I might have come to the end of my super steel lust

[jackknifeh]

So why would you polish out a bevel just to put a course micro bevel on it? Why not just stop at 600 in the first place and then do touch ups at a highter angle at the same grit? Seems to contradict the idea that polished edges last longer.

I think your post was to me. The back bevel at 30 incl for example could be polished for appearance if you want. Then a coarser micro bevel at 40 degrees incl I'd only use if I wanted a toothy edge on the knife for slicing tomatoes and stuff like that. Unless I wanted something like that I'd do just what you said. The OP was asking about trying to use micro bevels and asked about a coarser edge. I'm thinking he was talking about a toothy edge but not sure. If I want a toothy edge I'd stop at around a 220 water stone grit, not 600. I wouldn't strop. My 600 grit water stone produces more of what I'd call a smooth edge than toothy. Did that make any sense? Sometimes I don't say what I'm thinking exactly right.

If your post wasn't to me, forget everything I just said. :)

Jack

[Jet B]

So why would you polish out a bevel just to put a course micro bevel on it? Why not just stop at 600 in the first place and then do touch ups at a highter angle at the same grit? Seems to contradict the idea that polished edges last longer.

Exactly! That's why I asked the question. I understand the idea behind using a micro bevel because it puts more steel behind the cutting edge like a convex does.

What I don't understand completely is why some guys are experiencing better performance and longevity with these super steels when using that 600 grit microbevel. I think I read from one educated person that it has something to do with the high carbide volume in these steels and the tendency for the carbides to actually abrade and chip out of a polished edge faster on the actual cutting edge. I really don't understand the science behind it but I would like to. I have been leaving a high polished edge on my knives because I always thought it gives better edge retention.

I am posting this in your thread Evil D because if it's true, maybe it will help you with your 20cp chipping. You would be in a good position to test it out since you cut so much cardboard at work.

[jackknifeh]

Exactly! That's why I asked the question. I understand the idea behind using a micro bevel because it puts more steel behind the cutting edge like a convex does.

What I don't understand completely is why some guys are experiencing better performance and longevity with these super steels when using that 600 grit microbevel. I think I read from one educated person that it has something to do with the high carbide volume in these steels and the tendency for the carbides to actually abrade and chip out of a polished edge faster on the actual cutting edge. I really don't understand the science behind it but I would like to. I have been leaving a high polished edge on my knives because I always thought it gives better edge retention.

I am posting this in your thread Evil D because if it's true, maybe it will help you with your 20cp chipping. You would be in a good position to test it out since you cut so much cardboard at work.

I don't know anything about carbides at all. I always thought a smooth edge has better edge retention because the tiny teeth of a toothy edge will break off faster than a smooth edge will be damaged or dulled. This would hold true for the super steels as well as the older ones (if I'm right that is). I may not have uderstood your post.

Jack

[Jet B]

I think your post was to me. The back bevel at 30 incl for example could be polished for appearance if you want. Then a coarser micro bevel at 40 degrees incl I'd only use if I wanted a toothy edge on the knife for slicing tomatoes and stuff like that. Unless I wanted something like that I'd do just what you said. The OP was asking about trying to use micro bevels and asked about a coarser edge. I'm thinking he was talking about a toothy edge but not sure. If I want a toothy edge I'd stop at around a 220 water stone grit, not 600. I wouldn't strop. My 600 grit water stone produces more of what I'd call a smooth edge than toothy. Did that make any sense? Sometimes I don't say what I'm thinking exactly right.

If your post wasn't to me, forget everything I just said. :) Jack

I understand where you are coming from Jackknife, I was always under the impression that toothy edges cut aggressive but abrade faster and don't last as long as a high polished edge which is supposed to be great for push cutting but maybe less aggressive in slicing. I was under the impression that it was a trade off of performance vs retention.

What I believe some people are finding is that steels like S90V and M390 that have high carbide volumes and high hardness actually will cut aggressive AND last longer with that courser toothy micro bevel on top of a polished edge... I'm still a rookie in the overall scheme of things and have a lot to learn so if somebody like Ankerson who understands why this is true if it indeed is could enlighten me I would really appreciate it.

