Agent : Bob Dozier

[Cliff Stamp]

Not to sound like a smart a$$ Cliff, but of course the knife tip of that D2 Agent broke off when you tried to carve a bowl with it and pry out a chip of wood. For one thing it is D2 tool steel known for being brittle, and for another it is the "Agent" model. I don't think Bob had in mind carving bowls or flicking out chips of wood with that particular model when he designed it Cliff. He probably had more in mind concealed carry for back up as a tactical knife for an on duty police officer or undercover 'agent'.

I asked him what it was meant to do before I used the knife, his exact description was "tactical utility".

On the same note, you can't tell me that you didn't know that tip was going to break off or at least suspect that it would before hand in that particular test using a D2 knife blade.

It wasn't expected on that wood, with that penetration with the light force used. To be specific here is the part of the review you referenced :

"A note of caution however, during an attempt to make a bowl in a soft-medium density piece of pine, the tip of the Agent snapped off readily under light force. The knife had been pressed a quarter inch into the wood and an attempt was made to pry the chip up. About a half a centemeters of blade was lost, the knife was ~0.05" thick at the break point. The blade had a very slight bend in the tip, just a degree or two, barely visible. Thus when working with woods, either cut / score the surface to weak it, or keep the digging very shallow."

A lot of things like this though are hard to understand quantitatively, it would be informative if I had small vid clips to show just how easily it was being used.

Also as noted in the review, the work was then handled with another D2 blade with a similar tip geometry. I also noted how the work could be done with the same knife without inducing damage which is one of the goals of the reviews, they are not simple promotional tools.

That was the wrong test for this steel and this knife ...

Even when I know the knife would fail, I often still do the work as I don't simply do the reviews for me. They are also meant for users with different levels of experience who quite frankly might not expect the performance.

Take a look around the internet, there are lot of places where you can see D2 as being described as very tough, what this actually means has wild variations, so do terms like "tactical", "utility", "survivial", "emergency" etc. .

The thing that amuses me most about your post is that recently, as within the last few days I have recieved harsh critism from doing exactly what you seem to want, limiting performance due to what I knew would happen, I then get lambasted for "extrapolating".

Bob Dozier been around long enough to know how to make a good knife. Testing his knives IMO is unnesscessary.

Have not seen you post this on the positive reviews of his knives, nice to see as a maker you are unbiased in your perspective on feedback.

Yes, light carving in woods, cutting ropes, cardboard, various foods, plastics, etc . Obviously there is no way anyone would ever do that extreme use with a "tactical utility" knife.

Lots of makers with as much or more experience than Dozier constantly have their knives evaluated, possibly because they believe they don't know everything yet and might have something to learn.

Plus there are new knives being offered constantly, so it is obviously valuable to compare well known products to the newer offerings and see how the performance compares.

-Cliff

 

[STR]

I don't mean to what did you call it? Lambast. Whatever that means. I am not trying to berate you. I just feel that D2 is too brittle for that test.

Last few knives I've bought all came with a statement reminding the buyer that knives were for cutting and that they were not "pry bars".

And being a carver and whittler myself I can tell you that you don't make a bowl by doing it that way anyway. What you do is make straight cuts deep into the board. Then you slice into them to take the chunk out going deeper with each slice. When you have sliced to the depth of the first straight cut you make another straight cut and go deeper. In a survival situation a square bowl for holding liquids or food works fine. You can round it off later. No prying is necessary to make a bowl. Pry tests are particularly questionable with knife blades. Particularly with known brittle steels. I think that is why most manufacturers void warranty coverage if the knife is used to pry with.

 

[Cliff Stamp]

I don't mean to what did you call it? Lambast.

No that was in reference to the other ones, you were just stating a difference of opinion on scope of work in a review. That is fine, everyone wants to see what mosts interests them.

Last few knives I've bought all came with a statement reminding the buyer that knives were for cutting and that they were not "pry bars".

