Hair whittling edges?

[Pete1977]

How long do the hair whittling highly polished edges hold up during everyday cutting?

I personally prefer a coarse toothy edge on my knives but that is mostly because I cut rope and other fibrous or tough materials. I have polished the edges of some of my knives with a Lansky sapphire stone or the ultrafine Sharpmaker rods but they did not really hold up to the heavy duty cutting that I tend to do.

Am I missing something by not polishing the edges or is that more appropriate for an EDC knife rather than a work knife?

 

[stitchawl]

Pete, I'd say that it's not the polish that affects the longevity of the edge, it's the edge geometry. The first time I made a really high polished mirror finished edge, I did it on a 10 degree per side bevel that I put onto a hard working knife. The edge didn't last very long. I re-profiled the edge to 18 degrees per side and it lasted very well.

But... as you said, you are cutting rope and other fibrous materials, and like you, I found that for cutting of those sorts of things a toothy edge only sharpened to about 600 grit worked better for me than a polished edge.

Stitchawl

 

[handamerican]

Stitch - you're right on with that. I deal with some very talented wood carvers who stick with grits in the 600-800 range.

It's always going to come down to what the blade is used for.
Keith

 

[David Martin]

Pete, you right on with the info. you've realize about edges . Try a 100 grit and you'll be amazed at how long it last even in just general cutting . Mine will shave arm hair after extensive hard cutting . I have certainly examined my grit stragedy and usually sharpen toward a coarse grit . DM

 

[wongKI]

The polished edge will of course last different amounts of time depending on steel and geometry.

My S30V Military, although not quite hair whittling, was almost there, but it lost the edge pretty fast. Not razor sharp, but still very good working edge for very long.

The M4 Gayle Bradley hasn't been worked as hard, but so far it has cut through 1mm aluminium sheets and managed to shave after that.

 

[Jason B.]

The polished edge will of course last different amounts of time depending on steel and geometry.

My S30V Military, although not quite hair whittling, was almost there, but it lost the edge pretty fast. Not razor sharp, but still very good working edge for very long.

The M4 Gayle Bradley hasn't been worked as hard, but so far it has cut through 1mm aluminium sheets and managed to shave after that.

This is also a good example.

Some steels like different levels of finish, just finding what that is can be the tough part. Style of cut or cutting technique can also be big factors in how the finished edge cuts. For example: a coarse edge needs a sawing action to cut rope where a polished edge would need a push cut, trying to saw with a polished edge will get you no where fast.

 

[stitchawl]

Style of cut or cutting technique can also be big factors in how the finished edge cuts. For example: a coarse edge needs a sawing action to cut rope where a polished edge would need a push cut, trying to saw with a polished edge will get you no where fast.

THAT is an important point!!

Often we aren't even aware of how we cut things. I think we need to pay more attention to this point in our everyday cutting.

Stitchawl

 

[Jason B.]

THAT is an important point!!

Often we aren't even aware of how we cut things. I think we need to pay more attention to this point in our everyday cutting.

Stitchawl

It's one of the main things I've always payed attention to, how you cut, what you cut, how you sharpen, and the steel you choose will be the biggest factors in how you view performance.

It's the reason we search for that "one" knife with the steel we like most and sharpen it to where we feel it cuts the best. Also why we all have different points of view

 

[me2]

My high polish edge on my M2 mini-machete (5" blade) lasts quite a while. I checked it on cardboard and it would still shave hair above my skin after several feet of cardboard. I used to call this knife a puuko, but its not. Its just a piece of very hard sheet metal with a 10 degree/side edge on one side, in a clip point profile.

When I stocked shelves at a grocery store, I payed attention to how I cut. I use mostly push cutting for utility work, and started to sharpen accordingly. Used my way, my knives cut cardboard better than serrated edges. For other people, I tend to use a coarser finish, Fine India or similar if I do the sharpening by hand. If done on the belt sander, I'll finish with 120 grit then maybe 180 then the leather honing belt.

 

[singularity35]

This is also a good example.

Some steels like different levels of finish, just finding what that is can be the tough part. Style of cut or cutting technique can also be big factors in how the finished edge cuts. For example: a coarse edge needs a sawing action to cut rope where a polished edge would need a push cut, trying to saw with a polished edge will get you no where fast.

Now I know why my byrd crow was better than my millie in push cutting 3mm mountaineering cord. The crow had an almost mirror finish while the millie was toothy at 1200 grit finish.

I learn something here everyday. :thumbup:

 

[David Martin]

, trying to saw with a polished edge will get you no where fast.

If your talking about cutting sisal rope this would be an untrue statement . It will cut using a slicing motion not just pushing . Cardboard--ok . If you like a push edge thats fine . Still, this is a different point than what I'm talking about .
In edge retention the coarser sharpened edge delivers the goods in cutting most materials longer . Meat, sisal rope, filleting fish ect. Not to say there is not a place for the polished / more refined edge --shaving comes to mind quick or hospital surgery . Other items as well where edge retention is not the primary concern . DM

 

[Jason B.]

