Cardboard cutting; Steel vs. Geometry

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weeping minora

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Hello there all,


Since the heights of super steeldom seems to have no foreseeable end as to what steel we'll see summoned into a handle next; I thought it interesting to ask how everyone felt about certain steels performing better for cardboard cutting and whether you'd attribute a certain steel as "better" based on the composition of the steel itself, or the geometry of the blade? I've seen/read many of the statistical testing data sheets (huge thanks to Ankerson!) and I recently found VG10 (Delica) to stand up better in EDC cardboard cutting in comparison to S30V and even XHP (both in the Manix 2 format). All three steels were newsprint slicing sharp and while the Delica received notable dulling during my usage, it still out-sliced the other steels regardless of edge retention. After usage, the only steel to cut notebook paper cleanly was S30V. Both VG10 and XHP (albeit to a lesser degree) caught the paper at a certain point. No visible edge deterioration was seen upon inspection on any of the three knives. This was an unscientifically unaccounted amount of usage, though I put each knife through a similar amount of paces. In practice, I found the VG10 to actually be superior to either of the other mentioned steels, though statistically it's not nearly within the same class. I'd attribute these findings moreso to the geometry, rather than the steels themselves.


This makes me wonder how some of the super steels would react in regards to being in a different format of knife. Since I've strayed away from super steels due to not really needing them in my daily usage, for those who have, what's your take on steel vs. geometry for EDC and which would you find most useful for actual cardboard cutting throughout your day? That being said, which steel would you like to see most in any given knife?
 
Geometry makes a major difference in performance, much more with cardboard than with rope.

Unfortunately the graphs have long since been removed from the Buck servers, so they are no longer in the thread. But here is a thread from 2001 in which CJ Buck talked about tests that Buck ran, testing the effects of edge geometry on CATRA results. The CATRA machines cut sheets of abrasive paper, so the results are going be very similar to what would be seen with cardboard.

The results showed that 420HC used in a blade with an optimized shape could outperform a blade made of BG-42 if that blade were just a standard shape.
https://www.bladeforums.com/threads/catra-edge-testing-results.127499/
 
I can't see any one steel actually cutting anything better than another, " sharp is sharp ".
The difference will probably only be how sharp the knife still is after cutting a bunch of cardboard.

Based on basic logic I would have to say that edge geometry and thickness are the big factors.
Imho the best slicers will always be thin 1/8" or less ( 3/32 the best for wider knives) full flat ground blades and super thin relatively narrow blades being best for cardboard because there's less surface area to create drag.
 
weeping minora said:
In practice, I found the VG10 to actually be superior to either of the other mentioned steels, though statistically it's not nearly within the same class. I'd attribute these findings moreso to the geometry, rather than the steels themselves.
Click to expand...


Ignore the "statistical classes", whatever those are, and trust what you observe.

I don't know about the XTP steel, but I would expect more from VG-10 than S30V cutting just about anything.

Gaston
 
knarfeng said:
Geometry makes a major difference in performance, much more with cardboard than with rope.

Unfortunately the graphs have long since been removed from the Buck servers, so they are no longer in the thread. But here is a thread from 2001 in which CJ Buck talked about tests that Buck ran, testing the effects of edge geometry on CATRA results. The CATRA machines cut sheets of abrasive paper, so the results are going be very similar to what would be seen with cardboard.

The results showed that 420HC used in a blade with an optimized shape could outperform a blade made of BG-42 if that blade were just a standard shape.
https://www.bladeforums.com/threads/catra-edge-testing-results.127499/
Click to expand...


Very interesting read and results... Much appreciated knarfeng
 
Hickory n steel said:
I can't see any one steel actually cutting anything better than another, " sharp is sharp ".
The difference will probably only be how sharp the knife still is after cutting a bunch of cardboard.

Based on basic logic I would have to say that edge geometry and thickness are the big factors.
Imho the best slicers will always be thin 1/8" or less ( 3/32 the best for wider knives) full flat ground blades and super thin relatively narrow blades being best for cardboard because there's less surface area to create drag.
Click to expand...


The main difference in "better" that I was referring to is the characteristics of how the steel cuts. I find VG10 and XHP to be a cleaner cut compared to S30V, which is very aggressive and seems to micro-tear what it cuts, even with a mirrored edge.
 
Gaston444 said:
Ignore the "statistical classes", whatever those are, and trust what you observe.

I don't know about the XTP steel, but I would expect more from VG-10 than S30V cutting just about anything.

Gaston
Click to expand...


I brought statistics into play because many of the steels seen in tests I won't (and many others might not either) ever use them personally. Much of the testing of super steels (which are classed by their compositional structure) is done through cardboard cutting and since that transcends actual testing and into many peoples everyday work/chores, I figured it be a place to ponder the subject of steel vs. geometry. This was just a fundamental ground to show the general census as to what many have observed vs. my experience. I was interested in reading what others experiences were, regardless of scientific knowledge. Interesting notes that you mention regarding VG10 against S30V.
 
