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Wayne, I would like to welcome you and say how good it is to have someone with your knowledge taking part on this forum. I will keep my open for your posts.
-
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Friction Forged Blades : CATRA tests
- Thread starter Cliff Stamp
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@cds4byu
Just for Information
here is the link to Verhoevens publication
http://www.damaszener.de/projekte.html
See his data upon stainless. page 128 ff you will find definitons and why D2 is not a stainless.
And what i said in the first post ths saturation of Cr is higher so there of course a difference in corrosion resistance.
Just for Information
here is the link to Verhoevens publication
http://www.damaszener.de/projekte.html
See his data upon stainless. page 128 ff you will find definitons and why D2 is not a stainless.
And what i said in the first post ths saturation of Cr is higher so there of course a difference in corrosion resistance.
Cliff Stamp
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Here is the FFD2 and CPM S90V modeled :
There is no statistical proof that the FF blade has superior edge retention because the blunting factors are too uncertain because of a combination of three factors :
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
3) high uncertainty in the data
In regards to the initial low cutting ability of S90V. Based on examining the actual data there is a misconception in the above. 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.
The above data is also a very poor way to compare the blades because what it does it take two dependent variables which are highly noisy, divide them and magnify the noise and then plot essentially two dependent variables so now both the x and y axis are highly noisy. This actually reuquires very complex methods to fit properly even with simple models because this adds another element of nonlinearity into the problem. What should have been plotted is just the stroke count and amount of media cut. This would give a much smoother curve as the x axis variable is independent then and has no noise. It is also much more straightforward to rationalize as it just shows how much media is cut after a certin amount of passes.
The above graph attempt to show the sharpness after a certain amount of media is cut but as I noted it magnifies the noise and introduces an additional nonlinearity. I'll look at the other data shortly.
Have you tested a mild steel blade. Would you have any doubt that it would be inferior in CATRA tests? Considering that Roman has quantified edge stability based on carbide volume fraction and grain size it isn't unreasonable for him to speak of behavio on those issues.
As I said several times in the above, and noted in detail in the sharpness article, there is push cutting and slicing sharpness and you can be very high in one and low in another. If the slicing aggression is much lower initially, regardless of the push cutting test, it would indicate improperly formed edges which you would verify under magnification.
At the angle you noted FFD2 will easily outperform AEB-L because the edges are inherently stable.
Wayne, given the highly nonlinear behavior of blunting I would be really skeptical of a cutting ratio estimate within 5% by hand, especially on a scale which has a best the ability to measure sharpness several times that coarse an estimate. Just consider the following.
Lets assume your knife starts off at 5 lbs to slice through 3/8" hemp. You stop cutting once it reaches say 10 lbs. Now out of that first 5 lbs, about 1 lbs is for the sharpness. Thus you went from 1 lbs to 6 so your sharpness is 15% of the initial. Note that even a 1 lbs increase in force then corrosponds to a degredaton of 50% in sharpness.
In order to work at the 5% level you would need to be able to look at 1/10 of a lbs or so and this is just the start because that is just your measurement requirements and doesn't take into account the random variations in the steel, sharpening, cutting methods, and material.
As an example of the kind of variation seen in machine data, see Landes data where the variance is so high that steels switch places in terms of which is superior because of the influence of the random nature of how many carbides intersect the final sharpened edge line.
Have you verified your precision by some simple methods to remove any subjective bias. There are a couple of things you can do readily to ensure that you are not in any way effecting the results by personal judgement.
-Cliff
There is no statistical proof that the FF blade has superior edge retention because the blunting factors are too uncertain because of a combination of three factors :
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
3) high uncertainty in the data
In regards to the initial low cutting ability of S90V. Based on examining the actual data there is a misconception in the above. 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.
The above data is also a very poor way to compare the blades because what it does it take two dependent variables which are highly noisy, divide them and magnify the noise and then plot essentially two dependent variables so now both the x and y axis are highly noisy. This actually reuquires very complex methods to fit properly even with simple models because this adds another element of nonlinearity into the problem. What should have been plotted is just the stroke count and amount of media cut. This would give a much smoother curve as the x axis variable is independent then and has no noise. It is also much more straightforward to rationalize as it just shows how much media is cut after a certin amount of passes.
The above graph attempt to show the sharpness after a certain amount of media is cut but as I noted it magnifies the noise and introduces an additional nonlinearity. I'll look at the other data shortly.
