Coarse edge stropping

HeavyHanded

HeavyHanded

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Jun 4, 2010
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I recently picked up some heavy tooling leather to make a bunch of new strops. Couldn't resist making one for testing on some really coarse edges. In the past, stropping these generally results in only the tip of the edge being polished, many of the nooks and crannies still have small burrs from being ground on just one side (an unfortunate side-effect of the lower grit stones). Applying more pressure usually smooths out the scallops and what few "teeth" manged to survive having the burr reduced on the stone, not what you want when shooting for a saw edge. I decided to try some lapping compound for my reel mower. SiC, rated at 220 grit. Lightly wet the leather on the strop and worked in a small amount of the compound. I deliberately left an easily seen burr on one side and set about removing it. Worked wonderfully, and I regret that I'm too much of a Luddite to include pics. It removed the burrs from the scallops without smoothing out all the desirable irregularities. I'd expect this to further increase the longevity of the edge without making it less of a tough-material saw edge. With burr removed and and stropped on both sides, it parted free-hanging t-shirt material and some toilet paper. Went through 3/8 sisal like it was a bootlace, and shaved a surprising amount of hair from my arm. Further testing will have to wait till after the weekend and maybe longer (I'm coming up on some overtime at work).

Not trying to start a convo on the merits of this edge vs that edge, just sharing some interesting (IMO) results from some off-beat testing. Using a much larger grit than usual - matching the strop particle size to the grind size (nothing new but seldom thought about with grits of this size) seemed to result in a noticeable improvement. I wonder how it'll work on the turkey?

HH
 
Heavy, This is exactly what I found while conduction edge retention tests a while back . It really works . But this sort of finding goes against much of the thinking here and as a result some tried to tar and feather my findings and me along with it . So, be careful as many here think its only the highly polished edge that can cut . Good work ! DM
 
David, I'm all too aware of the general consensus around here, but the testing must continue (besides, I'm too much of a noodler not to try this sort of thing). Anyone that's done some testing across a wide variety of materials will have already come to the conclusion that for everything to be cut, there's a best edge to do the cutting. One size does not fit all. Plenty of room at the table for evr'body. It's only where they overlap that there's any real argument, and that mostly boils down to personal preference and the particular blade steel and RH.

Besides, I just did a bunch of work with my new translucent Arkansas and CO stropping compound, only fair to take a look at the other end of the spectrum with a 60 grit QEP stone and some lawn mower compound...

HH
 
O-I totally agree . There needs to be a balance in well based findings here in this forum . But not annihilate simpily because the data (though well founded) doesn't agree with the prevailing norm . Glad you found this and dared to share it here . We shall see where this goes this second time around . DM
 
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WHoowee, I'm not trying to poke anyone in the eye here, just posting some results that I thought might be of some use to others.

It did just occur to me that this would make it a lot easier to maintain the properties of a very coarse edge without having to put it back on a stone or file as often - one of the bigger drawbacks to the coarse edge that IMO cannot be easily tolerated, even if it does frequently lead to greater longevity for some applications.
 
I'm not sure where there would be a problem, many examples of sharp+coarse edges have been posted. I've shaved the hair from my arms with an edge formed by a 36 grit wheel (freehand, off the grinder), double-cut bastard file, and a cinder block. As you mentioned heavy, they just don't last very long.
 
I would be interested to see if the coarse stropping could slow down the blunting of the edge compared to no stropping at all. It seems like it could, due to it removing and shaping some of the weaker sawteeth that would be the first to fold out of the edge and reduce cutting efficiency.

I guess using 220 grit to strop with could be considered thinking outside the box... :D
 
Yes, I agree--my edges sharpened on a 100 grit Norton stone gave much better edge retention in cutting tests than the highly polished edges taken up to a black Arkansas and on up to Spyderco's 2000 grit ceramic . Yes, I also agree that it was difficult to remove the burrs during stropping after sharpened on the coarse stone . So, two things I learned and put to use: 1) using a lite sweeping motion for the last several strokes on the coarse stone helped to remove a lot of the burrs, then 2) I set up two strops one with coarse (325) diamond grit slurry applied and the other with xx-fine (.5 micron) diamond slurry applied and stropping on these gave me great results for the tests and subsequent use . So, yes there are items to learn and be explored in this area of knife sharpening and cutting knowledge . DM
 
Any Cal. said:
I would be interested to see if the coarse stropping could slow down the blunting of the edge compared to no stropping at all. It seems like it could, due to it removing and shaping some of the weaker sawteeth that would be the first to fold out of the edge and reduce cutting efficiency.
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I think you are right. I have noticed an improved edge holding on stropped coarse edges. It seems that stropping "cleans" the edge by removing weak teeth and aligning strong teeth.

Two other factors have to be taken in count. Shallower the sharpening angle, deeper the serrations. Carbides are an other factor; a blue steel higonokami will be toothier than a white steel one sharpened and stropped the same way.

dantzk.
 
