Sharpening---Which of these two practices is correct and why.

[Fred Rowe]

When referencing the sharpening angle on a flat ground blade, what do you reference the sharpening angle too?

The drawing on the left shows the blade center line being used as the sharpening angle reference.

The drawing on the right shows the blade bevel being used as the sharpening angle reference.

To what surface of a blade do you reference the sharpening angle, the center line or the bevel surface? Which of the two is the accepted industry standard; or is there a standard?

This question does not apply to convex grinds.

Looking forward to hearing what you think, Fred

 

[EdCaffreyMS]

I'm not sure there is an "industry standard"....at least nothing "hard and fast" that I'm aware of, with the possible exceptions of each factory knife having their own. When I first read the post, my mind went to the various sharpening systems on the commercial market......if memory serves, most of them have a clamp, that clamps to the spine of the knife.....which would indicate that the angle is being "judged" off the centerline of the blade. In the case of most of the knives I produce, it's kinda moot, simply because 99% of mine are flat grinds with convex edges.

What I do know for sure is that when it comes to a "custom" or "handmade" knife, there are going to be so many variations from maker to maker, that everybody is going to have a slightly different "standard" or at least opinion on edge bevel angles. That of course would be different if we're talking a factory/machine made blade.......using CNC/automated equipment will eliminate most of the variables that custom makers deal with, therefore a "set standard" could be established/maintained.

Those who grind blades by hand, without the aid of automation or jigs, cannot hope for the same repeatability from blade to balde.....which means that each "sharpening job" must be tailored to the specific blade. While some might think poorly of that, I choose to view it as one of the characteristics that makes each custom/Handmade knife unique and special.

 

[rjarois]

fred, the edge angles are given from the centerline plane of the blade. randy.

 

[Sean Cochran]

fred, the edge angles are given from the centerline plane of the blade. randy.

I would agree. However...

What I do know for sure is that when it comes to a "custom" or "handmade" knife, there are going to be so many variations from maker to maker, that everybody is going to have a slightly different "standard" or at least opinion on edge bevel angles.
Those who grind blades by hand, without the aid of automation or jigs, cannot hope for the same repeatability from blade to balde.....which means that each "sharpening job" must be tailored to the specific blade. While some might think poorly of that, I choose to view it as one of the characteristics that makes each custom/Handmade knife unique and special.

Very well said. I have to agree with Ed, that most custom makers are never going to have the exact same angle everytime, provided they are grinding free hand. What I have found though is that over time, with much practice and trial and error, you become trained to set the bevels very close every time. So much that it is hard to tell a difference between one knife and another from the same maker.
Using your jig Fred, one should be able to reproduce the close to the exact same bevel every time right?

BTW
I ground a kitchen knife for my wife this weekend. I had forgotten how much I dislike flat grinding over hollow. About half way through I thought "I bet that bubble jig would make this alot quicker"

 

[Knifemaker.ca]

Good Question Fred. I hadn't ever considered anything but the centerline as a reference - primarily because I always thought of a 20 degree bevel as a 40 degree inclusive edge. I think I still see it that way - unless you want to muck things up with a chisel grind. :34:

Gotta get me one of those jigs. I just can't wrap my head around the pictures, but I'm betting its different in the hand. :thumbup1:

Rob!

 

[BRad704]

I agree with everyone that said the first picture (using the centerline of the blade). And I have gotten pretty decent at setting about a 20-degree angle by hand with a 440 belt. Then I will use the Lansky to fine tune and get it sharp-sharp.

 

[Brad Anderson]

Sharpening angle should be based off of the blade centreline. If you base the sharpening angle off of the bevel, it will change the included sharpening angle depending on bevel width.

 

[rhinoknives]

Sharpening angle should be based off of the blade centreline. If you base the sharpening angle off of the bevel, it will change the included sharpening angle depending on bevel width.

Ok guys, I am a bit under the weather or just plane dumb tonight?:confused2:

You are saying Fred! Hi Fred! How are you doin??
That if you are putting a 20 degree angle edge on a knife, And you want to know if we would set the 20
on the center or the Primary or First Bevel? Right?
Well First thing that comes to mine is What kind of knife is this and do I want a chopper edge or a fine slicing edge?