Have you tested a mild steel blade. Would you have any doubt that it would be inferior in CATRA tests? Considering that Roman has quantified edge stability based on carbide volume fraction and grain size it isn't unreasonable for him to speak of behavio on those issues.
As I said several times in the above, and noted in detail in the sharpness article, there is push cutting and slicing sharpness and you can be very high in one and low in another. If the slicing aggression is much lower initially, regardless of the push cutting test, it would indicate improperly formed edges which you would verify under magnification.
At the angle you noted FFD2 will easily outperform AEB-L because the edges are inherently stable.
Wayne, given the highly nonlinear behavior of blunting I would be really skeptical of a cutting ratio estimate within 5% by hand, especially on a scale which has a best the ability to measure sharpness several times that coarse an estimate. Just consider the following.
Lets assume your knife starts off at 5 lbs to slice through 3/8" hemp. You stop cutting once it reaches say 10 lbs. Now out of that first 5 lbs, about 1 lbs is for the sharpness. Thus you went from 1 lbs to 6 so your sharpness is 15% of the initial. Note that even a 1 lbs increase in force then corrosponds to a degredaton of 50% in sharpness.
In order to work at the 5% level you would need to be able to look at 1/10 of a lbs or so and this is just the start because that is just your measurement requirements and doesn't take into account the random variations in the steel, sharpening, cutting methods, and material.
As an example of the kind of variation seen in machine data, see Landes data where the variance is so high that steels switch places in terms of which is superior because of the influence of the random nature of how many carbides intersect the final sharpened edge line.
Have you verified your precision by some simple methods to remove any subjective bias. There are a couple of things you can do readily to ensure that you are not in any way effecting the results by personal judgement.
-Cliff
Cliff Stamp
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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.
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.
It is also possible from the model (just use the equations) to find the other intercepts if so desired. If it is unclear then just ask and I can perform the required calcuations.
-Cliff
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.
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.
It is also possible from the model (just use the equations) to find the other intercepts if so desired. If it is unclear then just ask and I can perform the required calcuations.
-Cliff
I for one give Wayne G’s method much more credibility than all the graph and model mumbo jumbo. Wayne G. takes the knife in his hand and cuts until he feels it is dull, and then measures how much was cut. Then does the same thing again. I’ll trust honest experience over the other stuff any day.
Cobalt
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any steel that has the edge retention of S90V is more than most people would ever need and that is great. However, I hope that it is not like S90V in it's ability to resist sharpening as well. I can attest to S90V, it's old version 440V, and 420V being big pains in the ass when it came to resharpening. But I have to admit, I did like my serrated 440V Spyderco military because it would cut rope fo over a month without ever needing a touch up. It seemed like it would never dull. The diamond sleeves on my spy sharpmaker were the only way to go.
Cliff Stamp
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The sharpening issues are mainly an issue of suitability of the steel to the type of knife. Wilson's S90V knives sharpen very easily as they are quite thin at the edge and ground at acute angles. You also need knives with a high carbide volume to be very hard as otherwise there are issues with excessive burr formation. The latter is obviously not a problem for this forumulation of D2. I am curious though as to the reason for the benefit, I would really be interested to know the exact heat treatment of the S90V blade and the resulting hardness.
-Cliff
-Cliff
I've quickly read the 6 first pages, and I may have missed some details, so sorry if this have already been addressed
but have anyone already answered following questions:
1) in ERT test (fig2) how blade with same geometry can have different results on the first stroke (I have some speculations about it, but I'd like to "hear" a documented answer)?
2) since test is about edge retention shouldn't the blades be prepared (sharpened, heat treated...) in a way that they display similar initial sharpness?
3) Or is it that Friction Forging would systematically get better initial sharpness for same geometry (which seems a bit odd a priori, since you would rather expect the qualities to show in the long run,- but who knows?)?
but have anyone already answered following questions:
1) in ERT test (fig2) how blade with same geometry can have different results on the first stroke (I have some speculations about it, but I'd like to "hear" a documented answer)?
2) since test is about edge retention shouldn't the blades be prepared (sharpened, heat treated...) in a way that they display similar initial sharpness?
3) Or is it that Friction Forging would systematically get better initial sharpness for same geometry (which seems a bit odd a priori, since you would rather expect the qualities to show in the long run,- but who knows?)?
I give up!
