Convex edge, bevel edge, straight edge or other? I'm confused!

[SwampDude]

The knives I want to sharpen are just folders and fixed blade sheath knives from manufacturers like Case and Buck. Until I get better educated about the finer points of sharpening, I plan to use my Lansky system and hope for the best.

What edge is most commonly found on mass produced, personal-use knife blades? Some sharpening educational sources mention beveled and convex edges while others don't get into edge identification at all. Before I started trying to learn more about sharpening, I assumed most knife edges are simply 'V' shaped with angle of grind being the primary distinction.

Is blade edge geometry critical in understanding how to sharpen my 'common' folder and fixed blade knives? Are bevel, concave and other edge blades found on some mass produced personal knives? Are edge shape differences identified just by looking at them with the naked eye?

Thanks.

 

[rustyrazor]

IMHO the angle of sharpenening should depend on how you intend on using the blade. if its a hard use blade you are going to want to use a higher angle on your lansky like 30 degrees as it would have more "meat" backing up your edge and last longer than a thinner edge. the finer the edge the sharper naturally but also the thinner you sharpen it the more delicate it becomes. i as well use the lansky and sharpen my EDC folder fine to cut like a razor because i can resharpen it daily if required, however my "bush" knives get the 25-30 angle as it lasts longer with a bit more abuse and it may be days/weeks between a real sharpening and i need it to hold up.

 

[SwampDude]

IMHO the angle of sharpenening should depend on how you intend on using the blade. if its a hard use blade you are going to want to use a higher angle on your lansky like 30 degrees as it would have more "meat" backing up your edge and last longer than a thinner edge. the finer the edge the sharper naturally but also the thinner you sharpen it the more delicate it becomes. i as well use the lansky and sharpen my EDC folder fine to cut like a razor because i can resharpen it daily if required, however my "bush" knives get the 25-30 angle as it lasts longer with a bit more abuse and it may be days/weeks between a real sharpening and i need it to hold up.

Do you sharpen all of your knives with the Lansky without consideration of edge shape? In other words, do you assume all are 'V' edge and none are bevel edge or convex?

 

[G. Scott H.]

The vast majority of modern factory knives come with a V edge, which is to say two flat bevels that form a V shape. There are a few factory knives that come with convex edges, but I don't know of any from Case, Buck, and the like off the top of my head. I think at this stage your best bet for sharpening your knives is to clamp them into your Lansky, try to select the angle that appears to be as close to the factory angle as possible, and start from there. The best way to choose the initial angle is to color the edge bevels on both sides of the blade with a Sharpie marker, make a few very light passes with the stone, and then see whether the marker is being rubbed off just at the very tip of the V (indicating you need to use a slightly lower angle) or whether it's being rubbed off near the top of the V (indicating you need to select a slightly higher angle). I don't recall what the exact angles are on the Lansky system, but it's probably best to start off in the 20 to 25 degree slots. Most factory blades won't be any shallower than that, with a few exceptions, though they may be a bit steeper (30* for example). I wouldn't worry too much over the intricacies and nuances of sharpening until you learn a bit more. Start reading the Maintenance, Tinkering, and Embellishment section (where this will likely end up anyway) for a wealth of info on all aspects of sharpening.

Welcome aboard. :thumbup:

 

[SwampDude]

The vast majority of modern factory knives come with a V edge, which is to say two flat bevels that form a V shape. There are a few factory knives that come with convex edges, but I don't know of any from Case, Buck, and the like off the top of my head. I think at this stage your best bet for sharpening your knives is to clamp them into your Lansky, try to select the angle that appears to be as close to the factory angle as possible, and start from there. The best way to choose the initial angle is to color the edge bevels on both sides of the blade with a Sharpie marker, make a few very light passes with the stone, and then see whether the marker is being rubbed off just at the very tip of the V (indicating you need to use a slightly lower angle) or whether it's being rubbed off near the top of the V (indicating you need to select a slightly higher angle). I don't recall what the exact angles are on the Lansky system, but it's probably best to start off in the 20 to 25 degree slots. Most factory blades won't be any shallower than that, with a few exceptions, though they may be a bit steeper (30* for example). I wouldn't worry too much over the intricacies and nuances of sharpening until you learn a bit more. Start reading the Maintenance, Tinkering, and Embellishment section (where this will likely end up anyway) for a wealth of info on all aspects of sharpening.

Welcome aboard. :thumbup:

Thanks. I wanted to answer this basic question before getting too twisted up learning more about edge geometry. Bark River knives, or one of the other brands sold by Knives Ship Free, are made with a convex edge, so I thought it might be important to understand.

 

[Twindog]

Your Lansky is a good sharpening system. It creates a V edge, which is the kind of edge found on most knives, including your Buck and Case knives.

So start there. The basic idea is to make the two sides of the edge meet at a fine point. To do that, you have to match the angle of the stone to the angle of the edge. You can use the Sharpie trick that G. Scott mentioned to find the closest approximation to matching the Lansky angle to your edge angle. Or you can reprofile, which means grinding away at the edge until it succumbs to your stone's angle.

When your stone creates a good cutting edge, it will tell you so by also creating a burr, which is a fine wire edge that rolls to the side of your edge opposite of the stone. You can feel it with your finger. You want to remove that burr. The usual way to remove the burr is to use ever lighter strokes and ever finer stones.

So: Match the angle of the stone to the edge. Raise a burr the full length of the edge on both sides. Carefully remove the burr.

 

[simioh]

I use the Lansky on all my knives too (kitchen and personal). Like RustyRazor I also sharpen to the 17 degree slot since I can sharpen them up again whenever I want, plus most steels now-a-days can handle a 17 degree edge without being too weak, or having negative effects (of course my personal use, other people's uses might chip or roll an edge).

 

[G. Scott H.]

Bark River knives, or one of the other brands sold by Knives Ship Free, are made with a convex edge, so I thought it might be important to understand.

Yes, BRKs are convexed from the factory. I think Blackjack knives also come convexed (not totally sure), and Cold Steel convexes their San Mai III Recon Scout and Trail Master. There are a few others out there as well. Maintaining a convex edge is a different method. Some can do it on regular bench stones, but most use either wet/dry sandpaper over a compressible substrate (mouse pad, leather, etc.) or a belt sander with a slack belt (i.e. not up against the platen). You don't want to put a convex edged knife on your Lansky, as it will create a new V bevel, rather than maintaining the gentle curve of a convex.

Great advice from Twindog, too. I forgot to mention raising a bur. :thumbup:

 

[Allen R.]

As people have stated above most knives are going to come with a v -edge, I've found most production knives come with a pretty obtuse edge angle, the sharpie trick is going to be the only way to see if your actually hitting the edge of your blade or the bevel, The exception is Spyderco knives, they usually come with a more acute bevel than other production knives. Google knife grinds, or blade grinds , and search images and you will see an illustration of the different grinds, I don't want to post one up because I don't know who owns the image.

 

[SwampDude]

When your stone creates a good cutting edge, it will tell you so by also creating a burr, which is a fine wire edge that rolls to the side of your edge opposite of the stone. You can feel it with your finger. You want to remove that burr. The usual way to remove the burr is to use ever lighter strokes and ever finer stones.

So: Match the angle of the stone to the edge. Raise a burr the full length of the edge on both sides. Carefully remove the burr.

Please expand a bit on the removal of a burr. Are you saying to keep the sharpened side of the blade up to eliminate the burr with finer stones? In other words, sharpen the edge until a burr is raised, then use fine stones on the same side until the burr is eliminated? Then, turn the blade over?

I've ordered a Peak 10x loupe magnifier to actually see the burr (hopefully), which should help me know when it is raised and when it goes away. Eventually, I may be able to feel the burr instead of relying on sight.

 

[Allen R.]

Please expand a bit on the removal of a burr. Are you saying to keep the sharpened side of the blade up to eliminate the burr with finer stones? In other words, sharpen the edge until a burr is raised, then use fine stones on the same side until the burr is eliminated? Then, turn the blade over?

I've ordered a Peak 10x loupe magnifier to actually see the burr (hopefully), which should help me know when it is raised and when it goes away. Eventually, I may be able to feel the burr instead of relying on sight.

After raising a burr with the stone, you flip the knife, as the burr will be on the opposite side which you are sharpening, sharpen the other side of the knife and the burr will be on the other side, each time you go up to a finer stone you will be making that burr a little smaller, but it will continue to flip flop on you, depending on how fine of a stone you have will determine how small you can get the burr, your final step you can either strop the edge , or run the edge into some wood, (lightly ) to remove the burr, then strop. If you don't have a strop use a leather belt. Raising the angle up a bit and making feather light strokes on the stone will also break the burr off. The more knives you sharpen , you will find a way most comfortable to you to get that final burr off...

 

[SwampDude]

After raising a burr with the stone, you flip the knife, as the burr will be on the opposite side which you are sharpening, sharpen the other side of the knife and the burr will be on the other side, each time you go up to a finer stone you will be making that burr a little smaller, but it will continue to flip flop on you, depending on how fine of a stone you have will determine how small you can get the burr, your final step you can either strop the edge , or run the edge into some wood, (lightly ) to remove the burr, then strop. If you don't have a strop use a leather belt. Raising the angle up a bit and making feather light strokes on the stone will also break the burr off. The more knives you sharpen , you will find a way most comfortable to you to get that final burr off...

Thanks for the clarification. I think I've got it now. Once I master the basic skills, I hope to get good enough at this to pass the knowledge on to some other folks. I'm thinkin' making really sharp edges is gonna be fun, too.

 

[simioh]

Allen explained it pretty well, and it seems you understood the concept. Here's a quick picture I drew up to show what Allen was saying. In my picture I'm using the Lansky stone as an example, but it works the same on any other type of stones.

On the left side is when you first raise the burr on the opposite side of the stone. On the right side is the same edge, but now sharpened on the burr side in order to remove the burr until you feel it on the opposite side. Once you can feel a burr form on each side (back and forth as you switch sides), you finish off with lighter strokes, less pressure so that the end result is the removal of the burr without creating another burr on the opposite side.