Jet

[jackknifeh]

I understand where you are coming from Jackknife, I was always under the impression that toothy edges cut aggressive but abrade faster and don't last as long as a high polished edge which is supposed to be great for push cutting but maybe less aggressive in slicing. I was under the impression that it was a trade off of performance vs retention.

What I believe some people are finding is that steels like S90V and M390 that have high carbide volumes and high hardness actually will cut aggressive AND last longer with that courser toothy micro bevel on top of a polished edge... I'm still a rookie in the overall scheme of things and have a lot to learn so if somebody like Ankerson who understands why this is true if it indeed is could enlighten me I would really appreciate it.

Jet

Ok, gotcha. I'd like to hear what he says also.

Jack

[Evil D]

Yeah my understanding is that a toothy edge will work awesome for cutting cardboard, but you end up with one of two things when you use a toothy edge...rolled teeth/edge or chipped teeth/edge. Is this is something that you can get away with better with a high carbide steel like 20CP?

So far the micro bevel i put on isn't chipping near as bad. I have pretty great vision up close so under light i can still see them but they're extremely small. They're easier to feel if you run your fingernail down the edge. They're so small that i can still push and slice cut phone book paper and i can't feel any hanging up so that's good. I polished this micro bevel out to 3000 grit and then stropped on red compound.

[Ankerson]

I understand where you are coming from Jackknife, I was always under the impression that toothy edges cut aggressive but abrade faster and don't last as long as a high polished edge which is supposed to be great for push cutting but maybe less aggressive in slicing. I was under the impression that it was a trade off of performance vs retention.

What I believe some people are finding is that steels like S90V and M390 that have high carbide volumes and high hardness actually will cut aggressive AND last longer with that courser toothy micro bevel on top of a polished edge... I'm still a rookie in the overall scheme of things and have a lot to learn so if somebody like Ankerson who understands why this is true if it indeed is could enlighten me I would really appreciate it.

Jet

There is a balance or should I say optimal edge finish that maximizes both cutting efficiency (Slicing) and edge retention and from my own testing that seems to be in the 12-14 Micron range.

It's not just the high carbide volume steels either that benefit from a coarser edge, that's semi polished.

The more efficient the knife cuts the less force needed to make that cut, more force is never a good thing, that's in a draw cut.

The problem with the low alloy steels is that they really don't have the carbide volume to support that cutting edge when it's polished so what happens is it just goes blunt and it's done. Believe me people wouldn't believe how fast the lower alloy steels go dull on abrasive materials like rope or cardboard with polished edges. Now using a coarser edge increases cutting efficiency so that will help letting the edge cut longer before going dead.

Now I know this isn't what some want to hear, but that's really how it works.

With the high carbide steels this is even more effective because the carbides just take over earlier on.

I have seen the measured difference in edge retention of 50% or more depending on the steel.

[Evil D]

There is a balance or should I say optimal edge finish that maximizes both cutting efficiency (Slicing) and edge retention and from my own testing that seems to be in the 12-14 Micron range.

It's not just the high carbide volume steels either that benefit from a coarser edge, that's semi polished.

The more efficient the knife cuts the less force needed to make that cut, more force is never a good thing, that's in a draw cut.

The problem with the low alloy steels is that they really don't have the carbide volume to support that cutting edge when it's polished so what happens is it just goes blunt and it's done. Believe me people wouldn't believe how fast the lower alloy steels go dull on abrasive materials like rope or cardboard with polished edges. Now using a coarser edge increases cutting efficiency so that will help letting the edge cut longer before going dead.

Now I know this isn't what some want to hear, but that's really how it works.

With the high carbide steels this is even more effective because the carbides just take over earlier on.

I have seen the measured difference in edge retention of 50% or more depending on the steel.

Well, i'm not one to argue with someone who clearly knows more than me...so i'll give it a shot. Correct me if i'm wrong but isn't 14 micron around 1400 grit or so?