I find that all this additional nonlinearity, the highly noisy variables, initial rate of blunting has caused my misconception in the above. Then I considered the quantified edge stability based on carbide volume fraction and I got a headache. I find I have subjective bias so I’m going to take my slicing aggression out on some rope.
Wayne G.
I find that all this additional nonlinearity, the highly noisy variables, initial rate of blunting has caused my misconception in the above. Then I considered the quantified edge stability based on carbide volume fraction and I got a headache. I find I have subjective bias so I’m going to take my slicing aggression out on some rope.
Wayne G.
Well done Cliff it seems your accusatory argumentative posts have run off another very knowledgeable poster. Wayne please ignore him and continue posting your posts are valued by many here. Cliffs misleading posts, lies, and self promoting circular logic isn’t taken seriously by too many.
I have faith that reason will prevail and overcome the blizzard of non relevant opinions, tables and graphs.
As an example, Roman quotes from a source to prove that D2 isn’t stainless. Careful reading would have him considering that stain resistance was claimed only for the FF section of the blade. Reality is that three weeks in salt water has no effect on the hair shaving edge on FFD2.
As an example, Roman quotes from a source to prove that D2 isn’t stainless. Careful reading would have him considering that stain resistance was claimed only for the FF section of the blade. Reality is that three weeks in salt water has no effect on the hair shaving edge on FFD2.
Cliff Stamp
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I noted this in the above, what they are plotting is disceptive, it isn't what you think it is displaying. The plot is actually not dependent vs independent, it is two dependent variables and very misleading. It implies that the initial slicing sharpness is low for S90V, however the first point is actually the sharpness THROUGH the first 20 cuts, not the behavior at the start which is what the graph implies.
Wayne, let us not be so naive here. How many makers and manufacturers are constantly making huge statements of performance. Do not tell me that you believe everything that you hear in the industry. I have head on more than one occasion of performance benefits of more than 10:1 based on steel or heat treatment or some forging benefit. Read Cashen's article on the Hype in the industry now.
It is hardly unreasonable to ask for the actual material science to explain the performance. In fact this should be the EXPECTED and welcomed behavior on the forums. It is also hardly unreasonable to wonder about the stain resistance of D2 when even if ALL the chromium was in solution (which is no the case clearly) it would still not be corrosion resistant compared to the existing high stainless cutlery steels.
Because of this question being asked more information was obtained, and it was proposed that there was a galvanic facor in the blade. If this is indeed the case then it would also be of benefit to the user to know the main body of the blade is actually going to be lower than regular D2 in regards to corrosion resistance.
-Cliff
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And exactly how will this comment improve the tone in this thread? Given the source and the history involved, I expect a rapid descent into egroup hell. Why don't you guys just take it out into the parking lot?
Gordon
Sal Glesser
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Very interesting thread. thanx for posting.
A little passion is good, right
SSSSOOOOooooooo......
When is some of this "stuff" going to be available for a small production house to take a stab at doing a run?
sal
A little passion is good, right
SSSSOOOOooooooo......
When is some of this "stuff" going to be available for a small production house to take a stab at doing a run?
sal
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I want a "stuff" sandwich between two pieces of FRN. Where's our waitress?Very interesting thread. thanx for posting.
A little passion is good, right
SSSSOOOOooooooo......
When is some of this "stuff" going to be available for a small production house to take a stab at doing a run?
sal
- Joined
- May 9, 2000
- Messages
- 29,205
Will FF D2 be available to purchase as stock so that it can be used by knifemakers?
This is something that I may have missed, but how was it determined that D2 was the best steel to use in the Friction Forging process?
I did not see any contact info for DiamondBlades, LLC, though I did notice that someone had managed to phone them. Would it be possible for someone to post the contact info, or to email it to me?
http://www.bladeforums.com/forums/sendmessage.php?do=mailmember&u=110840
This is something that I may have missed, but how was it determined that D2 was the best steel to use in the Friction Forging process?
I did not see any contact info for DiamondBlades, LLC, though I did notice that someone had managed to phone them. Would it be possible for someone to post the contact info, or to email it to me?
http://www.bladeforums.com/forums/sendmessage.php?do=mailmember&u=110840
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Not saying I agree with Cliff, but where exactly did you find that? I looked back through and the closest I could find was that the graphs are deceptive because of the way they're set up, and he didn't even say it was intentional.
Thomas W
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If I misinterpreted this, I apologize.
He didn't say it wasn't either. I take plotting as intentional.Jared Stenoien said:
Wayne's word is solid in my book, everytime.