So how do you sharpen a rolled edge?

[Ken Cook]

Lynn T states that the CS AUS8 and San Mai III Trailmasters have rolled edges and then goes on to explain what a rolled edge is.
Now, Mr. T would have me believe that "...you will probably never have to sharpen it..."
To qoute Mr. Scott, "Ye kinna brrreak th' laws of physics!"
Obviously, if you don't leave the thing in the box and you actually USE it, you're going to have to sharpen it some time. I don't care what ANYBODY says.
So, how do you go about sharpening without losing this sooperdooper rolled edge?

BTW
Does anybody else think L.T. is going a little overboard with his "challenges."

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I cut it, and I cut it, and it's STILL too short!

 

[Markku Huttunen]

A difficult task without a ???? (some special equipment that most knife owners/users don't have). Could possibly be done by hand (Peter Hjortberger of Fällkniven mentioned this to a friend when speaking about the S1). And another Ken, Ken Cox, once described how he did a "convex" edge to one of his knives: first a few somewhat different angles (maybe with a Lansky or something), then lots of careful steeling (if I remember correctly). Not *quite* a rolled edge, but maybe near enough? (I've done something similar to my Carbon V Trailmaster and an Extra Large clip point Voyager.)

A nice weekend to all (and Happy Birthday to my 3 years old daughter, if she's reading this

)!

Markku

 

[Ken Cook]

If the rolled edge is as great as it's supposed to be, I'd be willing to invest in the equipment if I knew what I needed.

Markku,
Tell your little girl Happy Birthday for me too! 3 year olds are so much fun!


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I cut it, and I cut it, and it's STILL too short!

 

[bansidthe]

A special belt sander is used with a little slack in the belt. The belts are typically
1 by 42 inches. Lee Valley tools in canada carries them but i am sure that they are available in the U S as well. I think I have seen them at Home Depot.To get the final edge a very fine grit (600 or higher) is used.The slight slack in the belt allows it to wrap around the convex or rolled edge.

 

[Coronach]

OH...OKAY.

So a 'rolled edge' is the same thing as a moran or convex edge? Is 'rolled edge' a proper term, or is it another product of the Cold Steel Advertising Machine (like Carbon V Steel)?

Mike

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Hey! Uncle Sam!

(_!_) Nyah nyah nyah!

Refund! You lose!

 

[Cliff Stamp]

I asked Madpoet about this awhile ago as he was making one for me and this is what he said :

If I'm not using a sanding belt to put a convex edge on, I use emory paper or very fine grit wet/dry sandpaper on top of a leather pad that is attached to a wooden block. you lay the blade almost flat on the sandpaper, and press just enough so that the leather 'gives' a bit, so the edge comes out convex instead of flat. It take a little practice, but works good. If someone wanted a polished edge they could go from there to a very fine crocus paper and even rouge on the leather pad to strop the blade out.

There you go, no do-dads needed.

-Cliff

[This message has been edited by Cliff Stamp (edited 16 April 1999).]

 

[madpoet]

cliff,
You forgot the most important part ;-)
Pull the blade backwards, away from the edge, like you would use a leather strop. Otherwise the sandpaper has a relatively short lifespan.
It also helps if you can find it in the cloth backed variety, which holds up a lot better.
My dad's portable sharpening stone was a couple pieces of 600 and 1000 grit emory cloth in his wallet

madpoet

 

[David Rock]

Well, I'll tell you how I did it (with my Spyderco Moran fixed blade):

I sharpened it as a normal "v" grind until it in fact was, and now it's no problem at all.
Yeah, I know: it's like Alexander's method of untying the Gordian knot.

David Rock

 

[Ken Cook]

Perfect!

Thanks to all of you!
I really LOVE this forum. You cam come up with any question and get great answers like these every time!
Too COOL!
(Thanks Mike & Spark!)
Cliff,
Great alternative to the high dollar solution. (I'd rather spend the money on knives!)
Mad Poet
Don't know why, but the second I read Cliff's post I pictured using a stropping stroke. Thanks for the confirmation!
David,
What I want to know, is how do you TIE a gordian knot, and is it usefull in rappeling?

