Friction Forged Blades : CATRA tests

[cds4byu]

And I showed why your numbers and methods are severly flawed and produces not only misconceptions but is unable to actually prove numerically that there is a significant difference, again with a math defination, not an opinion.

-Cliff

I'm sorry, Cliff. I never saw your math definition that showed there is not a significant difference between the performance of the two different blades. Could you please explain it to me again?

Thanks,

Carl

 

[sputnick]

I'm glad the bickering stopped. If my wish came true there would be a lot more threads and makers like this. Three cheers.

To demonstrate that the 20 stroke measurement is consistent, I've included a plot of the total rope cut as a function of stroke number for the first 20 strokes. As you can see, the cutting performance is very linear for the first 20 strokes, and you can see that the proposed "much higher initial performance for s90V" doesn't exist.

What exactly is that a graph of? It looks like it simply logs the total amount of material cut as the test progresses.

In my opinion, the figure that best shows the improved performance of FFD2 compared with the other materials is this one:

On testing a number of different blade materials with our test geometry, we found that a REST value of 3.0 N represented a good mean value for the loss of shaving sharpness. As you can see, FFD2 has significantly more media cut than any other material, and yet has not exceeded a value of 3.0 N. This is also consistent with Wayne's hand rope cutting tests.

My only problem with this chart/test is that you did not test far enough beyond your shaving sharp point for the other steels. Sure the FFD2 remains inside of your cut off for longer, but what actually happens with the s30v and s90v? It would have been interesting to compare the behavior of those steels.

Do you have any micrographs of the before/after edges of the test blades? (I know i'm asking for a lot there.)

 

[Larrin]

I think it would be more interesting to see the FFD2 compared to CPM-M4. It might not qualify much for good comparison for advertizing, because it is only gaining use in custom knives and it is not a stainless, of course, but it would have a combination of wear resistance, high hardness, and edge stability much closer to the FFD2. AEB-L may have extremely high edge stability, but whoever heat treats it probably won't go higher than 60 Rc, which wouldn't be optimal as far as comparing to the FFD2 in this test (higher hardness would make it come closer, it's very tough so there's little danger of going too high), and AEB-L probably isn't wear resistant enough to compete in this test. AEB-L would compete best in push cutting, not slicing, though I guess a push cut is the sharpness test you are using. Also, we're mostly talking about hunting knives, where the slice cut is the major one anyway.

 

[Broos]

Very interesting, informative and entertaining debate... I have to agree with Cliff that the ultimate test is what happens when a person uses a knife.

He doesn't believe real world tests either, as presented by Wayne Goddard, because it does not fit into his own model for slicing behavior, and because WG does not have a scale with 1/10 lb accuracy. All data must fit into his model or it is verboten. Data presented using established, standardized, and accepted by industry methods will be attacked.

So let's see. He doesn't believe in tests done with a machine very similar to CATRA performed by experienced ME PhD PE's with years of lab experience and actual real world accomplishments, and he doesn't believe in real world tests done by a knife legend who has been doing these tests for decades. Despite his objections he does not offer an alternative test.

He uses a shotgun approach. He objects to everything, and hopes something sticks. He objects to points that have little or nothing to do with his main objection, obfuscating every debate. And he has repeatedly pulled the bias card out of his pocket here after his other arguments have been shown to be weak. He has changed his arguments numerous times in this thread, every time without mention or acknowledgement of his previous stance - all this shows a fundamental lack of scientific integrity. His goal is not to advance the general understanding, but to promote his theories and establish himself as the guru.

He has told the Professors that they have a fundamental lack of understanding about steel. He treats them with an utter lack of respect, and not even a veneer of courtesy as prev. stated by STeven.

Then he accuses Wayne G. of bias.

Deep down he is mad because they (like the rest of the entire knife and steel industry) have not forced their data into his model to be presented here. They had the audacity to use the industry standard and did not buy into his simplified cutting model.

He has been arrogance personified in this thread, stridently presenting his previous posts and his own theories on his own website as his basis in accepted theory and established fact.

