Coarse edge stropping

I appreciate the work that you have put into it David, but here is my thoughts.

For the way that you choose to cut, and the dullness you allow your knife to get to, your results are 100% correct.

In my case, I don't make multiple cuts on much of anything. If the knife won't cut straight through with light pressure, I sharpen it. To my mind, dull is the inability of a knife to cut straight through. An example of that is pushcutting rope, like the quickie test I posted in the Buck subforum.

For some users like myself, the ability of a knife to saw at something has little relevance to their uses. In this case, it is hard to say that a coarse edge shows twice or more edge retention, because to many, a knife that won't cut isn't considered to still have an edge.

I am not arguing your findings in the least, and will keep them in mind in case I ever need that type of an edge.

The only thing I am offering is that it isn't quite so clear cut as it may seem. In the way you cut rope, you could only get three cuts with a polished edge, which in no way compared to a coarse edge. In my test, the coarse edge failed miserably compared to the finer one.

The other question is the actual sharpened edge. Was the edge really as sharp as it could have been at the fine side? I would bet that many would have a difficult time getting D2 to a truly fine edge without dulling it on an arkansas stone.

In my testing on D2 with a fine edge, I was able to pushcut hundreds of feet of cardboard before the force required to do so got unacceptably high. That is quite a bit different than being able to make 3 cuts on 1/4" rope.

Once again, I am not slamming you, but just making the point that it isn't as simple as coarse edge>fine edge.
 
I think it all comes down to usage. I'm beginning to develop a clear philosophy toward this, and it goes something like "for max edge retention, use the most coarse edge that will acceptably do the job". Subsequent stroppings will only refine the edge further - as the edge gets progressively refined, one can put 'er back on the stone or just keep using it till retention begins to suffer.

I've noticed that a fine edge cuts cardboard with far less pressure than a coarse edge, but I've noticed just the opposite on rope and other tough items (such as ty raps and reinforced tubing) where the coarse edge will cut with far less pressure using a draw stroke. I've also noticed that the coarse edge seems to outlast the fine for just about every application that it can perform (contrary to what many have asserted). I understand what you're saying - Some tasks are not suited to a particular edge, and some people's cutting practices need to be taken into account as well.

HH
 
I don't normally push cut to me that is not my cutting style thats more like shaving . I'll move the blade some when cutting . I've also cut hundreds of feet of card board with a 440C blade sharpened on a fine diamond and coarse diamond . It takes a lot of cutting on card board to finally dull a knifes edge of decent steel . On that type cutting it helps greatly if the edge is thin and the bevel low 15 or less . Plus, I'm taking the edge to dullness not until it no longer will push cut . A blade must be sharpened very fine to push cut if thats the cutting you want to do all the time . Then don't concern yourself with edge retention just keep sharpening often . As that high degree of sharpness doesn't last in the numerous test I've conducted . An easy test for that is shaving . Just sharpen your blade to a high degree as you would for push cutting then start shaving and see how many shaves you get waiting two days between shaves . Which is a specialized area of sharpening . Of coarse you would not attempt to shave with a coarsely sharpened blade but you could do many more cutting chores with it . Like skin a buck ie. general cutting . Heavy, I agree with your findings as well and results from my testing echo those conclusions . DM
 
Thank you guys for realizing what I was trying to say.

It strikes me all of a sudden that it is much like the argument between large knives and small knives. Some believe that a large knife can do everything a small one can, and others do not. However, I would bet that a skilled user would make the best of their preferred tool, whichever one it happened to be.

In the same way, I imagine that if either watched the other one's uses and technique, they would understand some of the reasoning behind their preferences.

When I get out in the woods with a friend, we argue about whether a pack or a sled is better for carrying gear in the winter. Last winter, we traded for a while just to see how it went. I guess your arguments are enough that I will at some point 'trade' my own technique for a while to see if it can work for my own everyday uses.
 
David Martin said:
I don't normally push cut to me that is not my cutting style thats more like shaving . I'll move the blade some when cutting . I've also cut hundreds of feet of card board with a 440C blade sharpened on a fine diamond and coarse diamond . It takes a lot of cutting on card board to finally dull a knifes edge of decent steel . On that type cutting it helps greatly if the edge is thin and the bevel low 15 or less . Plus, I'm taking the edge to dullness not until it no longer will push cut . A blade must be sharpened very fine to push cut if thats the cutting you want to do all the time . Then don't concern yourself with edge retention just keep sharpening often . As that high degree of sharpness doesn't last in the numerous test I've conducted . An easy test for that is shaving . Just sharpen your blade to a high degree as you would for push cutting then start shaving and see how many shaves you get waiting two days between shaves . Which is a specialized area of sharpening . Of coarse you would not attempt to shave with a coarsely sharpened blade but you could do many more cutting chores with it . Like skin a buck ie. general cutting . Heavy, I agree with your findings as well and results from my testing echo those conclusions . DM
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I'm glad to see someone else confirm my findings. With a properly sharpened knife, you can cut cardboard for a long time. I've never had enough cardboard on hand to be able to dull a blade to the point that it wouldn't cut paper. Thats everything from AUS 8 to M2 HSS to 154CM, all quality steels for sure.

