Pseudo-recurve

[Shmackey]

If you read Joe Talmadge's writeup of the BM 710, he makes the astute observation that the "front" part of the recurve is really the business end. It drives the blade into the thing you're cutting as you slice. The rear part of the recurve is far less important.

With that in mind, I would think a pseudo-recurve that has only the front part would have 90% of the benefit and would allow you to sharpen on flat stones. When designing the blade, you just allow the edge line to continue trailing in toward the pivot, rather than curving back down away from the pivot. It's that curve where it goes away from the pivot that flat stones can't reach.

Are there any production folders like this?

 

[me2]

There were. I had an old Parker Cutlery balisong a few years ago. The widest point of the blade was about 1" wide, the width at the plunge grinds was about 1/8" or so less. It wasnt much, but it worked, and it was easily sharpened on a flat stone.

 

[Esav Benyamin]

It sounds like what you're describing is just a blade with a relatively big belly. A blade with an ordinary belly and an otherwise straight edge will have much the same effect if it's drawn through the material to be sliced with the tip somewhat down.

 

[Shmackey]

It sounds like what you're describing is just a blade with a relatively big belly. A blade with an ordinary belly and an otherwise straight edge will have much the same effect if it's drawn through the material to be sliced with the tip somewhat down.

Absolutely correct. But when you put it like that, it sounds like there's no magic. BM clearly used some kind of Slicing Fairy Dust on the 710.

 

[Esav Benyamin]

"... some kind of Slicing Fairy Dust on the 710."

Narrow blade, sharp edge, the handle tilts your grip forward.

 

[medusaoblongata]

What I think you're describing is a blade that gets wider towards the belly, rather than narrower towards the hilt. I'm pretty sure there is a Mad Dog knife with a blade like that. I don't remember what each of these terms means, but you can do a search, IIRC Walt Welch used to talk about these a lot: positive included angle, negative included angle, postive excluded angle, negative excluded angle. The wider belly, rather than the narrower back end reduces blade weaknesses, adds weight towards the front for a chopper, but makes the blade take up overall more space, which doesn't always work well in a folder.

 

[cmd]

You seem to be describing the profile of my Benchmade 42MC. It curves slightly out and widens for most of the blade to make a nice belly, then curves up to the tip.

From pictures the weehawk profile looks like it is build of mostly straight lines but mine is actually nicely curvey.

It does sharpen easily and makes a very good slicer, among other things.

 

[Joe Talmadge]

What I think you're describing is a blade that gets wider towards the belly, rather than narrower towards the hilt. I'm pretty sure there is a Mad Dog knife with a blade like that. I don't remember what each of these terms means, but you can do a search, IIRC Walt Welch used to talk about these a lot: positive included angle,

Yes, that's the term Mad Dog used ... the belly was a bit wider, and the profile was such that starting from the lowest point of the belly, the edge had to go slightly back up to meet the handle again. It's not quite as efficient in slicing as a real recurve, since a recurve has an actual curve to it that works like a light hawkbill, but it gets you some extra slicing performance without the sharpening hassles of a recurve.

 

[Cliff Stamp]

It's that curve where it goes away from the pivot that flat stones can't reach.

Mission does something similar, note line of the edge compared to the handle:

http://www.primoknives.com/images/mission006.jpg

The folder however isn't ground this way. The Spyderco Persian is though.

-Cliff

 

[Shmackey]

Exactly. You guys have got it. There's any number of ways to arrange for the blade line to be lower as the knife is drawn back--the Spyderco Ayoob being an extreme example of doing so without actually "pushing the belly forward." The trick is to make a design that does this subtly, effectively, and unobtrusively--the Spyderco Ayoob not being a very good example.

I'm not a knife designer, but it seems like you can accomplish this through changes in blade shape (e.g., Cliff's Mission picture), angle at the pivot (e.g., Ayoob), and angle created by handle ergonomics (e.g., the thumb ramp on the 710 creating a slight downward angle in saber grip). There are probably other ways too.

 

[Nick Hyle]

Most of Kelly Worden's Tactical ('Wortac') designs are set up like this. Google a pic of the Timberline Worden, look at how the edge drops down from the ricasso to the belly, right before the point.

But no recurve, e-e-e-a-a-a-a-s--y to sharpen on benchstones.

Now if only it was an Axis lock or a Spyderco MBC instead of a Timberline lockback.

I keep thinking of looking for one of the old REKAT Wortacs.