Its a general statement about technique and not speaking for edge retention in any way.

 

[Any Cal.]

How long do the hair whittling highly polished edges hold up during everyday cutting?

Since you are about the 17th person to ask this question in the last few days, and because I was curious myself, I decided to put together a quickie test to see how much it mattered.

I used 3 knives, each with a different steel and edge geometry, but two of them were sharpened to what would easily be considered a polished edge, and the last had been, but had dulled over time.

Each knife was used to cut 47'+ of cardboard box, which was 15 slices off a large piece I had, and my best effort was made to keep the same 1/2" portion of the edge cutting for the entire test. Doing things this way let me compare the untouched original edge to the used portion.

The final result was that there was a very small but noticeable functional difference. The edge that had been the sharpest was still the sharpest, but now, instead of tree topping hair it would grab closer to the base. The second edge that would grab hair close to the base now was closer to a hair scraping sharp, and the dull (relatively) edge still cut paper almost identically to the way it had.

To make a long story short, these blades pushcut through 47' of cardboard, and are still nearly as sharp as they were. If 47' of cardboard is nothing, because you use your knives all day long, then perhaps testing for your needs is in order. Otherwise, it is obvious that there isn't a huge penalty to having a nicely sharpened edge.

I used the specific amount of cardboard I did for ease of testing, and because I figured most people won't equal that much cutting with an EDC knife in a short period of time.

As far as choosing an edge for a work knife, I would say that you need to test your own knife/skills/technique/media out in order to make an informed decision. David Martin has done so on rope, and at this point he can say "My knife, sharpened my way, cutting with my technique, cuts sisal rope longer with a coarse edge."

 

[nozh2002]

How long do the hair whittling highly polished edges hold up during everyday cutting?

I personally prefer a coarse toothy edge on my knives but that is mostly because I cut rope and other fibrous or tough materials. I have polished the edges of some of my knives with a Lansky sapphire stone or the ultrafine Sharpmaker rods but they did not really hold up to the heavy duty cutting that I tend to do.

Am I missing something by not polishing the edges or is that more appropriate for an EDC knife rather than a work knife?

I do not know answer on this question because I do not know clear criteria which may identify "working edge". For polished edge this is simple - once I can whittle hair - it is done, if not - it may be polished but rolled and does not really sharp. When I was researching this using my thread cutting method to measure sharpness I actually see edge degradation after improper polishing and it was able to shave arm but was duller then before polishing.

If it whittle hair - then it is done and good.

For working or toothy edge - what is criteria that it is done and good? Cutting newsprint, shaving arm - this is too inaccurate. It should be something clear and simple as whittling hair.

So first - do you actually have you edge properly polished, meaning whittle hair? If not it may be duller at the beginning then your other edge.

And second - what is working edge, How I may recognize it. I really like to got to bottom of this and learn how to do it right, then I will be able to compare them myself.

Regards, Vassili.

 

[Noctis3880]

Hair whittling edges are more or less just for fun.

To me, "the" knife is my Spyderco Gayle Bradley in CPM-M4 high speed tool steel.

I went through about 10 cases of corn today(trimming away the stalk and excessive leaves and "hair"), which comes out to about 500 ears of corn.

The stalk is cut via push cutting by holding my knife in a reverse grip and pushing the knife on the jimping on the spine with my right forefinger while simultaneously pushing the corn towards the blade with my right thumb. The leaves and hair are cut with a slicing motion.

The knife was sharpened to a hair whittling edge prior to use and dulled to a certain point, at which point it seemed to retain a working edge forever. I define "working edge" in a very simple way: the edge can slice(not push cut) copy paper without catching or tearing it. By my standards, that's still a pretty sharp edge for non-knife people, and that's an edge that will do the job I want it to and still do it better than my coworkers' knives.

I think the trait where the edge seems to stop dulling and retain a working edge is due to the vanadium content, which would make it behave like the S**V series steel blades. However, the extremely high hardness of Rc 64+(at least I think it's around that high) and good toughness makes it less prone to edge rolling and chipping. I'd also expect that if I were only using the knife on softer materials(say, carrots, celery, and lettuce), it would retain that hair whittling edge for quite some time.

The lack of stain resistance is a bit of a concern as despite my efforts, water would get into the pivot area. However, most of the blade itself is mirror polished and barely has a patina(it just looks a little foggy). Once I take the knife apart and put a mirror finish on every millimeter of it, everything should be good:thumbup:.

My Manix 2 with CTS-XHP was more of a disappointment in comparison. Though admittedly that stainless steel has a very tough competition. According to the steel charts, the vanadium content is less than half that of regular D2, and I'd imagine there might be some tradeoff in toughness due to the higher chromium content(at least, people keep mentioning lack of toughness is why stainless steel is never used in quality swords). For whatever reason, that is why my Manix 2 lost a "working edge" after only 2 cases of corn(and become noticeably more difficult to trim) and failed the paper slicing test.

Though I believe Ankerson proved that the Manix 2 is not a "hard" use knife.

 

[Any Cal.]

