Explain the purpose of serrations to me, I DO NOT get it.


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Hand_Rifle_Guy
February 10, 2003, 02:22 AM
Seems more knives got 'em than not these days. It's a fairly modern convention, though. I've yet to see any kind of serious old-school knife that had 'em outside of the odd bayonet, which could conceivably be called on to saw something when camping in the field.

Like I said in the sharpening thread, I'm a professional woodworker. Serrations are counter-productive for any sort of carving or shaping, and they don't exist on chisels or planes, certainly. I find 'em worse than useless, actually, and wouldn't own a serrated knife regardless of quality.

So what're they REALLY for? Other than looking cool, that is. They don't open boxes all that well, and they're a pain in the butt to sharpen.

Someone explain this to an ignorant tradesman, please? What do you use 'em for?

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sm
February 10, 2003, 03:21 AM
My first notice were for cutting rope,In a "Marine/Sea " enviroment. Followed by cutting seat belts by LEO, EMT's ,Firefighters, etc...

Don Gwinn
February 10, 2003, 09:33 AM
Basically, that's it. They tend to grab fibers and force them against the cutting surface, so they can make it easier to cut rope, cloth, meat, etc. That's why bread knives are serrated.
Theoretically, they also stay sharp longer because there's so much more cutting surface than with a regular "straight" blade, which is also part of the reason for their cutting power. But they can't make the kind of clean, smooth cuts a sharp standard blade makes, nor are they as easy to sharpen, and that's why they don't appear on more knives. Planes and chisels are totally different devices that don't benefit from the advantages serrations offer. Each is pushed through the material rather than drawn across it, and serrations won't help that sort of cut. You wouldn't want to go to a job site and cut through 150 2x6 boards with a plane or a chisel, though. For quick, easy cutting of the fibrous wood material you use a saw and draw it across. To take a small, precise amount of material off the top, you push the blade through it. Same principle with knives.

Now, with all that said, you're right. I think serrations are vastly overused today. They just aren't needed as often as people think, and I think they too often get used just because they look cool or menacing to a lot of customers. They DO have their uses, though. Personally I prefer a very sharp, fairly thin edge over serrations, but to each his own.

jar
February 10, 2003, 10:47 AM
Serrations are a way to make a dull knife work. They don't do anything that a regular blade can do and are not even better at cutting rope or seatbelt but they are better than a dull blade.

sonny
February 10, 2003, 02:38 PM
I am an avid knife user-collector and while I prefer straight edged knives I have to admit that a serrated edge just happens to come in handy more often ...for me...than a straight edge.
I generally use it for aggressive cutting...yea, a straight edge will do the same thing in reality with a little more effort,I just don't use my straight edge knives when I don't have to....it must be the collector in me....I like to keep the edges "sharp and clean"
I have a few "beater" knives with both kinds of edges but when it comes to beatin the crap out of a knife day after day gimme the serrated one.

P.S. I can't stand combo edges!

Smoke
February 10, 2003, 03:02 PM
They're made for people like me that abuse their knives.

I've always carried a knife with full or partial serrations, that I at leat tried to be careful with. ANd another straight eged knife that I used and abused.

The serrated knife I kept and tried not to use much because I worked with cattle and horses when a sharp knife that could cut a catch rope or a cinch strap was a necessity. Of course it still got used to open the occasional snuff can or to cut strings off round bales if my other knife wasn't readily available.

Hkmp5sd
February 10, 2003, 05:04 PM
I carry serrated knives because I have absolutely NO skill in sharpening a knife. It is obviously some arcane art that eludes me. I can take the sharpest knife in the world and turn it into a butter knife in a matter of minutes. At least with a serrated knife, in addition to holding the edge a little longer, I can use it to saw through whatever I'm cutting.

gryphon
February 10, 2003, 06:15 PM
If you ever have to cut through skids full of boxes that are covered in that industrial strength shrink wrap, you'll be glad that you had the serrations. You'll be pulling down on the plastic and it gets too bunched up and you wind up cutting the same area more than once. With the serrations, it grabs hold of the plastic and allows for the area to be cut clean through.

At least I find this to be true for me.

Joe Talmadge
February 10, 2003, 07:05 PM
Serrations legitimately outperform plain edges on some materials, and provide advantages for people who either don't have the opportunity or don't have the know-how to sharpen themselves.

Serrated cutting perform is the result of a few factors. First, when you start the cut, you end up putting just the point of the serrations on the material, which means more localized pressure at those points, which means better penetration. In other words, where even a sharp plain edge might skitter across the top of hard poly rope, serrations bite in deeply. Next, each serration acts as a mini-hook blade, forcing the material into the curve instead of pushing it away. In addition, serrations are usually chisel-ground into a blade, so they're at a lower, higher-performance angle than a typical plain edge. Serrations can sustain a very low edge angle because the points tend to protect the scallops. Lastly, the combination of all of the above -- low edge angle, little hook blades, and penetrating points -- means the geometry of a serrated blade can help the knife keep cutting even when the scallops are technically not that sharp anymore.

