05-17-2018, 09:59 AM
Mr. KG, I don't understand why you assume Mr. Sharpco's question is about thinning the bevel. I think he would have worded it differently, but maybe I'm the one with the wrong impression.
(Quote, Mr. KG)
"Firstly, shall we not confuse over-thinned vs properly angled edge with sharpness as such.
Secondly, shall we not confuse toothy vs polished edge with sharpness as such. (Unquote)
I'm not sure what constitutes "over-thinned vs properly angled". That's highly subjective, and primarily based on usage. Your experience shows that the difference between "over-thinned" and "properly angled" is only 2 dps, which is astounding.
I'm not sure how to take level of refinement out of the equation. I mean that is probably the most significant quality of an edge. One thing I'm wondering is if coarse edges roll like refined edges.
I recognize Mr. Cliff Stamp's name, but I'm not very familiar with him at all. I understand he can be rather polarizing, but he has a lot of experience. From what little I've seen, he is a proponent of thinning edges pretty dramatically, but he also micro-bevels at a standard 15 dps, so that adds another unqualified variable to the equation. I understand you had no luck with micro-bevels, and my experience is the same.
Of course a common observation about thin primary bevels is that they roll, dent, chip or crinkle relatively easily. It's hard to argue simple physics. The only question is if it will withstand your usage.
If your Normal use is the Maximum that you are willing to use the knife for, it becomes easier to tailor the angle specifically.
A good example is the way you are able to sharpen at 10 dps for inexpensive, medium carbon, stainless, "meat cutting" blades. Meat is extremely soft and totally non-abrasive. In addition, meat cutters are not only experts at carefully using their knives, they also expertly maintain these 10 dps edges constantly.
However, I understand that you can't measure the sharpness of these blades with BESS media at 8 dps, because the test media actually disrupts the edge at that angle. To me, that is both unexpected and very revealing. It's pretty surprising that an edge with maximum performance is only two degrees away from an edge that fails on test media.
Inexpensive meat cutting knives are pretty much opposite expensive, EDC knives. In my experience, less than about 15 dps is too easily damaged, no matter what steel. I've certainly been down this road plenty of times, with lots of different knives.
These are identical blades. They are both Benchmade 710s in M390. The first is very close to the factory edge. It measures 18 dps, with a primary bevel width of < .040".
![[Image: m94HXEI.jpg]](https://i.imgur.com/m94HXEI.jpg)
Here is the exact same blade thinned with an EdgePro to about 8 dps. The width of the primary bevel is now about .20". Approximately 5x as wide.
![[Image: PCa6b1V.jpg]](https://i.imgur.com/PCa6b1V.jpg)
At 8 dps, the edge is very fragile. It takes practically nothing to chip or dent the edge. If I put a .020" dent in the edge, and have to remove... say a .010" thick layer off a bevel that is .20" wide and 3" long. That comes to .006 cubic inches/side.
The 18 dps blade is exponentially harder to chip, which is why it's not a linear equation IMHO, although I would certainly take Mr. Jan's advisement. I'm not sure if I would still have to remove a the same amount off a .040" wide surface 3" long, but that would be .0012 cubic inches/side, which happens to be 5x less. When you're talking hard, wear resistant steel, that means it takes an extraordinary amount of time to sharpen the wide bevel.
The big difference is at 8 dps, M390 is too fragile for typical EDC. It does hold up to BESS media with no damage at all, and it's exceedingly sharp. Actual sharpness was an afterthought, but like any polished EP edge (even regular 20 dps), it passed hair whittling easily.
Like every exotic steel blade I've ever thinned, which is a good pile of knives, by far the biggest affect on these blades is significantly reducing the amount of steel in the blade. It doesn't take long to remove years worth of steel, and I've got all kinds of puny blades to prove it. That is the main reason I just don't thin bevels much anymore.
At 18 dps, M390 cuts practically anything for a long time. I did not hesitate to cut the thick, dirt filled burlap sack holding the root ball of a 12' maple yesterday. I kept cutting the burlap for a minute, seeing if it would get dull. It definitely took the fine edge off, but it kept cutting the burlap very easily. There was no visible damage at all.
I didn't think to measure sharpness before I touched it up. 710 blades are hard to sharpen, with a recurve and long point, but after about 10 minutes on a 1k stone and a few passes on 8µ PDP, it was not consistent, but 79-122. For my purposes that's barely sharp enough for a refined edge, I just didn't want to spend more time on it.
Another fact IMHO is that it's virtually impossible for me to tell much difference between 8 dps and 18 dps in normal use. I'm sorry, but tooth/level of refinement has a much greater affect IMHO. That's something I can actually feel practically every time I cut anything.