I'd have to say my results are a little different for retaining that high degree of sharpness. I did some testing a while back using my Griptillain in 154CM, among others. I used cardboard as a dulling medium and for testing sharpness I would cut a plastic grocery bag. When I can't cut these anymore, I can still shave hair off my arm pretty easily. That BM Grip cut over 30 feet of cardboard on the same 1" of blade before it wouldn't cut the plastic bag. Now to be sure, it was duller than when I started, but it was still the sharpest knife 90% of people have ever seen. We're probably comparing apples and oranges if you're talking about shaving your face, but an arm shaving edge is still very sharp by most standards, except people here on BFC.
 
Me2, Your welcome . When Cutting card board to dull a blade I tape up all but one inch of the blade then start cutting . I've cut as much as 300' of card board using one inch of a 440C blade before I thought it was dull enough to require sharpening . Still, it could shave some arm hair w/ rash . All these blades could after finishing these test . Conclusion: 1) not sure ? but the blades had lots of burrs . 2) it must not take a high level of sharpness to cut 'some' arm hair . Using card board as a test medium takes time and a 'lot' of card board . DM
 
Very interesting. I don't think I've ever had that much cardboard available at once. What type of cutting were you using, i.e. push or slice? I don't generally tape the blade, but I limit the cutting to the same 1" area. When push cutting thread afterward I'll test in the center of the area, though I've only done this once.
 
I used both styles as 1" leaves little room to move for blade movement . I go to the grocery stores or feed stores and procure card board from the back room . Their usually good to give it to persons who need boxes for moving or storage . Then I'll cut the corners in order to lay the card board flat and take a measurement of its length and start cutting . It takes 10-12 or more large boxes and I cut 1/2" wide strips using this method, I know the length so then I merely count the strips . Its messy and my wife makes sure I sweep the floor . HA! DM
 
I have some boxes from screen doors that are 7 1/2' long. These are really nice for cutting strips from, since you can be very smooth and keep a very small portion of the edge doing the cutting. Also, you don't have quite as many small pieces to pick up!
 
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What edge last longer than the other depends on how you measure edge retention. If it is measured with push-cutting force, then a polished edge will outlast a coarse edge. If it is measured with slicing action, then the coarse outshines the polished.

The push cut relies on the reduction of the radius of the edge where the two sides meet. A coarse edge is not close to the edge radius of a polished edge because of the abrasive size and the fact that the blade thickens from the edge radius up to the top of the edge bevel. In the profile of a coarse edge, the low points are thicker than the high points; and the high points, or 'teeth' can only be thinned so much by the coarse sharpening media. So if we are measuring sharpness as the amount of force it takes to push cut thread, or measuring the radius of the edge, then polished edges win.

If we are measuring sharpness by the amount of downward force it takes to slice through rope, then the coarse edge wins. While the high and low points are thicker than the smooth bevel of a polished edge - they are still high and low points. The edge with a profile closer to a saw will do better in a task closer to sawing. And even for smooth edges, the linear movement of the edge during slicing increases the edge's ability to cut. The edge of a meat slicer disc is smooth, but it still cuts better when it is turned on and moving. Also, the effective edge angle is reduced by angular slicing, along with the focusing of pressure on the 'teeth'/coarse edge peaks.

I think it is agreed that increased sharpness means reduced effort in cutting. What isn't agreed on is the type of cutting. And that is why 'edge retention', ie 'sharpness retention', is not agreed on.
 
Not sure I understand your points but I'll go at this: you can use a coarse edge to push cut and the polished edge does not do well in cutting sisal rope as I discussed . I've yet to find a single butcher who cuts meat with a polished edge . Yet I've observed butchers to push cut . So, I tried this and found out why . The polished edge doesn't last as long as the more coarsely sharpened edge . I did utilize the finely sharpened edge and the coarse edge to push cut the chickens and found it didn't last as long as the more coarsely sharpened edge as that was part of the test . DM
 
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Sorry, should have mentioned where the info comes from

"Experiments on knife sharpening" - John Verhoeven
The 220 and 600 grit edge radii were 5 to 10 times larger than the polished edges (6000 followed by chromium oxide) Coarse edges were 2-4 micron, polished edges were 0.4 micron or slightly less. Coarse edges that were then stropped on CrO dropped as low as 0.8 micron.

"Cutting, by ‘pressing and slicing,’ of thin floppy slices of materials illustrated by experiments on cheddar cheese and salami" - Atkins & Jeronimidis
Slicing cuts reduce cutting forces compared to push cuts. There is an optimum feed to push ratio before friction reduces the effect. The geometry of a deli slicer is used.

