Full grind equal better edge holding?

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ricklee4570

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I have noticed that a blade that has a full grind (such as the Spyderco Military models) is considered by some to be better than other styles.

Is the full grind easier to sharpen and maintain an edge?
 
I guess I do not understand?

Sharpening in general terms occurs at the edge, and the grind (except for a few cases, like zero grinds) is the portion of the knife between the edge and the spine of the knife. If you go here and scroll down a ways there are images of various GRINDS. If you understand how to sharpen a knife, it should be little surprise that in GENERAL there is very little difference in sharpening and maintaining an edge on most common grinds.
 
I think that the preferrence is because of cutting performance as compared to ease of sharpening. FFG has certain marked advantages in cutting performance when cutting media that is thicker than the width of the blade.
 
Full grind blades are usually thinner, and the primary bevel is less acute at the edge.
 
It seems to hold a better edge because the blade profile allows the knife to continue cutting with ease longer than say flat saber grinds.
 
Bill DeShivs said:
Full grind blades are usually thinner, and the primary bevel is less acute at the edge.
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Exactly (except that the bevel is more acute at the edge). The taper of a full flat reaches the bevel at a more acute (thinner) angle than that of a knife with a saber grind of the same width (edge to spine) and thickness. Therefore the edge is more fine on a full flat grind than on a saber grind given the same blade width, spine width, and edge bevel.

As far as edge holding a knife with a flat grind should get sharper, yet it will probably lose its original sharpness a bit faster than a knife with a more obtuse grind.
 
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ricklee4570 said:
I have noticed that a blade that has a full grind (such as the Spyderco Military models) is considered by some to be better than other styles.

Is the full grind easier to sharpen and maintain an edge?
Click to expand...

Like other folks have said, FFG (Full Flat Grind) takes advantage of less angular transitions and creates less friction when the blade is going through material. So cutting performance is high.

Some of the disadvantages are the time and cost of manufacture since more metal needs to be removed from a knife blank to create the blade. Weaker edge compared to some other types of grinds due to less metal supporting the edge. Some sharpening clamps cannot hold a V shape blade consistently so edge angles can change during sharpening.

So a knife with FFG tends to be a good slicer. Add strong super steel to the mix and you can thin out the edge further with smaller angles and use thinner blades to create super slicers. Spyderco Stretch 2 in ZDP-189 is a good example.

If you get a chance to compare a Saber grind Delica 4 and a FFG Delica 4, you'll see the difference.

I was very disappointed with my first Saber grind Delica 4 when I went to break down a bunch of cardboard boxes with it. Regardless of how sharp the edge was, it had to push aside the material so far apart as it sliced through that it required a lot of force.

I have since then improved it by doing a couple things. I curved the transition area between the primary edge and the secondary edge and applied a high polish to both edges. Even though the angle of the secondary edge is still the same as it came from the factory and has similar sharpness, the knife sails through cardboard. It was all about friction.
 
dsmegst said:
Like other folks have said, FFG (Full Flat Grind) takes advantage of less angular transitions and creates less friction when the blade is going through material. So cutting performance is high.

Some of the disadvantages are the time and cost of manufacture since more metal needs to be removed from a knife blank to create the blade. Weaker edge compared to some other types of grinds due to less metal supporting the edge. Some sharpening clamps cannot hold a V shape blade consistently so edge angles can change during sharpening.

So a knife with FFG tends to be a good slicer. Add strong super steel to the mix and you can thin out the edge further with smaller angles and use thinner blades to create super slicers. Spyderco Stretch 2 in ZDP-189 is a good example.

If you get a chance to compare a Saber grind Delica 4 and a FFG Delica 4, you'll see the difference.

I was very disappointed with my first Saber grind Delica 4 when I went to break down a bunch of cardboard boxes with it. Regardless of how sharp the edge was, it had to push aside the material so far apart as it sliced through that it required a lot of force.

I have since then improved it by doing a couple things. I curved the transition area between the primary edge and the secondary edge and applied a high polish to both edges. Even though the angle of the secondary edge is still the same as it came from the factory and has similar sharpness, the knife sails through cardboard. It was all about friction.
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I did the same mod to a saber ground D4 as you did, plus I also eased the transition at the top of the saber grind where it transitions to the full thickness. Like you found, the difference in cutting cardboard is enormous due to reduced friction. What we did is sort of the "poor man's convex edge."
 
Damn near every knife I come across new could benefit by making the edge bevel thinner and more acute. Full grind says nothing about the thinness or acuteness of the actual edge bevel. It only really enhances cutting if the edge bevel is very thin and acute.

Ideally, a full grind blade should have a zero, or near zero edge. That is, no edge bevel, or an edge bevel that is extremely thin. This is the kind of geometry that makes a remarkable slicer that's also easy to sharpen. Unfortunately, almost no manufacturers make knives this way.
 
singularity35 said:
What's that?
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Here's a saber flat grind:

sc11pbk.jpg


And this is a full flat grind:

SC11FPBL.jpg


This would be a saber hollow grind:

sc41pbk.jpg


You can see the meaning a "saber" through the Native and the black Delica. If I could find a full hollow grind, I'd show you, but I don't know of any knives with a full hollow grind.
 
THG said:
Here's a saber flat grind:

sc11pbk.jpg


And this is a full flat grind:

SC11FPBL.jpg


This would be a saber hollow grind:

sc41pbk.jpg


You can see the meaning a "saber" through the Native and the black Delica. If I could find a full hollow grind, I'd show you, but I don't know of any knives with a full hollow grind.
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I thought an HG was just an HG and not a SG HG. If I understand correctly an SG is either high or low. Does that mean that the regular manix 2 is hollow saber grind then?
 
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Kind of hard to tell from pictures, but Case knives, such as the popular Sodbuster, are usually full hollow ground.
 
singularity35 said:
I thought an HG was just an HG and not a SG HG. If I understand correctly an SG is either high or low. Does that mean that the regular manix 2 is hollow saber grind then?
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Hmm... The section in Spyderco's catalog where they explain different grind types differentiates flat saber grinds from full flat grinds, but they list what I was calling "hollow saber grinds" as simply "hollow grinds."

If a "full hollow grind" doesn't exist, that would explain why I've never seen one (edit: apparently I missed Shecky's post above; there are full hollow grinds) and why Spyderco doesn't differentiate between the two in the catalog.

So at this point, I'm not 100% sure, but I believe the Manix 2 is a hollow saber grind the same way the regular Delica is a flat saber grind.

And yes, a saber grind can be high or low.
 
THG said:
Hmm... The section in Spyderco's catalog where they explain different grind types differentiates flat saber grinds from full flat grinds, but they list what I was calling "hollow saber grinds" as simply "hollow grinds."

If a "full hollow grind" doesn't exist, that would explain why I've never seen one (edit: apparently I missed Shecky's post above; there are full hollow grinds) and why Spyderco doesn't differentiate between the two in the catalog.

So at this point, I'm not 100% sure, but I believe the Manix 2 is a hollow saber grind the same way the regular Delica is a flat saber grind.

And yes, a saber grind can be high or low.
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Gotcha, thanks.:)
 
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