Testing Edge Angle.

[Cobalt]

that's a bit better than the 26 degrees you first posted

yup, I actually blew up his picture and measured correctly both edges and came up with 32. one side was 15 and the other 17. obviously not 35 or 36 or 38 either.

it is quite a bit better and reasonable. however, I did not see you mention in the other thread, that where he took his measurement was not where the damage was. He measured closer to the ricasso, yet the damage was closer to the tip where the edge was twice the width. Where were you then when he lied about the angle?

 

[Knife_Geek]

Great deiscussion.

We use CATRA Goniometers. We have a large one at the office and I have one at home.

A Russian forumite developed a very nice bevel guage. I communicated with him on reproducing the piece, but them I got snowed and it was placed on a "hold" shelf. We made quite a few protos refing the design. we could probably make some if there is interest. We cut them out with a lazer.

I'll dig one one up. We could probably cut out a few. The designer agreed to a royalty.

sal

I would Love to see spyderco angle guide produced and would buy one for sure.

 

[nozh2002]

Vasilli, looks like the wax thing did the trick. Good job.

Thanks to you, to 2brothers and to hardheart. I am "waxing" some blades I found in my collection with factory edge.

Idea is to see what angle is most adopted. And it looks like 30 degree plus minus few angles which did not make too much difference.

Thanks, Vassili.

 

[hardheart]

it is quite a bit better and reasonable. however, I did not see you mention in the other thread, that where he took his measurement was not where the damage was. He measured closer to the ricasso, yet the damage was closer to the tip where the edge was twice the width. Where were you then when he lied about the angle?

It was already a pile-on when I noticed the thread. I cannot comment on the edge bevel width because I do not know how Busse grinds their blades. Some makers like to leave knives thicker at the tip. When this is done, on purpose or because they do not sweep the blade with the belly during a flat grind, the edge is thicker and the angle is increased when sharpening at the tip to maintain the same bevel width. On a subsequent reprofiling of the edge to a lower and consistent angle, the bevel naturally widens as the thickness is reduced and the angle is changed from the original.

Either nozh sharpened at a different angle as he passed through the belly to the tip, or it wasn't the same thickness and/or angle as the rest of the edge to begin with. Since I don't know this, I can't comment from only side-on pics. Some factory measuements and spine shots would help, I lost track of that other thread and don't know if these were posted.

I had an edge bevel noticeably widen on a knife while holding the same angle throughout, but it was an extreme case of a variable grind. The knife did not have an edge ground at the point, and was left very thick at the tip due to lack of distal taper and a very deep belly with the point above the centerline.

 

[Cobalt]

It was already a pile-on when I noticed the thread. I cannot comment on the edge bevel width because I do not know how Busse grinds their blades. Some makers like to leave knives thicker at the tip. When this is done, on purpose or because they do not sweep the blade with the belly during a flat grind, the edge is thicker and the angle is increased when sharpening at the tip to maintain the same bevel width. On a subsequent reprofiling of the edge to a lower and consistent angle, the bevel naturally widens as the thickness is reduced and the angle is changed from the original.

Either nozh sharpened at a different angle as he passed through the belly to the tip, or it wasn't the same thickness and/or angle as the rest of the edge to begin with. Since I don't know this, I can't comment from only side-on pics. Some factory measuements and spine shots would help, I lost track of that other thread and don't know if these were posted.

I had an edge bevel noticeably widen on a knife while holding the same angle throughout, but it was an extreme case of a variable grind. The knife did not have an edge ground at the point, and was left very thick at the tip due to lack of distal taper and a very deep belly with the point above the centerline.

Most likely Noz used an edge pro to sharpen the knife and the angle changes when you get to the closer to the tip and the radius of the belly. you are exactly right the angle did change, but where he measured the width of the edge for his angle measurements that he himself later on admitted were 26-28, was still not the worst area. The area where the damage was was closer to 0.20 inches wide, which is considerably steeper than the 26-28 degree, 0.12 inch wide edge area, by over 50%. mistake? probably, but it took quite a bit to get him to admit it. He finally did.

 

[nozh2002]

This is some factory edges I found in my collection also I add scale with 1/32" near by:

Kanetsune Matagi - 32 degree

Bark River Highland - 25 degree

Bark River EK Night Fighter - 22 degree

I was surprised with Bark River - such a high angle!
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As I sad Cobalt is in my ignore list and for reason other then he is disagree with me and it is obvious why. It is clear on this picture what part of edge this angle was measured:

and this is picture of damage, and I guess it is enough about this.

This is not drastically altered paper thin edge actually bit more then 30 degree - as I was telling from the beginning. I think I made enough effort to make it clear. There is no other way to deny this but accuse me in lying. At this point I see nothing I can do any more then say I am not lying.

I think we should stop at that point - positive outcome of all this is that angle measurement method.
-------------------------------------------------------------------

Thanks, Vassili.

 

[Cobalt]

as this pertains to angles. take a look at Noz modded edge and compare to the factory edge. HUGE difference in angle there gungadin.