And you can tell which I would use from there.

To add to the mix here, I generally think that 20 is too thick except for Blunt trauma weapons & Tools.

I go for appox 15 on my Culinary knives based on the drawing on the right.

Like Ed in Montana I mostly Flat grind with a convex edge and it's freehand.

Did that help confuse anyone else? lol.

Great Topic Fred!


Also I think this applies to Convex edges too! :9: bevel
Laurence

www.rhinoknives.com/

 

[rjarois]

fred, the angles edge, or bevel are both given from the centerline plane. the actual angle that they are is a different issue. everyone uses different angles for the bevels depending on thickness, width etc. , and i like th use a 30 deg. for the edge. "15 deg. per side from centerline". randy.

 

[BossDog]

I always sharpen on a belt so all the edges I put on a blade are convex. I also sharpen according to the intended use. I put a much thinner edge on a kitchen and skinning knife than my folder I use to cut up small automobiles with.

 

[C Craft]

When referencing the sharpening angle on a flat ground blade, what do you reference the sharpening angle too?

The drawing on the left shows the blade center line being used as the sharpening angle reference.

The drawing on the right shows the blade bevel being used as the sharpening angle reference.

To what surface of a blade do you reference the sharpening angle, the center line or the bevel surface? Which of the two is the accepted industry standard; or is there a standard?

This question does not apply to convex grinds.

Looking forward to hearing what you think, Fred

OK OK, My head is beginning to hurt here. So I am going to revert back to my former Military training as far as the question, that is! I was always taught don't read anything into the question or read anything out of the the question. I don't begin to profess the knowledge and experience of some who have already spoke on this question. Therefore I am just going to give you my take on what is being asked!

When referencing the sharpening angle on a flat ground blade, what do you reference the sharpening angle too?

First let me say, I must agree with those who said the angle of the sharpeing angle is determined by what I intend the blade to do!

My take is this the sharpening angle is referenced to the blade bevel. However if you have to answer this question in reference to the The Lansky Sharpening System or a similar creation it is based off of the blade center line being used as the sharpening angle reference.

Technically speaking.When it comes to sharpening the real edge is done by creating another angle, and that angle is created by using the blade bevel being used as the sharpening angle reference.


As I read back over this it sounds like a lot of legal mubble jumbble. Fred it is too early in the morning to be contemplating the meaning of such things............er,......... I need another cup of coffee.:what!::biggrin:

EDIT:
OK I had that other cup of joe and if I had to clarify this with a why! The industry standard is based off of the blade center line being used as the sharpening angle reference. However I don't think that is how it works for a custom knife maker. When a custom knife maker does a blade with a flat grind he is looking for least resistance by using a flat grind to begin with and then the sharpening edge itself is his or her determination of how they want that given blade too preform.

I give up I am going to have another cup of coffee and let someone else work on determining the universe, because I truly believe that is about how complex this simple question is!!!!!!!!!!

 

[Fred Rowe]

This thread was posted to inspire discourse, not come to some final conclusion about grinding edges. I don't think there is a better way to improve what we do, than getting input from other makers interested in the craft.


Ten years, working as a surveyor along with 30 years building and fabricating stairways, has influenced me as a knife maker. I always think of knives in terms of degrees of angle. The pitch of the tang, the line of the spine and the grind of the bevels relate to each other in terms of degrees of angle. To me, every part of a knife relates directly to every other part of the knife. When I think over which grind would be best suited for a knife I take all parts of the knife into consideration, spine thickness, blade height, primary bevel angle, the length of the blade and most of all its intended use.
I figure most makers do this, whether they are conscience of it or not.

When it comes to referencing the edge grind it is, for me, a natural progression to tie it to all other parts of the blade. Since the cutting edge sits atop a blades two bevels I find the bevels themselves the best point of reference. Of course the bevel angle is directly related to the center line of the blade; So in the end, all the parts are related to all the others.

With the technique I use, I know the bevel angle for every blade I grind, with simple math I can relate it to any other part of the knife. The center-line or the bevels.

