“Discovered” the Hollow Grind WOW!

[Officer's Match]

Hollow grinds properly done are my favorite. They allow for a long useful blade life (obviously if not abused) in that the edge stays thinner after repeated resharpening longer than FFG, with widens immediately thru every resharpen. The deeper hollows of Sebenza's (pre-25) actually got smaller behind the edge for a number of sharpenings - just amazing grinds.

 

[gazz98]

This begs a similar question. Is the grind important when buying a knife?

Hollow or flat isn't a big deal for me. I do have more flat grinds (Spyderco) then anything else.

I should also mention I sharpen by hand and I'm not the best. What was a true, full, flat grind is now probably a double, flat grind with a secondary bevel.

My knives are fairly sharp and cut. I'm good.

 

[pxl]

Personally I don't get the point of hollow grind other than perhaps weight saving. A FFG with great geometry and thin behind the edge is IMO at least a match with shallow slicing and is superior overall due to its additional strength and versatility.

HG vs FFG is an almost religious debate though. You're not going to get many who will agree either way.

A hollow grind will not thicken up after resharpening. The primary bevel will stay reletively the same. Also the first part of the cutting with a hollow grind will prevent stick to the sides of the blade. And it is one of the oldest forms of knife making in the idustrialised era. Before that it was manly convex and saber.

 

[Pomsbz]

A hollow grind will not thicken up after resharpening. The primary bevel will stay reletively the same. Also the first part of the cutting with a hollow grind will prevent stick to the sides of the blade. And it is one of the oldest forms of knife making in the idustrialised era. Before that it was manly convex and saber.

I think you quoted me by mistake but I will say that although cutting might prevent stick, it does not prevent wedging up within the hollow when cutting something thicker than the blade (in comparison to a FFG) which is why kitchen knives are almost never hollow ground and why I really don't like using them with food. Even a thin full length hollow like on the Case Sodbuster Jr than I carried for a year simply wouldn't slice an apple as easily and cleanly as a FFG blade of the same size. Slicing an apple or through a height of cardboard with a leatherman is not fun at all due to that hollow for the same reason.

 

[pxl]

I think you quoted me by mistake but I will say that although cutting might prevent stick, it does not prevent wedging up within the hollow when cutting something thicker than the blade (in comparison to a FFG) which is why kitchen knives are almost never hollow ground and why I really don't like using them with food. Even a thin full length hollow like on the Case Sodbuster Jr than I carried for a year simply wouldn't slice an apple as easily and cleanly as a FFG blade of the same size. Slicing an apple or through a height of cardboard with a leatherman is not fun at all due to that hollow for the same reason.

You're right! This is what I mean. Only interesting for shallow cuts, not for food etc.

 

[eveled]

Hollow grinds properly done are my favorite. They allow for a long useful blade life (obviously if not abused) in that the edge stays thinner after repeated resharpening longer than FFG, with widens immediately thru every resharpen.

A hollow grind will not thicken up after resharpening. The primary bevel will stay reletively the same. .

This thickening you guys mention is because nobody is sharpening flat grinds correctly. IMHO.

The knife should be laid flat on the stone for a few passes to thin the blade a little with each sharpening.

This also has the added benefit of getting then keeping the blade flat and true. Most knife blades are wavy and have machine marks, that are polished.

The blade you think is perfect is usually far from it. The finish is hiding flaws.

consider the above excerpt from the RMK web site. Instead of waiting for the edge to thicken I give them a few passes each time I sharpen. Similar to how you’d sharpen a Mora, if that helps visualize it.

Most are unwilling to do this. For them the hollow grind makes the most sense.

It sounds crazy, but it really refines the entire blade. Try it on a kitchen pairing knife first and you will see what I mean.

On a side note this is also how I sharpen serated blades. Rub the flat side on the stone. No need to sharpen each seration with a round hone.

 

[Officer's Match]

I think you quoted me by mistake but I will say that although cutting might prevent stick, it does not prevent wedging up within the hollow when cutting something thicker than the blade (in comparison to a FFG) which is why kitchen knives are almost never hollow ground and why I really don't like using them with food. Even a thin full length hollow like on the Case Sodbuster Jr than I carried for a year simply wouldn't slice an apple as easily and cleanly as a FFG blade of the same size. Slicing an apple or through a height of cardboard with a leatherman is not fun at all due to that hollow for the same reason.