Oh and Noz has me on ignore because I disagreed with his testing analysis over a year ago. "if you disagree with me, I must put you on ignore."

 

[db]

It would be interesting to see convex edges analyzed with a high quality laser goniometer. When sharpening a convex edge, especially when using a medium with some "give" to it like leather- or rubber-backed abrasive paper, you're getting something very similar to a microbevel. So I would guess that even on our shallow convex blades, when done right, we wind up with a durable, final edge of better than 15 deg/side, ranging up to 20-25 deg/side. And given the way the edge is applied, even those more obtuse final angles really don't cost us much in terms of cutting performance -- perhaps explaining the almost mythical performance some ascribe to a convex edge.

Yes I do agree and also think a convex edge is much like a flat grind edge with a micro bevel, or a few micro bevels may be a better way to say it. I'm fairly sure about how shallow I keep the very edge because I don't use leather or rubber backing to sharpen both just haven't worked well for me. I use a sweeping type stroke on bench hones to get my convex edges. I'll use a belt if there is alot of steel to remove but even after that I finish by hand on stones, and just try to never raise the spine up so I produce a lower than 15 degree per side edge. Sometimes if I'm in a hurry I may cheat and raise the spine higher but it doesn't happen very often. I personally believe that how thin you are behind the edge is just as important and in alot of cases is more important in how well a knife will cut. So I guess that brings me back to the point that a degree or two on the very edge just doesn't seem to matter a heck of alot.

 

[Big Mike]

When it comes to edge bevel angle, I don’t give it much thought.

I convex my edges, and adjust my angles to meet my needs.

I do feel that a small change in terminal geometry can have a big effect on cutting efficiency or toughness.



But I think that this is the correct place for this discussion, and I give Vassili credit for taking a scientific approach to this subject.

I find this all very interesting.



"If you're not living on the edge, …you're taking up too much space."

Big Mike

 

[nozh2002]

I am doung this not to find difference in one degrre, but to find out what exact angle I have. I know that I sharpen my knives to 30 degree - bit over because I convexing very edge a little. However I was accused of lying, by Busse crowd, because edge shoulders on my blade I also convex and polish, I believe it decrease friction when cutting hard material like wood. Jerry Busse as well call my edge drastically altered paper thin. so this is the reason for me to accurately measure angle. Also I like to see is this angle something unusual which only I do to my blade.

In result - as I sad at the begining angle on my edge is 30 degree (32) and more then this - many factory edges are in fact 30 degree or less. Also Busse MT with Red G10 also has 35 degree angle - which is 3 degree different from my edge angle.

But all this need some acurate and reliable method to measure angle. Of course difference in one angle not big, but this is not about single degree difference. It is about 32 degree vs "drastically altered paper thin edge".

Thanks, Vassili.

 

[Knife_Geek]

Just for reference I would like everyone to compare Nozh2002's GW to this stock .200 thickness one

http://lundestudio.com/wallpaper/leprechaun-warden-4-hi.jpg

 

[Karda]

Just for reference I would like everyone to compare Nozh2002's GW to this stock .200 thickness one

http://lundestudio.com/wallpaper/leprechaun-warden-4-hi.jpg

I'm by no means an expert, but by comparison of the pics and from looking at the few Busses i've handled, the nozh2002 blade appears to have been drastically altered, and altered into a paper thin edge like its had the hell sharpened out of it.

On a side note...i don't think playdough would be the best choice of testing mediums. And wax would also be easily distortable.
IMHO using magic putty or jb weld or similar fast drying medium, on a well oiled blade would yield better results.
So theres a slight chance i could be wrong in what i'm seeing without a full length shot of nozh's blade. I swear i did a fully scientific and critical eyenalisis though.

 

[Dog of War]

Yes I do agree and also think a convex edge is much like a flat grind edge with a micro bevel, or a few micro bevels may be a better way to say it. I'm fairly sure about how shallow I keep the very edge because I don't use leather or rubber backing to sharpen both just haven't worked well for me. I use a sweeping type stroke on bench hones to get my convex edges. I'll use a belt if there is alot of steel to remove but even after that I finish by hand on stones, and just try to never raise the spine up so I produce a lower than 15 degree per side edge. Sometimes if I'm in a hurry I may cheat and raise the spine higher but it doesn't happen very often. I personally believe that how thin you are behind the edge is just as important and in alot of cases is more important in how well a knife will cut. So I guess that brings me back to the point that a degree or two on the very edge just doesn't seem to matter a heck of alot.

I also think using a bench stone is one of the best, and easiest, ways to produce or maintain a convex edge -- it was good enough for Bill Moran himself, after all -- because you have real control over the final edge angle. However I also like using emery paper or cloth on a stiff rubber sanding block, the kind used for auto body work; has less give than leather or certainly mousepad, but what little it has helps when working the belly and tip IMO. Also good for sharpening hatchets I've found.

