Not to put too fine an edge on it...

[bearedmonkey]

I'd think I was funny but I'm sure that line's been used ad infinitum around here.

Anyway.

So these diamond stones I got are just about my favorite new toy right now, and just about every blade in my house now has a shaving edge on it. I know I shouldn't be doing that with a chopper (ie: a BK2 which I *might* be receiving for Christmas), but if I did and it rolled... well couldn't I just sharpen that out? Basically my question is, as long as I've got the time to keep messing with sharpening knives, is there any permanent damage I can do to a blade by over-sharpening it/putting a fine edge on a knife used for blunt tasks?

 

[richard j]

i have been sharpening knives for many years and through all the feedback given to me, it seems a coarse edge holds up the best. i never go over 400 grit anymore before buffing the edge. i have had knives sharpened with 80 grit treetop hairs. try a coarse edge on your knives. i do finish off my edges on the slotted paper wheel instead of a strop.

 

[Frostyfingers]

Yes and no. It won't hurt your choppers and large blades to be sharp....just make sure the angle of the edge is obtuse enough to handle chopping. For instance, I like my axes shave arm hair. On the other hand, if you DO roll the edge, you will be forced to remove quite a bit of metal to fix it. Do this enough times and you'll wear your knives out sooner.

To end with my standard disclaimer: Do what you like and learn from it.

Frosty

ETA: Richard really knows what he's talking about. All too often people obsess over having the perfect edge, when you really don't need much to cut. I sharpen my garden knives on 400 grit sandpaper...and yes, they cut.

 

[bearedmonkey]

Can someone post a picture of what a rolled edge looks like?

 

[cziv]

i have been sharpening knives for many years and through all the feedback given to me, it seems a coarse edge holds up the best. i never go over 400 grit anymore before buffing the edge. i have had knives sharpened with 80 grit treetop hairs. try a coarse edge on your knives. i do finish off my edges on the slotted paper wheel instead of a strop.

You're convexing mostly though Richard aren't you? I think convex is best for choppers and thick blades isn't it? V edge for the thinner FFG stuff like a Spyderco Endura FFG? Does that sound right?

What knives are best for convex and which are best for keeping up with the V bevels like the factory sends them with? Lots of questions I know but I've never really seen any definitive answers about this. Most of us who don't have your equipment or skills with it, if we do, use stones and such.

I hate taking an expensive folder and putting it to the sandpaper & mousepad. It feels kinda risky for nasty looking scratches. I hand convexed two Izulas and they came out awesome but I only had $50 in them. I'd be scared to try it on a bigger $$ folder like one of my XM-18s, so I touch up the V bevel that's already on them as well as I can.

 

[HeavyHanded]

Personally I find a very refined edge works better on a chopper than a toothy or coarse one. The improvement in cutting through some materials is quite noticeable. I also find having some good tooth to an edge is a big step forward for knives that are going to be used with a drawing motion. All comes down to what you'll be using your edge for. Choosing the right edge treatment (coarse, polished, somewhere in between, wide or narrow inclusive edge angle etc) for what you'll be using your knife will increase longevity of the edge. That means fewer trips back to the stone = longer life for your tool. ALL knives are consumable tools, no point in grinding them to an early grave OR putting up with an edge prep that fails to perform well for a given task. Whatever works for ya, but don't be afraid to experiment.

Edit to add:

Its very unlikely you'll be rolling the edge whether its toothy or fine, thats usually a result of a too thin inclusive grind angle, not how sharp the apex is. If you follow the factory bevel it shouldn't be an issue.

 

[bearedmonkey]

Personally I find a very refined edge works better on a chopper than a toothy or coarse one. The improvement in cutting through some materials is quite noticeable. I also find having some good tooth to an edge is a big step forward for knives that are going to be used with a drawing motion. All comes down to what you'll be using your edge for. Choosing the right edge treatment (coarse, polished, somewhere in between, wide or narrow inclusive edge angle etc) for what you'll be using your knife will increase longevity of the edge. That means fewer trips back to the stone = longer life for your tool. ALL knives are consumable tools, no point in grinding them to an early grave OR putting up with an edge prep that fails to perform well for a given task. Whatever works for ya, but don't be afraid to experiment.