Cliff, tell us why CATRA, ASTM, ISO, or any other testing or standards organization in the world has not adopted your model and developed new machines to test according to your (still unknown) standards?

 

[Broos]

He has changed his arguments numerous times in this thread, every time without mention or acknowledgement of his previous stance - all this shows a fundamental lack of scientific integrity.

One example:

The amount of material per cut is greater for the FF blade thoughout the test. This test may not be a test of pure edge retention, but it does show that the D2FF blade, in this test, will outcut the other steels throughout the test, out to hundreds of cuts (with the same edge geometry and with the detailed sharpening done).

Cliff replies:

This as noted is simply because it started off sharper. -Cliff

then later...

This should be obvious because if the sharpness and geometry were the same why would the length of material cut be different?-Cliff

As Cliff would say, this statement shows a fundamental lack of understanding about steels.

Now later, after his *ss was handed to him, here is his new conclusion of the data.

Now based on the model and the results you can say that over the course of the material cut that the Friction Forged blade outcut the S90V blade by 30-50% more material under a given amount of work. This would be directly used by the used to infer how much more cutting you would be able to do with the knife with a given amount of fatigue.
-Cliff

So after 6 pages Cliff was able to interpret this data by manipulating it to fit into his model, and came up with the same conclusion he disagreed with 3 or 4 pages previous. Never a mention of his new conclusion contradicting his previous argument.

 

[Broos]

Another...

The biggest problem is number of data points. Really this is not a test of edge retention, but a test of cutting ability using the same sharpening procedures. Doing multiple tests with different baseline sharpening procedures would be interesting.

Cliff replies:

No, I showed in the above how you can perform a proper analysis on such a sample. The biggest problem is that they do not model the results correctly and thus can not make supported conclusions.-Cliff

The model again....

Now later here is his assessment of the data after he was forced to reconsider:

1) lack of data in the initial region where the rate of blunting is high
2) lack of data in the tail region of S90V
-Cliff

Again, no acknowledgement of his change in opinion.

 

[cds4byu]

(Quoting from my earlier post)

What exactly is that a graph of? It looks like it simply logs the total amount of material cut as the test progresses.

You're exactly right. It is the total amount of material cut as the test progresses for the first 20 strokes. I presented it in that format, because that's Cliff's preferred format (see, for example, the following):

Here is the relevant information modeled :

Note how the plot is much smoother and more stable. This is also due to cumulative plots being inhernetly an averaging process plus not plotting two dependent variables. Fitting this data is MUCH more robust because of these two issues and note the model parameters are precisely defined.

Cliff's earlier point was that we had biased the data by leaving out the early data points:

It was stated that the S90V blade does not cut as much material at the start. The first point measured is AFTER 20 CUTS. This is much too far too make such a statement as the initial rate of blunting can be very high for large carbide steels, especially if the edges are acute and/or polished. I would affirm if the cuts were measured at 2,4,8,16 then you would see a much higher initial performance from S90V.

So I plotted the data in Cliff's preferred way for the first 20 cuts. According to Cliff's model, there should have been a very high initial performance that dropped off after 20 cuts. However, the data actually shows a constant increase in the total amount of material cut after each stroke, which leads to a straight line plot. This means that there was no "much higher initial performance" as Cliff attested.

My only problem with this chart/test is that you did not test far enough beyond your shaving sharp point for the other steels. Sure the FFD2 remains inside of your cut off for longer, but what actually happens with the s30v and s90v? It would have been interesting to compare the behavior of those steels.

I agree, it would have been interesting. However, because the wear machine and the sharpness testing machine are two different machines, the test couldn't be fully automated. Every 20 strokes on the wear machine, we had to take the blade out, mount it on the REST machine, measure the blade sharpness, remove it from the REST machine, reinstall the blade on the wear machine, and cut another 20 strokes. In order to minimize the total testing time, we stopped when the blade consistently quit shaving (i.e. had a REST value of over 3.0 consistently). As it was, the testing took months to perform. The other data may have been interesting, but we were primarily concerned about the loss of shaving sharpness.