IMHO, there's only one question that matters. And you've already answered it.

Does it work for what you want to use it for.????

Since it obviously does, you have no need to apologize or justify your method to anyone! :p
 
hardheart said:
I'm not sure where there would be a problem, many examples of sharp+coarse edges have been posted. I've shaved the hair from my arms with an edge formed by a 36 grit wheel (freehand, off the grinder), double-cut bastard file, and a cinder block. As you mentioned heavy, they just don't last very long.
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Well, there's the rub. IME a coarse edge lasts far longer than a fine one in most cases, it just doesn't perform well for some uses. The biggie for me is that the newer steels like VG10, VG1, etc and to a lesser extent 154cm and ats34 don't hold a coarse edge anywhere near as long as Aus6, Aus8, 440c 420hc etc and would be better served with a refined edge. A lot of this I believe is the tendency for the harder steels to not be cut cleanly by the coarser particles found in the more aggressive abrasives. They chip out and what is left is rather jagged and very weak. As I mentioned earlier, I've had a tough time stropping the coarse edges with compounds in a normal range, they can't reach far enough into the valleys to remove the burr or further refine the edges. Next up will be some 120 grit lapping compound, but I'm concerned the particles might be too large to track into the scallops and will just rub the high points in between, much like what I find with a regular stropping of these edges. This is critical, as in my opinion the coarse edge doesn't cut with it's teeth so much as the scallops - anything that can be done to improve the edge on these scallops without smoothing the surrounding high points will be very welcome.

In addition to how durable I've found the coarse edge to be (when done on the appropriate metal) is that I believe the edge is more durable at the more acute angles. A acutely angled, finely polished edge can throw back light after cutting a single heavy ty rap. A similarly beveled coarse edge can digest that sort of fare all day long (IME), and being ground at an accute angle gives it a lot of efficiency for a cutting edge that's relatively broad. Is one really better than the other? I don't think so, but it all boils down to ease of maintenance and ease of creating the edge in the first place. Even on the better steels for applying a coarse edge, renewing the edge usually means putting it back on a stone/file whereas a fine edge can just be stropped a few times and put back in action. That makes it very tough to constantly keep a coarse edge in top form - its always going up and down on the performance curve and looses a lot more metal when being touched up. Enough to possibly negate the longevity of each individual sharpening. If I find that stropping with a larger abrasive is a viable maintenance routine for a coarse, I'd be hard pressed not to run with it on my hard-use knives that have the appropriate steels.

HH
 
HeavyHand, You've said a lot ! In your first par. are you saying you've tested all 8 steels sharpened coarsely and fine ? Then drew conclusions ! That alone would take sometime . Then if those 'other' steels preformed better with a finer sharpened edge, then how fine ? Yes, the strop is a key . Yet, I got more burr removal out of the stone than strop in the beganning . Which has much to do with technique . More to follow... DM
 
Heavy, In your 2nd par. where you say, "a fine edge can just be stropped a few times and put back into action". A few times . How many is this ? Some real numbers will help . Say, the coarse edge cuts 1200 cuts on sisal rope (an abrasive material) and the finely sharpened edge cuts 400 . The both are dull . Now, you strop and neither will cut as much as on the first time . But one started out cutting only 1/3 as much . So, after you strop it 3 times you've cut as much as the coarse did on the first sharpening . Give the coarse edge the same little touch up and you come out ahead still . Which I have to return to the stone anyway after that many stroppings . During my tests I found the strop helped, the stone helped more . DM
 
Heavy, You've made some good points here that will require much more work over time . 'Ease of maintenance' is your big right hook . How long can we make our knife last and keep it sharp with the least metal removal ? Within this a lot depends on what were cutting and how the steel handles that . DM
 
What I've tended to notice is that both coarse and refined edges dull a certain amount pretty quickly, and then cut at a level where I can't notice a large drop in performance for a while. The difference for me is that I rely on push cuts with the polished edge, and do aggressive slicing with the coarse edge. When doing something like breaking down boxes - I feel very quickly that reduction in push cutting sharpness, while the blade will still shave arm hair pretty easily. But if I'm slicing with a coarse edge, I slice pretty well for a while even though the edge won't take hair at all, or not without some scraping and discomfort.
 
Hard, Yes, I agree . My coarse edge even though it cut more will still shave hair but like you say, 'with more discomfort' than the finer sharpened edge . Yet, the finer edge breaks down sooner . My experience has been the tougher material, cut the quicker the edge breaks down . Try whittling a hickory axe handle to fit the head with a finely sharpened edge . Then try it using a coarsely sharpened blade . Which I'll admit is a hard test but its something I'll do once or twice a year . The bulk of my yearly cutting may be down the ladder a step or two from this but certainly more than just opening the mail . DM
 
Heavy Handed, I really like the insight. I am of the opinion that steel types and sharpening angles could make a definite difference on performance of coarse edges, but haven't talked to much of anyone who has actually considered it.

