Question about hollow grinds

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W.T. Beck

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Jul 9, 2001
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I tried searching on this subject but did not find a thread that directly addresses my question, which is: Is the hollow grind a useful one, or is it only used to cut manufacturing costs? My reason for asking this question is having read that it is easier and less costly to produce a knife with a hollow grind. Also, when I find rave reviews of knives on BladeForums, it seems that those knives most often have some kind of grind other than hollow. Convex and flat grinds get alot of praise, I've noticed.

So is a hollow grind any good, or just cheap?
 
Hollow grind blades look great and they will take a very sharp edge a bit easier than a flat ground blade made from the same material. But it´s not very useful for deep cuts and a bit fragile.

I don´t think it´s cheaper than a flat grind blade, one has to use a special contact wheel machine to do it.
 
hollow grinds make the blade alot thinner at the edge yet leaves thicker material on the back of the blade to keep it stiff, this means you can get a finer edge, cut throat razors are probably the best example of this. the disadvantage is the edge is weaker, this istn a problem for a razor or a gents folder but a working knife the edge would probably be too weak. youre right to a certain extent that its easy to manufacture, if you think about it the natural shape a blade would take if it were gound on a wheel would be a hollow grind so its easy to make with probably the most common grinding tool but not necessarily inferior, depends on what you want it for as do many things. knife edges are always a trade off between edge 'sharpness' and retention and edge strength, usually to get more of one you have to give up some of the other for example my fallkniven A1 is a convex grind difficult to do but its an exceptionally strong edge and although i can get it to slice paper its not a hair popper, I have a few flat ground knives, there middle ground, they will pop hairs but the edge isnt as strong, but they dont compare to a cut throat and a good quality hollow ground knife will take a better edge too (of course im assuming theyre all decent blade material etc) its just to do with the angles if you think about it the angle of a hollow grind is alot sharper than of a convex grind. draw profiles on a sheet of paper to convince yourself. the eternal struggle between sharpness and strength...
 
Part of the equation is just how deep is the "hollow" in the hollow grind. Straight razors take it to the extreme. At the other end, you have Darrel Ralph stuff, which is a hollow grind, but so shallow (like a 14" wheel?) it goes out near flat ground. The Spyderco Endura's (for a long time anyway, the new ones I think are flat) were hollow ground, but the grind was only about half the blade width, so it was an effective way of keeping lots of metal at the spine (strength) while getting a sharp edge with out having to much material right behind the cutting bevel. The older Bali-Songs had deep hoolow grinds, and I think (never had one) this made them wicked cutters without a lot of belly, and still lots of spine.
 
Quiet Storm,

I am sure I have seen some reference, more than once, to the hollow grind requiring less labor to produce than other grinds. However, I don't remember exactly which threads these comments were in. There was one where a custom maker was discussing a new project, and made the statement that the knife would have a hollow grind to reduce costs.

Maybe the reason is, as bladefixation says, that a hollow grind is a natural result of using a grinding wheel, whereas some more costly equipment or hand labor is required to produce other types.
 
I just think that many production knives tend to have rather sloppy hollow grinds. A correctly made hollow grind is a fantastic cutter, and offers a unique advantage over a flat grind. The knife can be sharpened many times over without increased thickness behind the edge. I well made hollow ground knife (Dozier!!!!) is a wonderful thing to those of use who use our knives often. And they look great to boot!!!
 
I remember hearing Chris Reeve say that he could not get the same amount of accuracy with the flat grind as he could with the hollow grind. That is why Chris stopped making flat-ground Sebenzas. There are only a couple hundred flat-ground Sebenzas floating around out there while the rest are hollow-ground. :)
 
I've seen some comments elsewhere about hollow grinds not being appropriate for chopping. I can see the point of avoiding large knives with hollow grinds, but how about smaller utility knives?
I wouldn't think a knife with a blade under 5 inches would be suitable for chopping, regardless of the grind.
 
WT,

One must consider the size of the contact wheel that is used for the hollow grinding. Smaller contact wheels, say 3", produce a very "tight" grind, not very usefull for typical cutting chores. Usually, they create a stronger spine and provide more material out at the point for blade strength. Large contact wheels produce an almost flat grind, better suited for everyday, utility type chores. My Hunting knives that are ground on a 12" contact wheel, after finishing have about a .005- .007 "Hollow" between the edge and the top of the grind line. Pretty close to flat ;) Normally I use an 8" or 10"wheel. This gives me a good balance of both properties.


Neil
 
Originally posted by W.T. Beck
Quiet Storm,

Maybe the reason is, as bladefixation says, that a hollow grind is a natural result of using a grinding wheel, whereas some more costly equipment or hand labor is required to produce other types.
Click to expand...

It would depend on the type of wheel used. We sharpen both ways using grinding wheels. Generally, restaurants get theirs hollow ground because it's a lot sharper for cooking, especially chopping vegetables and stuff, but they also tend to have them rehoned every week or two. You can keep a sharp edge on a hollow ground knife with an edgemaker or steel, assuming it's a decent steel to start with.
 
A hollow grind is only "weak" if it goes below the strength threshold of the steel being used (or something like that :)). No it would not be good in a chopper especially for soft or "live" wood, it would constantly bind (this is where convex excels), however in utility knives with "good steel" it can provide best cutter. You may want to be careful with deep hollow grinds with steels which are either characteristically soft or very brittle because it doesn't provide as much supporting material behind the edge as other grinds. However simple carbon steels or low-alloy carbon steels should be strong enough to take VERY shallow grind, even more complex alloy like A2 or now stainless like s30v should perform well with hollow grind.
Martin
 
Basically, I think you should use a hollow grind only if you are slicing, where you are dragging the blade. If you are pressing straight down it is easier to bend the blade and dull the knife.
 
Blade geometry is only as good as the design, nature of the steel and individual execution. I have one hollow ground blade, made about 150 years ago that is outstanding, but the man who made it knew what he was doing. The convex grind can be a club or a classic composition that challenges any material to be cut. Use the various examples that come your way and seek to understand why the perform as they do and you will find a vast frontier to explore.
 
W.T.
Every grind has a purpose.
I just like the best of both worlds for my knives.
The 14 inch wheel gives the user a semi flat grind that slices like a hollow grind. It is stronger that a smaller hollow grind IMHO.
The extra strength comes from the material that is left with the large wheel radius.
As for chopping, the 14 inch does a great job.
For fine cutting the 14 inch has great control.
This is just my opinion after using most all the grind styles I could find.
I dont think that any grind is cheap.
They all have different purposes.
 
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