[TheApostleP]

Wow... Who would have thought 2 or three years ago that we would all come to regard S30V as the old tried-and-true, unremarkable, "old pair of blue jeans" steel? When it first became available, I avoided it. You know the logic... "Why do I need to pay all that money when AUS-8 and VG-10 work just fine for half the money?!" But of course, eventually I succumbed, and now I own several Spydies and a Buck Vantage in S30V. I also own a Gayle Bradley in CPM-M4, a Benchmade 710 in D2, and have worked on some ZDP-189 blades for other guys. After all that, I'm glad people don't regard S30V as so super anymore -- mayble it will continue to decline in price. It just seems to me that the more current "super steels" have downsides that S30V does not. For my money, it's the best mix of edge-taking, edge-holding, chip-resistance, roll-resistance and corrosion-resistance I've ever owned. And no, I don't work for Crucible Steel :)

[Ankerson]

Well, i'm not one to argue with someone who clearly knows more than me...so i'll give it a shot. Correct me if i'm wrong but isn't 14 micron around 1400 grit or so?

That's around a 600 grit finish, more like 1,000 grit after stropping on what I use to knock off the burr.

There is a reason why the 400 grit edge finish was so popular for such a long time, it's because it worked.

[Ankerson]

Wow... Who would have thought 2 or three years ago that we would all come to regard S30V as the old tried-and-true, unremarkable, "old pair of blue jeans" steel? When it first became available, I avoided it. You know the logic... "Why do I need to pay all that money when AUS-8 and VG-10 work just fine for half the money?!" But of course, eventually I succumbed, and now I own several Spydies and a Buck Vantage in S30V. I also own a Gayle Bradley in CPM-M4, a Benchmade 710 in D2, and have worked on some ZDP-189 blades for other guys. After all that, I'm glad people don't regard S30V as so super anymore -- mayble it will continue to decline in price. It just seems to me that the more current "super steels" have downsides that S30V does not. For my money, it's the best mix of edge-taking, edge-holding, chip-resistance, roll-resistance and corrosion-resistance I've ever owned. And no, I don't work for Crucible Steel :)

S30V is an excellent user steel with the proper HT, I still use it more than any other steel.

[Cliff Stamp]

What I don't understand completely is why some guys are experiencing better performance and longevity with these super steels when using that 600 grit microbevel.

All edges will have some degree of roughness or tooth, even if you were to take it to the extreme for example and use a 0.05 micron diamond/cbn paste, there is going to be aggregate roughness in the edge which is higher than that simply due to issues such as aus-grain boundaries, primary carbides, etc. . The question then is simply what size of tooth on the edge gives optimal cutting ability and edge retention.

On a very basic level, if you are slicing or draw cutting then the lower the grit finish the higher the cutting ability and edge retention. If you do push cutting it is the opposite. If you use the finish which is opposite the cutting method then the performance will be very low in both respects so ideally you use two different knives for both and keep them at the ideal finishes.

For most people you are doing a mix of the two and thus the optimal finish will be somewhere in between, this is why Joe Talmadge advocated in the late nineties to keep one section of the edge very coarse and use that for the slicing and keep the rest of the blade very fine for push cutting. Which part of the blade is which depends on cutting technique.

Note that this effect of finish is so high that it swamps out steels readily, i.e., 420J2 with a very coarse finish easily outlasts D2 with a very fine finish if you are slicing rope for example. You have to of course get the very coarse finishes very sharp for this to happen, they still have to shave for example, you can't leave a very coarse edge poorly aligned with a huge burr and expect performance from it.

[Jet B]

Interesting stuff! Thanks guys. I see now how it works.

It's kind of a happy medium between an edge that is toothy at a very small scale but not so toothy as to cause the teeth to break off. So you get an aggressive edge that will slice with less force than a highly polished edge would require. Thus your edge can last longer because it cuts the medium with less force.

I'll give it a try. My edges aren't super polished anyway, I have a Wicked edge and I finish with 1000 grit diamonds then strop to a polish with 5 then 3.5 micron diamonds. If I understand correctly, after say doing those steps at a 30 degree inclusive back bevel, just go back to a few passes with the 600 grit diamonds at around 40 degrees inclusive to create the micro bevel and then strop again just enough to remove any microscopic burr? How much stropping is enough for that last phase? I find these strops polish pretty fast so I don't want to completely remove that coarse micro bevel with them.

[Ankerson]

How much stropping is enough for that last phase? I find these strops polish pretty fast so I don't want to completely remove that coarse micro bevel with them.

As little as possible, just what is needed to make sure the burr is gone.