I don't think the above situation requires a pry bar, if I had jammed the Agent into a tree and walked on it, that would be more of that kind of situation and obviously kind of odd as who would not think it would break in such a test. Of course you can do intentional breaks to check flexibility of the steel.

Very few knives however are meant to actually not do any prying, if this is really the case then you want really thin stock, full height grinds and full distal tapers. The Agent is overbuilt if it was to do no prying.

The warnings on prybars are there to give the makers and manufactures essentially a use limit for warrenty concerns. You actually have to pry with a knife if you cut anything stiffer than paper, few blades can't flex at all before they snap.

And being a carver and whittler myself I can tell you that you don't make a bowl by doing it that way anyway. What you do is make straight cuts deep into the board. Then you slice into them to take the chunk out going deeper with each slice. When you have sliced to the depth of the first straight cut you make another straight cut and go deeper.

I described cutting a hole directly after the break. It is just more efficient to pop pieces out if you don't actually have a curved blade to whittle one directly. Depends on the knife of course, with a light hunter with a full distal taper you have next to no point strength so you have to cut it out as the tip can't lift a chip.

-Cliff

 

[Dalko]

Charpy values measure strength and resistance to fracture at the same time. This is why they drop with lowering of HRC values. It isn't that the steel tends to facture easier, however the strength is lower so it bends easier when the hammer hits it.

Charpy values are a good place to start from, but you also want to look at the steels in use, try them out for a few HRC values and see where the performance goes. This is one of the reasons that you should ask a maker what testing he has done and what HRC they have looked at.


I have tried it at the lower values and the toughenss and flexibility isn't there. Busse used to run it pretty hard and they have high standards so it would seem sensible to me. I would not use A2 for a heavy knife anyway, get A8 or better. The toughness difference between Missions A2 and Johannings A8 is extreme.

-Cliff

Isn't the Young modulus the only one factor that determine the flexing strength of steel?

If we take two steel bars of the same steel (let's say 1095 for example) but one annealed and the other one heat treated to 60HRC, I think both will need the same force to be bent, but the annealed one will stay bent where as the heat treated one will return back to true if the elastic limit is not passed, but both will have needed the same amount of force to be bent (because the Young modulus does NOT change with heat treatment), right?

Concerning A8, would you favor A8 over 3V for a heavy use knife?

 

[Alpha Knife Supply]

STR & Scott,

How dare you question anything Cliff tests! Your experience, knowledge and logic mean nothing!

The mighty Cliff hath written it.
So let it be written, so let it be done by Cliff doing something the knife and/or steel was never intended to do.

 

[Blop]

Isn't the Young modulus the only one factor that determine the flexing strength of steel?

If we take two steel bars of the same steel (let's say 1095 for example) but one annealed and the other one heat treated to 60HRC, I think both will need the same force to be bent, but the annealed one will stay bent where as the heat treated one will return back to true if the elastic limit is not passed, but both will have needed the same amount of force to be bent (because the Young modulus does NOT change with heat treatment), right?

Concerning A8, would you favor A8 over 3V for a heavy use knife?

I want to know too!!!!

 

[Gossman Knives]

STR & Scott,

How dare you question anything Cliff tests! Your experience, knowledge and logic mean nothing!

The mighty Cliff hath written it.
So let it be written, so let it be done by Cliff doing something the knife and/or steel was never intended to do.

Give me a fricken break Reading this stuff makes me :barf: Anybody with an once of common sense can do these test for themselves. Listen to a real world user that's who counts.
Scott

 

[Cliff Stamp]

If we take two steel bars of the same steel (let's say 1095 for example) but one annealed and the other one heat treated to 60HRC, I think both will need the same force to be bent...

The annealed one has pretty much no elastic region and thus the stress strain curve immediately goes nonlinear and thus the force required to keep bending it will decrease rapidly compared to the hardened one which has the force increase linearly until it starts to plastically deform and this point increases with hardness.

Concerning A8, would you favor A8 over 3V for a heavy use knife?