Depends - I have an apple daily in my lunch, and always cut it with the knife I have on me. My high-hollow Inkosi is better at it than any FFG I have, including the SpydieChef, and I believe it is because it breaks the vacuum of the crispy Jazz apple I am slicing. That said, my flat ground Cheburkov is also excellent at this task, and I was really surprised at how great my Combat Troodon does it as well (both flat).

 

[Pomsbz]

Depends - I have an apple daily in my lunch, and always cut it with the knife I have on me. My high-hollow Inkosi is better at it than any FFG I have, including the SpydieChef, and I believe it is because it breaks the vacuum of the crispy Jazz apple I am slicing. That said, my flat ground Cheburkov is also excellent at this task, and I was really surprised at how great my Combat Troodon does it as well (both flat).

Every time I've made the 'apple' argument some CR users tell me that theirs works perfectly with an apple. I'd love to try one some time. The hollow is the only thing that kept me away from a Mnandi for years. Well until funds got a whole lot tighter.

 

[Mitchell Knives]

Crap!! I never knew that. I have been carrying knives for about 55 years. I have used them extensively for hunting, camping, fishing, hiking, etc. Some are full flat grind, some are nearly full flat, some are saber, and some are hollow ground.

Much more often than not, I use them for work. I have been a full time tradesman (carpenter/cabinets) for 45 years, and never knew that my preference for my flat ground hard work knives was because I didn't know how to use them. Even though you can shave arm hair with some of my saber grinds (harder still to sharpen than a full flat grind edge to spine) and my full flats after I freehand sharpen them, I never knew those were designed for the less enlightened or experienced. Who knew?

I have both hollow grinds and flats, and use them as I please. I use a full flat chef's knife constantly in the kitchen for my daily extensive meal prep (free hand honed a couple of times a week) and have other knives that I use in the kitchen that are full flat "granton" style. They are my meat slicers (you know, the kind of full flats used by professional chefs and servers) and I use them when I am catering small events as well.

That being said, my trusty American Lawman is a nearly full hollow grind, and it is a slicing fiend that works well in the field. It has taken a few years of good work out on site without any sign of damage. I take the use and design purpose of the blade and its geometry into consideration more than I do its label. Like any other aspect of a knife, the blade grind is important and valuable only if it is done well. Crappy hollow grind = crappy knife. Good hollow grind = good slicer. Likewise most other blade grinds and shapes. The value is in the execution.

Robert

I think you misunderstood my post. You are not the average user. I highly doubt that anyone on Bladeforums would fall into that definition. The average user views a knife as a "do all" tool rather than something designed to cut soft materials. They pry with their knives, use the tips as screw drivers, cut heavy gauge wire on concrete blocks, etc.

Factories/makers generally choose flat grinds due to the extra durability it provides for such users. They don't want unnecessary returns and warranty claims. This is why many factory knives are excessively thick as well. They are simply choosing a geometry that is less likely to fail under the use of the average person. I can't say I blame them.

Both hollow and flat ground blades can be amazing cutters. It just depends on how they are done.

 

[abcdef]

Try cutting an apple with a saber ground Endura.

 

[The_Knife_Man]

I'm starting to use my CRK more, including on food. I've been plesently surprised, I would have thought a ffg would have been better. I find food wise everything sticks to the blade of the PM2. Peeling and cutting up a mango was the easiest with the CRK. I can use dawn and water to clean it up without worring about rust on screws, pivots, standoffs.

 

[pxl]

Every time I've made the 'apple' argument some CR users tell me that theirs works perfectly with an apple. I'd love to try one some time. The hollow is the only thing that kept me away from a Mnandi for years. Well until funds got a whole lot tighter.

I must admit... the CR grinds are made in Knife heaven... for me they are the best!!

 

[Skidoosh]

I love my Spyderco GB1 because of the hollow grind

 

[Officer's Match]

View attachment 1343577



This thickening you guys mention is because nobody is sharpening flat grinds correctly. IMHO.

The knife should be laid flat on the stone for a few passes to thin the blade a little with each sharpening.

This also has the added benefit of getting then keeping the blade flat and true. Most knife blades are wavy and have machine marks, that are polished.

The blade you think is perfect is usually far from it. The finish is hiding flaws.

consider the above excerpt from the RMK web site. Instead of waiting for the edge to thicken I give them a few passes each time I sharpen. Similar to how you’d sharpen a Mora, if that helps visualize it.

Most are unwilling to do this. For them the hollow grind makes the most sense.

It sounds crazy, but it really refines the entire blade. Try it on a kitchen pairing knife first and you will see what I mean.

On a side note this is also how I sharpen serated blades. Rub the flat side on the stone. No need to sharpen each seration with a round hone.

