Testing Edge Angle.

I found the thread.

I have to say that my experience with INFI is similar to Vassili's. Busse knives come from the factory with thick primary grinds and secondary bevels easily +/- 20 per side. Sure they can be sharpened to split a hair but the overall package doesn't function very efficiently for regular tasks like slicing cardboard. I thin all my Busses to about 15 per side and convex the shoulder and they look pretty much like Vassili's pictures. If this constitutes major modification to a knife then I'm just at a loss for words. :eek:

I do also find the edge stability of INFI at acute angles, >=15, to be less than sturdy. I've rolled the edge on my Cultellus opening a clamshell pack. I've had dents and dings on the edge just from impacts on wood. INFI is a great steel for a variety of reasons but come on guys it still has its limitations. If you want uber-toughness you are going to have to sacrifice something and with INFI, in my experience, it is edge stability. When I first got my Game Warden I thinned it down to about 8 degrees per side and the edge was like an overcooked noodle. All of my Barkies have been thinned to 8 - 10 degrees and have maintained their edge stability so well that I haven't considered bringing the angle back up. But would these Barkies perform like a Busse in terms of overall toughness?, I highly doubt it :D
 
theonew said:
I found the thread.

I have to say that my experience with INFI is similar to Vassili's. Busse knives come from the factory with thick primary grinds and secondary bevels easily +/- 20 per side. Sure they can be sharpened to split a hair but the overall package doesn't function very efficiently for regular tasks like slicing cardboard. I thin all my Busses to about 15 per side and convex the shoulder and they look pretty much like Vassili's pictures. If this constitutes major modification to a knife then I'm just at a loss for words. :eek:

I do also find the edge stability of INFI at acute angles, >=15, to be less than sturdy. I've rolled the edge on my Cultellus opening a clamshell pack. I've had dents and dings on the edge just from impacts on wood. INFI is a great steel for a variety of reasons but come on guys it still has its limitations. If you want uber-toughness you are going to have to sacrifice something and with INFI, in my experience, it is edge stability. When I first got my Game Warden I thinned it down to about 8 degrees per side and the edge was like an overcooked noodle. All of my Barkies have been thinned to 8 - 10 degrees and have maintained their edge stability so well that I haven't considered bringing the angle back up. But would these Barkies perform like a Busse in terms of overall toughness?, I highly doubt it :D
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Flame suit on, but My experiences are exactly the same as yours. But I substitute Rangers for Barkies.
 
I'd really like to know why anyone really needs to know what the true edge angle is? So we can argue about a degree or two on a forum? I personally don't even think about angles anymore.
 
Making knife sharpness this scientific is really a waste in time. There is no ideal steel, angle, or finish because what you use a knife on continually changes. There are definitely a bunch of good ones.

If you have a single use for a knife, like whittling miniature trees from a single hair, I can see crafting the ideal blade to maximize your efforts.

Me, I just whittle some twigs when bored, cut everything from foam to drywall, pound knives through stuff...and a "shaving sharp" knife is more than plenty. Past "balding" my forearm, I really see all of this as nonsense and a waste of time.
 
More edge tested

First place in my edge retention test - Dozier KS7 - 31 degree

EAC-Dozier_KS7.jpg


Second place Yuna Hard II - 32 degree

EAC-Yuna-Hard-I.jpg


Buck Custom Shop 110 BG42 G10 - 30 degree factory edge

EAC-Buck110-BG42-G10-FE.jpg


I guess this is 2000 edge.

I guess it is clear how to do this, all you need candle, olive oil (any vegetable oil), piece of wood and digital camera. It will be nice to see more factory edges - I resharpened almost all my knives (may be I can find some), but it will be nice to see what edge different manufacturers put on their blades. Please, join this thread with your photos.

Thanks, Vassili.
 
theonew said:
In some respects I agree with both of you. But this is BLADEFORUMS, this is what we do here. Honestly why even bother posting things like this :confused:
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I guess we have pretty nice thread which leads to pretty nice way to measure edge angle in result of this discussion. This is ideal case of cooperation between people who have passion to knives - idea exchange etc etc etc. We research and discover something new useful and interesting having fun during this research.

