A medium bounds for performance : chopping

[Cliff Stamp]

Cliff, there is a difference between the ABS and PCC competitions. Only the latter admits all types of steels and makers.

Yes and what is the point you are making here? Are you arguing that if stock removal steels were allowed to be used then high carbide steels would dominate the ABS competitions? Are the tests used by the PCC more stressful, is the level of competition higher? Are the people who win the ABS tests being systematically outperformed by stock removal steels in PCC contests?

There is also a difference between doing very well and winning.

He has won, as have many others in very low carbide steels as hardheart has noted. As well, be specific, how much steel performance do you think is actually represented by the person who came in first and the others that placed? Will you even make the arguement that steel dominates user skill in those competitions?

And there seems to be a difference when Dan Farr says speed is good and when others say speed is good. You take exception to the latter and quote the former in making other points.

I was not referencing Farr's post to make a comment about speed being necessary, it was to show that 5160 knives can win in such competitions and to raise an issue about dynamic balance. I noted years ago that speed is necessary in a chopping knife when the wood is live and springy. Speed is however not simply determined by the center of mass of a knife and is strongly influenced by user strength.

As for my using a random kitchen knife to make judgements on kitchen knife steels, you use random production knives to make judgements on steels all the time.

When I know the steels and and the result correlate well to the several other hundred knives I have used and also match the materials properties, then yes, that will become a part of the information I will use to make judgements on that steel. Generally I would bound the performance by the extremes on the high and low end using a custom maker vs cheap production knife to do so.

Thus if you wanted to know how 12C27 performed then a $5 Mora will give you an indication of that, keeping in mind the hardness will vary from 50-60 HRC on such knives so try a couple at least. If you want to know the optimal performance then get a blade from Landes or a similar maker who specialized in the steel, or at least follow his heat treatement to get a 60/61 HRC blade with <1% primary carbide and minimal retained austenite to give near maximal edge stability.

-Cliff

 

[the possum]

Note the focus of weight here strongly speaks of a static measurement (weight forward) to determine a dynamic quantity (speed). Where I wonder is the dynamic balance point on that knife? Where is it located ideally for such knives, to me it would seem to be to be through the tip?

Note the part where he says the recurve helps prevent twisting. This means he must be chopping pretty far back on the edge, so there's mass actually leading ahead of the cut. Look how the blueing is worn off the blade on the rear half- this would seem to confirm it. I'm guessing the dynamic balance point just ends up where ever it wants to based on their "feel" for things, and then they use the knife accordingly. I have found tip placement to be ideal for my own uses, and I think my requirements may also apply to competition blades (a good combination of speed, maneuverability, & cutting power through the tip), but obviously they're making other placements work well enough for them.

Thanks for the link to Cashen's article. I had forgotten about that one.

I would wanted reduced shock in hand, better precision in the cut and more raw cutting ability. Ideally maybe 25%-50% better chopping ability than the Bruks on that size of wood. I would be surprised if better than that could be reached by a 10" blade.

Then you just have to stop messing with those puny little 10" blades. Especially on smaller woods & brush like this, I'll much rather use blade length (speed) to get the desired power rather than adding weight to a shorter design.

Without derailing the discussion, with my earlier question I wanted to point out that not every descision must be based on performance, and there's lots of paths to the same goal. I like knives. Using a finely crafted one for its intended purpose gives me pleasure. Fit and finish may not greatly influence performance once an adquate level is reached, but still adds to the overall personal experience using the tool. A grip made to fit my hand is probably gonna cost more (either money or labor) than a generic grip off the shelf.

 

[the possum]

Jerry, I admit I've also become a bit bored with this thread since everyone wants to rehash stuff that was covered ad nauseum in that S30V thread. So how about we move forward?

You use CPM-3V, right? Why? For the applications you use it for, could it be directly replaced by any of the stainlesses we're discussing here?

Here's some general thoughts on toughness vs. strength.
For me, it's all about keeping damage to a minimum. I'll take a milimeter long roll over a chip 2mm deep. I'll take a mm chip over a 3mm dent. But if I had to choose either rolling/denting or chipping to the same depth/extent, I'd probably go with plastic deformation simply because if the edge is showing signs of brittle failure, I'd be concerned that eventually the entire blade could do the same.