Edit to add:

Its very unlikely you'll be rolling the edge whether its toothy or fine, thats usually a result of a too thin inclusive grind angle, not how sharp the apex is. If you follow the factory bevel it shouldn't be an issue.

Well that's good to know. I'm pretty much following the factory edge anyway, and I guess I'm still experimenting with edges. My major concern is just that I'm so into my stone now that I know how to use it that I'm a little concerned I'm going to over-sharpen.

 

[richard j]

heavyhanded, you can have the both of both worlds. you can have a refined toothy edge if you finish the edge off right.

 

[HeavyHanded]

Well that's good to know. I'm pretty much following the factory edge anyway, and I guess I'm still experimenting with edges. My major concern is just that I'm so into my stone now that I know how to use it that I'm a little concerned I'm going to over-sharpen.

Buy more knives....

 

[richard j]

beardedmonkey, a rolled edge is exactly that. an edge that is rolled off to one side that you can actually see and feel.

 

[midnight flyer]

i have been sharpening knives for many years and through all the feedback given to me, it seems a coarse edge holds up the best. i never go over 400 grit anymore before buffing the edge.

I agree with you, but it is a fight I left long ago, after threads that span a few hundred posts of each end of the spectrum making their argument.

I am no steel sophisticate, but have been carrying and using pocket knives for almost 50 years. And then to bring into the light that I think some of my steels perform better when sharpened at different grit levels even adds to the melee and teeth gnashing.

I have a diamond chef's rod that is 600 grit. Almost everything gets the rod, and certainly all my work knives. I just don't go above that as the more refined edges don't last as long for me in practical every day job site use.

I might lightly strop my pen knives, peanuts, and a couple of others, but that's it.

Robert

 

[HeavyHanded]

heavyhanded, you can have the both of both worlds. you can have a refined toothy edge if you finish the edge off right.

Yes and no - based on my experience. I'm pretty good at getting refinement out of a toothy edge, and these cut fabulously with any edgewise movement and can be made to cut reasonably well with a pressure cut if the inclusive angle is not too broad. What I've found though, is any real amount of tooth will create a lot of drag when chopping or pressure cutting, especially into tough/hard materials. I like my pocket-sized knives to be somewhere between very coarse to moderate (approx 400-800 grit), but my dedicated choppers work best at 800-1000 or better and stropped till the grind pattern is smoothed out and the apex pretty much uniform. I did a bunch of tests on green and seasoned wood using different sized tools from pocket folders up to an axe and feel pretty confident about my results (always more to learn of course). A very easy test is to take a small knife, say 4" or under with a coarse edge prep'd however you favor, and chop some green branches about the diameter of a pencil or a touch thicker. Then do the same test with a more refined edge on the same knife, same edge angle. Since the tool has very little mass, you'll feel the change in resistance quite easily. Work up through to an axe using appropriately sized branches.

On the other side of the coin, do the same test only this time draw cutting rope, canvas or similar (just a small knife will do for this test).

This isn't to say that the "incorrectly prepared" edge will get dull faster, but that it won't work as well in the first place. That said, I do operate under the assumption that what works best will usually work the longest, and in my experience this is usually true. Always more to learn, but for every task there's an ideal edge prep and one size will not fit all. With all due respect, I'm not trying to be "smart" here, I'm sure you've done a ton of testing in your own right - we all run with what our experience tells us and this is what I've found.

 

[snowreaper1]

I thought that polished edges kept their edge longest because they are farthest away from dull. While a toothy edge is closer to dull so it will lose its edge quicker. Comparing knives with same geometry, steel, etc. But I'm no expert, just when this was explained to me it made sense.

 

[HeavyHanded]

I thought that polished edges kept their edge longest because they are farthest away from dull. While a toothy edge is closer to dull so it will lose its edge quicker. Comparing knives with same geometry, steel, etc. But I'm no expert, just when this was explained to me it made sense.