Thanks for posting your comments, Fred

 

[McClellan Made Blades]

Fred,
Great thread!!! My answer has already be taken, the blade bevel is based off the centerline. I'm not sure why it would matter so much what type of knife it was, as the design of the knife would dictate the geometry, please correct me if my thinking is wrong! For a kitchen knife, which most makers make very thin, the angle will be pretty steep, it would basically have to be, wouldn't it? I'm asking because the more I think about it, the more I'm not so sure.

I'd definitely say, that the angle of the grind is going to influence the cutting ability, the difference between a good cutter and an AWESOME! cutter. Wouldn't the angle of the bevel be about the same on knives that have the same width blades? With thicker stock, I can see that angle changing, in order for the grind to meet the centerline of the blade thickness. You have really got me thinking, something I should have already thought about, hopefully you or someone else can answer my questions. Thanks, Rex

 

[Fred Rowe]

Fred,
Great thread!!! My answer has already be taken, the blade bevel is based off the centerline. I'm not sure why it would matter so much what type of knife it was, as the design of the knife would dictate the geometry, please correct me if my thinking is wrong! For a kitchen knife, which most makers make very thin, the angle will be pretty steep, it would basically have to be, wouldn't it? I'm asking because the more I think about it, the more I'm not so sure.

I'd definitely say, that the angle of the grind is going to influence the cutting ability, the difference between a good cutter and an AWESOME! cutter. Wouldn't the angle of the bevel be about the same on knives that have the same width blades? With thicker stock, I can see that angle changing, in order for the grind to meet the centerline of the blade thickness. You have really got me thinking, something I should have already thought about, hopefully you or someone else can answer my questions. Thanks, Rex

Rex,

I'm glad it's got you thinking. I know it did me.

Your thinking is correct, I believe, what got me thinking about this is: someone dropped off some small folding knives and ask me to sharpen them. These were very small blades, maybe an inch. I don't make folders so I was in the dark as far as what the best angle to sharpen them was. I got some degree wedges out and started placing blades on them while they sat on the horizontal disc grinder. In the end it ended up being a 3 degree edge on most of them. 3 degrees per side.
I think we are so used to hearing 10 and 12 degree edges talked about that we get locked into those. There are a broad range of grinds that can be used depending on the blade geometry and use.
Blades of the same height most likely have the same degree, bevel grinds and as you say when the thickness of the blade changes, the bevel grinds are going to change in order to maintain a full flat grind.

I know when this guy picked up the folders he said they had never been so sharp.

Theres a lot to learn in the knife shop, I learn something everyday.

Fred

 

[McClellan Made Blades]

Rex,

I'm glad it's got you thinking. I know it did me.

Your thinking is correct, I believe, what got me thinking about this is: someone dropped off some small folding knives and ask me to sharpen them. These were very small blades, maybe an inch. I don't make folders so I was in the dark as far as what the best angle to sharpen them was. I got some degree wedges out and started placing blades on them while they sat on the horizontal disc grinder. In the end it ended up being a 3 degree edge on most of them. 3 degrees per side.
I think we are so used to hearing 10 and 12 degree edges talked about that we get locked into those. There are a broad range of grinds that can be used depending on the blade geometry and use.
Blades of the same height most likely have the same degree, bevel grinds and as you say when the thickness of the blade changes, the bevel grinds are going to change in order to maintain a full flat grind.

I know when this guy picked up the folders he said they had never been so sharp.

Theres a lot to learn in the knife shop, I learn something everyday.

Fred

Fred,
You really got me thinking!! It kinda hurts...
Kidding aside, I was thinking about it last night and I got to thinking that there should be a way to figure out a formula for the best angle for the bevel, based on the width and thickness of the blade. I will have to do more studying on it as there will probably be either some Geometry or Trig involved, it's been a while since I've fooled around with either!!! I'll see if I can figure something out, unless one of our smarter members would like to take a stab at it!!! PLEASE feel free to show us what y'all know!!! Using your Bubble Jig, it would be perfect for nailing the bevel to a specific angle. I'm working on a Santoku now, the blade on it is 2"+ wide, the widest blade I have ever ground, I just thought longer blades were more difficult, wider blades add an all new set of challenges. It wasn't that bad, as long as I didn't rush it, I took it very slow, checking the progress often, being a very thin blade I was a LOT nervous, so far it is turning out nicely! Thanks Fred for stirring up the brain cells!!! Rex

