Help skool me regarding blade thickness.

[evilgreg]

So much confusion.

Agree to disagree, I guess. In my experience, my thick bladed folders cut poorly in many cases, even if they're only thick at the spine. If you make any sort of deep cut, a thick blade produces reduced cutting performance.

Or maybe I'm just imagining that my scrawny, thin-bladed William Henry E10 out-cuts my brawny ZT knives (or even the hollow ground and reprofiled to a reasonable steep edge Southard that I usually carry). For actually cutting stuff, I've always found thin > thick, unless you're chopping or prying or whatnot--and I don't often see a need to pry or chop with a folder.

Most folders have blades that are IMO way thicker than they need to be, presumably because that's what folks want to buy. It's outright silly to suggest that a thick bladed knife like the ZT 0801 or Spyderco Southard can cut as well as a blade half the thickness, like a William Henry E10 (I'm just using these three as an example because they're knives I've been carrying of late). I carry the Southard and 0801 because they're fun, but outright cutting performance I'd have to admit the dainty little E10 actually cuts better.

Spine thickness effects lateral strength of the blade but has little effect on cutting efficiency without respect to blade-height.

Uh, okay, assuming the only type of cutting is surface slicing.

Edge thickness effects cutting efficiency and also edge-durability. A blade 1/4" thick at the spine can be just as fragile as a 1/16" blade at the edge, making it unsuitable for chopping into hard objects despite superiority in lateral strength. Similarly, a 1/4" blade can cut with the same efficiency as a 1/16" blade if they sport the same thickness behind the edge, depending on the cutting resistance of the material and the depth of the cut.

For benchmarks, use a standard box-cutter blade for thickness. If you need more lateral strength (i.e. prying), move up in spine thickness but grind as needed to keep edge-thickness the same. If you are not sure where to measure edge-thickness, it should either be where the primary bevel meets the secondary (edge) bevel (the shoulder) OR just measure 1/16" back from the apex (a common edge-bevel width).


Good general use cutting geometry = <1/16" wide edge bevel, <0.020" thick (<15-dps), followed by <5-dps primary bevel to the spine of whatever thickness. My $0.02

My $0.02: you can sharpen the crap out of a prybar like my ZT 0801 and it will never glide through a cardboard box like a box cutter, even if you could make it comparatively thinner and sharper at the edge, because the fat blade would still wedge and drag. Take a 1mm thick blade and a blade that is 4mm thick at the spine but ground just as thin at the edge as the 1mm thick blade, then slice up some vegetables using both and try to tell me that the thin blade doesn't cut better . . .

 

[SCWillson]

Lest we forget, tactical knives - which significantly influence mainstream working knives whether we like it or not - are designed to cut and pierce deep holes in human flesh, not produce neat little slices. So in a tactical blade increased thickness (and corresponding sturdiness) may well be a desirable feature even if it is not so desirable in a kitchen knife.

 

[evilgreg]

Lest we forget, tactical knives - which significantly influence mainstream working knives whether we like it or not - are designed to cut and pierce deep holes in human flesh, not produce neat little slices. So in a tactical blade increased thickness (and corresponding sturdiness) may well be a desirable feature even if it is not so desirable in a kitchen knife.

Not to be too much of a douche about this but which do you think most people on this forum use their pocket knives for more? Tacticool use or "ordinary" use? I would bet my life savings that more people have used a fat bladed Zero Tolerance knife to cut up some carpet or to open a package or to slice up an apple than stab another human, for example.

Thin blades cut better, and outside of tacticool fantasy land a beefy blade mostly just yields reduced performance for actual use. I like my folding pry bar knives because they make the lizard brain happy and they feel nice in the hand, but from experience I have to admit they're not as good overall at cutting things as thinner blades.

 

[chiral.grolim]

evilgreg, could you assist me by taking a few measurements? I'd like to make up a blade geometry diagram comparing your WH E10, ZT0801, & Southard, something akin to what i have done im my reviews (posted as an example only):

This will not only help make your case but also highlight the points others are trying to make and elucidate the physics involved, namely that a thick spine only matters on deep cuts into stiff material, i.e. cutting apart cardboard or kydex or styrofoam but NOT carpet, paper, flesh, hair, wood, etc. where the material is either very thin and/or bends away during the cut.

