SE Edge Angles

[Sharp24/7]

Just want to check something. Since SE knives are chisel ground, as far as edge angles go, is a 20 degree SE edge equivalent to PE edge that 20 degrees inclusive, ie 10dps?

[vivi]

yes

which begs the question why PE is ground so much thicker.....

[Sharp24/7]

yes

which begs the question why PE is ground so much thicker.....

No kidding! If I’m not worried about snapping off the points, why would I worry a ton about chips, etc.

[sal]

Hi Sharp24/7,

You might take a look a David's comments about teeth.

sal

viewtopic.php?f=2&t=84985

[RugerNurse]

yes

which begs the question why PE is ground so much thicker.....

No kidding! If I’m not worried about snapping off the points, why would I worry a ton about chips, etc.

Unfortunately lots of “reviewers” want to bash the knife through tough material and it might chip the edge more if it was thin. Makes companies grind thicker edges. If you want to abuse a knife, get a Mora

[vivi]

yes

which begs the question why PE is ground so much thicker.....

No kidding! If I’m not worried about snapping off the points, why would I worry a ton about chips, etc.

Unfortunately lots of “reviewers” want to bash the knife through tough material and it might chip the edge more if it was thin. Makes companies grind thicker edges. If you want to abuse a knife, get a Mora

Speaking of Moras, I mamaged to baton a stainless 760mg through an old road sign with no catastrophic edge failure, just general blunting. Also bent it 90 degrees while prying with the mid part of the blade without snapping the blade.

Tough knives for the $$. Local gun shop has em for $9 a pop, and I usually grab one any time I stop by for ammo. They make great gifts / loaners.

[Wartstein]

yes

which begs the question why PE is ground so much thicker.....

Said it in another thread already:

I'd really be interested in comparing a chisel grind PE Spyderco against the exact same model with an - of course chisel grlnd too anyway - SE edge (same edge angel for PE and SE).

Jusr to see how much of the performance differences are due to the teeth, and how much due to the steeper chisel grind of SE.

Now of course I could give a PE knife the exact same acute inclusive edge angel of an SE knife myself, but just in form of a v-edge.

For the closest possible comparison though both in chisel grind (since SE has that anyway) would be the way to go imo.

[Edited for spelling...]

[Evil D]

The bevel on serrated blades is supported by the thicker sections at each tooth, which greatly reduces (not eliminates) the risk of rippling the edge or other major edge damage. The way Spyderco make the serrations somewhat short in length between the teeth also really helps with this. This isn't to say that a 20 inclusive plain edge is going to fold the bevel over or fracture it out when used hard, but it is to say that it's more likely to happen with very thin PE than it is on an equally thin SE. While most edge damage can be avoided by changing how you sharpen, there does come a point when the cross section of steel behind the apex is too thin to support how hard you're using the knife and that's when you severely damage a blade. I don't think anyone is going to see this from opening boxes and doing food prep all day, you'd need to be doing far harder twisting cuts into a hardwood knot or something like that for it to be a concern.

So, they're not exactly equal, it really depends on the rest of the PE blade grind. SE blades tend to get thicker beyond the edge than PE, which combined with the thicker areas around the teeth help to make it "safer" to have a thinner edge cross section. If you had a PE that's equally thick in the same distance from the apex, you'd probably have really wide edge bevels, but this is where the thickness of the blade grind would determine how wide. A Shaman for example taken down to 10 degrees per side would be far wider than Chaparral or other blade that measures very thin behind the bevel from the factory. The Shaman would then also hold up to abuse better, but in turn wouldn't slice as well.

This is why I'd really like to see thinner blade grinds on SE knives, because I think the geometry around serrations can help to support the edge more and will make slicing far better than something like a Salt 2 that gets very thick very soon above the edge apex.

[vivi]

Wartstein, that would be a fun comparison to make.

Evil D, not sure I agree. My SE knives get edge damage more easily than my reprofiled PE knives, and I've taken a lot of different steels very thin. Some even too thin.

[Evil D]

Wartstein, that would be a fun comparison to make.

Evil D, not sure I agree. My SE knives get edge damage more easily than my reprofiled PE knives, and I've taken a lot of different steels very thin. Some even too thin.