 

[rhinoknives]

Fred,
You really got me thinking!! It kinda hurts...
Kidding aside, I was thinking about it last night and I got to thinking that there should be a way to figure out a formula for the best angle for the bevel, based on the width and thickness of the blade. I will have to do more studying on it as there will probably be either some Geometry or Trig involved, it's been a while since I've fooled around with either!!! I'll see if I can figure something out, unless one of our smarter members would like to take a stab at it!!! PLEASE feel free to show us what y'all know!!! Using your Bubble Jig, it would be perfect for nailing the bevel to a specific angle. I'm working on a Santoku now, the blade on it is 2"+ wide, the widest blade I have ever ground, I just thought longer blades were more difficult, wider blades add an all new set of challenges. It wasn't that bad, as long as I didn't rush it, I took it very slow, checking the progress often, being a very thin blade I was a LOT nervous, so far it is turning out nicely! Thanks Fred for stirring up the brain cells!!! Rex

Rex,
My formula is to have the thinnest edge possible for the flat grind with out chipping for a given steel & a given application for the knife.

440C to 57-59 & CPM-S35VN to 57-59 are the two steels I most use currently. I went for the right hand drawing because I am setting the edge to the flat grind angles.

I have a feeling most production knives are set to the 22 degrees from the center line because that's the way they did it before! And edges are set at 22.5 degrees because it's half of half of 90 degrees?:les:

A 2"er Rex? Now your cooking. My rhino Chop model is 2 3/4 deep at the heel, Yes it takes Patience for those tall flat grinds.

Yep! This has me using that old noggin!

Laurence
wwww.rhinoknives.com/

 

[McClellan Made Blades]

Rex,
My formula is to have the thinnest edge possible for the flat grind with out chipping for a given steel & a given application for the knife.

440C to 57-59 & CPM-S35VN to 57-59 are the two steels I most use currently. I went for the right hand drawing because I am setting the edge to the flat grind angles.

I have a feeling most production knives are set to the 22 degrees from the center line because that's the way they did it before! And edges are set at 22.5 degrees because it's half of half of 90 degrees?:les:

A 2"er Rex? Now your cooking. My rhino Chop model is 2 3/4 deep at the heel, Yes it takes Patience for those tall flat grinds.

Yep! This has me using that old noggin!

Laurence
wwww.rhinoknives.com/

Laurence,
You say the thinnest edge possible, can you give a measuremnet for that, I'm assuming you mean the thinnest possible without warping or other deformities during HT. I'm curious, because going down to .02 was making me a bit uneasy, I'll be watching it during the quench...well, checking right after it comes out, anyway.

What angle is generally used for edges on kitchen knives, does anyone know? Up until now I have done my sharpening by feel, the way I was taught to do it, I really can't knock it too much, it works, but I want to know the angle I set the edge at as I have had a couple of customers ask what the angle was, so I figured I had better know what it is. Not to mention, I like my knives to be repeatable, everything that can be. And it's good to know which angle performs the best for a given type of steel, grind, thickness, etc.

The knives I worked on last weekend I got them all the way down to .02, I "thought" I was getting down that thin before, but I don't think I was now that I actually measured with a good set of calipers, I measured before, but not with an old cheapo set of calipers, I've since gotten some better ones since the battery in the last pair died, I went ahead and bought a better set and it was an eye opener! Plus I've since bought a micrometer, haven't quite learned how to read it yet, but I can see the benefits of it. It should be even better at measuring the edges.

