M390 VS ZDP-189 Rope Cutting - Informal testing

[DennisStrickland]

thanks to gunny bob for the interesting very probable variant in vassili's testing.it would be interesting to see if the amount of defecation leaving vassili's rear orifice was equal in volume to the defecation emitted by his oral orifice.
dennis

 

[J.Mattson]

If I may for a moment be so bold, Jim, I'd like to pass along some information gleaned from an acquaintance of mine, who is a Tribologist currently doing research at the University of Florida. Tribology is of course the science that measures interacting surfaces in relative motion, and Dr. Dan logged into Bladeforums upon my urging to have a look at your results. He was most interested in the toilet tissue cutting and after consulting his reference materials came to the definitive conclusion that the reason Vassili's TP slicing differed from yours was due to a lessening of the coefficient of friction due to the high probability that Vasseli's was used.

Came very close to squirting coffee on the key board there…

 

[unit]

Thanks, I guess I got it. I do not think I am interested any more. Have a fun.

Vassili.

Astounding! To think this is all it takes?

Perhaps the funniest thing to me is that the differences in how a hair reacts to an edge may be FAR more attributable to hair than the edge. Talk about variables...

Seems that perhaps "heritage" could be a relevant discussion item?

 

[hardheart]

This is why abrasive attitude's like Vassili's really get in the way. Brand, ply count, softness, texture, etc of tp actually are important variables, but they get used as jokes because Vassili is critiquing from a point of superiority. Hair whittling turns into a dick measuring contest on who the best sharpener is instead of acknowledging that the person, hair color, and location on the body can result in us using hairs with micron thicknesses more than an order of magnitude off - plus the effects of the chemicals we or our significant others use to color, clean, stiffen, soften, etc. The variables Vassili does not account for are used to invalidate the possible effects of a wooden base. Done without considering that depending on sharpness and rope condition with the human hand involved, when the rope is cut, the wood may be sliced gently or impacted. The edge may be side loaded at times when hitting the wood. With a wood base, you can be checking transverse strength & toughness along with wear resistance, and doing it randomly.

Neither Vassili nor Ankerson measures cutting force when working on the rope, they check cutting ability at intervals against different materials. Vassili stops at a cut number that is essentially chosen arbitrarily, Ankerson stops at a subjective measure of how it feels to cut through paper. The tests, test conditions, and testers are different. What effect does body position, fatigue, mental focus, etc play in testing after you hit five or six hundred rope slices? Vassili is bringing up different results, but they are different tests.

There is actually a decent amount of research about these things - ergonomics for meat processors/butchers, slicing speed effect on cutting ability, variability in cutting performance due to moisture content of wood, fracture mechanics of media when cut by blades of different included angles, cutting performance of knives when cutting material that results in 'floppy offcuts' (they titled the research paper with this term, not me ) and a fair bit more.

There's stuff we can control for, stuff we can't, and imo, stuff we shouldn't. Because at the end of the day, these are hand tools being used in any situation and condition a human being is capable of doing work. Once you reach a certain level of control or number of cycles to measure a difference, then it probably isn't going to be noticeable to virtually anyone. I don't know how far we have to go to make the tests 'valid', but it seems it doesn't take much attitude to make the tests, and follow-up discussion, invalid or irrelevant to knives & what we were talking about in the first place.

 

[Ankerson]

Perhaps the funniest thing to me is that the differences in how a hair reacts to an edge may be FAR more attributable to hair than the edge. Talk about variables...

Seems that perhaps "heritage" could be a relevant discussion item?

Yeah you are right. :thumbup:

The hair I am using is Extremely fine so that would make a difference for sure.

I remember when I had my dog, her hair was much thicker than the Human hair I am using now. But then I don't really use hair to test anymore.

 

[Ankerson]

This is why abrasive attitude's like Vassili's really get in the way. Brand, ply count, softness, texture, etc of tp actually are important variables, but they get used as jokes because Vassili is critiquing from a point of superiority. Hair whittling turns into a dick measuring contest on who the best sharpener is instead of acknowledging that the person, hair color, and location on the body can result in us using hairs with micron thicknesses more than an order of magnitude off - plus the effects of the chemicals we or our significant others use to color, clean, stiffen, soften, etc. The variables Vassili does not account for are used to invalidate the possible effects of a wooden base. Done without considering that depending on sharpness and rope condition with the human hand involved, when the rope is cut, the wood may be sliced gently or impacted. The edge may be side loaded at times when hitting the wood. With a wood base, you can be checking transverse strength & toughness along with wear resistance, and doing it randomly.