Noctis, thanks for the observations. I really like seeing how knives get put to work by various users. Just out of curiosity, how long did it take to get to the 'working edge' in the work you were doing? And what was your method for finishing the edge?

Thanks.

 

[me2]

A working edge is what is left after a hair whittling edge has worked a while. Edge dulling has a unique curve when measured and graphed. It is easy to see in a graph of say, number of cuts vs. load to cut thread that the initial sharpness is lost pretty quickly, and then there is a point where dulling levels off and the knife keeps cutting beyond most expectations. IME, the high initial sharpness is controlled mostly by steel hardness and the long lasting working edge is controlled by the wear resistance. The graph looks like half a bowl, with a steep initial slope that levels off and flattens out.

Thus, a high hardness 1095 blade will hold a shaving edge for a reasonable amount of time, while a softer blade of say, S30V or D2, will loose that high sharpness quickly, but keep a working edge longer.

Keep in mind that most edges will conform to this pattern. Even my lowly Vapor in AUS-6 matched. I would start cutting cardboard or aluminum cans and it would loose its treetopping sharpness pretty quickly, but it still had the ability to scrape shave hair off my arm after over 700 inches of cardboard. One reason for such varied opinions on edge holding is the different standards people use. A 1095 or 1080 blade hardened to HRc 64 to 66 will keep that razor edge longer than steels like S30V or D2 or ATS-34. Some people like that type of edge, like me. However, D2 etc. will hold a working edge nearly forever. Its beyond my ability to dull these steels to the point that they wont slice paper anymore. I don't have time or enough cardboard. However, I have not been able to dull lowly AUS-6 to that point either, though I'm sure it won't take as long as the D2 etc.

This all presumes that the edges are used for cutting and are not taking damage. If gross denting of the edge or chipping are happening, the this trend is out.

I would disagree with Noctis' notion that hair whittling edges are just for fun. On my knives, that edge is useful, if for no other reason than I get the increased cutting ability and edge life before getting to the paper slicing edge. The paper slicing edge will be there regardless, so I like the overall longer edge retention of getting the knife hair whittling sharp to start.

 

[David Martin]

Your words not mine . I can draw accurate conclusions based on tests with others its harder . DM

 

[nozh2002]

A working edge is what is left after a hair whittling edge has worked a while. Edge dulling has a unique curve when measured and graphed. It is easy to see in a graph of say, number of cuts vs. load to cut thread that the initial sharpness is lost pretty quickly, and then there is a point where dulling levels off and the knife keeps cutting beyond most expectations. IME, the high initial sharpness is controlled mostly by steel hardness and the long lasting working edge is controlled by the wear resistance. The graph looks like half a bowl, with a steep initial slope that levels off and flattens out.

Thus, a high hardness 1095 blade will hold a shaving edge for a reasonable amount of time, while a softer blade of say, S30V or D2, will loose that high sharpness quickly, but keep a working edge longer.

Keep in mind that most edges will conform to this pattern. Even my lowly Vapor in AUS-6 matched. I would start cutting cardboard or aluminum cans and it would loose its treetopping sharpness pretty quickly, but it still had the ability to scrape shave hair off my arm after over 700 inches of cardboard. One reason for such varied opinions on edge holding is the different standards people use. A 1095 or 1080 blade hardened to HRc 64 to 66 will keep that razor edge longer than steels like S30V or D2 or ATS-34. Some people like that type of edge, like me. However, D2 etc. will hold a working edge nearly forever. Its beyond my ability to dull these steels to the point that they wont slice paper anymore. I don't have time or enough cardboard. However, I have not been able to dull lowly AUS-6 to that point either, though I'm sure it won't take as long as the D2 etc.

This all presumes that the edges are used for cutting and are not taking damage. If gross denting of the edge or chipping are happening, the this trend is out.

I would disagree with Noctis' notion that hair whittling edges are just for fun. On my knives, that edge is useful, if for no other reason than I get the increased cutting ability and edge life before getting to the paper slicing edge. The paper slicing edge will be there regardless, so I like the overall longer edge retention of getting the knife hair whittling sharp to start.

Is it possible to see those graphs and tests you mentioned?

Thanks, Vassili.

 

[me2]

I'll check to see if I saved my notes from my cardboard cutting on a RAT 1 folder pass around. I think I started with the thread cutting load at less than 10 grams freshly sharpened. I started at 10 cuts, then 20, then 40, 80, 160, 320, 640, 1280. Between 10 and 320 cuts, the drop was pretty quick, from 10 grams down to about 100 grams. Then between 160 and 1280 cuts, it went from about 100 grams to about 140-150 grams. Still shaved hair off my arm with some effort and still sliced paper with no problem.

The cuts were about 1.25 inches long and were done on the same 1.25 inch section of blade on some random corrugated cardboard I got from work. An actual connect the dots plot would look like a drunk snake, but a trendline will show the pattern I'm talking about. I haven't plotted my numbers, but if I can find them I'll do so and post a graph. This knife was tested agains a Byrd Cara Cara, which did marginally better, but that could be any number of things skewing the results.