone is fantastic btw, much better mirror than last 8000 grit.
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I went and visited Richard, and he showed me that test in person. It was pretty cool, and after a month or two of work I could get a few of my knives to pass that test :) As you mentioned, getting past this point is much more difficult though. Good thing I have plenty of years ahead of me :D
 
HwangJino said:
Wish he was closer to me, I wanna show him all my sushi knives.
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After visiting him I started understanding the different kinds of "sharp". His edges are way different than waterstone edges, it's very interesting.
 
I've talked with Richard quite a few times and I can't thank him enough for the paper wheel and belt sander lessons he gave me over the phone.
I've never done a video but jdavis882 has one on YouTube with a spyderco sage 2 push cutting paper towel.
 
Looked for syderco sage 2 video but couldn't find it.


It seems I was confused about push cutting paper towel, people use 4 fingers to hold paper towel,psh thats easy!

I was holding paper towel with 1 hand.....



anyways, I stumbled on a video and this guy couldnt cut through phone book (entire book, not 1 page), but claims it is still very sharp?

Wish I could post a reply with my sebenza because it sinks sttaight to the bottom and even some paper flies up. (Like squeezing a deck of cards)

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So is this an easy feat?
 
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Just tried that for the first time. What a mess! I would say that it's easier than the paper towels.
 
Honed_Edge said:
http://www.youtube.com/watch?v=n-8AHFAtaqU
SUPER Aggressive Edge Thanks to Diamonds

Search and you will find.
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I know of the 3 finger test but does anyone else cringe when he runs his finger down the edge knowing how sharp it is?

Side note, I've enjoyed reading through this. I have been using a lanskey diamond system with a strop block with green compound, took me a while to get good with it but I can get pretty darn good results.

Any who, it has been falling apart and I just broke the clamp, I am either going to go with another lanskey or upgrade to an edge pro if funds allow
 
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