Based on what I have seen with 3V, it looks impressive on paper, but A8 has performed better in the actual knives. With large knives wear resistance isn't that critical and just leads to machinability issues so in general simpler steels usually have the required performance anyway. Of course if you can get higher wear resistance with no cost then why not. With all such issues ask the maker and see what performance they will guarantee. If you can find someone that will support 3V at the level you want then there is really little risk in checking it out, and even if you are not satisfied, the knowledge gained is usually worth the shipping and handling.

-Cliff

 

[brownshoe]

Hey Mr. Razorback, Give us a break and explain your negative remarks. Again, why shouldn't someone test a Dozier knife.

Based upon your comment about the relevancy of the tests, I went back and re-read Cliff's review. A "tactical utility knife" could be expected to hold up against in fairly tough prying conditions, such as crates, door and window sills, maybe even a car door. The tip broke making a bowl. The only thing he did that I wouldn't consider "real world" is to use it as a billhook attached to a pole. However, in NF that may be a "real world" test.

As you said all the other tests are simple, and anyone with common sense can do them. So what's your problem with the tests? What tests should have Cliff done with a tactical utility blade? Strider or Swamp Rat would say we should chop concrete, pry open car doors, open paint cans, puncture 50 gallon drums...right?

Alright, I'll say what everyone is thinking. Dozier is a mythical hard use knife maker. This knife had tip breakage under conditions that are not extreme. Dozier is a mythical maker of great sheaths. This sheath dulled the edge of the knife due to poor construction. So what does this prove? Dozier and his shop crew are humans, not gods of knifemaking.

 

[Cliff Stamp]

"tactical utility knife" could be expected to hold up against ...

This has to be one of the most contested labels on Bladeforums, some people are really aggressive with it, and for them it means does not fail even in the harshest conditions, to others it just means it has a certain look. Some makers are really specific like McClung who has a checklist; cut proof sheath, insulated handle, etc. .

I wish people would forget about undefined labels and give a small blurb with each knife, tell exactly what it was designed to do optimally, the kinds of things it can do but for which you would be better off with a different knife, and the kinds of things it is really unsuitable for and what is likely to happen if for whatever reason you really need to do it.

Dozier specifically doesn't push the prying, hammering aspect, he is pretty upfront about the knives cutting well, having high edge retention and quality sheaths as the main aspects. I have however seen some of his customers get more aggressive including cutting into and through bone, batoning through heavy knots, etc. .

What I don't get is the contention at doing something that you know is going to cause a problem. It isn't like I am demanding a replacement for the tip breaking, you would have an arguement there as it is not fair to demand compensation for performance never stated which isn't reasonable. However as for the first asumption, based on the same logic I should not do a cutting test because everyone knows the knife cuts well also.

On a quick check before I did the review I called up every post here which reviewed his knives, some of them did lots of things which most people would not be surprised with but were very positive. Not once did I see RazorBack Knives comment that it was unnecessary to do such work to evaluate the knife, or complain about it in any way. The bias for negative vs positive is very clear.

And again, not everyone knows what to expect. Not everyone knows his knives, not everyone knows about D2, and even if everyone did, it doesn't hurt to do a consistency check every now and again, there are problems inherent in steels which the maker has no control of, and lots of other similar issues which can cause problems even if the maker does everything right. Plus it serves as a informative benchmark for other new makers.

-Cliff

 

[Gossman Knives]

Brownshoe, first off the word tactical doesn't mean squat. It's a marketing term. It's a generic word used for the look of a knife. Police officers carried the Buck 110 long before the so called 'tactical knife" came about. As far as I'm concerned use the right style knife for the job at hand. Mr. Dozier is known for his thin hollow grind. If you look at it and see how thin the tip is why in the hell would you pry with it? I've been selling knives at gunshows for over 8 years. I wish I had a dollar for every person that told me they broke the tip off their buck 110 trying to split the pelvic bone. Case in point, wrong tool for the job. Yes you can split the pelvic bone with a knife but not with the point. Hey I'm not against field testing, but when you do something the knife is not intended for you make it look bad for the buying public.
Scott

 

[Dalko]

I know guys that what I'm discussing with Cliff has become off topic and I apologize for that, but Cliff could you please clarify something for me? You said:

(...) the force increase linearly until it starts to plastically deform and this point increases with hardness.

