How important is blade thickness?

NjHart

NjHart

Joined
Jan 4, 2013
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As I continue my exploration into the world of well built and designed knives, I find myself placing a pretty high value on blade thickness. I know geometry, steel, and heat treat are also significant factors in both durability and cutting ability, but I worry I'm placing too much stock in blade thickness. How thick of a blade do you considering too thick for normal tasks? How thin before it becomes a liability point on the blade? And is it really all that important or are my worries the unfounded concerns of a newcomer? Thanks again yall!
 
Not being snarky, but you define what "normal" is for your knives. If you are chopping wood regularly, that might call for a thicker blade. If "normal" is cutting flesh, you might find that 1/8" is "thick."

Then there is fashion. The most popular pre-WW II all-round sheath knife was the Woodcraft pattern (I am hoklding a Ka-Bar example.), and it came is at 1/8" or slightly under. Thirty years ago, 1/4"-thick knives were hard to find. Yet, somehow, "normal" got done. Then it seemed like everyone and his brother thought 3/16" was flimsy. Now we seem, at least in numbers made, to be back towards 1/8".

It's a journey.
 
Thomas Linton said:
Not being snarky, but you define what "normal" is for your knives. If you are chopping wood regularly, that might call for a thicker blade. If "normal" is cutting flesh, you might find that 1/8" is "thick."

Then there is fashion. The most popular pre-WW II all-round sheath knife was the Woodcraft pattern (I am hoklding a Ka-Bar example.), and it came is at 1/8" or slightly under. Thirty years ago, 1/4"-thick knives were hard to find. Yet, somehow, "normal" got done. Then it seemed like everyone and his brother thought 3/16" was flimsy. Now we seem, at least in numbers made, to be back towards 1/8".

It's a journey.
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Totally a fair question, and I really should have better defined any parameters of "normal." I would call the normal range for me from light tasks (typically non precise) basic letter and package opening, splinter repairing and shaving hair to test my obsessive sharpening. On the harder use end, I'd say small limb cutting (1/4-1/2 inch is generally the biggest I'd go before finding a more suitable tool), cardboard cutting, and cutting of some moderate thickness plastics.

I also should also probably have been more specific in what I've noticed about my interest. When I see a 3mm blade thickness I'm cautious, at 4mm I'm happy, and at 5mm (provided the knife doesn't look like its suppose to be an axe) I'm probably considering the knife even if I don't care for some of its other features.
 
I agree that 1/8th is also a pretty versatile stock thickness, but then there's also applications when you cut in the realm of "bushcraft" where a thicker stock might help with splitting wood or on longer blades. For example, a 6" blade would probably benefit a little bit from a slightly thicker stock.

The shorter the blade becomes, the thinner the stock can get and still remain tough and strong, but on the other hand there's also task specific knives like fillet knives that should be very thin and long but are also more flexible.

I think the most exceptional slicers are 1/8th and under, and still very strong. I think anything that is .100" thick and 3" and under will still be really strong by evidence of most traditional slip-joint knives out there. There's a video of someone on here cutting open a can of food with some type thin-bladed slippie, and there's the classic "Alone in the Wilderness" documentary...

But I also think that blade thickness making poor cutters is also exaggerated a bit. Just a little bit of extra thickness to a blade adds significant strength, and given the right geometries still makes for very good slicers, and in addition to that sometimes a thicker geometry is nicer for different tasks. Sometimes the extra thickness gets in the way of some things as well, and it's nicer to have thinner stock blades for that.

I don't think there's any real hard and fast rules for what works better for what, and I'm sure there's a large level of personal preference involved.

I do think that knives seem to be getting a lot thicker and thicker, rather than thinner and thinner though. I think without naming any there's a few selections available around in 1/4th thickness that probably shouldn't be, but on the other hand there's blades where that thickness is a virtue. The ESEE 5 is designed as a downed-pilots survival knife for example, capable of cutting and prying yourself through a plane.
 
It's my firm belief that every knife should be designed and built from the edge up. "What do you want to cut?" is by far the most important question.

Blade thickness/width, profile, grind style, and edge geometry are absolutely paramount to a knife that performs well for any given task.

Steel selection, heat-treat, weight/balance, handle design and other considerations are very important, but secondary.
 
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Thickness at the spine can be a deceptive measure depending on the grind of the knife. The Spyderco Military and ZT 0200 are both 4mm thick at the spine but the ZT still sports a decidedly 'heavier-use' blade while the Military is frequently admired as a slicer. Very different blades despite identical thickness at the spine.
 
NjHart said:
I would call the normal range for me from light tasks (typically non precise) basic letter and package opening, splinter repairing and shaving hair to test my obsessive sharpening. On the harder use end, I'd say small limb cutting (1/4-1/2 inch is generally the biggest I'd go before finding a more suitable tool), cardboard cutting, and cutting of some moderate thickness plastics.
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You're describing at least three different knives, if we're talking about truly optimal performance/task. If you want one knife to do all those things, there will be a good deal of compromise. The market is glutted with knives that will do all of those jobs OK, but none of them excellently.
 
