Push-cutting serrations

[DocNightfall]

I have gotten the impression that the general consensus of posters on this forum is that in general, a serrated edge is poorly suited to push-cutting and that it can't be sharpened as keenly as a plain edge. (And that's why they snag.)

But I have trouble explaining to myself why this would be so. Maybe someone can help me out?

 

[harm]

try pushing a saw through a piece of wood?it's not all that difficult to sharpen serrations if u have a tapered or round sharpener

 

[DocNightfall]

How should pushing a saw (serrated blade) through wood be worse than pushing the backside of a saw (straight edge) through wood?

 

[Padawan]

This is purely speculative, since I have not done any actual testing regarding the issue. However, I would imagine that the angle of the serrated edge factors in. Most serrated edges are chisel ground and more obtuse than plain edges. If you were to sharpen the serrations to the same included angle as a corresponding plain edge, the performance would likely be similar.

 

[tirod3]

The effect of pushing a sharp v grind into wood causes the cells to be cut through boundary walls, just like a woodworking chisel.

A serrated edge has blunt points that penetrate into the fibers and wedge between the cell boundaries, separating them by tearing, like tiny splitting mauls. They aren't cutting. There is also more edge in use, as the effective length is greater because of the additive vertical teeth. Users report more resistance in separating material.

Try it.

 

[harm]

i used the saw as an example.also consider increased surface area with serrations,although this probably makes a difference on a microscopic level.take a close look at serrations - the wavy type that mission knives uses will work on push cutting because it has more sharpened edge compared to the wave/point type that is more common.the points will offer more drag due to being unsharped.but these are my opinions.i'm sure someone like Cliff Stamp will be able to offer a better explanation

 

[MSCantrell]

A serrated edge has blunt points that penetrate into the fibers and wedge between the cell boundaries, separating them by tearing, like tiny splitting mauls. They aren't cutting.

I think this is what DocNightfall was talking about. As I read him, he wants to know why everybody's got blunt points on their serrated edges, and why everybody says they can't be sharpened.

If I'm answering the right question here... it's not that it can't be done, it's just not as easy. A serrated edge takes more specialized equipment to sharpen than a plain one. Notice I said more equipment, not more skill.

To sharpen serrations, you have to have an abrasive, whether that's a natural stone, aritificial stone, sandpaper, or whatever, that can remove metal from that tight interior radius. A plain edge you can sharpen on just about anything. Like the bottom of a coffee cup. But a serrated edge needs gear.

Since most people don't own that gear, most people end up with "blunt points" on their serrations. This is common, but it's not necessary.

It's perfectly possible to have serrated edges that are just as sharp as any plain edge, at every point along the edge... it just takes the right tools.

So to get back to the original question, it's quite possible to push cut whatever you want with a serrated knife, if it's sharp. I have a Vic One-Hand Trekker in my pocket right now. I just push-cut a post-it note, to make sure I could do it, before I typed this. Easy.

So, "it can't be sharpened as keenly as a plain edge" = false.

"...in general, a serrated edge is poorly suited to push-cutting." This, however, is not necesarily false. I said above that it's no problem to get a serrated knife sharp enough to cut, say, a post-it note. However, I think what you may be reading is people alluding to the fact that it's awkward to do some particular types of push-cutting with serrated blades, like peeling an apple. The awkwardness doesn't have anything to do with sharpness or dullnes, but with the points digging too deep and the troughs not deep enough. Same with whittling. If you want a smooth and even cut, the serrations will prevent it.

Trickier to sharpen, yes.
Can't be sharpened as well, no.
No good for push-cuts, maybe.


Mike

 

[harm]

how about make it a straight edge.instant push cutting.of course u might need a belt grinder for that.

 

[shecky]

I've found serrated blades can push cut as well as plain edges. They simply need to be sharp.

Most serrated edges are chisel ground and more obtuse than plain edges.

I don't know if this is true. In fact, on some knives, it seems serrated bevels are much less obtuse than they would be on non serrated edges, chisel grind and all.

However, a more obtuse edge will have more difficulty than a more acute edge, all other things being equal.

A serrated edge has blunt points...

Serrated edges have blunt points? I have seen blunt serrated edges, though they were the result of hard use. I can't think of an instance where a serrated edge was supposed to be blunt anywhere along the edge.

 

[tenman]

Every partial serrated blade I own will push cut, not quite with the same efficiency as the plain edge portion, but good enough; the only tool I use to sharpen them is a sharpmaker. I would say the angle on the serrations is a tad steeper than that on the plain edge portion, but they are most definitely sharp. My favorite knife is a 710 HSSR, the serrations on that knife are wicked sharp.

 

[Padawan]

I don't know if this is true. In fact, on some knives, it seems serrated bevels are much less obtuse than they would be on non serrated edges, chisel grind and all.

I'm sure it varies by knife, but the ones I've seen appear to have the serrations ground at a very similar angle to the plain edge grind, and since they are only ground one one side, the results are a more obtuse inclusive angle. However, I haven't precisely measured them, so it's possible that you're correct. Either way, I agree that keeping them sharp is obviously the key to push cutting performance. :thumbup: