Flat vs Hollow grind

the flat ground is generally considered to be much more difficult to execute correctly.colbalt hits it on the head, not one of the competition knives used in contests is hollow ground. it was right in front of us but cobalt saw through to the entirely correct answer. Gary Randall told my brother the hardest grind to execute was the flat.certainly the man whom is in charge of randall knives knows something aboput knife bevels. in addition most good german knives imported to u.s. had flat grinds. nearly all the Pumas Except the earl,duke,prince;& empourer were flat grinds, all my weidmanshiels had flat grinds. flat grinds cut better & are stronger.
 
Ive only made a couple flat ground knives and they are harder for me than hollow grinding free hand. I know hollow ground knives have the priciples to hold a edge longer but it also depends if you compare the same steel . Convex will take alot more abuse and will be a little harder to resharpen when the time comes.
 
I love full flat grinds. They cut smoother and are stronger. The one thing I like about hollow grinds are that they are easier to sharpen.
 
I love 'em all. But my users are dominated by flat and convex grinds with convex edges. SOG knife is the only hollow I'm rocking right now.
 
Franciscomv said:
I like flat grinds and convex grinds a lot, but I use folders with hollow grinds, too (like the Spyderco Endura or Buck 110).

For fixed blades, I wouldn't trust a hollow grind very much, unless it was a small pocket fixed blade which will not be used too hard.
Click to expand...

The spyderco Endura is not a hollow grind it's a Saber grind. It goes down mid way and then it's a flat grind from there. No curvature whatsoever.

Just pointing out ;)
 
Jeff Clark said:
I like hollow ground on a hunting knife. It gives you the thinnest edge for cutting sticky sinewy material. It also works well on stiffer material if you are shaving or whittling material off the surface. If works well on rope.

The scales tip towards a full flat grind when you cut stiff material. For example I would rather use a thin flat ground blade to cut through a credit card than a similar hollow ground blade. In hard material the back shoulder of the hollow tends to bind.
Click to expand...

My thoughts exactly! :eek: Hollow grinds are great for slicing, where the full width of the blade is not engaged, but they suffer where the shoulder of the grind passes through the medium being cut. Because I cut mostly wood, paper, cardboard and plastic rather than animal skin and sinew, I prefer a flat grind/convex edge on my EDC folders and scandi or convex grinds on my fixed blades. I do have a few dedicated hunting knives with hollow grinds, but I prefer the others for frequent use.
 
I like the apple-seed shape the Japanese use, which is technically the fullest convex grind possible.
The only knife I have that uses it is one that I thinned out myself though. Theoretically sharp corners on the blade spine cause extra friction when cutting through material.
 
That's it!!!!

When I get home I am selling all my inferior Doziers!!!

How could Bob have fooled so many of us.. Thank god I found this thread.
 
harleyguy02 said:
That's it!!!!

When I get home I am selling all my inferior Doziers!!!

How could Bob have fooled so many of us.. Thank god I found this thread.
Click to expand...

I know they're great, but maybe they'd be better flat ground (though the grinding would have top be pretty much perfect to beat the large radius Bob uses)
 
I'm bringing this thread back from the dead. Most of my folders have been sabre or full flat grind. I have a Cold Steel American Lawman, which uses a high hollow grind, on the way. What are your thoughts now on flat versus hollow? For thise that prefer hollow, do you prefer a high hollow?
 
All of these variations make little sense to me from a practical point of view. I need pictures or a link showing me the difference and honestly, I probably wouldn't even realize the difference between one grind and another for the most part.

Where I notice a difference is when I am sharpening by traditional bench stone methods and it is mostly in a negative sense when sharpening takes a lot longer than I would have expected and I determine that I have generally ruined the original edge geometry.
 
I have a 1095 5" "bushcraft" knife with a hollow grind and it out performs any knife in the woods I have owned. The edge lasts very long. I can split wood for a fire, lots of it for a couple days and still be able to make fine feathers, cut notches, make tent stakes and so on. A couple weeks ago I batoned the knottiest piece of twisted pine I ever came across and the blade had so much flex in it, it looked like The leaf spring on my ranger if I were to over load it by 1,000 pounds. If I had my camera I would have taken a pic. Blade got pounded the rest of the way through and came out straight as an arrow. I was more worried about a scale breaking or popping off from the flex than the blade. When I got done I feathered it up and made a fire. If I expect one knife to do many tasks like baton, feather and butcher the hollow grind with a good carbon steel is the way for me. If a blade bends or breaks with a hollow grind during heavy work then the knife was made for show or taking pictures of or just doing cardboard cutting contests. A knife made to do work will not, no matter the grind.