Some people was not part of this and I can understand them being bit upset. Well there is many other thing which are not yet clear, may be next time...

Thanks, Vassili.
 
Originally Posted by db View Post
I'd really like to know why anyone really needs to know what the true edge angle is?

Quote:
Originally Posted by J_Curd View Post
Making knife sharpness this scientific is really a waste in time.

theonew said:
In some respects I agree with both of you. But this is BLADEFORUMS, this is what we do here. Honestly why even bother posting things like this :confused:
Click to expand...

You know something, your right. If we cann't post and talk about a degree or two on BFC then where should we. Knowing the edge angles may not really matter much but heck it is still kind of fun and interesting to find out about them.
:) I'm reading this thread after all, aren't I. :)
 
Nice results Vassili. Google has a link, here, that shows a similar method was used to measure the angle of stone tools. They used clay instead of wax.
 
db said:
I'd really like to know why anyone really needs to know what the true edge angle is? So we can argue about a degree or two on a forum? I personally don't even think about angles anymore.
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Hi, db. I've found that there's what you could call a threshold angle for particular blades and steels, below which edge retention falls off badly. This mostly affects the angle of the microbevel you want to use ... but if you don't use a microbevel, then it concerns the primary sharpening angle.

Speaking very generally, I've found that many quality steels perform well with a microbevel, or final edge angle, of 17 degrees/side, but will show marked deterioration of edge holding at 15 deg/side. So there's that couple of degrees you mention, and they're pretty important, IMO.

As for primary sharpening angle when using a microbevel, most of these steels work fine at 12 deg/side, with no advantage to going any more obtuse than that.

Now, as far as measuring existing edge angles ... well you can see there's a real problem if the edge has a microbevel, methods like those being discussed here aren't going to work very well.

However I personally kind of agree, measuring an existing angle isn't that important. I don't care much about factory/maker edges, I reprofile/resharpen all my knives anyway, so can just give them the edge and angle I want. And if I know I've sharpened a knife to 12 deg/side with a 17 deg/side microbevel, I don't need to measure it. :)
 
DoW I also regrind all my edges to my prefered angle. Back when I sharpened with jigs and really was concerned about my edge angle degree I really didn't see much difference under a 5 degree difference of edge angle. Now my edges are all a shallow convex that are no more than a 15 ish degree and more like a 10 to 12 per side. If I notice that the edge isn't holding up as well as I like I'll go back and raise the angle a little. If I think it isn't cutting as well as I like I'll lower the angle and regrind the edge a little shallower. I do all of this by hand and pretty much by feel and have only tried to find out what the edge angle is when in the forums and someone really wants to know. But to be truthfull none of my edges are the same and I believe the edge on any of my knives change every time I touch them up. I'd probably have to agree that a degree or two can make a difference at the lower angles and probably is more important if useing a jig or system to sharpen. However, it just doesn't matter for me and how I sharpen. I sharpen more by how the edges are effected and preform. I guess I look at what the knife work does and effects the edge rather than think about what a steel type can take for an edge angle.
 
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
 
db said:
DoW I also regrind all my edges to my prefered angle. Back when I sharpened with jigs and really was concerned about my edge angle degree I really didn't see much difference under a 5 degree difference of edge angle. Now my edges are all a shallow convex that are no more than a 15 ish degree and more like a 10 to 12 per side. If I notice that the edge isn't holding up as well as I like I'll go back and raise the angle a little. If I think it isn't cutting as well as I like I'll lower the angle and regrind the edge a little shallower. I do all of this by hand and pretty much by feel and have only tried to find out what the edge angle is when in the forums and someone really wants to know. But to be truthfull none of my edges are the same and I believe the edge on any of my knives change every time I touch them up. I'd probably have to agree that a degree or two can make a difference at the lower angles and probably is more important if useing a jig or system to sharpen. However, it just doesn't matter for me and how I sharpen. I sharpen more by how the edges are effected and preform. I guess I look at what the knife work does and effects the edge rather than think about what a steel type can take for an edge angle.
Click to expand...
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.
 
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