High performance edge

[Texas guy]

I have been meaning to do a write up on some edge research I have been doing for awhile now, so bear with the length. Hopefully some more of you try this and give more imput, besides isn't it fun to experiment with your Spydies?

Spyderco knives come with an industry leading sharp edge right out of the box that is capable of aggressive cuting. Yet I have always been able to easily make my Spyders sharper than they come new, bringing them up to that "chasing hairs off without touching the skin sharpness" you know, the polished edge separating newsprint kinda sharp. I actually enjoy bringing all of my Spydies up to this level of sharpness, and mainting them at this peak.
I noticed that even though these super sharpened knives shaved better than a Mach 3, they really couldn't do the aggressive cutting that a new factory edge could attain. Now we have all read the arguments for a polished edge against a "toothy" edge, but most people seem to be fixated on the super polished edge.
Ok, now we begin some study into edges. After giving it some thought I decided that if I carry two Spydies all the time I should keep one polished for push cuts and one Spydie toothy for other aggressive cutting. I have practiced countless hours sharpening to the finest edge possible, but let me tell you that a proper toothy edge IS NOT just a less sharpend knife, or JUST stopping on a lower grit. When a knife is sharpend on the belt grinder at the factory all the scratch pattern is perpendicular to the edge. This I believe is what creates the efficient cutting edge we see on new knives. Whenever a knife is sharpend on a Sharpmaker or bench stone, we pull or sweep the knife through laterally, creating a scratch pattern that is nearly parallel with the edge.
In my experimenting I decided to try a course DMT Diasharp bench stone. It is the uninterrupted surface stone with the course grit. Since I usually carry my Para and my Caly Jr., I wanted to leave my Caly polished and would do the experiment with my Para. I sharpened my Para Military on the coarse grit stone ALWAYS making sure that I only moved the knife edge PERPENDICULAR with the stone. I had to reposition the knife after every stroke since there was no lateral sweeping of the blade. After sharpening enough to remove the polished edge that was on the Para, and used lighter and lighter strokes, I ended up with a edge that looked surprisingly like a factory edge including the all-important scratch marks that are at a 90' angle to the edge. The only other stone that the knife touched besides the course diamond stone was ONLY 3-4 strokes on the brown Sharpmaker stone to take some of the hanging burrs off (use a course diamond stone and you will see what I am talking about).
So I went back to my daily carry of both my Para with it's new toothy edge and my always polished Caly. I have noticed that I take out the Para even more now instead of my Caly because it cuts so well. I suggest some of you try this, especially those who carry two Spydies anyways, and let us know what you find out.

[ront]

Good read Texas guy. Thanks alot. I love all the information I get on these forums :D :D .
I finally got the time to read all of your post. It makes alot of sense. I am going to give it a try. Thanks for taking the time to post this.

Ron

[bowarrow2000]

Hey Texas Guy glad to see your post. I too have been going with a med. grit DMT stone (blue) and getting much closer to that factory edge. Most of the time I will make a few passes over the fine DMT stone (red) for a final finish. Sometimes I will just use lighter strokes on the blue stone which does just a well. I also use the sharp maker some but perfer a bench stone for my sharpening jobs.
Nothing better than a sharp blade and a full clip in your 45.

[greencobra]

Interesting stuff there, thanks for taking the time to put it up.

[Plowboy]

Texas Guy,

Thanks for sharing this information. I done a bit of reading on this subject and it seems your experiments are similar to some I've read about. It is interesting the way your have the two knives with different approaches to sharpening. I've been mostly using the Sharpmaker, but I'll try a flat stone the way you describe.

Thanks again for posting this information. :)

[spydutch]

Thanks very much for sharing Texas Guy.

Since I only carry/use SE blades, my edges are always toothy :D

However, despite the fact that I can get my serrations cigarette paper slicing sharp, I still have a very hard time doing this on the plain edge part of my knives.

I only have the Sharpmaker with the standars 4 stones.

Suggestions will be very much appreciated.

[J.B]

Interesting topic!

While sharpening/ touching up all my PE blades in the same way, sharpmaker 204 white stones flat side and stroping on cardboard or leather belt, I experienced to like the toothy plain edge of a D2 blade the most. Because of it´s big carbides it seems to have those microserrations that "saw" really nice through everything. If I remember right it was Bob Dozier who said about D2 "It takes a lousy edge and holds it forever". The big carbides or lousyness of the edge on the downside are sometimes breaking out bigger than wished.