So long as the final or "terminal" edge angle is sufficient that you're not fighting limitations of the steel's inherent edge stability, then I agree a few degrees doesn't make much practical difference. But again that edge stability threshold is critical, and therein lies the biggest problem with some of the edge retention testing we see. For these purposes I always use CrockSticks or Sharpmaker to add the microbevel and final edge so that I know what the actual terminal angle is; also this produces a far more consistent edge than you would get going from a coarser hard medium and then stropping on charged leather. Now this kind of control may not be necessary at all in the field or other real world work -- so long as you're not trying to exceed the limitations of the steel, while otherwise being mindful of trying to run a more favorable blade geometry. So for testing you need certain, more rigorous standards and methods, and while you can use those all the time if you like, you can apply what's learned more loosely the rest of the time.

 

[Esav Benyamin]

On a side note...i wasn't aware they even had play dough in russia.

Any particular reason for the comment?
What part of Russia is California in?

Keep it friendly, there's enough controversy over the knives without throwing personal jabs into the mix.

 

[db]

I also think using a bench stone is one of the best, and easiest, ways to produce or maintain a convex edge -- it was good enough for Bill Moran himself, after all -- because you have real control over the final edge angle.

Heck if it was good enough for Bill Moran it is surely good enough for me. I kind of thought I was one of a very few that used stones to produce a convex bevel. Good to find out someone like Bill did the same.

So long as the final or "terminal" edge angle is sufficient that you're not fighting limitations of the steel's inherent edge stability, then I agree a few degrees doesn't make much practical difference. But again that edge stability threshold is critical, and therein lies the biggest problem with some of the edge retention testing we see. For these purposes I always use CrockSticks or Sharpmaker to add the microbevel and final edge so that I know what the actual terminal angle is;
...
this kind of control may not be necessary at all in the field or other real world work -- so long as you're not trying to exceed the limitations of the steel,
...
So for testing you need certain, more rigorous standards and methods, and while you can use those all the time if you like, you can apply what's learned more loosely the rest of the time.

All very good points and I agree with them. I also think that the thickness right behind the edge is commonly ignored in alot of these sharpness discussions. I personally believe what is right behind the edge is just as important or even more so as the edge is.
Lets not even start to talk about the handle and if it effects edge holding.

 

[nozh2002]

I think when sharpening without blade fixed in some king of mechanism like Edge Pro very tip of the edge will be always kind of convex just because hands shake a little bit.

What size this microbevel usually has?

Stone - because it did not bend under pressure will not round edge, but right leather base will do it as weel. At the Sharpness Record thread people were able to make hair whittling edge mostly 50/50 with Green Rouge and ceramic.

Thanks, Vassili.

 

[Karda]

Any particular reason for the comment?
What part of Russia is California in?

Keep it friendly, there's enough controversy over the knives without throwing personal jabs into the mix.

Sorry, it was more a commentary on the poor choice of testing mediums.
As he was on ignore at the time, i hadnt seen his location. My post has since been edited.

 

[hardheart]

Stone - because it did not bend under pressure will not round edge, but right leather base will do it as weel.

the convexing by stone comes from the inability to match the angle perfectly with every sharpening stroke. It's one reason I don't bother with the mousepad + sandpaper method, I get enough convexing of the edge just by freehanding on non-pliable abrasives.

 

[1234]

I am doung this not to find difference in one degrre, but to find out what exact angle I have. I know that I sharpen my knives to 30 degree - bit over because I convexing very edge a little. However I was accused of lying, by Busse crowd, because edge shoulders on my blade I also convex and polish, I believe it decrease friction when cutting hard material like wood. Jerry Busse as well call my edge drastically altered paper thin. so this is the reason for me to accurately measure angle. Also I like to see is this angle something unusual which only I do to my blade.

In result - as I sad at the begining angle on my edge is 30 degree (32) and more then this - many factory edges are in fact 30 degree or less. Also Busse MT with Red G10 also has 35 degree angle - which is 3 degree different from my edge angle.

But all this need some acurate and reliable method to measure angle. Of course difference in one angle not big, but this is not about single degree difference. It is about 32 degree vs "drastically altered paper thin edge".

Thanks, Vassili.

Now you lost me ?

I want this to be clear and take other approach to do angle measurement. I use clay and penetrate it with edge up to the shoulders. I was careful not to change this angle when I removed edge back. Then I made picture and zoom it up. Here it is:

Now it is possible to measure angle. It is clear that angle is no more then 20 degree, even it is little convex.

So in deed damaged edge has drastically altered paper thin edge.

My appologies. I am very sorry for all troubles I cause, to my excuse - I was very sure that angle is about 30 degree. I am glad that it is actually my fault not INFI.

If it is possible - can you duplicate this post to other related threads?

Sorry again, Vassili.

It is the same knife you are talking about , right ?

http://www.bladeforums.com/forums/showthread.php?p=6306943#post6306943

1234,,,,,

 

[nozh2002]

More edge angles:

G-Sakai Samurai Bowie - 30 degree

Spyderco Military CF BG42 - 33 degree

Microtech Amphibian - 30 degree

Kershaw Cyclone - 39 degree

Thanks, Vassili.