Very poor edge retention when cutting cardboard

[elevator man]

I look for opportunities to cut cardboard with my k390 delica. It's a joy. Thank you for that video on checking for a burr, definitely will be using that to verify edges next time I sharpen. But I can attest, like others here, if your using a knife with any good amount of vanadium it shouldn't be dull after some cardboard

 

[elevator man]

And thin! I now am greatly preferring the cutting of very thin blades. It helps power through thick tough materials pretty easily that some of my other knives would be stuck in

 

[elevator man]

Have we thought about changing this website's name from BladeForum to BurrForum? There is a preoccupation with burrs over here that I don't see on other knife-related sites.

Maybe a few edge leading strokes would help. Works for a lot of guys.

It's a real thing. I was having lots of edges deburred off stone, but drew one out stropping on balsa and it quickly folded at work the next day. Since have moved to stropping on diamond on denim and have eliminated burrs. It's a huge factor in success and enjoying my knives, and I don't think any if us have SEMs in our kitchen to verify no burr, so talking about it's helpful.

 

[TheOne45]

I don't think any if us have SEMs in our kitchen to verify no burr, so talking about it's helpful.

Indeed.
At least for me sharing sharpening and deburring experiences are far more constructive as posting photos of knives on a coffee mugs or cat heads....or asking about torx sizes. Buy a set of torx bits and find the one you need. I personally think a healthy man should have at least some basic tools at hand.
Whatever; back to topic.

As I could see most comments here are describing .... I don't know how to call it ... let's say a ''classic'' burr you can feel with your fingers. Some members here think there is no burr if they can't feel it with their fingers or there is no reflection looking at the apex with 30x loupe.
Well; there are burrs you can't feel with fingers and you can't see with 30x or 60x loupe. This burr will also fold or partially tear off and the knife won't cut news print.
There are people who do a couple of swipes with the blade on the bottom of a coffee mug and call it a day. Nothing wrong with that.
But there are also people who want to know what's behind all this ... how burr-free edge or different types of burr look under a heavy magnification. They also want to see .... how the edge looks like after stropping or steeling or after micro beveling or directly from very low grit stone. They also want to see .... how the knifes edge looks like if they do something new.

I don't know for others but I'm curious and I want to see and know. I have unlimited access to 600x optical microscope but sometimes I wish I could see something under the SEM microscope.
I happens to be there is a guy who has access to a SEM microscope and he is also a sharpening enthusiast. So; if someone wants to know more about different type of burrs and he wants to see how they look like under the SEM microscope and he is able to read something else besides short lines in comics here is a very interesting article:
https://scienceofsharp.com/2024/02/03/seven-misconceptions-about-knife-burrs/

 

[Brock O Lee]

if someone wants to know more about different type of burrs and he wants to see how they look like under the SEM microscope and he is able to read something else besides short lines in comics here is a very interesting article:
https://scienceofsharp.com/2024/02/03/seven-misconceptions-about-knife-burrs/

Thank you, this is a very insightful article!

 

[Ilikesharpstuff]

I was just looking and reading about this HIC Mule. Interesting.
They say HIC is more tough as conventional ceramic yet not as tough as steel so there is no warranty against breakage. But they had to add this hole in the blade and compromise it.
Makes no sense. Makes me wonder what genious designed this knife. He sure was not a mechanical engineer.

Spydercos have holes in the blades, this should be no surprise. Many people design knives who are also not mechanical engineers, that is also no surprise. Lastly, not every knife is designed to be beaten/abused endlessly without breaking. I don't think anyone considering the purchase of a ceramic knife would consider it for more than light/general use. The HIC is injection molded so the only weakness introduced by the hole is a thinner cross section near the tang. If you use the knife to cut and slice rather than pry and twist this is a non issue.

 

[TheOne45]

The HIC is injection molded so the only weakness introduced by the hole is a thinner cross section near the tang. If you use the knife to cut and slice rather than pry and twist this is a non issue.

Yeah, looks like I was carried away... again.
Guess I'm too short to understand this 'hole in the fixed blade knife' concept. As I see the only thing it does is to weaken the blade.
But don't pay attention to an old mechanical engineer who forgot how to 'go with the modern design flow'.
I wonder how Rezin Bowie would comment this 'serving no purpose' hole.
Please, no hard feelings. Just carry on. I'm just killing some time.
On the other hand the blade material is interesting.