E. g. S30V seems to behave similar up to a certain point. Jerry Hossom described it in this thread on knifeforums. The toothy factory grind "saw" with a grippy feeling that reminds me a bit of D2, but the same blade with a polished edge probably holds much longer. The very small microserrations of S30V factory edge may offer more working points for breaking out carbides than a shiny edge. Since S30v has a finer grain structure with smaller carbides than D2, this only takes place to a smaller extent.

As far as PE is concerned it looks like one has to decide between toothy feeling and longer edge holding capability. This does not mean the big serrations of SE blades (spyderedge). But I guess a S30V SE blade with a polished edge will hold the edge longer than the same blade with a toothy microedge.

Besides one has to be careful not to sharpen a blade too much. Like Jerry Hossom said in his mentioned thread: "You need to remember that not all knives benefit from a scary sharp edge. Some need a stronger edge and "scary sharp" frequently isn't."

By the way, all knife blades are serrated blades, some only have smaller serrations. :)

Best wishes,
JB

[mikewww]

Is a belt grinder out of the question for the average knife enthusiast ? The Edge Pro style of sharpener would seem to similate more closely the belt grinder, as it is just a very short segment of belt at the correct angle.

While I am blaspheming here, how about the Tormek. This even has a rotating leather strop on the opposite side.

Does anybody use either of these machines ?

[gull wing]

Thanks Tex

I have an edge pro, I think I may try it on "course" water stone. Funny, I never tryed cutting after using the course stone, always finished with the finer stones.

I freehand extremely badly!

[JDEE]

As far as PE is concerned it looks like one has to decide between toothy feeling and longer edge holding capability. This does not mean the big serrations of SE blades (spyderedge). But I guess a S30V SE blade with a polished edge will hold the edge longer than the same blade with a toothy microedge.

Best wishes,
JB

In all the tests I have conducted an aggressive edge will last longer than a polished edge when used on mediums such as rope etc. Of course if you change the medium to wood the result is reversed. I have conducted my tests with knives with the same blade and steel and also different steels. An AUS8 Kabar Dozier with an aggressive edge will out cut a Delica VG10 and a Paramilitary S30V with polished edges. As always with blades, steels and edges it is a matter of "horses for courses".

[Ed Schempp]

For this example I'd like to refer to my Persian design for the sake of discussion. The Blade of the Persian is hollow ground with about an 8 inch wheel. After this process there is a flat unsharpen edge about .005-.007 of an inch wide. The Blade is then sharpened with 220 grit 8 inch wheel. You have intersecting arcs on either side of the blade ending at the edge. When you have to sharpen the edge you have two choices; increase the edge angle or take off the shoulder. Using ceramic sticks that are flat means that it takes a while to turn the origninal sharpened arc into a plane. Because I use a belt grinder with a slack belt I reverse the original sharpened arc from concave to convex. I usually peel back the shoulder to where the sharpened zone on the blade doubles in width. This gives me a hamaguri or appleseed edge. I'm using a 400 grit belt and then buffing not polishing the edge. It gives me an almost polished seration. This edge has a continuous uninterupted angle of approach in cutting. Using the sharpmaker will give you a similar edge; because the blade is not fixtured there are a few degrees of varience in the angle of approach. A little bit of human error is not a bad thing; it probably gives a better more durable edge...Take Care...Ed

[The General]

Or put another way, its a convex edge like you get on the Sebenza. Certainly a very high performing edge that is very easy to put on.

Use a leather belt with a little give and some Flitz to strop or a little cardboard and flitz. Reprofile with a wet and dry fine paper over a mousepad or thick bit of rubber or similar that gives a little.

A great edge, but one I often just don't need. Few passes with a Sharpmaker Ultra fine stone and the slack belt gives me a hair popping edge every time.

[J.B]

These testing results and professional grinding insights are very interesting.

JDEE, I remember you are a fan of D2 yourself and would like to see it from Spyderco too. What you wrote about the differences between agressive and polished edges and Ed Schempp´s very nice professional input leads me back to what Texas guy wrote at the beginning.