Dull is dull, two planes coming together with an apex radiused from use or overstropping, or poorly joined. Sharp is sharp, two planes coming together cleanly. True enough with a larger abrasive doing the grinding at the edge, the apex will be broader overall (generally) but that doesn't mean at any specific point along the edge the two planes aren't coming together cleanly. The biggest difference between the two is that the edge will do different things well. A highly refined edge has fewer irregularities to cut with when the blade is drawn across a material - it won't "find" any corners to work with, but will have less resistance when used with a pressure or chop cut. It has less surface area across the apex to force into a given material and will sink in with less pressure. A coarse edge has a broader apex overall, creating more resistance when pushed into something, but all the irregularities or formations contribute to its ability to cut through materials when used with a draw (also has the effect of making the edge longer in length) it will separate the fibers/framework and create edges in the weave/structure of whatever its cutting. Always easier to cut into the edge or corner of something than it is to cut into a flat surface. If you have to cut into a flat, or the material is not likely to separate somewhat prior to severing, then chopping/pressure cutting is the better alternative.

A poorly prepared coarse edge is closer to dull than a well prepared fine edge, and a poorly prepared fine edge is closer to dull than a well prepared coarse edge. After that it all comes down to which is the better choice for what you cut most.

 

[midnight flyer]

A poorly prepared coarse edge is closer to dull than a well prepared fine edge, and a poorly prepared fine edge is closer to dull than a well prepared coarse edge. After that it all comes down to which is the better choice for what you cut most.

Not sure about all the rest of the post, but if you boil it all down, I completely agree with this part of it.

Robert

 

[bearedmonkey]

What does "preparing an edge" entail? Is that a fancy of saying stropping? Also, what's I'm this I'm hearing about over-stropping? I thought that was impossible...

 

[Dave Behrens]

I used to mirror polish every eged I made or owned, but I came to realize it added more to looks and not function. Now I sharpen from 180 to 400 grit on my grinder then diamond stone to de-burr, the arkansaw 800grit(guessing) for honing, then strop to remove any micro burrs. What I discovered is when I stopped at 400 grit on the grinder, rather than 1200+ the edge cut way WAAY better, even before removing the burr, I still don't know why but that is the way it is.

 

[unit]

Can someone post a picture of what a rolled edge looks like?

There is a lot more going on here than a rolled edge, but if you look at the portion of the blade toward the right of the split and notice how the light reflects off of the cutting edge as the knife is rolled back and forth (right at 2 seconds and 12 seconds)...you will see numerous rolls. Basically an edge should never reflect any light (the bevels do, but not the apex). Some of these reflections could be compressions (and in some cases perhaps chips), but in the case of the knife in this video, they are all rolls.

[video=youtube;z7LdEu6qcRw]http://www.youtube.com/watch?v=z7LdEu6qcRw[/video]

 

[HeavyHanded]

What does "preparing an edge" entail? Is that a fancy of saying stropping? Also, what's I'm this I'm hearing about over-stropping? I thought that was impossible...

As I'm using it, means grinding the two planes so they meet as cleanly as the grinding surface you're using will allow, and deburring them without rounding or broadening the apex. No wire edges, no burrs, no places where the apex is incomplete, and no enlarging/rounding of the apex due to addressing the aforementioned.

Certainly possible to overstrop an edge, especially if the strop is conformable to any extent and loaded with any sort of abrasive. Polishing is grinding on a smaller scale - that metal has to come from somewhere. No matter how soft you go, there's still going to be a small spike in pressure right at the apex.

 

[cziv]

There is a lot more going on here than a rolled edge, but if you look at the portion of the blade toward the right of the split and notice how the light reflects off of the cutting edge as the knife is rolled back and forth (right at 2 seconds and 12 seconds)...you will see numerous rolls. Basically an edge should never reflect any light (the bevels do, but not the apex). Some of these reflections could be compressions (and in some cases perhaps chips), but in the case of the knife in this video, they are all rolls.

"Death Waits In The Dark??" How bout "Rolls Wait On The Edge?"