 

[Seedy Lot]

I have been impressed with Spyderco K390 for cutting cardboard.

 

[Guy McVer]

I process a ton of cardboard each month and have a seperate knife specifically for that purpose.

2. Drop the micro-bevel. I sharpen my cardboard knives at 16 dps w/no micro. Unless you happen to hit a hidden staple I just don't feel the drop in cutting performance is worth the extra durability. Like I said earlier, I have specific knives that I use exclusively for cardboard and have NEVER chipped an edge. They may get dull, but I have yet to take any damage to the edge

I think there is truth to this, but it also really depends on what you want out of your knife. If you are doing a lot of slicing and not much else, then a micro bevel is going to reduce some amount of performance. How much reduction there really is, I can't say for sure. But it does stand to reason that there will be a performance reduction.

However, as you correctly point out, the micro bevel increases your edge durability, so for other tasks it is worth considering a micro bevel.

 

[David Mary]

I was just looking and reading about this HIC Mule. Interesting.
They say HIC is more tough as conventional ceramic yet not as tough as steel so there is no warranty against breakage. But they had to add this hole in the blade and compromise it.
Makes no sense. Makes me wonder what genious [sic] designed this knife. He sure was not a mechanical engineer.

The hole in the Mule blade is barely larger than the hole drilled into many folder blades for thumb studs. Yet I can count on no hands the number of times I have seen someone argue against the hole in a folder blade that uses thumb studs.

The larger hole in my reground Spyderco folding knives has caused zero failures. Also behold an unscientific demonstration of what 8Cr13MoV can do right out of my pocket (with my own regrind from factory plain edge, to ~.016" behind the edge serrated). I did not touch up the knife before this, and it has been riding in my bumming around the house pants without a touch up since at least two weeks. It gets used on all my home EDC tasks, and a significant amount of cardboard cutting as well. Actually the video will take a while. I'll post when it's ready.

 

[SwissHeritageCo]

The hole in the Mule blade is barely larger than the hole drilled into many folder blades for thumb studs. Yet I can count on no hands the number of times I have seen someone argue against the hole in a folder blade that uses thumb studs.

The larger hole in my reground Spyderco folding knives has caused zero failures. Also behold an unscientific demonstration of what 8Cr13MoV can do right out of my pocket (with my own regrind from factory plain edge, to ~.016" behind the edge serrated). I did not touch up the knife before this, and it has been riding in my bumming around the house pants without a touch up since at least two weeks. It gets used on all my home EDC tasks, and a significant amount of cardboard cutting as well. Actually the video will take a while. I'll post when it's ready.

I thought you ended up getting the S35VN option?

Let's see those frankeinstein's.

 

[David Mary]

Yes, then I gave it up so my cat could eat cat food instead of my toes. I hadn't tried it with my serrations, only my usual plain edge grind to something like .016" behind the edge, probably lower (easier to go thinner on plain edge than serrated). I determined, though, that I preferred a lower alloy, easier to sharpen steel, over a higher carbide steel where my custom geometry was concerned. That isn't to say that the S35VN is hard to sharpen, per se, more that it was enough extra work once it needed it, that I preferred the shorter sessions required by stropping on cardboard or honing for a few short passes on a ceramic stick, even if that was needed more often. The video, that is about 60% copied from my phone to my PC now, will show what you what my knife does to cardboard even after (at least) two weeks of regular use since it last touched a ceramic rod.

 

[SwissHeritageCo]

Yes, then I gave it up so my cat could eat cat food instead of my toes. I hadn't tried it with my serrations, only my usual plain edge grind to something like .016" behind the edge, probably lower (easier to go thinner on plain edge than serrated). I determined, though, that I preferred a lower alloy, easier to sharpen steel, over a higher carbide steel where my custom geometry was concerned. That isn't to say that the S35VN is hard to sharpen, per se, more that it was enough extra work once it needed it, that I preferred the shorter sessions required by stropping on cardboard or honing for a few short passes on a ceramic stick, even if that was needed more often. The video, that is about 60% copied from my phone to my PC now, will show what you what my knife does to cardboard even after (at least) two weeks of regular use since it last touched a ceramic rod.