There're more knives broken made of 1/8 that all others combine, 1/8 can't take baton. And baton was the war+ nightmare (still it is) of knifemaker's which the shift to more thickness because that. Or you're bushcraft your knife with yellow glove before warranty at head.
 
I also really like thick knives but I'm, somewhat sadly, moving away from them for the simple reason that I just don't see the practicality. For chopping it makes sense, mass is king if you're hacking something up, but I typically use my knives to slice much, much more frequently than for anything else. A thick blade can be nice to protect me from my own stupidity, but even cutting really nasty hard plastics is much easier with a thin, properly ground blade. Might have to change the edge geometry a bit so as not to chip it out, but still.
 
Last week I received my Gene Ingram fixed blade sodbuster in the mail. The blade thickness is right at .125" (eighth inch). It is D2 steel hardened to 60rc. The edge is super thin, but combined with proper steel and "short" blade length, the thickness of the blade is about perfect. It is full flat grind, and is a great slicer and would be great for EDC. This is an example of when blade thickness is based on application. Overall I have found that I personally have never needed more than .125"
 
james terrio said:
It's my firm belief that every knife should be designed and built from the edge up. "What do you want to cut?" is by far the most important question.

Blade thickness/width, profile, grind style, and edge geometry are absolutely paramount to a knife that performs well for any given task.

Steel selection, heat-treat, weight/balance, handle design and other considerations are very important, but secondary.
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That seems rather theoretically sound. As I'm a beginning collector with rather limited funds (and apparently expensive tastes), I've sort of struggled with where to begin in terms what I want and use the most. By far the biggest part of my utility stems from the enjoyment of my knives and the excessive research I put into trying to find exactly what I want and like. I also have a rather broad range of activities my EDC knife would be along for at least in a secondary sense. My starting point, and how wise it is can certainly be debated, is to invest in one knife that I like that can handle most of my activities to a good level, beyond ok but probably not to the level specialized excellence. Of course this has caused all sorts of massive long pro/con lists to be written- varying from weighing frequency of use, importance of activities, what activities are most fringe, etc. I wish I had a better answer, but it has been fun to consider and led me to short list of top considerations that are far more different than a discerning mind would probably like.
 
I have the Boker Haddock, the spine is 5mm thick but it sports a super thin hollow grind that will slice with the best of them. I'd say it depends on the grind.
 
ishiyumisan said:
There're more knives broken made of 1/8 that all others combine, 1/8 can't take baton. And baton was the war+ nightmare (still it is) of knifemaker's which the shift to more thickness because that. Or you're bushcraft your knife with yellow glove before warranty at head.
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Word.
 
Stock thickness doesn't have much to do with sharpness, but it has an awful lot to do with cutting ability. Using different grinds can help adjust the cutting ability of a blade, but you still have the ultimate spine thickness to contend with if you cut to the depth of the blade height. This also affects shallow work such as shaving wood if you do not balance the thickness, grind, and final edge angle. Strength can also be added in increasing width instead of thickness, but it is linear and not cubic.

For what you listed, an Opinel would probably handle it all, a disposable utility blade certainly would. Try one of those, or a decent quality paring knife. An important thing to keep in mind is if a blade takes damage, is it because of the overall thickness, or is it an issue just at the edge? Every sharpened knife edge is thinner then every knife spine (even the spine down the center of a double edge :p).
 
ishiyumisan said:
There're more knives broken made of 1/8 that all others combine, 1/8 can't take baton. And baton was the war+ nightmare (still it is) of knifemaker's which the shift to more thickness because that. Or you're bushcraft your knife with yellow glove before warranty at head.
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Do you have proof of this? I only ask because I baton a mora(sub 3/32") all the time and haven't broken it. Maybe a better statement is that "knives have to be made thick because of all the people who don't know how to use thin knives correctly and think that you should be able to do anything with a knife like say batoning through concrete." I've had several makers tell me that 1/8" thick knives can take a baton and a couple others that say that 3/32" can as well. And IME they're right.
 
NjHart said:
That seems rather theoretically sound. As I'm a beginning collector with rather limited funds (and apparently expensive tastes), I've sort of struggled with where to begin ....
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Here's my advice. As a beginner. Start thin, start slipjoint. If you "learn" on some sharpened prybar (and nothing wrong with them...great for bashing the bejeebus outta stuff), that's all you know. On the other hand, if you can learn to use a SAK to do everything you need/want to do (and all the tasks you listed can easily be done with a slipjont), you can use anything.

Once you know how to cut things, then you can have a blast deciding which grind/geometry/edge works best for you for each situation/material.
 
Shotgun said:
I've had several makers tell me that 1/8" thick knives can take a baton and a couple others that say that 3/32" can as well. And IME they're right.
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Agreed. :thumbup: Batonning is not about blade thickness. It's about technique.
 
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