Then there's something different about how you sharpen the two and that's where your difference is coming from, not so much edge type vs edge type. Is this even a debatable topic? If the geometry and the usage are the same, you'd at least see similar damage to the PE. If the geometry is thinner on one or the other, you'd see more damage. Either that or you're unintentionally using them differently. There isn't anything special about a thinned out PE that adds strength or edge stability, quite the opposite in fact, whereas serrations have thicker teeth close together that at least support the edge on the sides of a serration. Whatever difference you're seeing has to be due to how you sharpen each or how you use them. There's no other logical explanation.

[vivi]

Wartstein, that would be a fun comparison to make.

Evil D, not sure I agree. My SE knives get edge damage more easily than my reprofiled PE knives, and I've taken a lot of different steels very thin. Some even too thin.

Then there's something different about how you sharpen the two and that's where your difference is coming from, not so much edge type vs edge type. Is this even a debatable topic? If the geometry and the usage are the same, you'd at least see similar damage to the PE. If the geometry is thinner on one or the other, you'd see more damage. Either that or you're unintentionally using them differently. There isn't anything special about a thinned out PE that adds strength or edge stability, quite the opposite in fact, whereas serrations have thicker teeth close together that at least support the edge on the sides of a serration. Whatever difference you're seeing has to be due to how you sharpen each or how you use them. There's no other logical explanation.

Can't say I agree.

I've been using Pacific Salts since before you joined the forum in both edge types sharpened to similar angles, both with and without microbevels, using them the same way. My experience has been SE versions damage more easily than PE.

I'm not saying your experience is wrong and mine is right. I'm just saying what I've experienced is different than what you've experienced. I've cut things with thinned out plain edged knives that you've chipped serrated edges on without chipping the edge.

Either way it's certainly a debatable topic, considering we've each arrived at opposite conclusions through our own uses.

[Evil D]

Nah I'm just one guy with an opinion. Forget I said anything.

[Matus]

In a sense - when cutting something hard/ueven - the PE edge would still experience more of a 'slicing' with local pressure points, but SE edge experiences 'micro impacts' is it is moved along the rough surface of the object being cut. So that kind of situation SE edge might be prone to damage faster than PE. Of course - local geometry differences will have impact on the situation.

[zhyla]

No kidding! If I’m not worried about snapping off the points, why would I worry a ton about chips, etc.

Teeth chip out all the time on SE blades in my experience. I’ve had this happen a couple times but if you look at eBay it’s pretty clear the PE blades survive much better in the wild.

[Cl1ff]

There are a lot of biases to account for here and I’m not convinced of the difference between PE and SE respective resistance to deformation.
I’m curious about the different modes and patterns of deformation they experience, if any.
A whole new thread could be started where we may share our specific experiences in detail and discuss ways to further test or show these things. It’s important to distinguish if we want to test SE vs PE or are really just interested in SE Spydercos vs PE Spydercos, for example.

This would be really interesting to test in a lab, but I do have some thoughts based on our collective observations, so I’ll come back later.

Regarding the knives listed on EBay, though, I think there are some pretty big potential biases at play. Most people probably can’t repair serrated edges like they can a plain edge, serrated knives are probably used differently and by different people in general, damage is less obvious on already toothy looking SE, factory SpyderEdges being more acute than plain edges etc.

[JRinFL]

Fluting can increase stiffness of steel, so it is *possible* that both serrations and coarse sharpening are acting like flutes and increasing the stiffness of blade steel. Very difficult to prove without extensive testing or fairly high end computer modeling.

[zhyla]

There are a lot of biases to account for here and I’m not convinced of the difference between PE and SE respective resistance to deformation.

All other things equal (steel, bevel angle, usage, etc) I think the teeth points are inherently more vulnerable to breakage. Just like the pointy tip of a knife is more vulnerable than the rest of the edge because it's not as supported.

Regarding the knives listed on EBay, though, I think there are some pretty big potential biases at play. Most people probably can’t repair serrated edges like they can a plain edge, serrated knives are probably used differently and by different people in general, damage is less obvious on already toothy looking SE, factory SpyderEdges being more acute than plain edges etc.

All true. I mentioned it to counter the idea that "X is true because SE teeth don't get broken" -- they absolutely do. I think also SE was much more popular in the past than in the last ~10 years so a lot of the eBay SE knives are also pretty old.

Fluting can increase stiffness of steel, so

I believe this is a misconception.