My old EDC was a flat ground SOG and it was great for straight cuts, it was not nimble at all in any media I would cut. My new EDC I specifically looked for a hollow grind and I can cut circles in cardboard now if I need to, it also does not wedge in the cardboard as much and slices through much easier than a flat grind ever did. The hollow grind on my new EDC can also do duty in the woods for lighter work like tent stakes, notches and feathers if I want now. The old flat grind would wedge in the deeper you got making it hard for the edge to do its job, no matter how sharp it was. The hollow also cuts thick rope better when you make a loop and run the blade on the inside, same scenario, the flat grind wedges in easier and makes the cut difficult as you tighten that rope up against the grind that's getting thicker the more you cut.

Opening boxes, cutting tape or making a YouTube video slicing stacks of cardboard in straight lines a flat will do fine. Doing tasks in the woods, butchering, and EDC tasks the hollow grind is a far better option if you use the knife for a variety of tasks. Just my observation over the decades.
 
Boris74 said:
I have a 1095 5" "bushcraft" knife with a hollow grind and it out performs any knife in the woods I have owned. The edge lasts very long. I can split wood for a fire, lots of it for a couple days and still be able to make fine feathers, cut notches, make tent stakes and so on. A couple weeks ago I batoned the knottiest piece of twisted pine I ever came across and the blade had so much flex in it, it looked like The leaf spring on my ranger if I were to over load it by 1,000 pounds. If I had my camera I would have taken a pic. Blade got pounded the rest of the way through and came out straight as an arrow. I was more worried about a scale breaking or popping off from the flex than the blade. When I got done I feathered it up and made a fire. If I expect one knife to do many tasks like baton, feather and butcher the hollow grind with a good carbon steel is the way for me. If a blade bends or breaks with a hollow grind during heavy work then the knife was made for show or taking pictures of or just doing cardboard cutting contests. A knife made to do work will not, no matter the grind.

My old EDC was a flat ground SOG and it was great for straight cuts, it was not nimble at all in any media I would cut. My new EDC I specifically looked for a hollow grind and I can cut circles in cardboard now if I need to, it also does not wedge in the cardboard as much and slices through much easier than a flat grind ever did. The hollow grind on my new EDC can also do duty in the woods for lighter work like tent stakes, notches and feathers if I want now. The old flat grind would wedge in the deeper you got making it hard for the edge to do its job, no matter how sharp it was. The hollow also cuts thick rope better when you make a loop and run the blade on the inside, same scenario, the flat grind wedges in easier and makes the cut difficult as you tighten that rope up against the grind that's getting thicker the more you cut.

Opening boxes, cutting tape or making a YouTube video slicing stacks of cardboard in straight lines a flat will do fine. Doing tasks in the woods, butchering, and EDC tasks the hollow grind is a far better option if you use the knife for a variety of tasks. Just my observation over the decades.
Click to expand...

If you don't mind, could you please tell us who made the 1095 "bushcraft" knife in question? That sounds like something I'd like to look into buying. Thanks.
 
From wikipedia...

Ground_blade_shapes.png


Hollow is number 1.

I find that hollow grind is better in meat, which tends to self separate away from the blade. I find that hollow grinds tent to bind in potatoes, apples and wood when the sharp shoulder binds in the material.

But then, there are hollow grinds and then there are hollow grinds. Some have a very rounded radius in the transition from the hollow to the shoulder near the spine. And a very few, like the older Buck 110s (2 dot era) have a swell behind the edge that produces wonderful feather sticks and wood shaving curls (more like a convex or convexed sabre) but is less good as a slicer.

If you squint, you might be able to see both variations in this shot but it's much easier to see in hand.
Buck 110 by Pinnah, on Flickr

For food prep, I get so annoyed by the lack of slicing ability of a hollow grind that I almost always put them on a stone to flatten out the transition. Makes the blade much more versatile for my use.
 