Also, I like thicker blades, even in folding knives because my "ordinary" use includes lateral stress that has broken thinner blades, including cutting carpet, shingles, sheet-metal, and even boxes. It has nothing whatsoever to do with stabbing. I'd rather have a blade that continues cutting than one which cuts extremely well for that first inch and then snaps in half

 

[stabman]

1/16" for slicing, 1/8" for utility, 1/4" for hard use.
Work around in between these for higher or lower bevels.
Work around in between these for broader or narrower blades.

A good guide to things.

a thick spine only matters on deep cuts into stiff material, i.e. cutting apart cardboard or kydex or styrofoam but NOT carpet, paper, flesh, hair, wood, etc. where the material is either very thin and/or bends away during the cut.

I don't often agree with you, but I will when you're right. :thumbup:

 

[Shotgun]

Agree to disagree, I guess. In my experience, my thick bladed folders cut poorly in many cases, even if they're only thick at the spine. If you make any sort of deep cut, a thick blade produces reduced cutting performance.

Or maybe I'm just imagining that my scrawny, thin-bladed William Henry E10 out-cuts my brawny ZT knives (or even the hollow ground and reprofiled to a reasonable steep edge Southard that I usually carry). For actually cutting stuff, I've always found thin > thick, unless you're chopping or prying or whatnot--and I don't often see a need to pry or chop with a folder.

Most folders have blades that are IMO way thicker than they need to be, presumably because that's what folks want to buy. It's outright silly to suggest that a thick bladed knife like the ZT 0801 or Spyderco Southard can cut as well as a blade half the thickness, like a William Henry E10 (I'm just using these three as an example because they're knives I've been carrying of late). I carry the Southard and 0801 because they're fun, but outright cutting performance I'd have to admit the dainty little E10 actually cuts better.



Uh, okay, assuming the only type of cutting is surface slicing.



My $0.02: you can sharpen the crap out of a prybar like my ZT 0801 and it will never glide through a cardboard box like a box cutter, even if you could make it comparatively thinner and sharper at the edge, because the fat blade would still wedge and drag. Take a 1mm thick blade and a blade that is 4mm thick at the spine but ground just as thin at the edge as the 1mm thick blade, then slice up some vegetables using both and try to tell me that the thin blade doesn't cut better . . .

Not to be too much of a douche about this but which do you think most people on this forum use their pocket knives for more? Tacticool use or "ordinary" use? I would bet my life savings that more people have used a fat bladed Zero Tolerance knife to cut up some carpet or to open a package or to slice up an apple than stab another human, for example.

Thin blades cut better, and outside of tacticool fantasy land a beefy blade mostly just yields reduced performance for actual use. I like my folding pry bar knives because they make the lizard brain happy and they feel nice in the hand, but from experience I have to admit they're not as good overall at cutting things as thinner blades.

This is why there are so many styles. You have to put the right thickness with the right use. There are times when a thick blade is advantageous. Wood working is an obvious one but also I watched an Anthony Bordain show where he was in a sushi restaurant and the chefs were using what appeared to be 3/16" thick knives and I can see it working well for the types of food they were working with. The only draw back for food prep that I've encountered with thick knives that were ground well was on thick and hard vegetables like summer squash. On meats and thinner vegetables it's not a problem. I use both thin and thick knives. Thinner is definitely used most but there are times when a thicker blade just works better.

 

[evilgreg]

evilgreg, could you assist me by taking a few measurements? I'd like to make up a blade geometry diagram comparing your WH E10, ZT0801, & Southard, something akin to what i have done im my reviews (posted as an example only):

Quick rough measurement of these very dissimilar knives:

WH E10 (thin blade, hollow ground): 0.09" at the spine, 0.01" right behind the edge
ZT 0801 (thick blade, oddball steep wedge shaped blade that tapers again at the spine): 0.15" at the thickest (middle, not spine) and 0.04" behind the edge
My beloved Southard (thick spine, hollow ground): 0.15" at the spine, 0.02" near the edge

. . . namely that a thick spine only matters on deep cuts into stiff material, i.e. cutting apart cardboard or kydex or styrofoam but NOT carpet, paper, flesh, hair, wood, etc. where the material is either very thin and/or bends away during the cut.

Weird, your original post bashing the idea that folder blades might be a bit too thick skipped over this disclaimer that on some types of cuts spine thickness might matter after all.

