Edge bevel's, thoughts....

A

avoidspam

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OK, so I'm learning all the time:)

For me one of the things that seriously holds some knives back is the type of edge bevel, particularly on flat ground blades.... I suspect this type of edge has become common due to the ease with which a manufacturer can put a basic edge on a knife. In most cases it is an insurance policy too, leave the edge obtuse and you won't get too many returns....

I've got several hand made fixed blades which have full convex or scandi edges and they perform so well.

Sooo, as my sharpening skills improved I'd been toyng with the idea of working the bevel off on a traditional knife. Yesterday I took the plunge and went to work on my Schatt and Morgan Jack....

WARNING, scratched mirror finish!! WARNING

303B61A8-48B9-4500-9254-0F735408F9DC-463-000000D45338681F.jpg


I figured this knife would be a good candidate, both blades are 3mm thick, ATS-34 stock so they come with quite steep flat grinds (I'd caution about doing this on a thinner blade as you risk leaving too little behind the edge). I use the mousemat sharpening method so simply laid the blade flat on the wet and dry paper (400grit to start) and worked on both sides until a burr appeared. I then worked up to 1200 before stropping. As you can see the give in the mousemat, together with the grind angle means a convex bevel has been formed but shallower and without such a shoulder transition.

Now this knife works well! I've been whittling all day, no worries, just a strop to bring it back.

To me this would be where an older knife gets to eventually with hand sharpening anyway. I'll strop out the scratches..., maybe:)

Thought I'd share and get people's thoughts on bevels. Anyone else played...?

Enjoy the last of the weekend:)

Sam
 
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Good work, Sam. I hate a dull knife and will sharpen even a valuable custom or vintage knife if I feel that it needs it.

Once upon a time I would spend time convexing some blades but nowadays I just concentrate on getting both bevels to meet at an apex and remove any burr left over (if one was created).
If the bevels are too thick, I'll take them down.

(Of course, If it's a scandi-grind I try to keep that type bevel. If it's already convexed, the same.)

I find that sharpening by hand produces a bit of a convexed edge naturally in due course as it's impossible to maintain a perfectly flat bevel without the use of a jig. (At least for me.)

I've not worried about polishing out scratches I've put on my blades via sharpening. That's one affliction I've avoided (thus far).
 
Yep, those obtuse angles have to go on any new knife. Generally I use an edge pro (not very traditional, I know :o ) to thin the bevel. In my experience the edge geometry matters much more than the actual sharpness of the edge.
Any touch-ups are then done freehand and on a strop, so the edge gets a bit convexed over time.

And who likes a mirror polished finish anyway? A satin finish looks way better :)
 
The Edge Pro is nice for taking down the bevels. Mine seems to mostly gather dust in my shop but not because it isn't a time saver when needed. And just to prove I'm not a stickler about perfect finishes, I have never taped a blade to avoid the scratches I invariably get when I use it. C'est la vie.

I find that I mostly sharpen these days with diamond followed by ceramic (hand held in each case) and for daily touch ups I have a very fine piece of jasper (viking whetstone) that's perfect for either removing a burr or bringing back an edge (that doesn't need resharpening). I do have a bunch of other small stones (india, Finnish slate, Arkansas) that I enjoy using as well.

Most of my stropping is done on my jeans and my dedicated leather strops are not very pleased with me. :p
 
I'm with you, although it seems much less necessary on thin traditional blades than it does on modern tactical sharpened pry bars. I have used my Sharpmaker medium triangles freehand to take down the upper edge of the bevel, and then develop the convex edge by free-handing the rest. I have had great luck doing this on my TSF Beast, Spyderco GB and GB Air (my PT came convexed already). My Davison will get to that point eventually, but I won't mess with it much until the edge needs the work. It's best if I can take my time, and I don't want to screw up such a nice knife, plus the thinner geometry makes it much less important.

I think your observation about older knives is absolutely spot on--assuming they have been sharpened by hand, they almost always develop a convex edge, and it's always for the better. The convex plus thin geometry of traditionals makes them easily outperform most modern knives (at least, in knife tasks).

Did it take long for you to do this with sandpaper? I've found modern steels to be more resistant than I wish too (including ATS-34).

