Preferential edge type for "softer" steels?

[NJBillK]

For knives that carry steels like the early 90's schrade old timers, victorinox line (inox) and other comparable knives left around mid to upper 50s hrc, what type of edges do you folks prefer?

I just recently picked up a Vic Secretary that will be kept in my wallet and I was thinking I would sharpen each blade with a different finish, one toothy, one polished to see what I Prefer, but I was curious about is what the rest of you like on your personal users?

I mostly cut food grade plastics, pallet wrap, pallet banding, some cardboard (though I have a higher wear resistant knife for most cardboard), and other relatively low abrasion materials where some bite is preferential.

 

[Magnaminous_G]

For me, coarser, maybe 600 grit, very judiciously stropped

 

[Obsessed with Edges]

For knives that carry steels like the early 90's schrade old timers, victorinox line (inox) and other comparable knives left around mid to upper 50s hrc, what type of edges do you folks prefer?

I just recently picked up a Vic Secretary that will be kept in my wallet and I was thinking I would sharpen each blade with a different finish, one toothy, one polished to see what I Prefer, but I was curious about is what the rest of you like on your personal users?

I mostly cut food grade plastics, pallet wrap, pallet banding, some cardboard (though I have a higher wear resistant knife for most cardboard), and other relatively low abrasion materials where some bite is preferential.

Edge geometry at 30° inclusive or lower will make the bigger difference for the cutting types described. Especially down around 25° inclusive, the edge finish almost becomes moot for these types of cutting, and the steel type & hardness will largely determine how thin you can go at the edge. For the types of cutting you describe, I've tried and found useful any finish from 320 up through 2000+ on blades in anything from 1095 & CV, 420HC, X50CrMoV15 (i.e., Victorinox's stainless), 12C27Mod (Opinel), 440C, D2 and S30V/S90V. For cardboard in particular, a thinly convexed & polished finish at ~2000 or so minimizes drag and the effects of 'pinching' in heavy material, and therefore is a wicked slicer for cardboard.

At thicker geometries above 30°, a toothy bite is sometimes helpful to initiate a cut, as a more polished edge at thicker geometry will quickly lose it's ability to cut when the apex becomes even slightly less than perfectly crisp, after which it leaves rather thick & blunt geometry behind.

At a certain level of steel 'softness', i.e., low hardness and/or low abrasion resistance, a toothy edge will give up it's teeth just as quickly as a polished edge will lose it's crispness, so the choice between the two finishes is basically moot, if based only on edge durability. Harder and more wear-resistant steels will take and hold either finish very well; choose what you like for those.


David

 

[NJBillK]

Thanks!

Now to do some research and figure out what the actual ranges of hrc is on the models I have and compare them to my opinels. I love my Opi and regarding its ability to slice, it is one of my finer stock knives.

The only thing is that I would have to knock down the shoulders and thin out some of my knives to see how stable they are at a comparable thickness behind the edge...

The bad thing is that if they fail and keep chipping out or rolling prematurely then I have to grind them back and lose a bit of edge (unless I remove .1 behind the edge until it fails then grind that back a little bit).

Do any of you have any other ways of finding out just how far I can go while remaining stable?

 

[WuGod]

A lot of stability and if your edge can take it is how YOU use it. I sharpened a 3Cr knife to about 8 dps and it held up fine doing the kind of cutting you are until I slipped it under some plastic banding and twisted to cut the band and it chipped out.I have a RAT-1 at ~12 dps that does it no problem, a 1095 stockman at ~10 dps that bends a bit doing that but straightens on a strop.
Tldr you have to play with angles (and micro bevels) until it works for you. Fortunately once the edge is thinned it goes pretty quick to thicken it up a bit.

 

[HeavyHanded]

Thanks!

Now to do some research and figure out what the actual ranges of hrc is on the models I have and compare them to my opinels. I love my Opi and regarding its ability to slice, it is one of my finer stock knives.

The only thing is that I would have to knock down the shoulders and thin out some of my knives to see how stable they are at a comparable thickness behind the edge...

The bad thing is that if they fail and keep chipping out or rolling prematurely then I have to grind them back and lose a bit of edge (unless I remove .1 behind the edge until it fails then grind that back a little bit).

Do any of you have any other ways of finding out just how far I can go while remaining stable?

In general I find 30° to be pretty safe, and anything lower than that needs to be felt out. In the kitchen I get away reliably with something closer to 24-26 and that's where I keep 90% of my edges anyway, I just baby them a little when it comes to lateral forces. As I go under 30 the edge becomes increasingly more likely to fail laterally.

As for finish, while I prefer something with a lot of tooth for most EDU, if I'm going to be using the tool often I'll go with a finer finish - not because it cuts better but because its easier to maintain. These steels tend to respond well to backhoning/stropping on a hard surface. As I get more into more modern stainless my preferred finish tends to be a bit more toothy - 800-1000 ANSI.

 

[Obsessed with Edges]

Regarding the 'Opi' (assuming Opinel), I experimented with two I bought a few years ago, to see how thin I could take them; one is in their 'carbone' non-stainless XC90 steel and the other is their 12C27Mod stainless. I thinned each of them a LOT; I suspect they're at least in the low 20s inclusive, maybe slightly less. For non-abusive fine-slicing tasks, such as for food use (they're wicked for this), the stainless has been more durable; the 'carbone' model is more vulnerable to edge-rolling or denting from very light impact, so I have to be more careful with it. I think each would handle 25°-30° more durably for general EDC use, and this would also be true for most blades, I think. I just touched up the stainless one on my EF DMT Dia-Fold (rated 1200 mesh/9µ) yesterday, and that's a beautiful slicing finish for that blade.

And you don't necessarily have to give up too much steel in re-grinding a very thin edge to a more durable one at a slightly wider angle. Even a very small microbevel can protect a thin edge, and it'll become more durable with subsequent resharpening over time, as the edge gradually migrates back into thicker steel. There's no rush to grind off a lot of thin steel, all at once, to get back into the thicker portion of the primary grind; start with a microbevel at a wider angle of your choosing, and let it get there over time.


David

Thanks!

Now to do some research and figure out what the actual ranges of hrc is on the models I have and compare them to my opinels. I love my Opi and regarding its ability to slice, it is one of my finer stock knives.

The only thing is that I would have to knock down the shoulders and thin out some of my knives to see how stable they are at a comparable thickness behind the edge...

The bad thing is that if they fail and keep chipping out or rolling prematurely then I have to grind them back and lose a bit of edge (unless I remove .1 behind the edge until it fails then grind that back a little bit).

Do any of you have any other ways of finding out just how far I can go while remaining stable?