A blade with high strength but low impact toughness will likely seem better than a softer blade with high impact toughness during most things folks commonly use knives for. As long as the high strength blade has adequate toughness to get you through, you'll benefit from its higher strength. The edge on the softer blade may roll a bit while the harder edge seems unscathed. However, what if you do occasionally use the blade in an abusive manner that exceeds the strength of the harder blade? In that case, the softer edge will roll or dent a bit more, but the harder blade may get huge chunks blown out of the main grind. Finding the right mix of properties for your intended use is at the heart of the art of knife making. If we use a steel that has very high impact resistance while also at rather high hardness & strength, it sounds like a win/win situation to me.

 

[Cliff Stamp]

Note the part where he says the recurve helps prevent twisting. This means he must be chopping pretty far back on the edge, so there's mass actually leading ahead of the cut.

Yes, I should have been more clear, I was speaking of the ping pong ball and other cuts which require a very fast blade. The maximum speed will be through the tip so it would seem that for maximum precision that would be where the dynamic balance should be located.

The 2x4 cutting would be for maximum power, not hand comfort, as it is very short term cutting, likely ten chops or less. So it is going to be about the point for maximum momentum transfer which will be close to the center of mass and thus very far back on the blade.

Especially on smaller woods & brush like this, I'll much rather use blade length (speed) to get the desired power rather than adding weight to a shorter design.

Yes, I generally prefer about 14-16" for working brush knives, when I go beyond this I find the blade is a bit too long and I can not work close to myself, for pure machete type use, go out to 18-22" at least.

Fit and finish may not greatly influence performance once an adquate level is reached, but still adds to the overall personal experience using the tool.

How long does this last though with a using tool?

If we use a steel that has very high impact resistance while also at rather high hardness & strength, it sounds like a win/win situation to me.

That is actually very easy to get, just don't ask for high wear resistance at the same time. Just get a low carbide steel which forms lathe martensite and gets about 58-62 HRC. There are piles of these, the ABS guys use them, though they generally favor the ones with more carbon than optimal for toughness and they do not react well in general to questions like "What happens if I smash the edge into a rock?" The answer tends to be "Yeah, don't do that."

In regards to stainless replacements, pick your maker. There are guys making tactical knives out of the most brittle steels you can imagine, 154CM, S30V, S90V, S125V, even T15. There is just no common accepted standard on performance, even for edge retention let alone something as controversial as high impact toughness. If you want toughness and general behavior similar to 3V then you are going to have to look at 12C27M rather than S90V. Again, forget about stainless and look at the general properties, lathe martensite, minimal carbide volume, very fine ausgrain, etc.

-Cliff

 

[Cobalt]

not tha it matters to most of this discussion, but here are two examples of bending in wood and bending n a vice. I know this was discussed earlier.

 

[the possum]

Yes, I should have been more clear, I was speaking of the ping pong ball and other cuts which require a very fast blade. The maximum speed will be through the tip so it would seem that for maximum precision that would be where the dynamic balance should be located.

Ah. I've never cut a ping pong ball. But I'd think speed in and of itself wouldn't be paramount, but rather maneuverability, to follow the moving target.

So it is going to be about the point for maximum momentum transfer which will be close to the center of mass and thus very far back on the blade.

Not sure about that one. I think it would depend on if you're chopping with the whole arm from the shoulder, vs. quick snapping cuts with wrist rotation. I generally seem to get max chopping power even on thick woods further out on the blade.

How long does this (fit & finish) last though with a using tool?

Many years of hard use. And when I say that, understand my personal feelings on this matter are just that; everyone else is free to disagree. I'm not talking about keeping that flawless satin finish pristine here. I'm saying that even with scratches and stains from use, there will be enough of the original finish left somewhere that will show you how much work went into the knife. -I can appreciate old things for what they once were. A perfectly fitted guard should still be perfectly fitted years from now. Some areas will actually get more polished from use, and deep scratches left in the finish will really become apparent then, without that satin finish to hide them. A mellow piece of wood or stag, that's aquired a natural patina (and a few dents) with genuine use, is totally different to me than material that just had a crappy finish or lines from the start. (added-) Likewise, if the grind lines are crooked as they come from the maker/factory, well, they probably aren't gonna get any straighter with use. And I have personally experienced a performance issue in that regard. Uneven grinds can cause hidden stresses in the steel from the quench, which later manifest themselves as a warped blade after heavy use. (naturally, the method of heat treatment will also play a large role there.)