-Cliff

What I understand from this, is that the elastic limit increase with hardness, but when forgers soften the spine of a big chopper for example, isn't it to give the blade more flexibility (increasing the elastic limit)? Isn't it in contradiction with what you just said?

 

[Ebbtide]

nevermind.

 

[Jeff Clark]

When forgers draw the temper on the spine of a blade they are lowering the elastic limit so that the blade bends plastically sooner. In a sense they are weakening the blade to reduce the likelihood that it will crack. They are not increasing the elastic flexibility of the blade. They are increasing the plastic ductility of the steel.

The Young's modulus of steel tends to be the same whether it is hardened or not up to some point like say 20,000 pounds per square inch. At that point the unhardened steel stops stretching elastically (it stops being able to spring back to its original shape) and starts to stretch plastically (sort of like taffy). This is where the unhardened steel starts to work harden while also tending to thin a bit faster as it is stretched beyond its elastic limit. The stress/strain curve stops being a nice straight line at this point (becomes non linear). A prime way of saying that it is nonlinear is that if you release your tension on the sample the elongation does not go to zero as the tension goes to zero (it has taken a set).

When you harden the steel you increase the elastic limit, you don't change the baseline Young's modulus. One way of looking at it is that you can make equivalent coil springs out of 1095 at any hardness from about 20 RC (or whatever it is annealed) up to about 68. If you drop the springs on a table from about a quarter inch height they will bounce about the same. If you raise the spring up to an inch or two the soft springs will fail plasticaly, get shorter and not rebound as high, but they won't break. The 40 RC through 68 RC springs will bounce about the same. If you drop the harder springs from about a foot or so the 68 RC springs will break and not rebound, the soft springs will get even flatter and the ones in the middle will bounce about the same. As you go higher you will break the 66 through 56 RC springs and flatten some of the ones below the mid 40's RC. You will eventually find that somewhere in the high 40's (maybe very low 50's) you get the most bounce with the highest margin away from breaking. We'd call that a spring temper. It would not make a good hard edge, but it would make a springy pry bar. That is the hardness a forger wants for the body of his blade while he wants the elastic limit on his edge to be even higher so that it will not roll over under pressure. So when he has his edge at 60 RC it has a higher elastic limit than the spine at 48, but the same Young's modulus.

The trick is that plastic deformation allows metal to move around to even out the load. This reduces sensitivity to irregularities in the metal and irregularities in the shape of the metal. It reduces the tendency for cracks to concentrate stresses and for cracks to spread and break the metal.

 

[STR]

Cliff.

There is a lot of what you do that is very informative and or educational. It just puzzles me sometimes to see you do something like this tip snap. That is all I was ever saying. I felt that you had to know that D2 steel ground that thin and at that Rc hardness would snap in that bowl test. I know guys that have broken the tips of their D2 knives from Bob, from Knives of Alaska and other makers using this steel just trying to stick them into a log or rough sawn table top while they were using it so they could free both hands up temporarily.

That is how easy D2 snaps. It is very brittle steel at the 60 plus Rc hardness and the sole reason I've been saying all along that Queen is making a mistake by manufacturing so called Whittlers out of this steel in their three blade folders. Three very thin and very hard blades I might add. I've read numerous reports of the tips snapping under otherwise normal delicate work with these folders. Some of those reports are posted here on the BF. So in that light I'm not holding it against anyone that the tip on this Agent knife broke like it did.

I'm just shocked that with the experience of the person doing the test that he didn't know how 'fragile' and brittle this steel was and realize that indeed the tip wouldn't last for one or two flicks in this type of task.

I like D2 for the edge it keeps but for me it is just like a file in your shop. You drop a file on the concrete floor what happens? It snaps. Pretty much the same thing with a D2 blade at a 60 plus Rc hardness too. For me that is a big red flag. D2 at is best working hardness to be a knife is too brittle for a tactical or survival type of knife in my opinion; let alone a combat one.