We all seem to like the microtoothy factory kind of edge for feeling and/ or edge holding abilities. Only the grinding processes to reach this kind of edge differ. We add more or less convex grind to the edge, some do knowingly, some do by a little good human error.

Using bench stones sounds a bit exhausting. As long as I have neither a Tormek nor D.G.G´s nice bike :D , I ´d have to give our maybe too strong and too coarse belt grinder a shot. In a movie from the internet in which Bladesmith Andrew Jordan from Holland sharpened a bowie knife on his belt grinder it only lasted a few seconds. It didn´t look like he had to finish the edge further. I just found the movie in which the sharpening is shown after 22.00 minutes: Link for broadband connections and link for slower connections .

Best wishes,
JB

[ront]

This thread is great. I too really like the toothy edge that the Spyderco knife comes with from the factory. I have some yarn that I test sharpness with. That toothy egde cuts right through it while the smooth polished edge, that really cuts the hair off of my arm, just slides over it until I add more pressure. I am going to try one of my knives on one of my diamond stones and see what I can come up with. Thanks for all of the good info!!

Ron

[Ed Schempp]

In the custom industry it is very difficult to find a polishished CPM steel blade. I worked with S60V or 440 V when it came out. I tried hand polishing and machine polishing of this steel; it is near impossible. On stainless blades that I wanted to mirror polish, I would take to 600-800 grit. At about 320 grit with CPM steels you start dragging Vanadium carbides off the surface of the steel. They can be RC84 in Hardness and easily scratch a 220 grit mark on the surface you are trying to polish.

The carbides on the edge are the same size as the ones that leave a scratch when I try to mirror polish. The steel matrix holding these Carbides is usually a smaller grain so you can get this material sharper than 300 grit, but it is a challenge...Take Care...Ed

[mikewww]

I just watched the video that JB pointed to. Very interesting to see the various grinding techniques. A lot of work goes into blade-making, and my admiration goes out to the blade-makers. I think I will just stand back and admire the work.

One thing : The knifemaker mentioned Micarta, and pronounced it "mee-carta". I have always said "my-carta" . Which one is correct ?

[ront]

Ok, so if I am attempting to immitate the factory edge, would I use a course or a fine diamond stone?
Also JB, great video, thanks for sharing!! What a nice knife! It did make me have another question though. In the video, when he is sharpening the blade, he is sharpening away from the blade. I usually sharpen into the blade as if slicing something. Am I doing it the correct way for the best results or is he?
Sorry guys, I am just eating this info up!! I want to learn to put the best edge on a knife as I can. There is just so much to learn!!

Thanks, Ron

[J.B]

Ront, you are welcome, I´m glad you like it. The reason Andrew Jordan has ground away from the edge is in the power of the belt grinder. The other way around it simply would not work and it would be too dangerous, because without much doubt the blade would be snapped away and could cause serious injuries.

To imitate the factory edge Texas Guy wrote "In my experimenting I decided to try a course DMT Diasharp bench stone. It is the uninterrupted surface stone with the course grit. ... The only other stone that the knife touched besides the course diamond stone was ONLY 3-4 strokes on the brown Sharpmaker stone to take some of the hanging burrs off (use a course diamond stone and you will see what I am talking about)."

Best wishes,
JB

[ront]

Thanks, J.B, I kinda thought using the wheel was the reason for going the other way, but was not sure.
I have a Smith Course Diamond stone, so I till give this a try I think.

Thanks, Ron

[Texas guy]

After spending so long polishing down to the finest grit, at first I find it felt wierd to only touch up on a coarse stone. But, the edge cuts so well I quickly forget that it dosn't shave arm as easily. But the knife now cuts through rope, cord, boxes, wood or anything else you actually cut in real life with ease. Besides, I always have my Caly Jr. with a polished edge that I use to "show off" and shave hair, or split newsprint.
For now I have been getting great results with the DMT coarse stone, but I do intend on trying the DMT fine grit also.
In doing my research on edges I read from several sources that hard steels, such has S30V, prefer softer stones because the hard ceramics flop the burr too much weakening the edge. I believe that the diamond stone cuts aggressivly enough to prevent this flopping of the burr. I have noticed this on the Sharpmaker, where I can oversharpen the blade creating a weak edge.