 

[Cliff Stamp]

Cobalt, that is an example of how wood makes all such bending meaningles, without pictures anyway. That first knife has a total apparent bend of more than 45 degrees but the blade itself is bent about 15 and the rest is just the wood deforming.

That is a nice example of a rubber knife:

[/QUOTE]

But I'd think speed in and of itself wouldn't be paramount, but rather maneuverability, to follow the moving target.

I assumed they judged the speed and distance.

I think it would depend on if you're chopping with the whole arm from the shoulder, vs. quick snapping cuts with wrist rotation. I generally seem to get max chopping power even on thick woods further out on the blade.

Static wood in a vice or actual brush?

..if the grind lines are crooked as they come from the maker/factory, well, they probably aren't gonna get any straighter with use.

This though isn't as much fit as it is defective workmanship. I am defining it differently I think. To me it can not be a functional issue if it is a finish one, it has to be aesthetic only. Consider as a counter example the very rough finish left as-forged on the Bruks axes. They do not polish them intentionally, would you see this as a detraction?

-Cliff

 

[Cobalt]

That Rubber knife is a Dogfather

 

[Cliff Stamp]

Yeah, not a bad flex, the vice itself is distorted under the force, but it would be safe to say that through the guard there is a bend of 75-85 degrees. So you have the ability to take a large bend, high strength, chops through concrete with little effect, seems fairly strong and tough to me - let me guess, low carbide steel with about 0.5% carbon in solution in austenite?

-Cliff

 

[the possum]

Static wood in a vice or actual brush?

Well, I generally don't chop anything in a vice, but above I was talking about wood thick enough that it's pretty solid on its own. Meaning treetops & long limbs 7"-10" thick. I generally find that I chop between halfway down the blade to about 1/3 back from the tip, which is still considerably forward of the balance point. The tip does still chop thick wood about as well if I swing it fast enough, but I generally chop at a more leisurely pace on wood that thick. On lighter "brush" (brambles, clumps of grass, sticks/branches up to a couple inches thick) I go all the way out to the tip for speed.

Consider as a counter example the very rough finish left as-forged on the Bruks axes. They do not polish them intentionally, would you see this as a detraction?

Yeah, sounds like we're just looking at it differently. In fact, I'm not really sure how I would define my feelings here or where to draw the line. No, I wouldn't see the as-forged finish on Bruks axes as any problem. I guess it just boils down to whether the maker achieved a good example of craftsmanship on whatever style he was going for. I've seen as-forged "finishes" that look like utter crap, too.

 

[Cliff Stamp]

Technique has a lot to do with it as I would imagine does length of blade. On small length knives there is not that much difference between the point and the choil compared to the total radius of the swing anyway as the knife is short compared to your arm.

My main issue with the smaller knives is simply that when I cut forward on the 10" knives I can feel them "coming back" as they enter the wood. They tend to simply not want to go into the wood as the wood wants to make them counter rotate. Of course the dynamic balance point is also no where near the tip either.

On larger parangs I will chop far forward of the static balance point as the performance is maximum there. It would be interesting to measure maximum momentum delivered and note at what mix of speed+momentum the chop depth is maximized.

As an example of something that I would not call fit and finish :



Note the lock bar is much thinner, the pins are also uneven, not flush with the micarta or even square and have a peened finish. The primary grind is also uneven and the edge has a non-functional recurve near the choil which will prevent sharpening on a flat stone. This is a custom small lockback. These things I would not call aesthetic as they impair function.

Now in contrast, I have many custom knives with scratched blades, handles have little chips and dents, etc., basically exactly what is seen with wear. In short, if the knife would look like the same after use then I see no need to go further. Fit should also not include things like large gaps, especially in knives which can cause lock fouling and the like, or the pins be abrasive in hand or cause the handle to catch on the pants and such.

-Cliff

 

[Cobalt]

Yeah, not a bad flex, the vice itself is distorted under the force, but it would be safe to say that through the guard there is a bend of 75-85 degrees. So you have the ability to take a large bend, high strength, chops through concrete with little effect, seems fairly strong and tough to me - let me guess, low carbide steel with about 0.5% carbon in solution in austenite?

-Cliff

look at what it took to get it to flex:

one badazz blade for sure and very underrated and ,thankfully, underpriced

 

[Cliff Stamp]

Yeah no arguement there, high strength and toughness, nice combination. Who designed the white paper protective sheeting, Super Dave Osborne?