My solution is to carry more than one blade, but I end up using a 400 grit, 18 dps blade way more than a 2k grit 10 dps blade by a very wide margin. It is always fun to use a super sharp blade when the need arrises, so I don't mind carrying one.
(Quote, Mr. KG)
"Firstly, shall we not confuse over-thinned vs properly angled edge with sharpness as such.
Secondly, shall we not confuse toothy vs polished edge with sharpness as such. (Unquote)
I'm not sure what constitutes "over-thinned vs properly angled". That's highly subjective, and primarily based on usage. Your experience shows that the difference between "over-thinned" and "properly angled" is only 2 dps, which is astounding.
I'm not sure how to take level of refinement out of the equation. I mean that is probably the most significant quality of an edge. One thing I'm wondering is if coarse edges roll like refined edges.
I recognize Mr. Cliff Stamp's name, but I'm not very familiar with him at all. I understand he can be rather polarizing, but he has a lot of experience. From what little I've seen, he is a proponent of thinning edges pretty dramatically, but he also micro-bevels at a standard 15 dps, so that adds another unqualified variable to the equation. I understand you had no luck with micro-bevels, and my experience is the same.
Of course a common observation about thin primary bevels is that they roll, dent, chip or crinkle relatively easily. It's hard to argue simple physics. The only question is if it will withstand your usage.
If your Normal use is the Maximum that you are willing to use the knife for, it becomes easier to tailor the angle specifically.
A good example is the way you are able to sharpen at 10 dps for inexpensive, medium carbon, stainless, "meat cutting" blades. Meat is extremely soft and totally non-abrasive. In addition, meat cutters are not only experts at carefully using their knives, they also expertly maintain these 10 dps edges constantly.
However, I understand that you can't measure the sharpness of these blades with BESS media at 8 dps, because the test media actually disrupts the edge at that angle. To me, that is both unexpected and very revealing. It's pretty surprising that an edge with maximum performance is only two degrees away from an edge that fails on test media.
Inexpensive meat cutting knives are pretty much opposite expensive, EDC knives. In my experience, less than about 15 dps is too easily damaged, no matter what steel. I've certainly been down this road plenty of times, with lots of different knives.
These are identical blades. They are both Benchmade 710s in M390. The first is very close to the factory edge. It measures 18 dps, with a primary bevel width of < .040".
Here is the exact same blade thinned with an EdgePro to about 8 dps. The width of the primary bevel is now about .20". Approximately 5x as wide.
At 8 dps, the edge is very fragile. It takes practically nothing to chip or dent the edge. If I put a .020" dent in the edge, and have to remove... say a .010" thick layer off a bevel that is .20" wide and 3" long. That comes to .006 cubic inches/side.
The 18 dps blade is exponentially harder to chip, which is why it's not a linear equation IMHO, although I would certainly take Mr. Jan's advisement. I'm not sure if I would still have to remove a the same amount off a .040" wide surface 3" long, but that would be .0012 cubic inches/side, which happens to be 5x less. When you're talking hard, wear resistant steel, that means it takes an extraordinary amount of time to sharpen the wide bevel.
The big difference is at 8 dps, M390 is too fragile for typical EDC. It does hold up to BESS media with no damage at all, and it's exceedingly sharp. Actual sharpness was an afterthought, but like any polished EP edge (even regular 20 dps), it passed hair whittling easily.
Like every exotic steel blade I've ever thinned, which is a good pile of knives, by far the biggest affect on these blades is significantly reducing the amount of steel in the blade. It doesn't take long to remove years worth of steel, and I've got all kinds of puny blades to prove it. That is the main reason I just don't thin bevels much anymore.
At 18 dps, M390 cuts practically anything for a long time. I did not hesitate to cut the thick, dirt filled burlap sack holding the root ball of a 12' maple yesterday. I kept cutting the burlap for a minute, seeing if it would get dull. It definitely took the fine edge off, but it kept cutting the burlap very easily. There was no visible damage at all.
I didn't think to measure sharpness before I touched it up. 710 blades are hard to sharpen, with a recurve and long point, but after about 10 minutes on a 1k stone and a few passes on 8µ PDP, it was not consistent, but 79-122. For my purposes that's barely sharp enough for a refined edge, I just didn't want to spend more time on it.
Another fact IMHO is that it's virtually impossible for me to tell much difference between 8 dps and 18 dps in normal use. I'm sorry, but tooth/level of refinement has a much greater affect IMHO. That's something I can actually feel practically every time I cut anything.
My solution is to carry more than one blade, but I end up using a 400 grit, 18 dps blade way more than a 2k grit 10 dps blade by a very wide margin. It is always fun to use a super sharp blade when the need arrises, so I don't mind carrying one.