Do you have any micrographs of the before/after edges of the test blades? (I know i'm asking for a lot there.)

Unfortunately, we do not. The next time we do the testing, I will try to get micrographs before and after. Our microscopy lab and our blade test lab are not at the same site.

Thanks for the questions. Please let me know if I've not been clear.

Thanks,

Carl

 

[PatriotDan]

This has been asked a few times but aint seen answer so... will friction forging be available for all knife manufacturers?

 

[Broos]

Cliff's model is provided below this msg fyi.

Cliff goes on and on about his model of cutting behavior. He insists over and over that industry standard data be manipulated to fit into his model.

Funny, when I was in school we were not as interested into making the data fit into our model, but interested in knowing how things were going to react in the real world. We made the line fit the data, and we did not argue about trying to make the data fit into our theorized model.

The test methods presented here will yield consistent results that model behavior based on real world tests - ie. the CATRA tests or very similar tests. These are the best devices available to consistently gather data about cutting performance. The alternative is a test like Mr. Goddard does. Cliff attacks both of these tests, and of course offers nothing better to actually test performance.

What benefit is there to take this practical and repeatable data, that can be easily related to real world knife use (as Mr. Goddard has shown), so it fits somebody's simplified theory of cutting behavior?

I'll tell you, there is none. Because if you ever want to use the data practically, repeat your results, or collect more data, and do it on a practical and industry standard testing machine, you will have to convert it right back into the form that the Professors presented it here.

Oh I forgot there is somebody who can benefit, the guy who came up with the model. I wonder why he hasn't yet convinced CATRA of his model, and why they have not come up with a machine to test for his mystery coefficients. I'll tell you why, because there is no practical benefit and no greater understanding to be gained by anyone in doing so.

I'm fully aware that Cliff will take my posts, take a few word quote here, and a few word quote there, and refute every single item he can refute using a myriad of nearly incomprehensible arguments. He will not answer or even acknowledge questions he cannot answer, and he will not acknowledge or admit his mistake when he changes his positions once again to battle another assault on his pseudo-science. For this, I apologize to my fellow members in advance.

Bruce

Cliff's model.
-----------

C(x)=Ci/(1+a xb)
Here Ci is the initial cutting ability, which is dependent on the geometry of the knife and properties of the material being cut. The value of a depends on the ratio of the forces Fe/ Fw and along with b depends on the characteristics of the material being cut and the properties of the steel. In general the main influence of b is on long range blunting where a is more important in the short term.

The benefit of using the above model is that the parameters can be correlated to properties of the steels and thus predict behavior. As a starting estimate the dependance of b would be expected to be similar to
b(p,h)~1/(p*h*wr)
Where p is the probability that a carbide will tear out on a given cut, h is the size of the hole and wr is the wear resistance. The probability of carbide tear would be related to the strength of the martensite and nature of the carbides (size/amount), grain size, and other properties. Note this is for slicing, for push cutting this would invert :
b(p,h)~p*h/wr
As in push cuts when carbide comes out the performance drops rapidly as the holes just bind up in the material.

---------------
END QUOTE

 

[PatriotDan]

Broos, you and Cliff not pals then huh ...

 

[cds4byu]

This has been asked a few times but aint seen answer so... will friction forging be available for all knife manufacturers?

PatriotDan,

I can't answer that question. I'm not involved in the business aspects. Right now all the resources involved in doing the friction forging are tied up in getting the DiamondBlade knives to market. There's a fair amount of tooling involved in getting set up, and the process has to be tailored to each individual edge design and blade thickness.

I expect that decisions about friction-forging blade blanks for other knife makers will be handled once the current product line is cleanly established.

Carl

 

[PatriotDan]

Thanks Carl :thumbup:

 

[cds4byu]

A lot of you have wondered about market timing, etc. Here's a press release from DiamondBlade that may answer some of those questions.

DiamondBlade Press Release

Please be aware that this is a press release, not a scientific paper, so there may be opinions expressed and claims that may not be substantiated by the material included in the release. However, if the release raises any technical questions, I'll be happy to do my best to provide data and analysis that support the claims with which I'm familiar.