I'll be sharpening several knives I've been working on this past weekend, I hope to have some great info on setting the edge for these, 1 is a Santoku (in W-2), 1 is a camp knife (in W-2) (made a lot differently than any before) and the last one is a hunter (in 1084) or more of an skinner type blade. Looking forward to getting these 3 done,I usually don't work on more than 1 at a time, but I've got my boys in the shop with me working as well.They have talked me into getting back into hunting, I explained to them that money is tight with the building of the new home, and if they wanted to go hunting we would all have to have new equipment, and if they wanted to go, they will have to help me make a lot of knives to fund this new adventure! So, we are working on a "production run" of the hunter I mentioned earlier. Eventually, I'll post in the For Sale forum, explaining the why's, how's and how much's. These will be relatively inexpensive, all of the extra's will be in the way of labor, like adding a hamon to the blade, stuff I won't have to buy out of pocket. The sheaths right now will probably be Kydex, possibly leather, as I do have a good amount on hand right now. We will have to sale a lot of knives with the prices I have in mind!!! But, like I told them,
"It all depends on how bad you want to do something, because anything worthwhile, is worth working for!" Maybe they will learn something while having to invest their time and sweat into this and maybe they will appreciate the equipment they get a lot more! Thanks for the info, Rex

 

[Fred Rowe]

Rex,
My formula is to have the thinnest edge possible for the flat grind with out chipping for a given steel & a given application for the knife.

440C to 57-59 & CPM-S35VN to 57-59 are the two steels I most use currently. I went for the right hand drawing because I am setting the edge to the flat grind angles.

I have a feeling most production knives are set to the 22 degrees from the center line because that's the way they did it before! And edges are set at 22.5 degrees because it's half of half of 90 degrees?:les:

A 2"er Rex? Now your cooking. My rhino Chop model is 2 3/4 deep at the heel, Yes it takes Patience for those tall flat grinds.

Yep! This has me using that old noggin!

Laurence
wwww.rhinoknives.com/

I think you are onto something about the accepted use of 22.5 degrees when it comes to sharpening. I do no for a quite a long time 35 degrees was the accepted norm for edges.
I started trying out different sharpening angles on my big knives [ 2 to 2 1/2 inches at the heal] I knew the the flat ground bevels where at 2 to 2 1/2 degrees per side so I ask myself what were the possibles. You could use the standard 10 to twelve degrees per side [ from center-line] but hey, what would 8 degrees per side result in. With this experimenting I found out that altering the sharpening angle by as little as a degree per side makes a big difference in how the blade cuts. Now when choosing a sharpening angle I have broken the habit of picking the standards, instead I ask myself what are the possibilities.

Laurence,
You say the thinnest edge possible, can you give a measuremnet for that, I'm assuming you mean the thinnest possible without warping or other deformities during HT. I'm curious, because going down to .02 was making me a bit uneasy, I'll be watching it during the quench...well, checking right after it comes out, anyway.

What angle is generally used for edges on kitchen knives, does anyone know? Up until now I have done my sharpening by feel, the way I was taught to do it, I really can't knock it too much, it works, but I want to know the angle I set the edge at as I have had a couple of customers ask what the angle was, so I figured I had better know what it is. Not to mention, I like my knives to be repeatable, everything that can be. And it's good to know which angle performs the best for a given type of steel, grind, thickness, etc.

The knives I worked on last weekend I got them all the way down to .02, I "thought" I was getting down that thin before, but I don't think I was now that I actually measured with a good set of calipers, I measured before, but not with an old cheapo set of calipers, I've since gotten some better ones since the battery in the last pair died, I went ahead and bought a better set and it was an eye opener! Plus I've since bought a micrometer, haven't quite learned how to read it yet, but I can see the benefits of it. It should be even better at measuring the edges.

I'll be sharpening several knives I've been working on this past weekend, I hope to have some great info on setting the edge for these, 1 is a Santoku (in W-2), 1 is a camp knife (in W-2) (made a lot differently than any before) and the last one is a hunter (in 1084) or more of an skinner type blade. Looking forward to getting these 3 done,I usually don't work on more than 1 at a time, but I've got my boys in the shop with me working as well.They have talked me into getting back into hunting, I explained to them that money is tight with the building of the new home, and if they wanted to go hunting we would all have to have new equipment, and if they wanted to go, they will have to help me make a lot of knives to fund this new adventure! So, we are working on a "production run" of the hunter I mentioned earlier. Eventually, I'll post in the For Sale forum, explaining the why's, how's and how much's. These will be relatively inexpensive, all of the extra's will be in the way of labor, like adding a hamon to the blade, stuff I won't have to buy out of pocket. The sheaths right now will probably be Kydex, possibly leather, as I do have a good amount on hand right now. We will have to sale a lot of knives with the prices I have in mind!!! But, like I told them,
"It all depends on how bad you want to do something, because anything worthwhile, is worth working for!" Maybe they will learn something while having to invesulst their time and sweat into this and maybe they will appreciate the equipment they get a lot more! Thanks for the info, Rex

Great to hear you have engaged your sons in this project.