Cheers,
Daniel
 
For me it's not just the edge angle, it's how thick the blade is just above the bevel. The two factors together determine how much steel has to be removed to get to a good edge. In my experience, Buck, Case, and GEC blades usually do not require much metal removal, merely refining the existing edge. Queen blades have a tendency to be oblique edges and a thick blade. This means a lot of steel to be removed. The fact that they mostly use D2 does not help matters.

My normal process is to use an extra coarse DMT stone to remove metal until reaching the desired edge angle. Then finish on a Sharpmaker. Once I have a good edge, I maintain it using a Sharpmaker. I've used other methods and other abrasives, but this is what I use most often.
 
Nice to get your thoughts, looks like we're all on the same page:)

Daniel - yes it took a while!

Sam
 
"Give me your tired, your poor,

Your dull, neglected slipjoints yearning to breathe free,

The wretched refuse of your kitchen drawer.

Send these, the edgeless, tempest-tost to me,

I keep my stone beside the golden door!"

:p
 
avoidspam said:
LOL!

Such a gift we have amongst us;)
Click to expand...

41rzLEo1pDL._SX300_.jpg


When she was in a bit of a hurry, she did her touch-ups on the bottom of a ceramic coffee cup...See the things we learn here that are left out of the standard history books? ;)
 
Good pics and good post, Sam. :thumbup:

Almost all of my knives eventually get at least some convex in their edge bevels. My favorite method to re-bevel a blade is to use a guided setup (Lansky or DMT Aligner, most of the time; also have a Gatco) to put a more acute V-bevel on first (usually ~30° inclusive or a little less). Then I'll gradually take down the shoulders of the bevel using wet/dry sandpaper, finishing anywhere between 400 - 2000 grit, over one of my leather & oak strop blocks. It's amazing how little needs to be taken from the shoulders of a V-bevel, rounding & smoothing it just so, to really make a huge difference in cutting. In heavy or tough material, like cardboard or wood, or very stiff plastics, the resistance to the blade really drops off. And aside from aesthetic preference, a highly polished convex makes a big difference with a very thick blade too, if using that blade for cutting the same types of heavy material.
 
Interesting Emma Lazarus posts Elliott. I knew the lines you were para-phrasing, but from The Ballad of Sacco & Vanzetti, had to look Emma Lazarus up. Always something to learn here :thumbup:
 
What constititues a sharp edge has more to it than is first apparent. In addition to what has already been referred to, the degree of finish of the edge bevel is also important and something which i need to understand better.
For example, i've read that for slicing tomatoes or flesh, a slightly toothy edge (say finished to a ~400 grit) will slice better that a highly polished edge. But, is this so for a very thin blade, or more important for a slightly thicker blade that is not intended as a dedicated slicer ?
And what degree of finish is best for cutting rope ? or green sticks ? etc. There likely is an optimal thickness just above the edge, edge angle, edge profile (convex or flat) and edge finish for each different type of substance that could be cut.
But as most of use will use most of our blades for a variety of cutting some sort of compromise of these variables is needed.
I'm still trying to consistently get a super sharp edge with varying results.
roland
 
This is something I have messed around with a lot. What I have found is a sharp edge is a sharp edge. It is possible to sharpen a knife with a mirror edge that even under 400x magnification has no micro serrations visible. If you execute this edge well simply touching it will cut into your finger. Forget about running your finger along the edge...

I hear a lot about how a mirror polished edge will not cut a tomato, flesh, cloth etc. I have come to decide people that feel this way have yet to experience a truly sharp mirror polished edge. I feel a lot of the problems that occur with first time mirror polishers is they want the blade to be shiny above all. Little, if any, attention is paid to the actual apex. The apex is the most important. Yes, having a thinner edge with smoothed down shoulders also adds to cutting performance, but sharp really is sharp.

Over the last few years I have posted a lot of videos of seriously scary sharp edges on all types and sizes of knives. I use my knives and I never leave an edge that will not hold up to hard work.

I also hear how an edge with micro serrated apex can not be as sharp as a mirror polish edge. This I am not sure I believe, as my definition of sharpness is how thin the actual apex is, or lack of bluntness of the apex. However you want to look at it.