Heardheart, I have seen similiar, but with one caveat. It seems like some materials have a minimum sharpness required to cut through them. I have noticed that with fine edges, I can cut many feet of cardboard with little added effort, though the edge will no longer shave. With a coarser edge, the length of cut is reduced considerably, and soon binds in the cut. It is my theory that it is due to the better geometry of the fine edge, since it is finer and has more support behind it.

David, if a coarse edge is better for carving, why do wood carvers tend to keep such fine edges on their carving tools? Why don't they just use a serrated edge? I am OK with the idea that a coarse edge could make slicing cuts longer in certain steel types, but find it difficult to believe that it will pushcut more effectively as well.
 
Lopping off wood to fit a handle to an axe to me isn't carving . Carver's do much finer type work . Not all wood carvers use a finely sharpened edge either . I know many who sharpen up to a fine India (320 grit) . And I've not been talking 'push cutting' . Again your inserted words .Like Heavyhand said, theres room at the table for this type discussion and the information should be put forth . DM
 
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David Martin said:
HeavyHand, You've said a lot ! In your first par. are you saying you've tested all 8 steels sharpened coarsely and fine ? Then drew conclusions ! That alone would take sometime . Then if those 'other' steels preformed better with a finer sharpened edge, then how fine ?...
...
DM
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Yeah, I did a test a while back involving Aus6,Aus8, 154cm, 14c28n, and VG1, as well as side by side tests with just Aus8 and VG1. The fine edge was what came off my fine Arkansas and followed up with a Franz Swaty hone - painfully time consuming but "hair whittling" sharp though not quite what I can now get from my translucent Arkansas and CO strop. Coarse edge was from a 60 grit SiC stone. Right off the bat the 154cm, 14c28n Sandvik, and the VG1 didn't take a coarse edge that well - it just didn't feel or look like the grind on the stone was "imprinting" in the steel like it does on the Aus and 440c steels (IME Buck's 420HC is one of if not the best steels for a coarse edge followed by 440c and then Aus8). This jibes with what I found doing side-by-side with two CS Voyagers, one Aus8 and the other VG1. The Aus8 took the edge better and held it far longer than the VG1 (I almost sent it back to CS with a nastygram). However, the VG1 takes a better fine edge and it lasts longer than the Aus8 by quite a bit. I have not tested VG10, but from the number of folks that have reported chipping on ceramic hones with this steel, I have to assume it won't respond well to large-grit media. This could very well be one of the reasons so many people have nothing good to say about coarse edges in general, the steel they're using might not be conducive to it, and the stone they're using might not work well for it. I've never used the DMT 120 grit, but for a lot of "fine-edge aficionados" this stone is probably their only coarse, doesn't seem to do a very good job for this application, and they're probably trying it out on some very ceramic-like steels. The ability of the steel to cleanly accept the grind pattern, and the media to present a good grind, is essential to good performance IMO. The other factor in addition to these, is that for a lot of folks "coarse" can be as fine as 600 grit - not very coarse in my book.



Heavy, In your 2nd par. where you say, "a fine edge can just be stropped a few times and put back into action". A few times . How many is this ? Some real numbers will help . Say, the coarse edge cuts 1200 cuts on sisal rope (an abrasive material) and the finely sharpened edge cuts 400 . The both are dull . Now, you strop and neither will cut as much as on the first time . But one started out cutting only 1/3 as much . So, after you strop it 3 times you've cut as much as the coarse did on the first sharpening . Give the coarse edge the same little touch up and you come out ahead still . Which I have to return to the stone anyway after that many stroppings . During my tests I found the strop helped, the stone helped more . DM
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I've never done exhaustive tests on the two in side-by-side endurance tests, but from a personal use standpoint, I have to admit I agree with this pretty much completely. Since I haven't done any real testing re true amounts of metal removal, I have to give it some benefit of the doubt.


Any Cal said:
I have noticed that with fine edges, I can cut many feet of cardboard with little added effort, though the edge will no longer shave. With a coarser edge, the length of cut is reduced considerably, and soon binds in the cut. It is my theory that it is due to the better geometry of the fine edge, since it is finer and has more support behind it.
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I think some of this has to do with edge bevel, and like I said earlier my experience is that a coarse edge tolerates abuse with acute edges far better than a fine edge. I will admit, when it comes to cutting cardboard a fine edge will do it with less pressure, at least initially, but then I also said I believe that for every material there's a better edge. It could be that for cardboard a fine edge is better, but then again I still believe that the coarse edge will outlast the fine even in this case if the test were run for a long enough time frame. At the least, the coarse can be used to saw back and forth when it will no longer cleanly draw cut. No such option with the finer edge when it dulls.

This convo could go on and on, but I'm going to try and confine it to a simple discussion about stropping techniques for a coarse edge. When I get around to trying out the 120 grit I'll be sure to put it back up on this thread.

Thanks to all
HH
 
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