How to sharpen Case Finns concave grind

[BPRoberts]

Got a nice pair of mostly new Case Finns for cheap today. They have the trusty "good enough" Case factory edge on them, but I have some questions about getting them really sharp/maintaining them. Case's website lists them as a "concave" grind, which isn't a term I'm familiar with. Google leads me to believe it's similar to a hollow grind, like on a razor. How do I sharpen these things? Line them up with the spine by rocking like I would a razor? Just treat it like a flat grind and let the stone sort it out? Other tips? Grateful for any kind of advice. 

[stuntzombie]

I imagine you would just sharpen the edge like you would normally. Just figure out the edge angle and go from there.

[nate j]

I don’t own one of those, but I strongly suspect that if you’re able to get a good look, you will see that the primary bevel is a concave/hollow grind, while the secondary bevel (actual cutting edge) is a flat grind.

If by “treat it like a flat grind” you mean like a standard flat grind with secondary bevel, that should work out just fine.

[SteveC]

Got a nice pair of mostly new Case Finns for cheap today. They have the trusty "good enough" Case factory edge on them, but I have some questions about getting them really sharp/maintaining them. Case's website lists them as a "concave" grind, which isn't a term I'm familiar with. Google leads me to believe it's similar to a hollow grind, like on a razor. How do I sharpen these things? Line them up with the spine by rocking like I would a razor? Just treat it like a flat grind and let the stone sort it out? Other tips? Grateful for any kind of advice. 

Concave is just another name for hollow grind .

[BPRoberts]

I don’t own one of those, but I strongly suspect that if you’re able to get a good look, you will see that the primary bevel is a concave/hollow grind, while the secondary bevel (actual cutting edge) is a flat grind.

If by “treat it like a flat grind” you mean like a standard flat grind with secondary bevel, that should work out just fine.

Tried to get some better pics, not sure it helps. That is in line with how it looks/feels to me. When I set it on a stone, it doesn't do the "rock" like most other hollow grinds I have.

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Concave is just another name for hollow grind .

How would you sharpen it? My understanding is that you do hollows "flat to the stone" using the spine to judge the angle, unlike a flat grind where you set the angle and keep only the edge on the stone.

[SteveC]

Tried to get some better pics, not sure it helps. That is in line with how it looks/feels to me. When I set it on a stone, it doesn't do the "rock" like most other hollow grinds I have.

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How would you sharpen it? My understanding is that you do hollows "flat to the stone" using the spine to judge the angle, unlike a flat grind where you set the angle and keep only the edge on the stone.

I follow the edge on all my knives when using a stone laying flat. I use a Lansky turnbox for most sharpening . Or my diamond stones in a holder I made that  holds the stone vertically at the same angles as my Turnbox.

[stuntzombie]

I can't say I've ever heard of laying a hollow ground knife flat on the stone and using the spine to judge the angle. All the ones I've seen, all that would do is remove metal from the shoulder above the edge.

That Case Finn looks exactly like a Queen fixed blade I had years ago. I just sharpened it like every other knife, just keeping the edge on the stone.

[nate j]

Any knife with a flat secondary bevel, including these Case Finns, should sharpen up essentially the same way.  For sharpening purposes, it does not matter what the primary grind/bevel is, because that part of the blade isn’t the part that gets sharpened anyway.

Now, blades that don’t have a (flat) secondary bevel, such as scandi or convex, require different techniques…

[BPRoberts]

Had a little time tonight and sharpened normally. Worked great. Now I need to go catch something to use them on...

Thanks for the advice.

[nate j]

 

[powernoodle]

When in doubt you can also do the Sharpie trick, where you blacken the secondary/cutting bevel and then confirm that the Sharpie ink has disappeared after sharpening.