Polished vs Non Polished Edges Cutting Results

hardheart said:
I have been wondering about primary grinds and any effects on rope cutting. Since the rope is cut as individual strands, not even the full thickness at the top of the edge bevel would have an effect on the downward force of the cut. But depending on how the rope is held, there would be some compression of the rope that is in contact with the surface of the primary grind. The thinner/more acute the primary grind, the less of the downward cutting force would be translated to a force perpendicular to the blade surface, and a compression normal to that.

Something else that can affect perception of coarse edges is that the velocity of the blade as it moves in a slicing motion increases cutting ability and reduces effort in the cut. If you have a tendency to slice with coarse edges, then you may think it is the edge finish helping things out when it is also the slicing action itself also providing some benefit. But coarse edges also provide deeper cuts with less downward force in a pure slicing action, and polished edges cut more easily in a true push cut.
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That's why I separated the Custom knives from the factory blades, to keep things apples to apples.

Most factory blades start at 15 LBS of downforce with the Polished edges.
 
as with any info of a semi- tech nature; it's really best to read it several times. i ca'nt think in 3 dimensions well as is required to be an engineer or architect. many of our members are very quick at the hard sciences so a one time fast reading & they've got it. myself i need to read it several times & TRY TO SOLIDIfY THE PICTURE IN MY BRAIN. i find that going over the info slower that it gets easier to comprehend. the recent stuff by knarfeng was tabled out in a easy format for myself to conjecture.jim's got a little more techy with the percentages & comparing of different alloys & bevels. however even i was able to follow it fairly well so i think most members should be able to comprehend the significance of the tests. really what i'm trying to say is the way it was set up with variables at a minimun the tests showed some very good info.
dennis
 
Damn Jim, this sucks. I have been debating purchasing an Edge Pro Apex, but held off thinking that my DMT gets the job done just fine. So much for that theory now given your test results.
 
jurisprudence said:
Damn Jim, this sucks. I have been debating purchasing an Edge Pro Apex, but held off thinking that my DMT gets the job done just fine. So much for that theory now given your test results.
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+1 on that, Jim's edges are so sharp i cut myself every time i just look at them. :D How's life been treating you old friend. ;)
 
This is interesting and confirms something recently explained to me by Jerry Hossom in a discussion about how blades lose sharpness.

Something I was wondering is how it would work with simple, clean carbon steels with good, small grain structures such as 1084, Hitachi white, etc.

Jim, and Phil W., thanks for all your work advancing our knowledge and doing it in such an accessible way.

Joe
 
The Mastiff said:
This is interesting and confirms something recently explained to me by Jerry Hossom in a discussion about how blades lose sharpness.

Something I was wondering is how it would work with simple, clean carbon steels with good, small grain structures such as 1084, Hitachi white, etc.

Jim, and Phil W., thanks for all your work advancing our knowledge and doing it in such an accessible way.

Joe
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Thanks Joe,

It's very interesting because a definite pattern starts to develop with all the steels. It's more defined when the steels are at optimal hardness though and it really shows up.

They start out at say 15 LBS then go up to around 16 or 17 and stay there for awhile then on up to 18 and higher, that will vary depending on the steel. There will be a weight they stay at for awhile once the edge stabilizes then once it starts to break down it starts to increase towards that 20 LB stopping point.
 
Ankerson said:
Thanks Joe,

It's very interesting because a definite pattern starts to develop with all the steels. It's more defined when the steels are at optimal hardness though and it really shows up.

They start out at say 15 LBS then go up to around 16 or 17 and stay there for awhile then on up to 18 and higher, that will vary depending on the steel. There will be a weight they stay at for awhile once the edge stabilizes then once it starts to break down it starts to increase towards that 20 LB stopping point.
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This sounds similar to Vasili's (nozh2002) results/graphs. Have you looked at them?
 