DennisStrickland said:
the flat ground is generally considered to be much more difficult to execute correctly.colbalt hits it on the head, not one of the competition knives used in contests is hollow ground. it was right in front of us but cobalt saw through to the entirely correct answer. Gary Randall told my brother the hardest grind to execute was the flat.certainly the man whom is in charge of randall knives knows something aboput knife bevels. in addition most good german knives imported to u.s. had flat grinds. nearly all the Pumas Except the earl,duke,prince;& empourer were flat grinds, all my weidmanshiels had flat grinds. flat grinds cut better & are stronger.
Click to expand...

I don't quite get where goes the argument -unexpected to me- that flat ground blades are harder to make: In what way is this related, in any way, to their performance or value?

The reality is that sabre-grind hollow ground blades are always superior for normal use, if only because they remove metal exactly in the place where it is the most difficult to remove neatly when you sharpen... You have to remove metal away up from the edge first in all other knives, and that is exactly where you make mistakes and put scratches on the sides...: Isn't it easier to have this metal off to begin with? Just above the edge, without scratching the side...

All the other grinds make no effort to prevent you from scratching the sides when sharpening at the lowest angles, like 10° per side (20° inclusive is around where, to me, sharpness really begins, 40° inclusive being unsafe and unuseable to my mind)... No matter what has been said about this, 20° inclusive is plenty strong enough for chopping, and almost overkill when the edge base is over 1 mm wide...

The other advantage of hollow grinds is that, by virtue of being saber ground, you get way more mass above the edge than on the typically distal tapered flat ground blade: This means it chops deeper with less effort (below maximum effort is the way you should chop safely in actual use). Sure, chopping competition knives are all flat ground, but how many of them are less than a ridiculous 2" wide? Why are they so wide? Because there is no other way to make the less efficient flat ground design blade-heavy enough to work well...: Do you want to lug that kind of absurd volume all the time, when your knife could be almost half as wide?

Make a typical distal-tapered flat ground blade, but one that is a reasonable 1.2" -1.4" wide, and then make a heavy hollow ground blade with the same stock that is not wasted away by distal tapering...: Good luck now with your narrower flat ground blade in chopping contest vs the hollow grind!

Another way chopping competitions distort the picture is that the competition tasks typically ask ridiculously deep work out of the blades, so the depth of the material would cause drag on the hollow grind's secondary grind line: The reality of chopping with a normal size (9" or under) knife is you can never get much deeper than 1/4"-1/2" per chop on a 4" branch, and 4" is already getting on to be a bit too much for any chopping you should reasonably attempt with a "regular" knife (unless you are really intent on expending huge energy, without any fear of running out of it)... Batoning should take over from there, if not earlier... Saying a flat-ground blade is best for in-the-field use, because chopping competitions use them, is like saying a Formula 1's design is best for a fast commute...

I used to be a huge fan of distal tapered flat ground blades, but after owning the Cold Steel Trailmaster, the Fallkniven Odin, and remembering how weightless was my father's 7 1/8" Sabatier Jeune straight back "boy scout" bowie (a truly flat ground knife, not "swollen" for extra weight like the convex ground Odin), I've come to realize the pattern is best suited for smaller slicing knives, say up to 6".

Additionally, what the Odin has opened my eyes to, being worse than others flat ground knives in that respect (because of its swollen convex edge carrying far up the side), is that the flat ground blade is typically horribly scratched up all over with ugly curved scratches from sheath dirt, all the way down to the edge's belly, while, on the contrary, a hollow ground sabre grind confines the scratches to the narrow flat area, keeping friction and dirt away from most of the side of the knife, especially the edge... Not only that, but because the scratches are confined to the upper rear side of the blade, they look straight and appropriate, not like a godawful ugly mess...

The reason Randalls are such valuable knives is because they combine hollow grinds with very thin 0.5 mm edges: My father's Sabatier was still very thin-edged and sharp after a war and 40 years, but that was because the edge was thin and it did not have any kind of "fattening" convex edge: Put a convex edge on this thing, and unless it is incredibly thin and fragile at the edge, after a few years it will be duller, where a hollow grind V-edged Randall will still be just as sharp after decades of sharpening, and will problaby look a lot less scuffed up on its side from sheath wear...