It is interesting that you don't know any butchers who polish their edges

"The effect of blade finish and blade edge angle on forces used in meat cutting operations" - McGorry, Dowd, Dempsey
In this paper, they show that the "polished" edge (900 grit followed by stropping with compound) reduced cutting force, grip force, and cutting time to fleece lambs over 400 and 600 grit edges. There was also an improvement in those factors for cutting the shoulders, but not as significant. 21 meat cutters volunteered for this one.
 
This thread is interesting but, David, your giving vague descriptions of your test, your sharpness levels, Pictures?, edge angles and geometry, and the way you bring your data to the table is in the form of "the final word" instead of "this was the outcome".

Its seems as though there is a bias to edge types and yours being in favor of the coarse edge. Please don't take this as a insult of any sort because its not, its just a observation of the thread.

Though I like sharp and refined edges I have also done much of my own testing, I have many abrasives is many sizes along with many years of user experience so testing of how a edge performs at different grits is nothing new to me. I've done this stuff before.

Many others have also done this testing as hardhart has shown. The coarse VS fine argument is a never ending one but has shown repeatedly that a finely sharpened edge with minimal metal deformations at the edge performs best with most cutting needs.

If you as a Japanese chef to use a blade sharpened at 200 grit he would most likely scoff at the idea telling you that your disrupting the flavor and texture of the food, and in some cases you are. Take for example the Murray Carter example of cutting a apple with a coarse or fine edge.

Again this is not a argumentative response so please don't take it that way.
 
I understand, this is what I'm talking about . If you had cut up one chicken you'd know what I was meaning/describing . I've not read of you guys performing tests only quoting someone else's results . I am stating this' was the test and this was the outcoming and described the manner of cutting as well . I go into numerous meat markets and a few have strops, most all have a Norton 313 Tri-hone as their only sharpening stones . A lot of those guys don't use the 320 grit fine India stone while sharpening their blades just the medium crystolon . (I've noticed the 320 grit edge will push cut .) So, there must be a lot of 'disrupting the flavor of the food' going on . They do that because they have found the edge lasts longer . In past tests I've named others who have conducted tests that showed the coarsely sharpened edge lasted longer so, I'll not belabor the point here . DM
 
I have cut up chicken. And beef, pork, fish, vegetables, cardboard, rope, plastic, rubber, cloth, etc.
 
This has been an interesting thread. I'm starting to agree that in order to truly see and understand all sides of the arguments, we'd all have to be in the same place to watch together.

I've had good luck keeping a super sharp edge while push cutting through wood (whittling), and lost it almost immediately when slicing through cardboard. I've always thought that perhaps slicing tears at the very edge more, while push cutting is more supported by the steel behind it. But I really don't know.

In any event, the pleasure should be in the journey, the destination can sometimes be optional...
 
I think too many variables can be entered when speaking of how a meat packer or butcher sharpenes his/her edge. They care less about the quality of cut and more about what cheap sharpening tool will get a working edge back on their knife the fastest. Its like a show I watched once on a meat packing production line, each cutter had a warthog V steel (i think that's what its called) that they ran the knife through after each completed trimming of meat. Did they know what they were doing? Highly doubtful but they knew if they didn't use that device their knife would stop cutting. I doubt that the guys you see using a coarse especially those that only sharpen at work could actually sharpen at any higher of a grit, so again you run into the issue of "that's all they know"

The disruption of the foods flavor is real but someone not taught this will never know. Its for the same reasons that you see the coarse stones or V sharpening steels usually being over used, the user was not properly informed so that's all they know.


As for my testing? I've simply learned, and in this learning I've found its best to keep to myself. My views would be argued like anyone elses and the variables would be endless.

I'm all for a coarse edge on the right steel or for the right job just not for everthing.
 
sodak said:
I've always thought that perhaps slicing tears at the very edge more, while push cutting is more supported by the steel behind it.
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This would make sense. As the coarse edge is drawn through the media to be cut, the material is collected in the valleys of the irregular edge and then the peaks separate it as the pressure becomes sufficient to force it apart. This is continuous as the edge cuts deeper into the material, so there is constant concentrations of force on the 'teeth'. That's how cutting works anyway - taking the force we apply and focusing it into extremely high pressure on a small bit of steel. The polished edge relies on a very narrow radius to focus, while the coarse edge relies on 'teeth' to do it. This would also be why there is a difference in efficacy between vertical and horizontal motion for the edge types. The polished edge blunts as the narrow radius wears/blunts by the tremendous force, and the coarse teeth fail with their minimal size and structural support.
 
Now this, though off our topic has some validity to it . I've never seen a meat cutter in my territory use a V type sharpener only stones . Then yes possibly the fastest manner to get a working edge . Though not what I did as I do know the difference and all the meticulous checking assoicated with it inorder to validate a legimate test . Which is what I posted before you guys to take a shot at . Now, it down to, I didn't word it right . I never said the coarse edge was the right edge for everything (your words). I said it last longer based on these test and I'll contiue to hold to this until someone shows me legimate tests validating the contrary . So, we have a divided camp . DM
 
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