Geometry will make a difference, so you have to control for it in any testing. Two knives, even if the edge is identical will feel different if the rest of the blade of one is causing additional drag. Egros will to a degree as well since most of the time you are going by feel, and unless you are doing testing with straight edges, it could be by luck that one knife starts catching on the newspaper test before the other simply due to a factor you miss noticing.
To Gaston's point about trusting what you observe, that's a nice idea, but your observation will almost certainly have bias. You know which knife you like better, which one was more expensive, which one is "easier" to sharpen so none off that is trustworthy.
to Hickory's point about an edge is an edge, that is true. However two knives with two different steels won't have the same edge. They won't have the same polish off the same stone, as carbide size and stability will come into play. Worse if you are free-handing as you may have induced more change than you think.
At the end of the day, all the evidence I've seen under controlled testing suggests that geometry can make a greater difference, but once you control for that, material (both composition and heat treat) are still measurable factors that are worth noting. Nothing will save a super-steel if the geometry and egros are bad, but while even a crap steel will preform really well if everthing else is right, it won't do it for very long.
 
Gaston444 said:
Ignore the "statistical classes", whatever those are, and trust what you observe.

I don't know about the XTP steel, but I would expect more from VG-10 than S30V cutting just about anything.

Gaston
Click to expand...
Gaston has been spreading his anti cpm steel "opinion" despite the overwhelming majority along with science that disagree.

Anyone reading his posts should be warned he is a "special case". Spark should give him a banner, like he did brown shoe.

Geometry is obviously an important factor in how much effort it takes to part material, but at that point sharpness of the edge isn't so much important because you're using the knfe as a wedge basically and forcing it through material.

Modern steels can maintain thin geometry AND high wear resistance because they have finer grain structure makings them stronger and tougher to support thin cross sections and maintain apex shape under stress.

In short, modern cpm steels can be taken to thinner more effective geometry, still have durability while being thin for peace of mind, and excellent edge retention. All good in my opinion.
 
Geometry trumps steel in terms of edge holding by a good margin. Geometry determines cutting ability, ie how much effort is required to make the cut with equally sharp blades.

I have found 2 very different steels to be indistinguishable in terms of edge holding when cutting cardboard. This was both in structured testing and in an afternoon of cleaning out the garage.

If you want to limit cutting to just cardboard, buy the thinnest blade, sharpen to the lowest edge angle you can manage, and get the least expensive steel you can. In short, get a box cutter, thin the edge angle and resharpen them instead of throwing them out.
 
Not exactly a member of the 'super steeldom club' mentioned by the OP but this humble carbon steel Opinel #12 with its paper thin blade, is a cardboard cutting machine.

I never much cared working with the dedicated store bought cardboard cutters and instead opted for the Opinel route.

I cut it down with a Dremel and it works like a charm though it may not have have the lasting edge like many modern 'wonder steels.'

No matter to me - I have two and anyway, they are a breeze to sharpen.

The Opinel gets scary sharp.

https://imgur.com/y60RlM8
 
The perfect example of geometry importance is box cutter blades. Even when dull enough to safely be ran across skin they can zip through cardboard like nothing. A fresh blade cuts a lot better, of course, but a dull box cutter actually can hold its own against something like a Medford (they are just synonymous with sharpened bricks).
 
I don't believe that between steel, heat treat and geometry one is more important that the other.
All these factors have to come together as one, for a knife to be a good cutter/slicer.
Change anyone of those variables and you will get different testing results. Even in box cutters my bi-metal blades will out last my cheaper Stanley blades.

Buck's carta test showed that a different geometry was better for their targeted market.
It shows that for that one carta test with 420HC, the E2K grind worked better than their old flat grind.
It did prove that all things being equal, better steel in this case ATS-34 cuts longer than 420HC.

I view Buck's test as kind of a marketing gimmick, that made a case for Buck's continued use of 420HC.
I must not be part of Buck's targeted market segment. When they put their E2K grind on the 301, I never bought another Buck.

I have a Benchmade 586 with M390. It's .100 thick at the spine and .015 behind the edge.
My Queen D2 Barlow is 63 thick at the spine and .015 behind the edge.
The Queen is also much thinner from edge to spine than the Benchmade.
With out a doubt the Queen barlow it will out slice that Benchmade, when cutting cardboard.

What I don't know is how long it will out slice the Benchmade. If I keep cutting is there a point where the better steel will out cut the better geometry? Or will the better geometry continue to out cut the better steel?
 
For consideration in this discussion, I provide the following test that was performed with a mild steel knife: CLICK

Geometry has a massive impact on cutting ability. Steel may increase wear resistance, but the place where it would have the largest impact (and, oddly, rarely is used to full advantage) is in allowing thinner feasible geometries.
 
Ankerson has done cutting tests of various blades and with similar edge geometry the steel composition makes a big difference. I did my own informal tests using identical blade geometries and saw some differences from one knife to another, but my results didn't match his.
I cut a lot of cardboard this past weekend with a Maxamet Spyderco Mule and an old Cold Steel folder. The Cold Steel had a relatively thin blade and did well on curving cuts. The Spyderco Mule did well in straight cuts, at first it zipped through the cardboard, but eventually it dulled and required more force for the cutting.
And I agree- depending on the type of cardboard and the direction of the cut a thin blade will work much better.
 
There's also technique and handle ergonomics... and types of grip.

I'd rather use the handle on a $10 Opinel in 1095 to an M4 Spyderco Mantra if I had a half an hour of cardboard cutting duties...yes I prefer M4 as a steel, but there are many determining factors with the mindset of "right tool for the job." I also don't understand the popularity of the saber grip for long, arduous tasks.

Then there's the technique of putting the cardboard closest to your hand for better leverage, and using a hammer grip so your chest, arms, and back are doing the work instead of your thumb.

Add a short, thin, Wharncliffe style blade and you're good to go.
 
I don't have anything new to add at this time but I am interested in seeing where this goes.
 
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