Versus a sharp plain edge, serrations tend to do really well in hard material, like hard poly rope, hard plastics, etc. The penetrating points and scallops greatly assist in cutting. You can narrow the performance gap with your plain edge knife by clever sharpening: reduce the edge angle on your blade, and use a coarse or x-coarse finishing grit (DO NOT RAZOR POLISH!). It's possible to get a plain edge to approach the performance of a serrated blade in poly rope by sharpening this way, although the plain edge will need to be re-touched much more often.

I prefer plain edge to serrations. On the other hand, I think the pendulum has swung back maybe a bit too far, from years ago when serrations were all the rage, to now where many folks on the web seem to think they're useless. Serrations can outperform a plain edge in some materials, and do have some nice properties, especially regarding how long they cut effectively. That said, overall I think a plain-edge knife sharpened wisely is a better choice.

Joe

LeadPumper
February 11, 2003, 09:14 AM
I used to only carry regular, shapened blades. Found that on some things, the blade didn't have enough 'tooth' to rip through. It got dull in no time.

Then I switched to fully serrated, and found that when I needed to slice something smoothly, it got ripped all apart.

Now I carry a 50/50 serrated tanto point. Sharp up front for slicing, serrated in back for ripping.

I've found what works for me.

Get the knife thats going to cut it for what you need.

-LeadPumper

Pheonix
February 11, 2003, 09:21 AM
It is the best thing I have found for cutting the rubber hose at work.

Guyon
February 11, 2003, 10:46 AM
My advice? Pick up a decent serrated Spyderco and try it on a variety of materials--not just wood. You'll get your answer.

And all serrations are not born equal. Some companies have better serrations than others.

I don't like serrations myself. In fact, I don't believe I currently own a serrated or partially-serrated knife. I don't like to fool with sharpening them, and I figure I can always make do with a plain edge.

Joe Talmadge
February 11, 2003, 12:03 PM
I used to only carry regular, shapened blades. Found that on some things, the blade didn't have enough 'tooth' to rip through.

Now I carry a 50/50 serrated tanto point.


Lead, if that works for you, great. What I don't like about partially-serrated blades is that if I have (say) a 4" blade, functionally it's like I'm carrying a 2.75" plain edge and 1.75" serrated edge, but I can't use the entire 4" blade together. What I mean is, sometimes I need a full 4" blade for what I'm doing, and having the partial serrations there -- where the serrated edge is always chisel-ground out-of-line with the plain edge -- gets in the way. Just one of many examples: if I pull my knife out to use for a little food prep, I really need one long 4" blade, not a little plain edge that's out-of-line with a little serrated edge.

My solution: be a little more clever about how I sharpen. When I sharpen, I razor-polish the entire edge. Then I go back and run the last 1.5" or so of the blade (the part where the serrations would be on a partially-serrated blade) over a coarse hone. That leaves me with one long 4" blade where the entire blade can be used for food prep and the like, but now the last coarser section of blade is quite effective at slicing. The coarse section might not be quite as effective as serrations would be, but neither do I have to compromise away my ability to use the entire 4" edge at once ala a partially-serrated blade.

Your mileage may vary, obviously! But overall, I've found that I like a dual-grit plain edge much better than a partially-serrated blade.

Joe

PS One more quick note about slicing. While serrations do well at slicing things (e.g., rope), push-cutting is more effective than slicing. By dropping the angle of my plain edge knife down to 15 degrees per side or so, the edge becomes so effective that I can often push-cut through things that I'd otherwise have to slice through. So although serrations might be nominally better slicers through certain materials, the real win is when I can push-cut. Just another example about how important a good sharpening plan can be. You won't be able to push-cut through everything, but do a good job sharpening and you'll obviate the need for slicing (and hence serrations) a lot of the time.

Inspector Callahan
February 12, 2003, 02:59 AM
The first serrated knife I owned was a Spyderco Police. I still have it. I keep the edge maintained with my Sharpmaker. It cuts like a chainsaw. I agree with Guyon, not all serrations are created equal. Spyderco's serrations cut WAY better than anyone else's, in my experience. I've added quite a bit to my Spyderco collection since that Police. All have been Spyderedge. If I wanted a plainedged knife I'd buy a Randall.

I participated in the Lum Chinese passaround review over at Bladeforums. It was my first experience with a plainedged Spydie. Nice knife, excellent quality, smooth operation. What was missing, however, was that violent cutting ability I had grown so fond of. Sure it would cut. But it was in a totally different class.

Don't get me wrong, plainedged blades have their place. I couldn't imagine skinning with a serrated blade. But the only plain blade I actually carry is a Gerber money clip that's been long discontinued. It serves as a scraper, but mostly it just holds money. My hunting knife is a Buck Pathfinder that is excellent for skinning. It sits in a drawer for about forty eight weeks a year.

Cheers. :)

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