Sharpening angles

[CPP]

I read Joe Talmadge's Steel FAQ on this forum. Actually, I read it a few times as it is incredibly informative. In the introduction the author says:

This leads to the general rule:

To really see the advantages of a better steel, exploit that
steel in your sharpening program. If you're going to sharpen
all your knives at the same angle regardless of steel, you
might de-emphasize steel choice somewhat.

While it wasn't the purpose of the article to address this issue specifically, he gave the example of sharpening S30V at 15 degrees to "take advantage of S30V's superior
toughness" in order to "see a large leap in cutting performance, along with the extra wear resistance." I suppose it would be possible to deduce the proper sharpening angle from this example using a particular steel's toughness as a guideline but that is much too advanced for me and would result in little more than guess work.

Is there a systematic way to determine the sharpening angle for various steels? Or, better yet, a chart by an expert mentioning the angle for different steels to achieve optimal performance?

 

[JR88FAN]

S30V toughness?!
Toughness to me is the ability to resist chipping or fracture.
I have never used a steel more prone to chipping than S30V....

Maybe there is some "secret HT" Spyderco/BM etc don't know about, but I am at the point where I refuse to even try Striders HT of S30V..

Junk chemistry...it was obviously missing Vanadium.

Now that I got that rant out of the way, there is no "optimal angle" because it is greatly effected by:


A: The HT/HRC
B: What you are cutting????
C: What's behind the edge (complete geometry)

 

[singularity35]

I just usually thin my bevels down and when they can't support the angle, I just microbevel until the steel can support the angles.

 

[CPP]

S30V toughness?!
Toughness to me is the ability to resist chipping or fracture.
I have never used a steel more prone to chipping than S30V....

Maybe there is some "secret HT" Spyderco/BM etc don't know about, but I am at the point where I refuse to even try Striders HT of S30V..

The article was written in 2005 when S30V was cutting edge. And, judging by your response, there is no easy answer in determining an optimal angle because an "optimal angle" is relative. Does this mean I will more or less be sharpening my knives at the same angle until I am familiar enough with steel types, heat treats and so on to figure the angle out myself?

 

[JR88FAN]

The article was written in 2005 when S30V was cutting edge. And, judging by your response, there is no easy answer in determining an optimal angle because an "optimal angle" is relative. Does this mean I will more or less be sharpening my knives at the same angle until I am familiar enough with steel types, heat treats and so on to figure the angle out myself?

Relative is a great word to use.

I think experimentation is the best way to go.

I did that with a couple of knives last year with the help of Josh @ REK.

We took one of my Striders (CPM154) and an XM-18 20CV and thinned them both out.
I kinda let Josh take his best guess based on the steel and on a lot of info on how I use my knives.

I can't remember the exact numbers but both where full regrinds, I think they where both around 15DPS, but we left more behind the edge of the XM because it was a Wharncliff and the tip really tapered off thin.

They both took everything really well, and I put together threads on my use/abuse/findings on the "experiment"

But this is just two steels, two HT's, two complete regrinds from the flats down with very precise amounts left behind the edge for my specific use.
We didn't even know if they would stand up, but the point was to see if we could take two knives not known for slicing ability, make them into above average slicers without sacrificing too much of what they where originally designed to do...

I can't say that I could transpose any of what we did to other knives/steels/types of usage...

 

[Etna]

Let's see, I have blades in 420HC, 440, 440A, 440C, 3Cr13, 7Cr17, 8Cr13MoV, 9Cr18Mov and 12C27. And i take all of them down to 20 degrees per side.

I seriously cannot feel any difference in cutting performance and edge retention except in the 3Cr13, which basically has no edge left to speak of after a box or two.

 

[Wowbagger]

I know he is talking about knife thickness but he is also talking about the idea of starting thin edged and shallow angle and if the edge does not hold up TO THE WORK YOU ARE DOING with the knife then grind / sharpen it back to a couple degrees wider angle.

It is easier to start too thin and too shallow angled than start thick and obtuse angle and try to find the optimum from there. If it rolls, if it dings, if it chips then make the edge more robust until it holds up. I cut some pretty tough hard plastic (wire ties) with an extremely shallow angle on a blade that is less than 1.5 mm at the spine.

To me 15° per side is pretty wide; I like shallower angles and very thin blades.
also
If you look at the rope cutting tests everything that is at the top (high number of cuts) is very thin behind the edge.

[video=youtube;bTdkJG-ITo4]https://www.youtube.com/watch?v=bTdkJG-ITo4[/video]

This is how I roll with hand wood working edge tools . . . as shallow and thin as possible . . . if it is showing damage I beef it up. Thinner / shallower means less effort and if I am hand planing all day it sure adds up.
PS: Talking EFFECTIVE cutting angle (not just edge angle) and I use bevel up planes a whole lot so this is more applicable . . . that would have to go to a whole other forum to get into that.