This is why there are so many styles. You have to put the right thickness with the right use. There are times when a thick blade is advantageous. Wood working is an obvious one but also I watched an Anthony Bordain show where he was in a sushi restaurant and the chefs were using what appeared to be 3/16" thick knives and I can see it working well for the types of food they were working with. The only draw back for food prep that I've encountered with thick knives that were ground well was on thick and hard vegetables like summer squash. On meats and thinner vegetables it's not a problem. I use both thin and thick knives. Thinner is definitely used most but there are times when a thicker blade just works better.

I seem to have wandered into some kind of weird twilight zone where people believe down is up.

Alright, I give up. Experience, physics and basic geometry be damned, I'll just go along to get along. Fat-ass pry bar knives cut better than thin blades and the trend towards absurdly beefy blades comes with no disadvantages whatsoever.

Also the sky is green and the tinfoil hat I'm wearing to make myself feel better about my tacticool knives keeps the orbital mind control lasers from affecting my thoughts.

Thick blades cut better. Got it

 

[stabman]

I seem to have wandered into some kind of weird twilight zone where people believe down is up.

Alright, I give up. Experience, physics and basic geometry be damned, I'll just go along to get along. Fat-ass pry bar knives cut better than thin blades and the trend towards absurdly beefy blades comes with no disadvantages whatsoever.

Also the sky is green and the tinfoil hat I'm wearing to make myself feel better about my tacticool knives keeps the orbital mind control lasers from affecting my thoughts.

Thick blades cut better. Got it

I'm glad you stuck with reasoned arguments rather than resorting to sarcasm...

 

[evilgreg]

I'm glad you stuck with reasoned arguments rather than resorting to sarcasm...

Ha, I tried the reasoned arguments first--read my earlier posts. Also, isn't your sarcastic post about my use of sarcasm a touch hypocritical?

 

[stabman]

Also, isn't your sarcastic post about my use of sarcasm a touch hypocritical?

Yes.
There's always room for hypocrisy.

 

[evilgreg]

Yes.
There's always room for hypocrisy.

Amen, brother--how else would I be able to give my kids good advice? "Listen to your mother!" "Be respectful of others!" "Don't play with that, it's dangerous!" Without hypocrisy my parenting options would be severely limited

 

[chiral.grolim]

Spine thickness effects lateral strength of the blade but has little effect on cutting efficiency without respect to blade-height.

Edge thickness effects cutting efficiency and also edge-durability. A blade 1/4" thick at the spine can be just as fragile as a 1/16" blade at the edge, making it unsuitable for chopping into hard objects despite superiority in lateral strength. Similarly, a 1/4" blade can cut with the same efficiency as a 1/16" blade if they sport the same thickness behind the edge, depending on the cutting resistance of the material and the depth of the cut.

...
Weird, your original post bashing the idea that folder blades might be a bit too thick skipped over this disclaimer that on some types of cuts spine thickness might matter after all.

My original unedited post is quoted above. Please note the underlined "blade height" and also the the second part, "depending on cutting resistance of the material and the depth of the cut".

NOWHERE did I "bash" the idea that folders might be too thick. I bashed the idea that spine thickness is sufficient to declare a knife to be a poor cutter. Spine thickness only matters in cutting IF the cut is deep enough into a sufficiently resistant material. If the cut is completed or the material folds away from the blade at the edge shoulder or before, then spine thickness doesn't even come into play in the cutting (though it may come into play in resisting lateral stress). Indeed, spine thickness only comes into play if the cut continues to the depth of the spine. YOU failed to insert ANY disclaimer into your original statement. You should say, "thinner blades cut better through materials x, y, z, etc."


I am working on those graphs

 

[evilgreg]

My original unedited post is quoted above. Please note the underlined "blade height" and also the the second part, "depending on cutting resistance of the material and the depth of the cut".

NOWHERE did I "bash" the idea that folders might be too thick.

Original and unedited? Are you sure? It seems to me that you've edited out this bit, the bit that gave me the impression that you disagreed in a somewhat scornful manner, or even "bashed" the idea involved:

So much confusion.

It's possible that skipping the inflammatory bit might, by some, be considered editing . . .

FWIW, I love my thick-bladed knives as much as the next guy. I'm playing around with the terrible-cutting but totally loveable ZT 0801 while I sit through the world's most boring conference call at the moment. The knife is a chunky, heavy wedge, but I love it all the same.