Neither Vassili nor Ankerson measures cutting force when working on the rope, they check cutting ability at intervals against different materials. Vassili stops at a cut number that is essentially chosen arbitrarily, Ankerson stops at a subjective measure of how it feels to cut through paper. The tests, test conditions, and testers are different. What effect does body position, fatigue, mental focus, etc play in testing after you hit five or six hundred rope slices? Vassili is bringing up different results, but they are different tests.

There is actually a decent amount of research about these things - ergonomics for meat processors/butchers, slicing speed effect on cutting ability, variability in cutting performance due to moisture content of wood, fracture mechanics of media when cut by blades of different included angles, cutting performance of knives when cutting material that results in 'floppy offcuts' (they titled the research paper with this term, not me ) and a fair bit more.

There's stuff we can control for, stuff we can't, and imo, stuff we shouldn't. Because at the end of the day, these are hand tools being used in any situation and condition a human being is capable of doing work. Once you reach a certain level of control or number of cycles to measure a difference, then it probably isn't going to be noticeable to virtually anyone. I don't know how far we have to go to make the tests 'valid', but it seems it doesn't take much attitude to make the tests, and follow-up discussion, invalid or irrelevant to knives & what we were talking about in the first place.

That's why I said my tests aren't conclusive or the final word. :thumbup:

 

[unit]

Hair whittling turns into a dick measuring contest on who the best sharpener is instead of acknowledging that the person, hair color, and location on the body can result in us using hairs with micron thicknesses more than an order of magnitude off .....


There's stuff we can control for, stuff we can't, and imo, stuff we shouldn't. Because at the end of the day, these are hand tools being used in any situation and condition a human being is capable of doing work.

<clapping and cheering>

Yes! Precisely!

I do acknowledge that all observations are useful (some more than others) and I am grateful that people share them. I especially enjoy being part of a community that argues these points of minutia...it sort of flies in the face of the concepts that some hold regarding what sort of cave man hangs out on a forum talking about knives.

I can point to problems with CATRA not being very applicable to the real world cutting that I do on a given day, and (on the extreme other end) it is quite an easy target to hit if you want to shoot holes in my "testing" that explores EXACTLY what I do.

The reality is, I do not cut with PERFECT mechanics. I side load the blade variably due to my being human and imperfect. I sometimes exit the substrate and contact what lies behind it...so sue me? I am guessing most others reading this fail to use IDEAL mechanics once in a while...part of the purpose of edge testing is to achieve an edge that reduces the stress and allows the worker to cut with less fatigue...and ideally will be able to use mechanics that come with not feeling fatigued.

I see value in all testing and demonstrations so long as they are honestly presented, and make no attempt to intentionally obscure reality.

Thanks everyone.

 

[hardheart]

Yeah, these are all tests, we just need to see just what we are testing. The M390 rolled and the ZDP chipped. The ZDP probably has ~4 Rc over the M390. M390 quite possibly has higher toughness with lower carbon, but other than Cr, we also don't know what carbide formers ZDP has.

With a different setup, cutting different materials (with & without wood & possible effect of humidity on rope), measuring different factors, with different machines doing the cutting (our testers) there is no way to call out one or the other for doing it wrong or having bad results. Hell, we're probably using the 'wrong' edges compared to the people who would be cutting rope 200-700 times without sharpening. Who's gonna repeat these tests with a serrated edge or a PE sharpened on a SiC stone mounted on a ship deck?

 

[Noctis3880]

What it all boils down to is whether or not the edge will get you through the day at work without having to force your knife through whatever you're cutting. In that respect, a FFG blade in 440C might outshine the old Endura ZDP-189 with a saber grind.

I just go for the new super steels on account of being a massive steelhead:thumbup:.

Ergos are of course, just as important. As I stopped touching my BM 755 MPR once I got my 710-1.

 

[MiG Angel]

If I may for a moment be so bold, Jim, I'd like to pass along some information gleaned from an acquaintance of mine, who is a Tribologist currently doing research at the University of Florida. Tribology is of course the science that measures interacting surfaces in relative motion, and Dr. Dan logged into Bladeforums upon my urging to have a look at your results. He was most interested in the toilet tissue cutting and after consulting his reference materials came to the definitive conclusion that the reason Vassili's TP slicing differed from yours was due to a lessening of the coefficient of friction due to the high probability that Vasseli's was used.