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I cut it, and I cut it, and it's STILL too short!

 

[Walker]

Madpoet's method sounds do-able at home. How long does it take to finish an edge like that? One hour? Ten hours? Longer? My attention span is a concern, too.

A question for those of you who use a belt sander:
I have always steered clear of mechanical sharpeners, primarily because of iron/steel's inability to transfer heat effectively. A motor grinder allows a lot of friction, which causes heat buidup, which does not dissipate rapidly in iron/steel (that's why your kitchen pots have copper clad bottoms - copper transfers heat well). The thinner the iron/steel, the higher the heat retained; heat would therefore be highest at the thinnest part, the cutting edge. High heat left to cool is "annealing," which, done properly, is a part of the blade's heat treatment. Done improperly, as in grinding an edge, it will ruin your edge.

The pro's I've watched have used water-cooled grinders to prevent this unplanned annealing, or have worked their blades with bare hands to sense the temperature rises (still risky, because the temperature can be above the critical level at the edge before the heavier stock of the blade gets a significant rise).

What prevents this phenomenon when using a belt sander to lay on a convex edge?

[This message has been edited by Walker (edited 17 April 1999).]

 

[P.J.]

Walker:
Practice, it takes time and a few burnt edges to be able to sharpen on a slack belt. Pick up a bunch of garage sale knives to practice with, it's cheap and they are handy for tackle boxes, etc.

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P.J.
YES,it is sharp, just keep your fingers out of the way!
www.silverstar.com/turnermfg

 

[mps]

Everytime this thread comes up it just leaves me wondering how folks that can effortlessly put a convex edge on an ax or hatchet with nothing more than a file or coarse hone, can be so intimidated by a mere knife. I think the knife industry and the public's general drift away from farm implements have really contributed to the misunderstandings of the various methods to sharpen a knife. Prior to Moran, the convex edge was considered by many to be the sign of the novice knifemaker, since it's so much easier to put on than anything requiring crisp grind lines. It's *O*L*D*. It's also very, very effective for certain things where a thicker blade stock is useful. Various names I've seen associated with this very useful edge are: rolled, convex, appleseed, Moran, ax and #@&!.

As madpoet points out the only things really needed to maintain a convex edge knife are a simple bench stone and a backwards, spine leading sharpening stroke coupled with a little bit of wrist roll.
That's how I maintain my Blackjacks, and it's how my grandad taught me to sharpen a simple camp knife back before sharpening jigs and fixtures were considered necessary.

mps

 

[MCK]

Awesome information. One question; is this technique applicable for chisel ground blades? And if so, should the blade be drawn, spine first, with the flat side down or the angled side down? (I hope that makes sense!?)
Thanks, MCK


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It is better to have and not need, than to need and not have.

 

[Ken Cook]

mps
You obviously haven't seen the edge of my axes and mauls. VERY straight, chrisp, SHARP angled edge. yeah, I do it with a file, but I never even thought of using a rolled edge on them.
I guess the question I failed to ask, is;

Is the rolled edge "better" and if so, for what uses?


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I cut it, and I cut it, and it's STILL too short!

 

[madpoet]

Walker,
As long as you keep your blades relatively sharp, its only takes a few minutes to restore the edge using an emory cloth over a pad, and a strop. One trick is to just use a different section of the emory cloth once the one you're working on plugs up with residue, to keep it cutting fast.
The thinner the bevel, the more material you will be trying to remove, but the easier the knife is going to cut. The only drawback is that it will also be easier to roll the edge over or chip it on some steels if you go excessively thin.

Sharpening on a belt sander, you do have to watch it so that you don't burn the edge, especially at the tip. Its easier to do a good job starting out if you use a finer grit, but a new, sharp belt. Once you have the feel, you can use up to a 400 grit belt that is pretty well worn out for putting the final polish on an edge.

