SE performance is more than simply teeth vs no teeth.

[dsvirsky]

If you read the product description in the Spyderco online catalog, you will see that it is designed to sharpen both plain edge and serrated blades. Would you expect less from Spyderco?

[Jimandchris2]

You're a legend Dave. Thank you

[SpyderEdgeForever]

Can one of you fact check this for me, please? A fellow knife user told me all knife edges including what we call straight plain edges are serrated at the micro and molecular level...and that is why they cut..vs the older theory that they cut based on the wedge principle of separating material. He claims that a smooth edge down to the molecule level will not cut, so therefore, all edges are serrated.

[Evil D]

Can one of you fact check this for me, please? A fellow knife user told me all knife edges including what we call straight plain edges are serrated at the micro and molecular level...and that is why they cut..vs the older theory that they cut based on the wedge principle of separating material. He claims that a smooth edge down to the molecule level will not cut, so therefore, all edges are serrated.

This is what most refer to as a "toothy edge". Look up pictures of edges under a microscope and it looks sort of like a spikey mountain range.

[SpyderEdgeForever]

Thank you David. I started looking these up and found many before and after sharpening. In some the toothiness is very distinct.

[Aladinsane]

WOW! I've been printing this thread out a few pages at a time and reading through it at my leisure, and I am really impressed! Lots of good information in here! I was opposed to serrations for years, but now I see that was due to fear, ignorance, and other's opinions. I'm really wanting to try out a SE knife now! I suppose I'll have to look at the Spyderco catalog and see what I like that's available in SE. Leafjumper perhaps?? Thanks to everyone who has contributed!

[sal]

The folks that hang on this forum are really good about honestly sharing their thoughts and experiences.

sal

[Bill1170]

Can one of you fact check this for me, please? A fellow knife user told me all knife edges including what we call straight plain edges are serrated at the micro and molecular level...and that is why they cut..vs the older theory that they cut based on the wedge principle of separating material. He claims that a smooth edge down to the molecule level will not cut, so therefore, all edges are serrated.

Hi SEF, it’s all a matter of degree. All matter reduces down to atoms eventually, so essentially granular, but at a vastly finer scale than the crystalline structure of ordinary metals.

Obsidian scalpels are used in extremely delicate surgeries because of how very sharp and smooth the edges are. What I’ve read is that obsidian blades can be on the order of 50 times sharper than the sharpest steel edges possible. This is because obsidian is a glass, and glasses lack a crystalline structure. The attainable sharpness of steel edges is limited by the size of the crystals at the edge.

Glasses like obsidian are structured like liquids that are super-cooled but not crystalline. The flaked edges are very sharp and very smooth, to the atomic level. They cut very well on soft tissue without disturbing adjacent structures. This is why neurosurgeons use them.

[SpyderEdgeForever]

Can one of you fact check this for me, please? A fellow knife user told me all knife edges including what we call straight plain edges are serrated at the micro and molecular level...and that is why they cut..vs the older theory that they cut based on the wedge principle of separating material. He claims that a smooth edge down to the molecule level will not cut, so therefore, all edges are serrated.

Hi SEF, it’s all a matter of degree. All matter reduces down to atoms eventually, so essentially granular, but at a vastly finer scale than the crystalline structure of ordinary metals.

Obsidian scalpels are used in extremely delicate surgeries because of how very sharp and smooth the edges are. What I’ve read is that obsidian blades can be on the order of 50 times sharper than the sharpest steel edges possible. This is because obsidian is a glass, and glasses lack a crystalline structure. The attainable sharpness of steel edges is limited by the size of the crystals at the edge.

Glasses like obsidian are structured like liquids that are super-cooled but not crystalline. The flaked edges are very sharp and very smooth, to the atomic level. They cut very well on soft tissue without disturbing adjacent structures. This is why neurosurgeons use them.

Bill thank you so very much for this informative reply. This helps. One thing I would love to see is a compound of obsidian and a polymer for knives if it would work. Or obsidian metallic alloy.

[olywa]

sigh...

[vivi]

Thank you David. I started looking these up and found many before and after sharpening. In some the toothiness is very distinct.

SEF,

Though the following images are plain edged knives and razors, I thought you'd find these threads interesting:

viewtopic.php?t=90677

viewtopic.php?t=92690

viewtopic.php?p=1635813#p1635813



You wouldn't think it by looking at the 200x image, but this was a shaving sharp edge.

I'd say what you heard about all edges being serrated to some degree is true.

But cutting tools meant for push cutting are still often using wedge action. A very obvious pair of examples are splitting axes and straight razors.

Neither of these tools are used on a slicing cut generally. Straight push cuts. They function with a wedge action.

Most cutting tools are used with some degree of slicing motion. With these, having some degree of toothiness to the edge will increase cutting efficiency. This can be achieved by factory grinding serrations, sharpening at low grits, or both.

[Bill1170]

What Vivi said. I will, as a woodworker, add chisels and plane irons (means blades) because these are used for push-cutting and work best with a polished edge. Toothiness only detracts from their efficiency.

