Diamond Knife?

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FlyingMuskrat

Joined
Jan 9, 2006
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What would you people think of a knife with a solid diamond edge? Assume that a diamond large enough could be found or made. And that some rich crazy knife knut wanted to turn it into a small knife. It seems like something similar could be done with other precious and semi-precious stones.

There would be absolutely no burring on the edge, but you could only sharpen it with diamond abrasives. Seems like chipping would be your main enemy.

So, Do you think that diamond could form a good edge? Do you think it would hold it for a appreciable time?
 
FlyingMuskrat said:
What would you people think of a knife with a solid diamond edge? Assume that a diamond large enough could be found or made. And that some rich crazy knife knut wanted to turn it into a small knife. It seems like something similar could be done with other precious and semi-precious stones.

There would be absolutely no burring on the edge, but you could only sharpen it with diamond abrasives. Seems like chipping would be your main enemy.

So, Do you think that diamond could form a good edge? Do you think it would hold it for a appreciable time?
Click to expand...

You may do some experiments with glass. Glass is harder then steel and edge on broken pieces are very good. No burring of course - try this first, it will be cheaper then piece of diamond ;)

Thanks, Vassili.
 
I've never handled one myself, but diamond knives are frequently used as surgical tools and in laboratories for cutting ultra-thin slices of material to be viewed under a microscope. The blades are really small and fragile of course. A Google search for "diamond knife" turns up a lot of info.
 
Well, diamonds are used for ultra-microtomes. They are cleaved along certain crystal orientations. In an ultra-microtome they hold up fine but that isn't exactly EDC conditions.

Far more interesting is layer by layer growth of diamond, which is already done for other applications. You could deposite a very thin (nanometers) layer of diamond onto a simple metal blade.
 
by sharpening do you mean on a stone or by knapping? glass is a popular medium for beginning knappers or when propper material is otherwise difficult to obtain
 
I've heard that some surgeons use scalpels made from obsidian. They're sharper than any steel scalpel, and the incisions supposedly heal faster and with less scaring because of the cleaner cut.
 
Why would you do that? The edge wouldn't be sharper than a steel knife because the theoretical minimum edge radius would be given by the abrasive, glass isn't any harder than hardened steel and it is a whole lot more brittle.
 
HoB said:
Why would you do that? The edge wouldn't be sharper than a steel knife because the theoretical minimum edge radius would be given by the abrasive, glass isn't any harder than hardened steel and it is a whole lot more brittle.
Click to expand...

I belive that with knaped stones/glass it is much easier to obtain the absolute minimum edge radius since at the ship line if done correctly the edge comes down to a single molocule of glass which is as sharp as it gets.(this is some minor speculation on my part)
 
I've read the knapped glass edge can be 500 times thinner than a ground steel edge. But some glass knives are also ground, I believe for convenience and consistency. The advantage over steel then is probably just dictated by the application and an inability to introduce a metal blade to the work.
 
Its the application of what you can do with an obsidian, glass, flint, or other stone blade. What makes them knappible is there brittleness, that is also there limiting factor. I'm not an expert knapper but I can make a serviceable blade or point, and I have spent a few weeks living off the land with only obsidian blades you rethink everything you want to cut. Most of the time you break or smash things so you can save your precious blade for cutting hide, food prep., and cordage. things that cant be broken. you never cut fire wood with your hand axe, break fire wood and save the hand axe to cut atlatl darts or make a bow and arrows, or carve dead-fall triggers.You loose so much more material when you touch up the edge of a knapped blade. They do get scary sharp but its such a fragile edge.
 
FlyingMuskrat said:
What would you people think of a knife with a solid diamond edge? Assume that a diamond large enough could be found or made. And that some rich crazy knife knut wanted to turn it into a small knife. It seems like something similar could be done with other precious and semi-precious stones.

There would be absolutely no burring on the edge, but you could only sharpen it with diamond abrasives. Seems like chipping would be your main enemy.

So, Do you think that diamond could form a good edge? Do you think it would hold it for a appreciable time?
Click to expand...


:D Major Geek Warning!:D

In the Star Trek episode "Arena", a reptilaform called a "Gorn" knapped a dagger (more a spike, really) from a HUGE diamond.

Jim L.
 
HoB said:
Why would you do that? The edge wouldn't be sharper than a steel knife because the theoretical minimum edge radius would be given by the abrasive, glass isn't any harder than hardened steel and it is a whole lot more brittle.
Click to expand...

I am not sure if I understand you, please explain it a little more.

Isn't the theoretical edge radius on steel knives also given by the abrasive?
 
I read once that a glass's blades edge can be as thin as one molecule. I don't know how true THAT is. But, flint and glass tools have been used for thousands of years and there is evidence that ancient peoples performed surgery (including major surgery) using these tools.

Using an abrasive on a peice of glass probably wouldn't sharpen it as much as chipping peices off.
 
builderman0924 said:
I belive that with knaped stones/glass it is much easier to obtain the absolute minimum edge radius since at the ship line if done correctly the edge comes down to a single molocule of glass which is as sharp as it gets.(this is some minor speculation on my part)
Click to expand...

Did you read post #8? If I understand correctly, the idea was not to knap it but to grind it, hence my question why one would want to do that?
 
FlyingMuskrat said:
I am not sure if I understand you, please explain it a little more.

Isn't the theoretical edge radius on steel knives also given by the abrasive?
Click to expand...

Yes, precisely, so you gain nothing by grinding glass instead of steel. If you are trying to get a lower edge radius by fracturing/knapping/cleaving then that is a different issue. I just don't see why you would want to grind glass to an edge. You gain nothing in sharpness an lose a lot in durability.

In principle you can grind glass just fine with the right tools, polishing as well, is done all the time for optics.
 
What you would gain by grinding glass instead of steel is the utter lack of a burr. As I understand it once your two edge bevels meet, a burr is the only thing stopping you from being super sharp. I guess your abrasive would limit your sharpness some; but people say that they can get tree toping edges from very coarse abrasives, so that would be less of a factor with proper technique.

The idea behind this thread is that if you made a knife out of something that didn't burr, you could make a super sharp blade very eaisily.
 
Oh, now I understand. I missed the point of eliminating the burr. Well true but this is the trait-off that you will always have to deal with. The more ductile and more abrasion resistant the material the more stubborn the burr will be, but then again both traits are also desired for edge durability. So somewhere, there will be the ideal trait-off for you application. Glass seems to me to be to far on the brittle side. But all of this is neglecting an important potential: When you have something like glass, you might actually get a better edge by cleaving/breaking than you could achieve by grinding on any material.
 
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