Some comments on ZDP-189 vs VG10 edge retention

Gator97 said:
You lost me there...
What I said was that the force, especially the lateral force has the rolling (or deforming) effect, just on thicker edges it's less pronounced, because the edge is stronger.
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Yeah, now that would be true all other things being equal. :thumbup:
 
Gator97 said:
Ok, I figure we're on the same page then :)
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Yeah. :)

Now if the Spine thickness is the only difference everything else being equal it wouldn't have any effect on the edges.

Say one blade was 1/8" and the other was 3/16" but the edges were the same profile and thickness.
 
I agree with your conclusions. Steel choice between these two is not nearly as important as the grind.
 
So for simplicity's sake:

a 1/8in thick scandi grind(zero edge) blade with edge angle at 25 deg inclusive will wear at the same rate as a 1/4in thick brutish scandi grind blade at the same 25 deg...when pushcutting cardboard?

Even though the force applied to the thicker blade edge while pushing the blade forward/down is higher? The force the edge is subjected to has no effect?
 
PatriotDan said:
So for simplicity's sake:

a 1/8in thick scandi grind(zero edge) blade with edge angle at 25 deg inclusive will wear at the same rate as a 1/4in thick brutish scandi grind blade at the same 25 deg...when pushcutting cardboard?

Even though the force applied to the thicker blade edge while pushing the blade forward/down is higher? The force the edge is subjected to has no effect?
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Exactly because the Spine on the thicker blade will take most of the added pressure.

The pressure on the cutting edges would be about the same.
 
Must be Monday morning, but I am not getting this at all.
We have 2 blades, identical edge angles, identical blade grind and geometry, correct? The only difference is the blade thicnkess, correct?
And the statement is the pressure on the edge is identical(or almost identical) even if the force applied to the spine is let's say 2x greater for the thicker blade?
If I got that right, you are saying pressure will be similar because thicker blade has wider edge "area"?
 
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Gator97 said:
Must be Monday morning, but I am not getting this at all.
We have 2 blades, identical edge angles, identical blade grind and geometry, correct? The only difference is the blade thicnkess, correct?
And the statement is the pressure on the edge is identical(or almost identical) even if the force applied to the spine is let's say 2x greater for the thicker blade?
If I got that right, you are saying pressure will be similar because thicker blade has wider edge "area"?
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I am sorry, there has to be a mis-understanding here. If a 1/8" thick blade is ground to the top and a 1/4" blade is ground to the top then the geometry can NOT be the same unless the 1/4" thick blade is MUCH wider than the 1/8" blade. I am sure that it is I who am not grasping the concept. Please help me to understand.
A. G
 
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A. G. Russell said:
I am sorry, there has to be a mis-understanding here. If a 1/8" thick blade is ground to the top and a 1/4" blade is ground to the top then the geometry can NOT be the same unless the 1/4" thick blade is MUCH wider than the 1/8" blade. I am sure that it is I who am not grasping the concept. Please help me to understand.
A. G
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mr. Russell, I replied this earlier on, this is the question I was asking:

a 1/8in thick scandi grind(zero edge) blade with edge angle at 25 deg inclusive will wear at the same rate as a 1/4in thick brutish scandi grind blade at the same 25 deg...when pushcutting cardboard?

Even though the force applied to the thicker blade edge while pushing the blade forward/down is higher? The force the edge is subjected to has no effect?

So the edge angles are the same, the grind type is the same(scandi grind), in this case neither of the grinds go all the way to the spine. The thicker blade grind/edge of course goes higher up towards the spine because of blade stock thickness.
 
I think you have a valid point.
I was assuming a simple wedge configuration, and then the pressure would be distributed over a larger area.
I'm not sure myself I have the correct picture in my mind.
 
PatriotDan said:
mr. Russell, I replied this earlier on, this is the question I was asking:

a 1/8in thick scandi grind(zero edge) blade with edge angle at 25 deg inclusive will wear at the same rate as a 1/4in thick brutish scandi grind blade at the same 25 deg...when pushcutting cardboard?

Even though the force applied to the thicker blade edge while pushing the blade forward/down is higher? The force the edge is subjected to has no effect?

So the edge angles are the same, the grind type is the same(scandi grind), in this case neither of the grinds go all the way to the spine. The thicker blade grind/edge of course goes higher up towards the spine because of blade stock thickness.
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Dan, thank you for trying to help me. I still have a problem, if a 1/8" thick blade is flat ground to a 0 bevel and a 1/4" thick blade of the same width is also ground from the spine to a 0 bevel then the angle CANNOT be the same.

I just became aware that I am talking about flat ground to the spine and you are talking about grinding "Scandi" or 1/2 to 1/3 of the way up the blade.

I am sorry, I am lost in the past when a "Scandi" blade was only 1/16" thick and therefore needed to be ground only part of the way up the blade.

I see that I have butted into a discussion where I do not belong. Sorry for having wasted your time.
A. G.
 
well this is what i love aboht the forum. started out with simple cutting now we're into stress dynamics with applied force pressure which now increases the abrasion equation. if i'm on the same page as you guys. really simple cutting can sure involve a ton of physics. however its all good.
 