You sir, are one hilarious sumbich.

Good thread stuff like this is always interesting and I'm a total steel snob too. Then I realize even if steel x is microscopically better than steel y, who's going to make it in a high quality frame lock for me? That I like? That's one of my issues. Can you hand me half of that tissue?

 

[gunmike1]

Great testing and thread, Ankerson. Getting Sal Glesser and Phil Wilson so involved always makes for some great info, and I can really appreciate how much work you put into this test after doing a test on D2 and CPM D2 a couple years ago. I found the results virtually identical (turns out they were both about 62 RC) so it was pretty much a tie, but the repeated difference that you have found definately shows a clear difference in edge retention for how you cut rope.

I know your problems with the hair just severing rather than whittling, I have the same problem when I polish out my edges (especially Spyderco's CPM M4). I hand sharpen on waterstones and finish on lapping films and get pretty nice mirrors, but your Edge Pro edges are really a thing of beauty, not to mention your sharpness results are pretty amazing with your TP slicing.

Mike

 

[Jason B.]

Mike, good to see you again

 

[Ankerson]

Great testing and thread, Ankerson. Getting Sal Glesser and Phil Wilson so involved always makes for some great info, and I can really appreciate how much work you put into this test after doing a test on D2 and CPM D2 a couple years ago. I found the results virtually identical (turns out they were both about 62 RC) so it was pretty much a tie, but the repeated difference that you have found definately shows a clear difference in edge retention for how you cut rope.

I know your problems with the hair just severing rather than whittling, I have the same problem when I polish out my edges (especially Spyderco's CPM M4). I hand sharpen on waterstones and finish on lapping films and get pretty nice mirrors, but your Edge Pro edges are really a thing of beauty, not to mention your sharpness results are pretty amazing with your TP slicing.

Mike

Thanks Mike.

 

[sodak]

He's baaaack! Good to see you again Mike!

 

[gunmike1]

Well, after months of health stuff (finally found to be lovely mold that I finally had completely killed out last week) and an insane work schedule I have a little time for the forums again. Getting the shipping notice on my M4/Ti Millie helped to reboot the knife gene as well. I sure missed a some great stuff in the last few months, especially the 18 pages of this thread. It's good to be back.

Mike

 

[Ankerson]

Well, after months of health stuff (finally found to be lovely mold that I finally had completely killed out last week) and an insane work schedule I have a little time for the forums again. Getting the shipping notice on my M4/Ti Millie helped to reboot the knife gene as well. I sure missed a some great stuff in the last few months, especially the 18 pages of this thread. It's good to be back.

Mike

Glad to see you back Mike. :thumbup:

 

[black mamba]

More great testing, Jim. Do your results with the manilla rope correlate highly with your cardboard tests, in other words, do they present the same challenge to the edges?

Has there been any comparison testing of cutting plastic, as in zip ties, etc.? At least for EDC usage, cardboard, rope and plastic would be the most common articles cut.

 

[Ankerson]

More great testing, Jim. Do your results with the manilla rope correlate highly with your cardboard tests, in other words, do they present the same challenge to the edges?

Has there been any comparison testing of cutting plastic, as in zip ties, etc.? At least for EDC usage, cardboard, rope and plastic would be the most common articles cut.

Yeah it does pretty much.

Manilla rope is harder on the edges than the cardboard though.

Haven't done any plastic cutting yet.

 

[crabhab]

Jim,

Thank you for taking the time and money to produce material like this. I have been trying to absorb as much as possible. Your videos are entertaining and informative.

Do you have any suggestions for wives? My wife is tired of me sharpening my knives and cutting various items around the house. She is a clinical social worker and keeps diagnosing me with various disorders

 

[Ankerson]

Jim,

Thank you for taking the time and money to produce material like this. I have been trying to absorb as much as possible. Your videos are entertaining and informative.

Do you have any suggestions for wives? My wife is tired of me sharpening my knives and cutting various items around the house. She is a clinical social worker and keeps diagnosing me with various disorders

Yeah just tell her that you are testing to make sure that the knives are performing as good as they can. :thumbup:

Try and get her involved by sharpening your kitchen knives and show her how well they cut, she will see and feel the difference.