I have shown edges at 400x with micro serrations that will split hairs with great ease:
L1020705.jpg

D2 - 40 micron 3m finishing mesh

I tend to go with a micro serrated edge on my tradtionals and folders. This is not because a mirror polished edge will not cut as well at first, it is because once the mirror polished edge begins to blunt it starts to lose effectiveness quicker than a micro serrated edge in my experience.

Here is what the edge of my 85 looks like after months of stropping to keep the edge keen:

L1020688.jpg


same magnification fine human hair:

L1020690.jpg


Here is what a normal finished edge looks like off my translucent stone:

L1020619-2.jpg

O1 - ~900 grit

Make no mistakes that edge will push cut and pop hairs like a demon.

Now here is what a used and up kept mirror edge looks like under magnification:
L1020670.jpg


That edge in person can be described no other way that SCARY.

Here is a very short video of my machete with a mirror polished edge performing a few tasks:

[video=youtube;fX95Kil5t0s]http://www.youtube.com/watch?v=fX95Kil5t0s&feature=plcp[/video]

I have put that edge through beatings to see what it can take. Concrete walls around the barn by accident, rock hard woods. I like tested.

Here is another video of the same edge slicing through a grape after seeing this on here. I had to try:

[video=youtube;5qGxaIxKmq4]http://www.youtube.com/watch?v=5qGxaIxKmq4[/video]

So, to finish, I always come back to sharp is sharp. Working down a nice convex edge with little shoulder transition is always a huge performance gain.

Here is the latest look at the machete's edge. Just touched up on a leather belt with black compound:

RGlzdHJpY3QgMTEtMjAxMjEyMDEtMDAxMjguanBn.jpg


Its the kind of edge that has to be experienced to be believed.

Sharp mirror or not will cut a tomato. Sharp will cut.

Kevin
 
Nicely done Kevin:)

Agreed on yours and rprocter's thoughts. I thought a lot of people would have gone through this process waaay before me.... I guess what I wanted to do was bring this info back because it's clear to me that if you delve into this a little there's a lot to learn (see Kevin's post:)) and a huge amount of benefits to be had.

I think sharpening free hand really shows you how the edge works, yes there's no point mirror polishing anything until you've got the edge right, that means patiently working until your taking metal right up to the edge. I'll then do a few balancing strokes before hitting the strop. My axe will slice tomatoes once it's had a good strop.

You could look at it this way, by getting the balance right by rounding the shoulders of your edge bevel you are allowing all the hard work you've put into the edge to shine...

Practical benefits also include less wear and tear on your knife, pivot etc.

All good steps towards nirvana;)

Sam
 
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Wow! Those are some impressive pictures and videos. If I ever reach that level of sharpening ability I fear for my own well-being.

DJK
 
Richstag, what equipment do you use to get the "Scary Sharp" edges?...I want to try it as well.
 
Nice skills Kevin...

richstag said:
I tend to go with a micro serrated edge on my tradtionals and folders. This is not because a mirror polished edge will not cut as well at first, it is because once the mirror polished edge begins to blunt it starts to lose effectiveness quicker than a micro serrated edge in my experience.
Click to expand...

That's the thing I learned as well. When honing your skills (pun intended), you eventually learn how to get a knife sharp :eek: and then go back to sharp for EDC knives. Although I tend to have one blade of the sharp :eek: variety for those pesky little skin thingies at the base of the fingernails.

And the experience of slicing a tomato with a mirror polished edge is just amazing. Just pull with two fingers on the handle and the tomato is split in half without moving :)
 
All I can say regarding Kevin's pictures and videos is stunned silence. I mean, just... wow.

I'm carrying a small DMT stone, a small angle guide and a junk knife to practice free hand sharpening in my spare moments. One thing I've concluded is that it is a skill that must be earned. My attempts at the mouse pad approach to convex edges has been similar.

Given the constraints on my time, it's a lot easier for me to put a 17 degree secondary bevel and 20 degree primary bevel on most of my knives using a Lansky. This followed by the wet/dry "stropping" that David (OwE) described and normal stropping and I'm done.

I won't be push cutting grapes this way, but I can get a dead dull knife hair popping pretty quickly and reliably this way. Perhaps once life settles down more...
 
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