Flat Grind versus hollow grind: A CLOSER LOOK

[dedguy]

While we're on the subject do any high-hollow ground Spyders exist? If not I think it could make for an interesting knife. Probably a smaller knife, in the Cricket/Navigator/Kiwi/etc. sort of range size wise as the blade would be comparativly brittle. I think that may be the only blade geometry that Spyderco hasn't dealt with?

[Andre V]

To complicate this matter more.

A hollow grind is achieved using contact wheels, these wheels come in a variety of diameters from large to small.

You can use a larger wheel and get a very slight sloping grind or smaller wheels can give you a more rounded grind. You can have a fairly high hollow grind with a larger contact wheel which will give you similar slicing performance to a full flat grind. It depends on the application of the knife.


Personally i prefer a hollow grind, but use both and like both.

[Bolster]

While we're on the subject do any high-hollow ground Spyders exist?

And if they don't exist, why don't they? With all the design know-how that goes into a Spyderco, I'm guessing there's a good reason Spyderco doesn't employ full-hollow grinds? Are they overly fragile?

[yablanowitz]

The top knife in my photo earlier in this thread is a full hollow grind and is thin enough at the edge that I can flex the edge over my thumbnail. I mean that I can set the edge on my thumbnail on the side of the blade at the edge bevel, run my thumb along the length of the blade and see where it is from the other side. That little jewel cuts like crazy, as long as the material being cut has a thickness less than half the blade width. On thicker materials, the curve of the hollow grind tends to wedge, since it is trying to push the materials apart at an increasing rate, rather than at a constant rate as a flat grind would.

The only major drawback I can see to the full hollow grind like that one is you don't dare apply lateral force while cutting. How many times have you twisted a blade a little to pop a little piece out of the wood you are whittling on? I do it all the time, but not with that knife. I have a feeling the first time I do, it will snap a big chunk out of the blade.

I don't know of any full hollow grind Spydies, and it may be that making them thin enough to cut well makes them too weak to meet Sal's standards.

[Fred Sanford]

I used to really care about grinds, now I realize that no matter what grind a knife has (if it's a Spyderco) it will cut like the dickens. I no longer worry about it.

Some days I prefer the clean lines of a full flat. Other days I like seeing the grind lines of hollow saber or flat saber. I love the grind lines on the Captain.

For the record, to this day, the sharpest most awesome slicer I have ever used is the Centofante III. That is a razor sharp thin blade and it is like a laser. I belive it's hollow ground.

[Jazz]

Wow, you guys all have excellent comments - this forum is very educational.
I like full flats the best - nice, clean easy slicing. I like hollow, but I put fairly thin edges on most of my knives and, for example, on my native it's quite thin.
The top of the grind comes fairly close to the stone when sharpening it. Now if I keep this angle up, eventually the top of the grind will touch the stone
and mangle my knife. With a full flat this won't happen. This knife is so sharp
and has nicked me a few times, but no, it's not that ridiculously thin that it'll chip. I hope y'all can make sense of this. Thanks for the education :)

[jaislandboy]

And if they don't exist, why don't they? With all the design know-how that goes into a Spyderco, I'm guessing there's a good reason Spyderco doesn't employ full-hollow grinds? Are they overly fragile?

While not "full" hollow ground, the Ocelot's blade and most / if not all the current byrd line is around 2/3 hollow ground (from edge to spine)..... like the Cara Cara, Flight, Crossbill, Raven for example....
For what I use a folding knife for....(light duty stuff like paper/cardboard/package/envelopes/clam-packs) i favor full flat ground blades (at the moment)..... :rolleyes:

[peacefuljeffrey]

Are flat ground knives sharpened by laying the blade flat against the stone? I would think that might facilitate sharpening, since that one variable is eliminated. By that I mean, keeping a consistent angle while moving down/across the stone.

The only flat-ground blade I have that is suitable for being sharpened in this manner is my Cold Steel "The Spike" (drop-point version). It came sharpened that way. You should picture a blade with a cross-section like an isosceles triangle, where the acutest angle is simply very sharp.

When the knife needed its first sharpening, I did not grind a bevel at the edge]almost[/i] flat on the stone, and sharpened lightly. I was careful to keep a tiny angle above flat, because otherwise I would have been marring most of the flat of the blade. (As someone else said, that would make sharpening a pain because you'd be grinding the full flat.)

For other knives, like the Military, Para Military, Chinook III, etc. you will find that the "flat grind" is not a flat grind in the strictest sense, because the actual cutting edge is beveled at higher angles than the flat of the blade itself.

I do prefer flat-ground blades to hollow ground ones, if only because of the perception that they are stronger, not as dainty and thinned-out.

-PJ