One benefit of the 'convex' edge is that it doesn't have the drag of a traditional double bevel. The other is the relative strength the edge has even if it is fairly thin, making it more resistant to chipping. The convex profile actually leaves more steel reinforcing the edge than a flat grind. That's one reason it is used on axes and mauls, since it can take a beating, though the profile they use is thicker than a knife edge too.
One problem I have seen lately is that the quality of the 'steel' and heat treat used in most newer axes leaves them relatively soft compared to something like an old Plumb or Estwing or Collins axe. They're not quite dead soft, but most of what you buy off the shelf in a hardware store isn't even spring tempered, let alone a hard edge.

Carried to its extreme, (a Moran camp knife is a good example of this), the entire blade can be convex right down from the spine to the edge, allowing you to have a strong, stiff blade out of relatively thin stock, even when it is distal tapered to the tip of the blade.
What you're more likely to see are flat ground blades with convex edges, which work almost as well, but are easier to make. Either way, a properly done convex edge works well, and I think it is worth the time to maintain one, and convert your other blades over to it if you're not totally wedded to the 'lansky' style sharp bevels.

madpoet

 

[Rusty]

One other term you may hear used sometimes is a "cannelled" ( spelling? ) edge. Same thing. And I just sharpen the edge normally. By the time you've turned it from a rolled to a V cross section grind by doing this, you'll probably retire the knife cause you're sick and tired of looking at that old thing.

 

[Mike Turber]

Great question and answers! Learn something new everyday and you even learn before you even think to ask the question.

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Best Regards,
Mike Turber
BladeForums Site Owner and Administrator
Do it! Do it right! Do it right NOW!
www.wowinc.com

 

[David Rock]

What about this:

If I sharpen free-hand on normal stones, using the traditional technique as learned by most Boy Scouts, and with a bit of inevitable slop in keeping the angle consistent, am I not getting a fair imitation of the highly-touted convex edge?

David Rock

 

[Ken Cook]

David,
I only know about the rolled edge from what I've learned here, but "slop" in a standard beveled edge is never a good thing.
Even though you have more contour than with a single bevel, I'd bet you probably end up with even more drag than a single bevel.
Not only that, but if you look at your edge through a good magnifying lens, you'd probably see a "wobbly" edge. By this I mean, the edge isn't straight down the length of the blade. This is easy to find when you try cutting a piece of paper ala' sharpness testing. The blade will catch in the paper at any "step" in the edge.
Hmmm, I'm having trouble finding a way to describe this. Anyone with better nomenclature, if you can understand what I'm driving at, feel free to explain it a little better!


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I cut it, and I cut it, and it's STILL too short!

 

[mps]

Since it has more "cheek" immediately behind the edge to support the edge, the convex edge is good at chopping. The extra "cheek" of metal helps split materials like a wedge. That's why one finds convex edges on axes. That's also why simply rolling any blade that came from the factory hollow or semi-hollow ground won't duplicate the performance of a true convex blade or even a flat grind made into a rolled edge. OK, That's reasonable sounding enough.

Here's one part of the q that I can't answer. Why do I see an increase in *slicing* performance using something like convex ground BlackJack hunting knives over hollow, flat and saber ground similar sized and shaped knives????? (Actually, I know why convex beats hollow.... the blade doesn't bind in the work. But better than flat???) I've assumed that it was more because the BJ's in q are A2 and the other knives I'm comparing them to aren't, but it could also have to do with the grinds. The concept of a fat-behind-the-edge knife beating thinner profiled knives in side by side slicing makes NO sense to me and is not evidenced by results of any other grinds than full convex blade shapes. Any thoughts?

I guess it could be that with a true convex blade, the cheek of the blade pushes the material out of the way of the edge as soon as it's sliced, thus creating less drag and less contact time with the actual edge resulting in less edge deformation. Obviously with something like a hollow or semi-hollow grind the material can tend to close back on the blade causing more binding and more edge contact time, but on a flat or saber grind is it really that pronounced?

If I ever make it through the folder tests that have me so bogged down right now, I ought to really do some serious side-by-side fixed blade comparisons to see if what I think I'm seeing is reality or assumption. Hmm, more damn work. I'd sure be interested in seeing a 5" lockback folder made with a convex A2 blade. (Hey, I can dream can't I?

mps