For a while at my old company, I was the lab metallurgist. We got rid of the old guy. That lasted long enough for me to try it just to see if it would work. It won't. I didn't break it, but I did make a noise. Sometimes curiosity gets the better of you and you must learn not to pee on the electric fence the hard way, not just because someone told you it was wrong.
 
PatriotDan said:
Thanks for showing your results, very easy to understand. I wish you would publish more of your testing here.

About cardboard cutting, would you think a thick bladed knife that requires more force to push through cardboard also reduces the edge retention compared to same HRc in same steel and grind but thinner stock? Or only the force required to cut is increased?
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Um... I thought it might be easier to answer the original question. ;)

I found that, when cutting cardboard, a thicker blade requires more force, so the "perceived" edge retention is lesser. But the blade thickness does not appear to affect the actual sharpness of the edge.

-If you take a thin blade of an alloy that has a lower inherent edge retention.
-And a thicker blade of an alloy that has a higher inherent edge retention.
Then use them to cut cardboard.
If you judge by the effort needed to cut the cardboard, you will swear that the thin blade is made of an alloy with better edge retention than that of the thicker blade.

I use "thin blade" and "thick blade". but you are really looking at the all of the geometries of the angles. One of the measurements that is significant to me is the thickness of the blade just above the bevel. The thinner the blade is there, the better it will slice cardboard and a number of other materials. I don't hunt anymore. But I'd bet that the difference would be noticeable when skinning.

Oh, oh. another wall of text. :eek:

I love all the participation. It's how we all learn.
 
PatriotDan said:
a 1/8in thick scandi grind(zero edge) blade with edge angle at 25 deg inclusive will wear at the same rate as a 1/4in thick brutish scandi grind blade at the same 25 deg...when pushcutting cardboard?
Click to expand...


This is the type of question I'm always asking myself when I am perusing this forum. It's a great question, and is the kind that has to be asked before you can come up with a good test. The answer is that it all depends on how you define wear.

For Knarfeng's test, he is making visible observations & comparisons of sharpness (or wear) after each edge cuts the same material the same number of times. Force to cut is not a consideration in this definition of edge retention.

We can also define edge retention as the slope of a graph of force required to cut versus number of cuts, or the slope of a graph of sharpness versus number of cuts. You would have a problem with your two dissimilar blades with a test for this definition of edge retention.

Like the theory that some steels (ahem d2) wear, but keep a good toothy edge that cuts well despite the wear (due to those massive & sometimes controversial carbons - can you really sharpen them?).

A visible observation is a good (I mean how else are you going to do it?) method for determining wear, but not the best method for quantifying force required to cut.

Thanks for the thread and results, Knarfeng.
 
broos you have established a viable variable we are eagerly waiting the results of your coming tests. thanks for joining in, we welcome all input & certsainly like to see other members set up their tests & give us a report.
 
knarfeng said:
Um... I thought it might be easier to answer the original question. ;)

I found that, when cutting cardboard, a thicker blade requires more force, so the "perceived" edge retention is lesser. But the blade thickness does not appear to affect the actual sharpness of the edge.

-If you take a thin blade of an alloy that has a lower inherent edge retention.
-And a thicker blade of an alloy that has a higher inherent edge retention.
Then use them to cut cardboard.
If you judge by the effort needed to cut the cardboard, you will swear that the thin blade is made of an alloy with better edge retention than that of the thicker blade.

I use "thin blade" and "thick blade". but you are really looking at the all of the geometries of the angles. One of the measurements that is significant to me is the thickness of the blade just above the bevel. The thinner the blade is there, the better it will slice cardboard and a number of other materials. I don't hunt anymore. But I'd bet that the difference would be noticeable when skinning.

Oh, oh. another wall of text. :eek:

I love all the participation. It's how we all learn.
Click to expand...
So in fact you've just proven the carboard test to be useless in edge retention testing. Since it doesn't test the edge but the thickness of the blade?

Am i getting that right?
 
lx if i'm getting this right what they are implying is if the edge bevels are same geometry but the blades further back are varied in thickness the thicker blade because of resistance although == in sharpness requires more force to go the same distance in cardboard. although they are = in sharo the added pressure required to push the knife thru the cardboard would appear to make that knife seem duller.however the sharpness is the same but the wedge shape behind the blade makes the thicker blade seem duller. in fact at the edge both knives have equal sharp at the edge. hope i'm correct in this analogy, & it helps explain.
 
lx if i'm getting this right what they are implying is if the edge bevels are same geometry but the blades further back are varied in thickness the thicker blade because of resistance although == in sharpness requires more force to go the same distance in cardboard. although they are = in sharo the added pressure required to push the knife thru the cardboard would appear to make that knife seem duller.however the sharpness is the same but the wedge shape behind the blade makes the thicker blade seem duller. in fact both knives have equal sharp at the edge. hope i'm correct in this analogy, & it helps explain.
 
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