Interesting. I carried a 8Cr13MoV tenacious for over a year and it would dull extremely quickly. For reference I used the sharpmaker to keep it honed.

 

[me2]

I was gonna say..

Why are you even on here?

For cardboard cutting, drop the edge angle as low as possible and finish the edge on as coarse a grit as you can. 10 dps and finish with a DMT blue coarse diamond.

How do you judge when it’s dull? Years ago I sharpened a Chicago Cutlery small Santoku on water stones and a Sharpmaker at 12/15 dps edge/microbevel angles and cut over half a mile of cardboard. Was it duller than when I started? YES. Would it still slice paper and cut a folded piece standing upright in two with one swing? Also yes.

Now, slicing paper is a pretty low standard without further qualifications. We’re there snags? We’re there places where the edge would catch? We’re the cuts fuzzy? All yes, but it still cut.

 

[David Mary]

Interesting. I carried a 8Cr13MoV tenacious for over a year and it would dull extremely quickly. For reference I used the sharpmaker to keep it honed.

Agreed. I never got the factory geometry to do this:

 

[callsign]

With s30v I’ve had the best luck keeping a good working edge up to 600 grit, 10 passes with ceramic, and 10 passes on the strop at 20 dps. It always comes out hair shaving sharp but holds up well for me and my use cases. However, I’ve found cardboard to be quite brutal on just about any edge. I think it’s due to all of the glue and mild epoxies holding it together.

 

[Zenturio]

Hi together,

I had some time to repeat the tests.

I sharpened a S30V Shaman, 1000grit Diamond on a guided system (17dps). There definately is a burr right off the system, there is no way to avoid that. I did very light strokes in the end to minimize the burr.

After that, I did 3 edge leading strokes on a fine Spyderco Gauntlet rod, maybe 1 or 2 degrees higher than the system angle, trying to knock off the burr. After that the knife was able to easily shave off arm hair in both directions.

After that, I stropped on a kangaroo strop loaded with 1.5 micron KME CBN emulsion. I guess that I removed any burrs. The knife was able to cut hair in half, but I needed a relative movement along the edge to cut it.

By feel I would say that the edge was quite aggressive and very sharp.

Here pictures through a 15x loup (not the best picture quality), after the stropping:






Then I cut approx. 25ft of heavy carboard:


That was the point the knife stopped shaving armhair cleanly. The edge started to reflect light. It was still able to cut phonebook paper quite good.

Here you can see a little edge damage:



I also had a S30V Shaman NIB (DLC). That knife acted exactly the same as the Shaman I sharpened before. As you can see, that carboard was quite abrasive as the DLC got damaged (it is actual wear and no residue) after cutting 25ft of the mentioned cardboard.



Now the final question, do you think I had a burr left after my progression? Could I do something else to increase wear resistance, or is it within normal range?

Thanks and best regards,
Oliver

 

[elevator man]

I have found success in deburring right off the stones by using a guided diamond system (dmt) start with coarse stone strokes both ways until I've raised a burr from both sides. Then deburr by going to only edge leading strokes on coarse stone very light pressure reducing strokes per side. Then I use only edge leading strokes on the fine stone, only deburring/refining scratch pattern. Same with extra fine then extra extra fine. No edge trailing strokes after deburring with the coarse stone. It'll blow hair off my arm at this point.

Then I strop a few passes on 3 micron diamond on denim stapled to mdf. Then. 5 micron on denim stapled to mdf. I'm pretty much 100 sure i have zero burr off the stones and that stropping substrate has caused zero burrs so far. My edges have been holding up great, so far. Still testing. I can tree top beard hairs once I strop.

 

[Glock Guy]

Now the final question, do you think I had a burr left after my progression? Could I do something else to increase wear resistance, or is it within normal range?

I don’t think this is a burr problem, but an edge retention problem. As many have said (myself included) S30V is just NOT a great choice for cardboard, so if you are planning on cutting a lot of it I would say your best bet is to get some other type of high wear steel like S110V, K390, or Maxamet.

On a side note, my H1C blade arrived, but I’m out of town until Saturday. If you wouldn’t mind, I could post my thoughts on H1C vs. cardboard here just so others contemplating trying that out can get some actual feedback.

 

[elevator man]

I agree, not an expert by any means, but 25 feet cut with s30v and just loosing shaving sharpness sounds pretty good for s30v actually