Cliff also showed the same results as far as a general progression in edge dulling. Very fast initial loss of sharpness and then a plateau. Even with all the past controversy, some trends manage to show up. CATRA REST testing supports most everything we see in homebrew tests as well.
 
hardheart said:
Cliff also showed the same results as far as a general progression in edge dulling. Very fast initial loss of sharpness and then a plateau. Even with all the past controversy, some trends manage to show up. CATRA REST testing supports most everything we see in homebrew tests as well.
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I remember those tests that he did. :)

Yeah the same basic results keep coming up over and over.
 
Thank you for going to the effort to do those tests. I enjoy getting to look over data like this.

Do you have any chart logging the progression in force over the series of cuts? I ask because I am wondering 1)how much difference the initial difference in sharpness provided in # of cuts, and 2)what the curve looked like as sharpness fell off/force increased.

Could you try cutting without rope to see how much the blade dulls from the contact with the board itself as a baseline? I would expect this to be less of a factor due to the hardness of the blades, but wonder just how much impact it has on each type of blade.

What was the grit size used for the polished and the unpolished?

Have you done any similiar to this that use a pushcut rather than a slicing motion?
 
Not long ago a member posted the test results form IIRC a commercial butcher or meat packing house that did a study on edge finishes and their performance. There findings were also the same, the more refined edge lasted longer, made cutting more efficient, and required less sharpening.

Thanks for the test Jim, keep'em up.
 
Any Cal. said:
Thank you for going to the effort to do those tests. I enjoy getting to look over data like this.

Do you have any chart logging the progression in force over the series of cuts? I ask because I am wondering 1)how much difference the initial difference in sharpness provided in # of cuts, and 2)what the curve looked like as sharpness fell off/force increased.

Could you try cutting without rope to see how much the blade dulls from the contact with the board itself as a baseline? I would expect this to be less of a factor due to the hardness of the blades, but wonder just how much impact it has on each type of blade.

What was the grit size used for the polished and the unpolished?

Have you done any similiar to this that use a pushcut rather than a slicing motion?
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The wood has almost zero effect on the edges the way the slicing is done.
 
knifenut1013 said:
Not long ago a member posted the test results form IIRC a commercial butcher or meat packing house that did a study on edge finishes and their performance. There findings were also the same, the more refined edge lasted longer, made cutting more efficient, and required less sharpening.

Thanks for the test Jim, keep'em up.
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Thanks. :D
 
It is a good time to be a knife nut with all the new knowledge being added to the body of knowledge. Thanks for your time, effort, and money expended on this.
 
This is one of my favorite subjects. It's my belief the polished edge will also be more resistant to chipping and corrosion. As Phil suggested, coarse edges contain little bitty stress risers which can invite trouble (something I believe helps explain the variations in performace reported with S30V). They can also trap moisture, which would be even more important with tool steels of course.

Thanks for sharing this. It was a massive amount of work and greatly appreciated.
 
Ankerson said:
The wood has almost zero effect on the edges the way the slicing is done.
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So you have a baseline of some sort to show that?

Still interested in actual data from the tests as well... # of cuts, definitions of each group, etc. Was there another thread that had all of your findings from these tests where they could be looked at?
 
Jerry Hossom said:
This is one of my favorite subjects. It's my belief the polished edge will also be more resistant to chipping and corrosion. As Phil suggested, coarse edges contain little bitty stress risers which can invite trouble (something I believe helps explain the variations in performace reported with S30V). They can also trap moisture, which would be even more important with tool steels of course.

Thanks for sharing this. It was a massive amount of work and greatly appreciated.
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Thanks Jerry. :thumbup:

Any Cal. said:
So you have a baseline of some sort to show that?

Still interested in actual data from the tests as well... # of cuts, definitions of each group, etc. Was there another thread that had all of your findings from these tests where they could be looked at?
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I suggest you do some testing, I won't release the raw data to the public, way too much work to give away for free. ;)
 
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