 

[chiral.grolim]

Original and unedited? Are you sure? It seems to me that you've edited out this bit, the bit that gave me the impression that you disagreed in a somewhat scornful manner, or even "bashed" the idea involved:



It's possible that skipping the inflammatory bit might, by some, be considered editing . . .

FWIW, I love my thick-bladed knives as much as the next guy. I'm playing around with the terrible-cutting but totally loveable ZT 0801 while I sit through the world's most boring conference call at the moment. The knife is a chunky, heavy wedge, but I love it all the same.

First off, I said I was quoting my original post which included the "disclaimer" you ignored, not that I was including the entire thing.. Second, how was that "inflammatory"? It isn't even debatable. The notion that spine thickness in and of itself impacts cutting efficiency is confused, for it reduces cutting geometry to a single measured value. Also, was that the only part of the post that you read when you suggested that I didn't include any sort of "disclaimer"?

FWIW I can't graph comparisons of those blades without those other aspects of geometry I mentioned, i.e the distance from the apex to each measurement, "blade height".

 

[galactorrhea]

Somewhere around 2mm to 3/32" is good. Blades on SAKs and Case knives are about ideal thickness.

 

[Bigfattyt]

Hardball,
There is a trend in knives these days to be on the THICK side to put it mildly! Stick around for a few years and you will see this sharpened pry bar pocket knife trend go back to something a little more reasonable.
There are many aspects of knives that follow trends just like fashion of ladies dress lines, Heels etc or rocket fins on a car for another example. There are new and innovative ideas in knives now as well. You will learn the diff as you learn more.

For starters, Look at, fondle and use all of the different kinds you can, to get a true hands on feeling for the different kinds of knife designs. Those old butcher knives you mentioned sound great!

I don't think the sharpened pry bar will ever die. Too many people buy a knife for looks and never really use it to do "knife" chores.

They may knock a branch off a bush or tree now and again, to make a marshmallo roasting stick, etc.

They may make a few sticks for kindling.

I had a 6 inch blade with 5/16 spine that had a tall full flat grind. It worked for butchering an elk, and I have used it on a cutting board and got by. But it would never be the king of food prep. The knife I replaced that niche with is 3/16 and still over built for my use.

I just think, too many people are more worried about looks and toughness, than how a knife actually does its intended task for the chunky knife to ever disappear.

I know in my collection, I am moving away from super thick to thinner. As an added bonus, not only to they cut better, but they are simply loads lighter.

 

[Rhinoknives1]

You are correct that sharpened pry bars will always be around and I make one every now and then because they can have a cool factor like you mentioned. How much they really get used it another thing as you noted.

If it's a tall enough blade, you can make a decent cutter out of most any thickness but then the weight factor comes in to the equation.

When customers ask me how to pick a knife design?
I tell them something like this.
For a given task we want the best blade geometry, a adequate thickness for lateral strenght, without adding too much weight.
I realize those three guidelines are open to interpretation and selection by each individual, but it gives you a starting point for people to use for their selection process.

 

[SCWillson]

Not to be too much of a douche about this but which do you think most people on this forum use their pocket knives for more? Tacticool use or "ordinary" use? I would bet my life savings that more people have used a fat bladed Zero Tolerance knife to cut up some carpet or to open a package or to slice up an apple than stab another human, for example.

Thin blades cut better, and outside of tacticool fantasy land a beefy blade mostly just yields reduced performance for actual use. I like my folding pry bar knives because they make the lizard brain happy and they feel nice in the hand, but from experience I have to admit they're not as good overall at cutting things as thinner blades.

I don't disagree with you in the least. My point was simply that many knives are made to look tacticool because that's what mall ninjas buy, not that those knives are in any way superior - or even as good - for everyday tasks like slicing. That's why I always carried two (or more) knives. My EDC gets whipped out several times a day for routine tasks whereas I have never once pulled out one of my tactical folders in the ten or so years I've carried one.

People on these forums are probably exceptions, as I'd bet 99.999% of knife users never visit a knife forum or read a knife magazine. But Joe Average, who is far more likely to buy his knife at Walmart or at a sporting goods store, isn't likely to consider such things as blade profile or thickness. Probably the only concern for most is size, how it looks, and whether it's stainless steel.