That is "regrinding" rather than sharpening IMHO.

 

[marrenmiller]

I've never observed a hollow grind "wedging" at the shoulders in anything, but I mainly cut food and cardboard with my knives. I'm not sure what you'd need to cut for that to start being a problem, but I've compared flat and hollow ground knives with similar edge thicknesses and grind heights and never found the hollow to be worse in any tasks whatsoever. I'd welcome suggestions on something I should cut to test that, though.

 

[eveled]

That is "regrinding" rather than sharpening IMHO.

What it is called doesn’t matter. The point is with a flat grind knife it gets thicker as you sharpen it down. To avoid this and maintain its geometry. it has to be laid flat on the stone either a little each time or a lot once in a while. It’s the nature of the beast.

The hollow grind eliminates the need for this maintenance.

 

[marrenmiller]

Just went and performed a dumb little test, as work is boring me at the moment.

I cut up a Fuji apple with two knives that I feel are good representations of flat and high hollow grinds. The hollow ground knife is a Something Obscene Company J-Cape V3, which is made by WE Knives. The flat ground knife is a Sharp By Design Evo Typhoon. This clearly isn't scientifically rigorous, but I feel it's a decent comparison as both have the same stock thickness of 4mm, both have nearly the same grind height (the Evo is about a millimeter taller, though), and both are around .015" thick at the edge after being sharpened. However, the EVO has a more polished edge applied via KME and it's sharpened to around 16 dps, whereas the J-Cape has a more conventional medium coarseness edge I touched up by hand with DMT stones, and it's closer to 20 dps. The EVO has a fuller, though it's chamfered and smooth so I don't think it'll contribute to binding at all.

I found the J-Cape sliced the apple easier, full stop. There was no sudden binding at the shoulder when slicing in any capacity, and the force required throughout the test was lower than for the Evo. Even though the EVO had a more acute and polished edge and I was push cutting through the apple, and the flat grind is slightly taller than the hollow grind, the hollow grind still won. I've yet to conceive of a task I can put these two knives through which doesn't result in the same outcome.

 

[lambertiana]

I think you quoted me by mistake but I will say that although cutting might prevent stick, it does not prevent wedging up within the hollow when cutting something thicker than the blade (in comparison to a FFG) which is why kitchen knives are almost never hollow ground and why I really don't like using them with food. Even a thin full length hollow like on the Case Sodbuster Jr than I carried for a year simply wouldn't slice an apple as easily and cleanly as a FFG blade of the same size. Slicing an apple or through a height of cardboard with a leatherman is not fun at all due to that hollow for the same reason.

This argument is only valid for shallow hollow grinds with thick blade stock. The wedging in a hollow grind blade is determined by the thickness at the shoulder and the height of the shoulder from the edge. If a deep hollow grind has the same height and thickness at the shoulder as a full flat grind has in blade thickness and height at the spine, they will behave in a very similar fashion. While it is true that many hollow grind knives have a shallow hollow grind with thick blade stock, there are many exceptions to this.

 

[marrenmiller]

This argument is only valid for shallow hollow grinds with thick blade stock. The wedging in a hollow grind blade is determined by the thickness at the shoulder and the height of the shoulder from the edge. If a deep hollow grind has the same height and thickness at the shoulder as a full flat grind has in blade thickness and height at the spine, they will behave in a very similar fashion. While it is true that many hollow grind knives have a shallow hollow grind with thick blade stock, there are many exceptions to this.

Plus the argument that kitchen knives are flat ground misses something very crucial about knife making; it would require an impractically large contact wheel to hollow grind a tall, thin slicing blade like a chefs knife, or some sort of concave grinding tool and incredibly precise CNC control. For those kinds of knives, flat is the only thing that's feasible. If you could make a hollow ground knife like that, I bet it would cut noticeably better than a comparable flat ground chefs knife.

 

[Mr.Wizard]

Plus the argument that kitchen knives are flat ground misses something very crucial about knife making; it would require an impractically large contact wheel to hollow grind a tall, thin slicing blade like a chefs knife, or some sort of concave grinding tool and incredibly precise CNC control. For those kinds of knives, flat is the only thing that's feasible. If you could make a hollow ground knife like that, I bet it would cut noticeably better than a comparable flat ground chefs knife.

Very large wheels are common in knifemaking in Japan and used to form the urasuki on single-bevel knives. If a double sided tall hollow grind was thought to be superior they would already be set up to do it. However they do not, as far as I know.