When sharpening kitchen knives the final edge needs to be very keen. Being able to take a thin slice from tthat tomato is a must. So how steep can you go. There is a point where the edge cannot be any steeper; it will start to disappear as you sharpen it. But taking that into consideration you can put a very steep edge on a kitchen knife.
When I put an edge on a fillet knife that is 5/8" at the heal I go with 6 degrees per side from the center line.

Have a good time on the batch of knives, Fred

 

[rhinoknives]

Laurence,
You say the thinnest edge possible, can you give a measuremnet for that, I'm assuming you mean the thinnest possible without warping or other deformities during HT. I'm curious, because going down to .02 was making me a bit uneasy, I'll be watching it during the quench...well, checking right after it comes out, anyway.

What angle is generally used for edges on kitchen knives, does anyone know? Up until now I have done my sharpening by feel, the way I was taught to do it, I really can't knock it too much, it works, but I want to know the angle I set the edge at as I have had a couple of customers ask what the angle was, so I figured I had better know what it is. Not to mention, I like my knives to be repeatable, everything that can be. And it's good to know which angle performs the best for a given type of steel, grind, thickness, etc.

The knives I worked on last weekend I got them all the way down to .02, I "thought" I was getting down that thin before, but I don't think I was now that I actually measured with a good set of calipers, I measured before, but not with an old cheapo set of calipers, I've since gotten some better ones since the battery in the last pair died, I went ahead and bought a better set and it was an eye opener! Plus I've since bought a micrometer, haven't quite learned how to read it yet, but I can see the benefits of it. It should be even better at measuring the edges.

I'll be sharpening several knives I've been working on this past weekend, I hope to have some great info on setting the edge for these, 1 is a Santoku (in W-2), 1 is a camp knife (in W-2) (made a lot differently than any before) and the last one is a hunter (in 1084) or more of an skinner type blade. Looking forward to getting these 3 done,I usually don't work on more than 1 at a time, but I've got my boys in the shop with me working as well.They have talked me into getting back into hunting, I explained to them that money is tight with the building of the new home, and if they wanted to go hunting we would all have to have new equipment, and if they wanted to go, they will have to help me make a lot of knives to fund this new adventure! So, we are working on a "production run" of the hunter I mentioned earlier. Eventually, I'll post in the For Sale forum, explaining the why's, how's and how much's. These will be relatively inexpensive, all of the extra's will be in the way of labor, like adding a hamon to the blade, stuff I won't have to buy out of pocket. The sheaths right now will probably be Kydex, possibly leather, as I do have a good amount on hand right now. We will have to sale a lot of knives with the prices I have in mind!!! But, like I told them,
"It all depends on how bad you want to do something, because anything worthwhile, is worth working for!" Maybe they will learn something while having to invest their time and sweat into this and maybe they will appreciate the equipment they get a lot more! Thanks for the info, Rex

Yes! I mean the thinnest possible with out chipping or deformities as you mentioned.

I am not a trained machinist and with the convex edges I put on mine & Customers knives in my shop I am really at a loss at how to measure it exactly other than years of this have taught me to look at the blade, And it's intended use and I have a developed a feel of how to lean it into the slack belt for the thinnest edge possible without Chipping or "Distorting" the edge.

If it's a cleaver I am leaving some metal behind that edge as the weight of Blunt trauma separate's that pork bone, 22 degrees appox.

If we are after paper thin slices of tuna or Cucumber I am at 10-11 Degrees or less is a guesstomint!.

One of the biggest things I've learned in life, Business and even Romance! Is we get programmed that that's the way people did it before us, So that's the way that is best!

Is pure Hogwash! and all the real changes in the world are done by people that dared to question and find a better way!

Laurence
www.rhinoknives.com/