Knife Test?: I called BS on this.

I see that now.....


The labeling of D2 as brittle does not describe its true nature though. When most hear brittle the thought of chipped edges and cracked/ broken blades come to mind.


About this whole edge on edge thing..... Go try and chop a 16d nail and tell me what happens..... I bet the nail wins. Or better yet smack your edge on some reebar and see what happens. I've done these things.... its not pretty. What will it prove? It proves that the larger surface area wins regardless of hardness.
 
knifenut1013 said:
I see that now.....


The labeling of D2 as brittle does not describe its true nature though. When most hear brittle the thought of chipped edges and cracked/ broken blades come to mind.


About this whole edge on edge thing..... Go try and chop a 16d nail and tell me what happens..... I bet the nail wins. Or better yet smack your edge on some reebar and see what happens. I've done these things.... its not pretty. What will it prove? It proves that the larger surface area wins regardless of hardness.
Click to expand...

I have hit rocks and Concrete with more than one of my Busses... No, not on purpose and it wasn't pretty, not really bad either.
 
knifenut1013 said:
.....It proves that the larger surface area wins regardless of hardness.
Click to expand...

That statement is a bit too bold. Hardness sure plays a big role too. Maybe couple RC point do not make much difference, but 10 points... how about more...

Here is an example :)

[youtube]qIITpLYAMUE[/youtube]
 
I think it is a bogus test. If a test. To many variables. Geometry, steel, heat treat, tempering ....

Could be wrong but seems the blade in the vise takes more of a blow ...
 
I wonder what the Rc of a rock is :)

I actually have some pictures of my Regulator that hit a small staple in a 2x4 that I can post tomorrow. It didn't chip but deformed more than I thought for its thickness.
 
I've cut up a hood from a Nissan with an 5160 blade that was around 58-59 RC.

No edge damage ....... I think the hood was softer and not as tough.:D

IMG_1784.jpg
 
knifenut1013 said:
I see that now.....


The labeling of D2 as brittle does not describe its true nature though. When most hear brittle the thought of chipped edges and cracked/ broken blades come to mind.


About this whole edge on edge thing..... Go try and chop a 16d nail and tell me what happens..... I bet the nail wins. Or better yet smack your edge on some reebar and see what happens. I've done these things.... its not pretty. What will it prove? It proves that the larger surface area wins regardless of hardness.
Click to expand...

Darn. I was gonna bring up the rebar thing and then you went and posted this lol. Oh well, I'll bring it up again. If you think edge geometry doesn't matter, take any knife, made of any steel, give it an edge of 20 degrees inclusive, stick it in a vise like that, whack the edge with an inch-thick piece of rebar and see what happens. Obviously the conclusion you're gonna come to is that the rebar makes a superior knife. :D

In reality, like Finkelstein said, edge geometry really *is* the only factor here. If both knives were ground to the same angle then other factors would come into play, but the fillet knife edge is always gonna lose to the axe edge in a test like this.
 
What about bolt cutters?
The geometry for cutting steel is well known, and I guess it wouldn't be a stretch to say that cutting steel requires that the cutting blade be extremely stable. Making scissors out of a pair of blades just makes a mobile platform for that.

While shears can get pretty close to not cutting at all (and just "shearing" instead), most of the ones I've seen do have some sort of bevel, although extremely obtuse.
Funny thing, since shear blades are flat ground, even flat shears will have a 90 degree inclusive edge, and I'm pretty sure I've seen a few fixed blades with edges at those angles.
 
effer said:
That statement is a bit too bold. Hardness sure plays a big role too. Maybe couple RC point do not make much difference, but 10 points... how about more...

Here is an example :)

[youtube]qIITpLYAMUE[/youtube]
Click to expand...

I sorry I'm not multilingual.

I've seen this before though and when he was cutting the pipe, yes, it made it through, but it was also as sharp as a butter knife after.

You can make anything out of parts of what I say but if you do not read it all you will never get my point.
 
knifenut1013 said:
I sorry I'm not multilingual.

I've seen this before though and when he was cutting the pipe, yes, it made it through, but it was also as sharp as a butter knife after.

You can make anything out of parts of what I say but if you do not read it all you will never get my point.
Click to expand...

I don't really know what he's saying in the video either.

Sorry for not using your whole quote. But I'm sure everybody understands what you're saying. I just wanted to point out that hardness of material cannot be completely taken out of equation, but I'm sure everyone knows that as well.
 
http://www.bladeforums.com/forums/showthread.php?t=136448&highlight=edge
Click to expand...
Good thread, and I am glad that Cliff Stamp replied to Mr.Busse's post in it, giving a more detailed (and lengthy) conclusion regarding such experiments: edge-geometry vs. HT quality, questioning at what ratio of angle:angle does geometry give way to RC (assuming a proper HT) as the deciding factor in which blade receives the deeper cut... and assuming that these two aspects of each blade are most important (i.e. steel-types are similar enough to have negligible influence over this specific sort of treatment).
In this specific case, it is hypothesized that geometry is the over-riding factor. Should experiments continue along the same lines in an effort to determine the quality of the bladesmith's product (vs. blade of known excellent quality, e.g. Busse), the next step is to challenge that first hypothesis, as others have suggested, to control for geometry. The more controls present in an experiment, the more precise the conclusions which can be drawn from the results.


It's great that some members of this forum can carry on a civilized dialogue concerning a topic pulled from Noss's forum, even if the conversation is really repetition of previous threads. Hopefully Falcor finds the thread linked by Mr.Busse enlightening. I am sure many would appreciate the revival of a site like cutleryscience.com to delve into these topics, though I doubt Falcor intended such a grandiose expedition. *shrug*
 
I feel that this thread is on the verge of being a cool lesson in tooling engineering and design. What occurs to me, is that some basics (such as moduli of elasticity and geometric stress analysis in alloys with respect to vectors of force) would be of benefit in the laypersons understanding of what really happens when the SHTF.
Any engineers or toolmakers out there care to chime in?
 
Just understand that this is a test of steel hardness, not knife performance. There are many aspects to overall knive performance.
 
Arakiel said:
I feel that this thread is on the verge of being a cool lesson in tooling engineering and design. What occurs to me, is that some basics (such as moduli of elasticity and geometric stress analysis in alloys with respect to vectors of force) would be of benefit in the laypersons understanding of what really happens when the SHTF.
Any engineers or toolmakers out there care to chime in?
Click to expand...

We have. Hardness and shape are both important. When cutting end grain wood with a chisel buckles the edge, there are two ways to fix it. Make it harder (stronger) or make it thicker. However, each can only be taken so far. Razor blades will buckle no matter how hard they are and 90 degree edges won't cut well no matter how sharp. In this case we don't have that kind of difference in material hardness, so geometry plays a more significant role. We have a competition cutter (Busse) vs. a robust short sword/tanto type design. I'd still like to see some actual measurements, other than the depth of dent/chip.
 
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