[SpyderEdgeForever]

Thanks to you both vivi and Bill. Very interesting and it amazes me how an edge so smooth on the macroscale level can have ridges and jagged patterns on the micro level. And so my next question is, from your experience with serrated edge performance before and after sharpening, which is:

1 easiest for both experienced and non experienced sharpeners to resharpen with the right tools.

2 has the smoothest cutting action on fibrous materials like cardboard and cordage?

[Wartstein]

Thanks to you both vivi and Bill. Very interesting and it amazes me how an edge so smooth on the macroscale level can have ridges and jagged patterns on the micro level. And so my next question is, from your experience with serrated edge performance before and after sharpening, which is:

1 easiest for both experienced and non experienced sharpeners to resharpen with the right tools.

2 has the smoothest cutting action on fibrous materials like cardboard and cordage?

Can´t answer your questions for Vivi and Bill and probably also not in the way they could, just want to point you to another thread (actually started by Vivi) about low grit sharpening, you might find it interesting

viewtopic.php?p=1368196#p1368196

Vivis posts actually made me try out my own, basic versions of coarse edges and I must say I really like those in my use!
Yes, the sharpening process is "easier" like in at least quicker, I feel they hold an edge longer and "grab" material better (try for example to cut a plastic bottle WITHOUT piercing it with the tip first: A coarse edge will do a much better job, while a smooth edge might even "glance off" a bit).

That said: Unlike Vivi I still like true SE even better than coarse PE.

[Bill1170]

Hi SEF,

I don’t know how easy sharpening is for others. SE is pretty easy on the Sharpmaker, but overall plain edges are easier to sharpen than serrated edges (for me).

Spyderedges that have been tuned up on the Sharpmaker are my favorite pocket knife blades for corrugated cardboard because of three things. First, the serration peaks can initiate cuts through tape without needing to use the tip. Second, the serrations trap the material as I cut, resisting the tendency of the blade to back out of the material. Third, the very low included edge angle just performs brilliantly.

[Wartstein]

....

Spyderedges that have been tuned up on the Sharpmaker are my favorite pocket knife blades for corrugated cardboard because of three things. First, the serration peaks can initiate cuts through tape without needing to use the tip. Second, the serrations trap the material as I cut, resisting the tendency of the blade to back out of the material. Third, the very low included edge angle just performs brilliantly.

Very well said and imo true for many more materials than "just" corrugated cardboard (peaks initiating the cut - scallops grab material - very acute angle, but still strong enough edge)

[SchoonerBum]

I can’t speak to cardboard but I’ve cut a lot of cordage over the years, mostly synthetic but some natural fiber stuff also, ranging from #9 seine twine up to 6 inch diameter soft towlines. Almost universally, my experience has been that a serrated (but not snaggy) edge cuts a little easier but a plain edge makes a neater cut. I tend to use both at work, I carry a plain edge for work that needs to be nearly finished and general use and I carry a serrated edge for emergencies and any dirty or gritty cutting that doesn’t need to look nice or have the end re-whipped to be used again.

My favorite way to cut line if I have the option is to lay it over a block of wood and use a wooden mallet to essentially baton the line apart with a plain edge. It is the easiest and tidiest way to cut line that I’ve found so far.

[Bill1170]

I can’t speak to cardboard but I’ve cut a lot of cordage over the years, mostly synthetic but some natural fiber stuff also, ranging from #9 seine twine up to 6 inch diameter soft towlines. Almost universally, my experience has been that a serrated (but not snaggy) edge cuts a little easier but a plain edge makes a neater cut. I tend to use both at work, I carry a plain edge for work that needs to be nearly finished and general use and I carry a serrated edge for emergencies and any dirty or gritty cutting that doesn’t need to look nice or have the end re-whipped to be used again.

My favorite way to cut line if I have the option is to lay it over a block of wood and use a wooden mallet to essentially baton the line apart with a plain edge. It is the easiest and tidiest way to cut line that I’ve found so far.

That makes sense. Line that’s been push-cut (includes batoning) has a Iot neater end than line that’s been cut by toothy slicing.

[40mm]

Hey kids. Been out of the loop for awhile, but finally came to my senses and I sourced another serrated H1 Dragonfly. Last one I had was used, and the prior owner rounded the edges beautifully. Worn in to perfection. I only have the grey and white rods for my Sharpmaker, but wondering which angle you would use to get started round off the teeth?

[Wartstein]

Hey kids. Been out of the loop for awhile, but finally came to my senses and I sourced another serrated H1 Dragonfly. Last one I had was used, and the prior owner rounded the edges beautifully. Worn in to perfection. I only have the grey and white rods for my Sharpmaker, but wondering which angle you would use to get started round off the teeth?

Might be that in the 30 degree setting the rod does not even hit the very edge, but just in the 40 degree setting, you'd have to try that.

If this is the case I'd go 40 to round off the teeth, because actually reprofiling the edge with just the brown rod should be a looooong process, even with H2...

You could order diamond/CBN rods though, or as some here appearantly have done successfully wrap very coarse sandpaper around your sharpmaker rod (personally no experience with that approach).