Sharpening Knives in the Field

[coiloil37]

Fair, the only one I can see being of any significance in my case is if I'm leaving a burr that is then rolling over in use.

I'll have some answers for myself as I have a 120x loupe coming to inspect my work following sharpening, and 3 hogs to slaughter in a few weeks to see if there is any meaningful change in performance.



Just for general information for others.

Currently I strop about 4 times (give or take a few) processing a pig. If an edge can stay sharp enough to hold the knife with similar contact amount and pressure as a pencil for skinning the entire animal without stropping I'll have to change my opinion. I really hope to find I am the problem as it would be nice.

Which knife are you using? If it’s not obvious by type of knife, which steel is it and what stones are you using to sharpen? What type of strop are you using and what’s on it?

 

[Marbles]

Which knife are you using? If it’s not obvious by type of knife, which steel is it and what stones are you using to sharpen? What type of strop are you using and what’s on it?

MKC Jackstone in Magnacut, CRK Inyoni in Magnacut, and a custom Gersh Blades in Magnacut.

Stones are Shapton orange (1000) and wine (5000) stropping with fine green compound followed by extra fine (leather strop).

 

[coiloil37]

MKC Jackstone in Magnacut, CRK Inyoni in Magnacut, and a custom Gersh Blades in Magnacut.

Stones are Shapton orange (1000) and wine (5000) stropping with fine green compound followed by extra fine (leather strop).

I don’t have time to look at those specific knives, their stock thickness and heat treat but here’s the first thing that jumps out at me.

Magnacut uses vanadium and niobium carbides. Vickers hardness is 2900 and 2500 HV respectively.
Your stones are fused alumina oxide with a vickers hardness of 2000 HV. Your also using chromium oxide as a stropping compound with a hardness of approx 1900HV.

The point I’m trying to make is the carbides are what give modern steels the long lasting edge we are chasing. The caveat is that the sharpening media has to be harder than the carbide. If it’s not, the steel matrix is abraded around the carbide but the carbides themselves are not effectively shaped on the stone and are then under utilised and incapable of giving you the edge your chasing.


Diamond has a hardness of 10k HV and is more then capable of cutting the carbides.

I used to own a full set of naniwa super stones. Then I got into modern steels and struggled for a few years. Probably close to 15 years ago I switched to DMT 8” bench stones and diamond paste for my stop and those problems went away.

So sure, a burr may be one of your problems. The fact you aren’t cutting the carbides in your magnacut is also a huge problem.

I’m busy building a boat so not going to put to much time into explaining this. There is a ton of information online and I would suggest you go look down that rabbit hole if you want the best performance from your cutlery.

 

[Marbles]

I don’t have time to look at those specific knives, their stock thickness and heat treat but here’s the first thing that jumps out at me.

Magnacut uses vanadium and niobium carbides. Vickers hardness is 2900 and 2500 HV respectively.
Your stones are fused alumina oxide with a vickers hardness of 2000 HV. Your also using chromium oxide as a stropping compound with a hardness of approx 1900HV.

The point I’m trying to make is the carbides are what give modern steels the long lasting edge we are chasing. The caveat is that the sharpening media has to be harder than the carbide. If it’s not, the steel matrix is abraded around the carbide but the carbides themselves are not effectively shaped on the stone and are then under utilised and incapable of giving you the edge your chasing.


Diamond has a hardness of 10k HV and is more then capable of cutting the carbides.

I used to own a full set of naniwa super stones. Then I got into modern steels and struggled for a few years. Probably close to 15 years ago I switched to DMT 8” bench stones and diamond paste for my stop and those problems went away.

So sure, a burr may be one of your problems. The fact you aren’t cutting the carbides in your magnacut is also a huge problem.

I’m busy building a boat so not going to put to much time into explaining this. There is a ton of information online and I would suggest you go look down that rabbit hole if you want the best performance from your cutlery.

The vanadium carbides in MagnaCut are 1-2 microns and the niobium carbides are even finer. For comparison DMTs finest diamond lapping compound is 1 micron. DMTs extra fine diamond stone is 3 microns.

Carbides will be crushed using a water stone and become part of the swarf. Exposed carbides at the edge add in edge retention, though very keen edges are made up from the steel and not carbides, even when diamonds are used.

Burnishing also plays a roll and will shape metal with much softer material, such as an unloaded linen strop.

Further, the inventor of Magnacut documents reports of the Shapton stones sharpening it better than DMT diamond or CBN stones.

The carbide making water stones not work both flys in the face of experience and what is known about how edges are shaped from electron microscope. It is a pretty theory though.

 

[coiloil37]

The vanadium carbides in MagnaCut are 1-2 microns and the niobium carbides are even finer. For comparison DMTs finest diamond lapping compound is 1 micron. DMTs extra fine diamond stone is 3 microns.

Carbides will be crushed using a water stone and become part of the swarf. Exposed carbides at the edge add in edge retention, though very keen edges are made up from the steel and not carbides, even when diamonds are used.

Burnishing also plays a roll and will shape metal with much softer material, such as an unloaded linen strop.

Further, the inventor of Magnacut documents reports of the Shapton stones sharpening it better than DMT diamond or CBN stones.

The carbide making water stones not work both flys in the face of experience and what is known about how edges are shaped from electron microscope. It is a pretty theory though.

It’s true that the carbides in magnacut are very fine relative other steels and that’s one of the reasons it takes a keen edge and exhibits excellent edge stability.
It’s also the case that I only have two magnacut knives and I don’t use them that much. The most I’ve done in one trip with my James Sponaugle was six deer and I never noticed any loss of cutting aggression. The other is the benchmade fillet knife but I’ve got a Phil Wilson filleting knife that does all the heavy lifting around here so it’s seen very little use.

My personal progression from naniwa stones to DMT started with steels that have much larger carbides like D2, S30v, S90v and S110v along with some m390 etc. and the change in edge retention was noticeable. I’ve been using DMT stones longer than magnacut has existed so that’s the only way I’ve sharpened it. In other words, I’ve never tried to use a softer sharpening media on magnacut.

Now as for what you’re trying to say. Maybe to some of it but all of it reads to me like a form of confirmation bias where your choosing to believe what you want because it suites your purpose. I’ve read Larrins reports on his steel and even read the OG report where he presented his new steel to the world and said that Devin Thomas had success sharpening on shapton stones.

That doesn’t change anything in my mind. I can’t imagine a world where I would intentionally sharpen my knives with a media that’s softer than what’s in the blade. I prefer to cut my apex. I mean the steel matrix and the carbides. Burnishing the edge may feel sharp but it’s not good for wear resistance. Could be why I can run through six to ten animals and still shave my arm when I’m done and your not seeing the same performance.

I also don’t have any use for an edge refined to 4 um like your 5k stone is doing. I stop around 45 um, then 3 or 4 passes at 25 um to refine the edge a shade and a couple 3 or 4 passes on a strop loaded with 5 um diamond. I want refined teeth left in my blade. It’ll pop arm hair and it’ll still be cutting long after a finely refined blade has given up or plugged with fat and grease.



Anyway, you do you. I hope you find some success with burr removal. If not, maybe consider your sharpening media.