Gaston
 
Last edited:
shootist16 said:
I'm bringing this thread back from the dead. Most of my folders have been sabre or full flat grind. I have a Cold Steel American Lawman, which uses a high hollow grind, on the way. What are your thoughts now on flat versus hollow? For thise that prefer hollow, do you prefer a high hollow?
Click to expand...

I am one that prefers a high hollow, especially after experiencing them in my customs from Trevor Burger, Des Horn, Andre van Heerden and Andre Thorburn.

Each has pro's and cons.

Flat gives you strength behind the edge but with repeated use will thicken up on you. I generally have to thin my flat grinds out after a year of use.

Hollow grinds (especially high hollows) remains thin behind the edge for many years if sharpening but will not give you the strength unless you thicken it up.

Most people seem to have experience with shallow hollow grinds and the shoulders tend to bind in material then. In my experience high hollow grinds do not do this. I have to admit, my experience with the American Lawman has been pleasant and the blade was surprisingly thin for a production knife.
 
Gaston444 said:
The reality is that sabre-grind hollow ground blades are always superior for normal use, if only because they remove metal exactly in the place where it is the most difficult to remove neatly when you sharpen... You have to remove metal away up from the edge first in all other knives, and that is exactly where you make mistakes and put scratches on the sides...: Isn't it easier to have this metal off to begin with? Just above the edge, without scratching the side...
Click to expand...

This is not my experience. It is definitely true that a thin hollow grind will continue to cut while dull, particularly in a self-separating medium. This is one reason why Buck moved to a thinner hollow grind around the year 2000. For knives that are likely to be undersharpened by a general public that doesn't sharpen knives, this can be an advantage. This said, Victorinox and many others have shown that a thin flat grind will do the same thing. The key here being the the thickness of the blade above the edge, not the thickness of the spine or the taper of the grind to the spine.

Grind affects more than sharpenability and cutting performance when dull. It also affects cutting performance when sharp in a wide variety of materials. Hollow grinds, even high hollow grinds, will bind noticeably (for me) in potatoes and apples unless the transition at the shoulder is rounded of flattened. Buck used to do this with their hollow grinds in the 60s and 70s but the norm now is for a clean, sharp shoulder that will bind when slicing. Rounded shoulders on hollow grinds are so uncommon, I have a hard time referring to them as hollow grinds. Better to differentiate them as a (good but rare) variant. In any event, flat grinds outperform hollow grinds, even those with rounded shoulders in slicing tasks, at least for me. I've proven this to myself repeatedly with side by side kitchen work.

I also find that a slightly thicker convexed EDGE does much better when working with wood, particularly tasks like making shavings or feather sticks for fire. My conviction is the wider edge on the underside of the cut creates a sliding fulcrum which gives better cutting angle control while the wider edge on the upper side of the cut acts like a cutting wedge, causing the wood to curl nicely. It's easy to get this sort of edge on a convexed saber or scandi grind or on a convex grind but practically unheard of on a hollow grind. The Buck 110 from the early 70s I posted above is an exception. It is noticeably thick behind the edge - something some folks call a semi-hollow grind. It's so uncommon, I can't put in the camp of hollow grinds unless it's pointed out. As one my expect, that Buck isn't a very good slicer for the same reason.

Lastly, on the issue of performance, I don't worry about scratches on my user knives. Not in the least. YMMV.


The other advantage of hollow grinds is that, by virtue of being saber ground, you get way more mass above the edge than on the typically distal tapered flat ground blade: This means it chops deeper with less effort (below maximum effort is the way you should chop safely in actual use).
Click to expand...

I think you're using the term "saber ground" in a manner different than I am used to. My understanding is that a sabre grind is similar to a what we often call a scandi grind, as shown in figure 3 in the diagram I posted above. See: http://en.m.wikipedia.org/wiki/Grind#Typical_grinds

Could you explain in what way you're using the term? As I see it, a hollow grind is the polar opposite of a sabre grind.
 
You must log in or register to reply here.
Back
Top