Don't get me wrong. D2 does cut and hold an edge very well when properly heat treated. Hell I've used a White River Skinner from Bob that I got from A.G. Russell for the last few years on my deer and it works great for cutting and does hold an edge well compared to any other knives I've used. Honestly though Bob is fooling himself thinking he can sell this steel in the survivalist tactical or combat market along side the Striders, Emersons, Busses and Jones Bros stuff I've seen.

D2 just won't hold it's own for the many facets needed in a real tough survival or combat/tactical tool. I mean would you make a sword, even a short one out of this steel? I don't think so. One wack the right way from another and you have two halfs. One half in your hand and the other on the ground. You may have three pieces by the time the other hits the ground depending on how it falls. In a hand to hand combat situation for heavens sake don't drop that D2 blade on the ground. If you do pray that it hits the sand and not something hard.

I'm afraid D2 will never be anything other than a very good cutter and edge keeper. There are better choices for survival, weapon back up, and tactical and or combat knives. (I hate that word tactical but it fits here since Bob said that is what the knife was for "Tactical utility"!)

 

[Gossman Knives]

Cliff, why don't you post pics of you doing your testing. I think it would be more believable if it could be seen. I looked at your site, no pics, just the knives. What's up with that? I didn't do a search on BF, but from recent tests by you again no pics. Let's see you testing in action instead of typed words. It might make it more satisfying.
Scott

 

[Dalko]

When forgers draw the temper on the spine of a blade they are lowering the elastic limit so that the blade bends plastically sooner. In a sense they are weakening the blade to reduce the likelihood that it will crack. They are not increasing the elastic flexibility of the blade. They are increasing the plastic ductility of the steel.

But why do folks say that a drawn back spine blade is more flexible than a thru hardened one?

And when people say « more flexible » does that mean the blade is easier to bend or can be bent farther without taking a set?

 

[Gossman Knives]

Dalko use this as an example take a Twizzler licorce stick and a wooden dowel rod of the same size. Bend them, which one will break first? Kind of a silly example but it's along the same line. With the back softer it has more flexibilty.
Scott

 

[Jeff Clark]

When they say that the spine is more flexible they mean more flexible like a piece of copper wire not more flexible like a spring. I remember when I first ran across this shocking realization. I was in my early teens and saw adds for a wonder knife called a "Norse King". It was made out of laminated Swedish steel. It took an incredible edge, you could hammer the edge through a coin, and you could bend the blade 90 degrees without breaking it. I just had to have one of those. When I got it in the mail I was incredibly disapointed when I found that it didn't bend like a spring. It was probably the easiest to bend knife that I owned. With my fingers I could bend it to take a set. I think I might have even phoned or written to the company to be sure that I didn't get a defective knife. Nope, that is just how you make a knife that can bend 90 degrees without breaking, you have to make at least the outer surface of the thicker parts soft.

 

[Dalko]

When they say that the spine is more flexible they mean more flexible like a piece of copper wire not more flexible like a spring. I remember when I first ran across this shocking realization. I was in my early teens and saw adds for a wonder knife called a "Norse King". It was made out of laminated Swedish steel. It took an incredible edge, you could hammer the edge through a coin, and you could bend the blade 90 degrees without breaking it. I just had to have one of those. When I got it in the mail I was incredibly disapointed when I found that it didn't bend like a spring. It was probably the easiest to bend knife that I owned. With my fingers I could bend it to take a set. I think I might have even phoned or written to the company to be sure that I didn't get a defective knife. Nope, that is just how you make a knife that can bend 90 degrees without breaking, you have to make at least the outer surface of the thicker parts soft.

So, what I understand is that having a drawn back spine blade offers the only one advantage of not breaking but plastically deform when bent too much, right?

It doesn't need greater force to bend it nor it will bend farther without taking a set... it will only bend farther without breaking, right?