The patent file on 3V contains a wealth of information on that steel and deals with much of what is being discussed here, strength/hardness, toughness/carbide volume, etc.

-Cliff

 

[Cobalt]

Yes, I'd like to see some pics of other thru-hardenned knives bent like this. Heck I'd like to see any knife bend like this. :thumbup:

 

[Cliff Stamp]

Ed Schott had a picture of a 3V knife bent to a large angle, of course with any bend you have to be wary of the tapers. You can easily get huge bends if you taper the tip and just before the handle to make them both very thin as then just those sections will bend. But in this case that Swamp Rat knife is not so tapered which makes the bend that much more impressive.

-Cliff

 

[Elen]

Yeah, not a bad flex, the vice itself is distorted under the force, but it would be safe to say that through the guard there is a bend of 75-85 degrees. So you have the ability to take a large bend, high strength, chops through concrete with little effect, seems fairly strong and tough to me - let me guess, low carbide steel with about 0.5% carbon in solution in austenite?

-Cliff

Scrap Yard uses "SR-77", which, I believe, is a Busseism for S7 with a really nice heat treat. And if my memory serves me correctly, S7 has roughly 0.5 % carbon...

 

[Cliff Stamp]

Yeah, that is kind of an obvious counterpart to S7 not being a high performance knife steel, anyone really want to state those knives suffer from low edge strength. Busse is one of the few people who do live demonstrations of crashing the edges on his knives into hard objects and noting the damage is minimal. Hard to debate public emperical evidence.

-Cliff

 

[Kohai999]

Yeah, that is kind of an obvious counterpart to S7 not being a high performance knife steel, anyone really want to state those knives suffer from low edge strength. Busse is one of the few people who do live demonstrations of crashing the edges on his knives into hard objects and noting the damage is minimal. Hard to debate public emperical evidence.

-Cliff

Someone cut-n-paste this for Cliff's benefit, please.....

Jerry makes a great product. Infi is good stuff.

EVERY edge from the factory that I have gotten has been charitably put, obtuse. The arm hair got "shaved" out of the box, but "scraped" is more like it.

While the points would probably penetrate a concrete block, they also only penetrated about 15 pages of a Seattle phone book.

It costs me almost $100 to get a decent point(swedge grind) and edge put on my Busses by Siegle, which I consider worth it, but please don't hold up Busse knives as the paragon of sharp.

You regularly thrash on obtuse edges, but even my last BTAC from Busse, which is a woods knife configuration, was about 25 thou at the transition.

Best Regards,

STeven Garsson

 

[Torm]

Someone cut-n-paste this for Cliff's benefit, please.....

Jerry makes a great product. Infi is good stuff.

EVERY edge from the factory that I have gotten has been charitably put, obtuse. The arm hair got "shaved" out of the box, but "scraped" is more like it.

While the points would probably penetrate a concrete block, they also only penetrated about 15 pages of a Seattle phone book.

It costs me almost $100 to get a decent point(swedge grind) and edge put on my Busses by Siegle, which I consider worth it, but please don't hold up Busse knives as the paragon of sharp.

You regularly thrash on obtuse edges, but even my last BTAC from Busse, which is a woods knife configuration, was about 25 thou at the transition.

Best Regards,

STeven Garsson

Quoted for Cliff's benefit, as you requested Steve.

 

[Cobalt]

Jerry makes a great product. Infi is good stuff.

EVERY edge from the factory that I have gotten has been charitably put, obtuse. The arm hair got "shaved" out of the box, but "scraped" is more like it.

While the points would probably penetrate a concrete block, they also only penetrated about 15 pages of a Seattle phone book.

It costs me almost $100 to get a decent point(swedge grind) and edge put on my Busses by Siegle, which I consider worth it, but please don't hold up Busse knives as the paragon of sharp.

You regularly thrash on obtuse edges, but even my last BTAC from Busse, which is a woods knife configuration, was about 25 thou at the transition.

Best Regards,

STeven Garsson

I agree with you that Busses have come with inconsistent edges. I have some that came dullish, but I have some that are the sharpest factory knives I have ever had.


If you ask for the zero edge, you will get a severely sharp knife out of it.

Oh and as ugly as the assymetrical edge is, it is the best edge I have ever had. Maybe not the sharpest, but it stays sharper longer than most edges and is easier to touch up. It is just ugly but very efficient.