[razorsharp]

So why would you polish out a bevel just to put a course micro bevel on it? Why not just stop at 600 in the first place and then do touch ups at a highter angle at the same grit? Seems to contradict the idea that polished edges last longer.

Polished edges are sexy,we all know that, and lost of us know that on some steels, we lose bite. When you add a coarse micro bevel, we get a sexy 'edge' that has a high performance bite in it

[Zenith]

Interesting stuff! Thanks guys. I see now how it works.

It's kind of a happy medium between an edge that is toothy at a very small scale but not so toothy as to cause the teeth to break off. So you get an aggressive edge that will slice with less force than a highly polished edge would require. Thus your edge can last longer because it cuts the medium with less force.

I'll give it a try. My edges aren't super polished anyway, I have a Wicked edge and I finish with 1000 grit diamonds then strop to a polish with 5 then 3.5 micron diamonds. If I understand correctly, after say doing those steps at a 30 degree inclusive back bevel, just go back to a few passes with the 600 grit diamonds at around 40 degrees inclusive to create the micro bevel and then strop again just enough to remove any microscopic burr? How much stropping is enough for that last phase? I find these strops polish pretty fast so I don't want to completely remove that coarse micro bevel with them.

The last stropping is very light in my experience and require 2-3 passes at the most.

On a side note, the reason why I go to high polish and then a small course micro bevel is for two reasons. It looks pretty and it might be my subjective mind but it feels as if the high polish does not bind it material that much when push cutting.

[Jet B]

As little as possible, just what is needed to make sure the burr is gone.

Thanks Jim, I'll give it a try next time I sharpen my M390 Milly. Not like I have even come close to dulling this thing yet though... I can't find enough cardboard around home to even need to resharpen it since my initial polish I did.

This whole scenario kind of explains to me why my Fallkniven F1 with it's convex edge was performing so well when all I did was strop the factory edge a bit after getting it. It would have had a nice aggressive grained edge that was very strong because of the convex and free of any micro burr from my stropping.

[Cliff Stamp]

If I understand correctly, after say doing those steps at a 30 degree inclusive back bevel, just go back to a few passes with the 600 grit diamonds at around 40 degrees inclusive to create the micro bevel and then strop again just enough to remove any microscopic burr? How much stropping is enough for that last phase?

None, if you are stropping to remove a burr then the edge was not formed correctly. The only reason you need to strop in general is because you can not sharpen edge-into with the particular hone, i.e., leather or something soft. If you are leaving coarse edges with a burr the edge retention is going to be fairly poor, that is the main reason why people have the misconception that coarse edges blunt quickly, the teeth crack off, etc. as all they are seeing is burr collapse. This isn't a problem which can be solved by a fine grit strop either as that will both change the grit of the edge and tend to leave the edge over stressed. The burr has to be cut off with the same stones that shaped the edge if you want optimal edge retention and cutting aggression.

[Jet B]

The last stropping is very light in my experience and require 2-3 passes at the most.

On a side note, the reason why I go to high polish and then a small course micro bevel is for two reasons. It looks pretty and it might be my subjective mind but it feels as if the high polish does not bind it material that much when push cutting.

Good point Zenith... I have a fondness for those shiny polished bevels too. I'm definitely going to try putting the coarse bite on my edge too now. I'll do like you say and keep the last strops to a minimum. I have had a tendency to strop a lot with this WEPS since it goes very fast and seems to almost convex my bevels when I get carried away. I guess convexing of the edge on a microscopic scale is what stropping is supposed to do anyway.

[Ankerson]

None, if you are stropping to remove a burr then the edge was not formed correctly. The only reason you need to strop in general is because you can not sharpen edge-into with the particular hone, i.e., leather or something soft. If you are leaving coarse edges with a burr the edge retention is going to be fairly poor, that is the main reason why people have the misconception that coarse edges blunt quickly, the teeth crack off, etc. as all they are seeing is burr collapse. This isn't a problem which can be solved by a fine grit strop either as that will both change the grit of the edge and tend to leave the edge over stressed. The burr has to be cut off with the same stones that shaped the edge if you want optimal edge retention and cutting aggression.

Yep, exactly. :)

I don't have a burr once I finish sharpening, my SIC stones cut very clean, I strop just to put the finial touch on the edge, that is what I call the burr, but it's not really a burr.