Cliff Stamp
BANNED
- Joined
- Oct 5, 1998
- Messages
- 17,562
ColoradoDave :
With use, edge damage will set in at the 100 to 10 micron level depending on the nature of the cutting, carpet is about 100 microns, hemp rope about 10 micron. Examining the edge of this knife and various steels the behavior isn't significantly different in type, the magnitude varies with steel properties, some chip, wear or roll more than others. I should really get a decent photo magnifier so I could illustate this with some pictures.
So would I except I have seen it with ceramic blades. While the ductility is low for LM1 if you get it thin enough, it will take a set. After doing 62 cuts into hemp rope for example, the edge was down to about 20% of optimal slicing aggression, after steeling it was within a few percent of freshly honed. Looking right down into the edge, the deflections can be seen, and are a fraction of a mm, on the order of 100 microns.
rdangerer :
He joined right after Chad234 / Eric_Draven was banned for the second time. His first posts with the hillbilly persona are nearly identical to the way that Draven intruduced himself. His recent posts in the above on angles are near identical in structure and wording comments Chad and later Draven has made. His last post in this thread has a near insane level of irony considering his previous posts. That is the downside to anon internet postings, and why in most forms with a long history they are all ignored. It is also why a lot of the discussion forums require real name registeration as it massively cuts down on trolls.
R. W. Clark :
That was essentially what I was looking for. The tip taper is fairly thin, I have not seen a steel knife with that profile which could do heavy wood digging (1/2"+ thickness), with that geometry. However with them you are farely safe on examining it because they will all bend (will most will anyway).
Is this with the rougher finish you noted in the above? No steel blade will push cut then either, as the edge is just a saw. What you are describing isn't an inherent propertly of LM1 just general cutting mechanices. For example look at cutting with a skew chisel vs an ordinary one. The skew chisel, at the same level of sharpness, can given cleaner cuts. Lee talks about this in detail in his book on sharpening.
As you are cutting in a way which is very much a slice, the blade will continue to cut long past the point in which is would have stopped push cutting. This allows more material to be cut, with any blade material even mild steels. One of the reasons I stopped doing cardboard comparisons in this manner was that it required far too much cardboard as even really cheap knives (SAK's and such) would cut for vast periods of time.
What needs to be considered here is the size of this effect. As the metal wears you can see deformations and chips which are just sub-mm in size (~100 microns). These will produce distortions of the edge which will vastly mask effects on a sub molecular level. Consider various steels, all which has greatly different grain structure and levels of carbide segregation, these can vary by more than ten to one. However if you sharpen them at some fairly coarse grit level, say 100 AO, they all slice the same. Why, because the structures formed by the abrasive are so large they completely mask the underlying structure which is only micron in size (and even that this is still far larger than molecular).
I have finished four rounds of carpet cutting, three on hemp (three different rolls), one left to do, when that is done I'll repeat it on a more coarse abrasive, 80 or 100 AO and see if it behaves significantly difference from steel when also used at that level. This isn't looked forward to however because it makes a massive change in slicing aggression in general which greatly induces edge holding and thus requires *lots* more material to be cut.
-Cliff
Would be particularly interested in hearing what you're seeing under magnification as the edge degrades with use ...
With use, edge damage will set in at the 100 to 10 micron level depending on the nature of the cutting, carpet is about 100 microns, hemp rope about 10 micron. Examining the edge of this knife and various steels the behavior isn't significantly different in type, the magnitude varies with steel properties, some chip, wear or roll more than others. I should really get a decent photo magnifier so I could illustate this with some pictures.
I'm guessing with this material, the edge may not roll ...
So would I except I have seen it with ceramic blades. While the ductility is low for LM1 if you get it thin enough, it will take a set. After doing 62 cuts into hemp rope for example, the edge was down to about 20% of optimal slicing aggression, after steeling it was within a few percent of freshly honed. Looking right down into the edge, the deflections can be seen, and are a fraction of a mm, on the order of 100 microns.
rdangerer :
Want to unveil your former alter-BF-ego for us anytime soon?
He joined right after Chad234 / Eric_Draven was banned for the second time. His first posts with the hillbilly persona are nearly identical to the way that Draven intruduced himself. His recent posts in the above on angles are near identical in structure and wording comments Chad and later Draven has made. His last post in this thread has a near insane level of irony considering his previous posts. That is the downside to anon internet postings, and why in most forms with a long history they are all ignored. It is also why a lot of the discussion forums require real name registeration as it massively cuts down on trolls.
R. W. Clark :
Treat is as you would any other material considering the taper and the thickness at the point.
That was essentially what I was looking for. The tip taper is fairly thin, I have not seen a steel knife with that profile which could do heavy wood digging (1/2"+ thickness), with that geometry. However with them you are farely safe on examining it because they will all bend (will most will anyway).
At perfect 90s it does not push cut worth a damn, but with a slight change in the blade it will slice till the cows come home.
Is this with the rougher finish you noted in the above? No steel blade will push cut then either, as the edge is just a saw. What you are describing isn't an inherent propertly of LM1 just general cutting mechanices. For example look at cutting with a skew chisel vs an ordinary one. The skew chisel, at the same level of sharpness, can given cleaner cuts. Lee talks about this in detail in his book on sharpening.
As you are cutting in a way which is very much a slice, the blade will continue to cut long past the point in which is would have stopped push cutting. This allows more material to be cut, with any blade material even mild steels. One of the reasons I stopped doing cardboard comparisons in this manner was that it required far too much cardboard as even really cheap knives (SAK's and such) would cut for vast periods of time.
As to edge wear. LM1, as with any other amorphic metal, has what is called "edge band shearing" (there is a more scientific name but I can never remember it). Basically this is what you see when a sheet of plate glass breaks. The edges tend to break at sharp angles and the tend to be very sharp. This is happening with LM1 and it is the way that it wears (on a microscopic level of coarse). As the molicules on the very edge fail and break away from the rest of the material the seperate at 45 degree angles and tend to leave "dished" voids. This can also be looked at as really tiny flint knapping. So what is happening is that the edge is being replaced with a fresh edge at the point of failure.
What needs to be considered here is the size of this effect. As the metal wears you can see deformations and chips which are just sub-mm in size (~100 microns). These will produce distortions of the edge which will vastly mask effects on a sub molecular level. Consider various steels, all which has greatly different grain structure and levels of carbide segregation, these can vary by more than ten to one. However if you sharpen them at some fairly coarse grit level, say 100 AO, they all slice the same. Why, because the structures formed by the abrasive are so large they completely mask the underlying structure which is only micron in size (and even that this is still far larger than molecular).
I have finished four rounds of carpet cutting, three on hemp (three different rolls), one left to do, when that is done I'll repeat it on a more coarse abrasive, 80 or 100 AO and see if it behaves significantly difference from steel when also used at that level. This isn't looked forward to however because it makes a massive change in slicing aggression in general which greatly induces edge holding and thus requires *lots* more material to be cut.
-Cliff