Thanks,

Carl

 

[sputnick]

PatriotDan: Grinding a blade out of flat stock with several different areas of hardness ranging from ~40 to ~67 without ruining any of the tempers would be interesting and likely not fun if done by hand in a custom shop. As for sharing the steel blanks or process with other manufactures, that doesn't make much business sense especially when the product is brand new. If DiamondBlades is making a product everyone wants why share it? Same with INFI and their heat treating process. Of course, since the FF process is done directly on the edge the maker would have to submit a blade design to the manufacturing house and all the maker would be doing is forming the final bevels, finishing, and handling...making it even more unlikely that "sharing" would occur, at least in the near future.

cds4byu: Crystal clear, thank you. How long does a single run of one test blade take? I would expect the most time consuming part of the process would be in having to move the blade from one apparatus to the next and back again, repeatedly. Micrographs are certainly one of the handiest diagnostic tools around for actually determining edge condition, if not extraordinarily impractical.

 

[PatriotDan]

Sputnick ,that's exactly why I asked it. To see If DiamondBlades is going to go INFI on it

 

[Kohai999]

Sputnick ,that's exactly why I asked it. To see If DiamondBlades is going to go INFI on it

While I understand your meaning, we have to be clear.

INFI is a steel. FFD2 is a process. It doesn't seem that anyone is calling DiamondBlade knives a different steel, just that it is subjected to a process that makes very desireable changes in it.

It is MUCH easier to farm out a steel, than it is a process for working it. Jerry Busse controls the steel very closely, but he HAS let some pieces of it out for custom makers.

It is very unlikely that DiamondBlade would do this for a variety of reasons, but it WOULD stand to reason that they would eventually let makers contribute designs for consideration of production, resulting in a limited, yet mutually satisfactory increase in models offered.

Best Regards,

STeven Garsson

 

[cds4byu]

cds4byu: Crystal clear, thank you. How long does a single run of one test blade take? I would expect the most time consuming part of the process would be in having to move the blade from one apparatus to the next and back again, repeatedly.

I've not done the tests myself (DiamondBlade hired technicians to run them). I think you're right that the most time-consuming part of the process is the switch from one machine to the other.

If I were to go into knife sharpness testing in a big way, I'd probably design a machine to do both the ERT-like wear testing and the REST sharpness test in an automated fashion, by moving the blade from one station to another. But it would be a reasonably expensive machine, and nobody that I know of wants to pay for its development. After all, sharpness testing is a cost center, not a profit center.

Carl

----------------------
It is not necessary to believe things in order to reason about them
It is not necessary to understand things in order to argue about them.
- P.A. Caron de Beaumarchais, French Author, 1732-1799

 

[Kohai999]

If I were to go into knife sharpness testing in a big way, I'd probably design a machine to do both the ERT-like wear testing and the REST sharpness test in an automated fashion, by moving the blade from one station to another. But it would be a reasonably expensive machine, and nobody that I know of wants to pay for its development. After all, sharpness testing is a cost center, not a profit center.

Carl

Here we get somewhat into my area of knowledge and understanding. The way to get the funds to develop a machine like this is to either go to the sharpener manufacturers(Norton, Seippmann....) or the cutlery manufacturers(Buck, Benchmade, Gerber, Kershaw, Spyderco......) and make the argument convincingly of your service/machine.

It can be done.

Best Regards,

STeven Garsson

 

[PatriotDan]

While I understand your meaning, we have to be clear. INFI is a steel. FFD2 is a process.

Got it, like the SR-77 and SR-101.

 

[Kohai999]

Got it, like the SR-77 and SR-101.

Well, on Scrapyard Knives to produce SR-77, they call what they do "Transversion Wave tempering". I don't know what that is. I seem to remember that they started out with S7 shock steel as the base for the blades.

As far as I have been able to follow, the Friction Forging process is proprietary, and has not been used on knives before. That would make this process unlike any other, again AFAIK.

Best Regards,

STeven Garsson