what finish to put on edges?

[gunmike1]

The white sharpmaker stones seem to give me the best combination of push cutting and slicing edge sharpness and retention on my knives for my light duty uses, while I use the corners of the brown rods for more cardboard intensive work. The steels I use are AUS-8, VG-10, S30V, and the steel used in Byrd knives.

Depends on the hair and exactly what you mean. If you are serious about sharpness you want to move to a definate test. The easiest one to use in a quantitative way is to push cut newsprint. There are several ways to do it. I pinch the sheet of newsprint between my fingers and the further away from that point you can push the blade into the paper, the sharper the knife. With a really sharp knife you can get out to 3+ inches.

-Cliff

The sharpest knife I had ever seen until I got my Spyderco R2 was a factory sharpened Native, which can push cut newsprint about 1.5" from where you hold it. At the time the best I could do was about 3/4" from where I hold the newsprint, but since I bought a 60-100 power lighted microscope from Radioshack and minimized my burrs I can now get knives close to that Native with the white sharpmaker stones. I thought that was about as sharp as you can get a knife. But my new R2 can pushcut newsprint over 3" (just under a full blade length) from where I hold the newsprint, and this is by far the sharpest knife I have ever used. It also has excellent slicing aggression. The grind is a thin flat grind, and the edge is very thin and around 10 degrees. I will put some calipers on it later to see how thin it is. I guess this knife shows me I have a long way to go in my sharpening technique to get truly sharp knives.

 

[CMSpeedy]

I've searched, but cannot find if old leather belts can make a good strop. I want to use it with no abrasives to polish a few edges up. Will it work?

 

[Cliff Stamp]

I've searched, but cannot find if old leather belts can make a good strop. I want to use it with no abrasives to polish a few edges up. Will it work?

Not significantly. I use plain leather to clean edges of debris before finishing honing, but it has no significant abrasive quality on its own.

I guess this knife shows me I have a long way to go in my sharpening technique to get truly sharp knives.

Spyderco does that to most people.

Another interesting thread would be discussion of crystal shape, structure and density of different abrasive media, which I think must be important factors. Also effects of an abrasive slurry vs. dry honing. Maybe I'm mistaken, but there seems to be a lot more involved than just the "grit" of the abrasive.

Indeed, bottom line though what you are interested in is the push cutting and slicing sharpness produced at a given angle and these are easily measured, even though the nature of the abrasive generally isn't. I would much rather see those two qualities determined for the various abrasives rather than grit/micron numbers.

-Cliff

 

[Ben Dover]

Cliff,

I have never had a knife sharp enough to push cut newsprint. But I'd like to!

Would a combo of Norton waterstones of 220,1000,4000 and 8000, followe by stropping with CrO on leather be adequate, or do I need something finer?

I also have glass and abrasive paper up to 1500 grit. Would that be better than the waterstones, especially if I bought some 2500 and finer grit paper???

Thanks in advance,

Ben

 

[Cliff Stamp]

What you need depends on the steel. I have sharpened blades to that point using the coarse side of a cheap hardware stone which is about 90 grit and costs $2. However you need a fairly soft and low carbide steel to use that hone well as it tends to skip on the harder and especially heavy vanadium steels.

However an x-coarse DMT plate will abrade most anything and it can leave an edge shaving with the ability to push cut newsprint. The ability increases as the finish increases. With 1200 DMT I have seen blades push cut at 3 inches from the hold point with 15 degree bevels. You could likely go further with a decent finishing abrasive.

These are not burrs or wire edges either, these are edges which retain the ability to slice paper after dozens of meters of cardboard and will even keep a fine shaving edge for quite some time. In general the more extreme you go with initial sharpness, the directly better the edge retention. Forget about that "too sharp" nonsense.

Adjust the edge bevel to the required minimal durability and then sharpen to the maximum you can. I would not get too caught up in trying to reach Clark level on the first blade you sharpen. Just try to get a little better with each blade. Fundamentally keep in mind that it is a very simple process which consists of two steps :

1) shape the edge and make the bevels meet

2) remove the abrasive debris, fractured and deformed steel from the very edge, all of which is ususually called "the burr"

Most people get frustrated and never get beyond step one because they are honing at the wrong angle or using way too fine a stone. A simply 10x magnifier elimates this problem completely.

The second part is a bit tricky until you realize what is going on. Use a clean abrasive, elevate the sharpening angle, go very light, use short passes and alternate sides.

-Cliff

 

[bbcmat]

Cliff - when you quote angles - do you mean per side or total (included) ?

What is a "short" pass on the final touch - can't picture it. Edge into stone? Forward or lateral movement - or a combination of both?

THx

MAT

 

[hardheart]

Forget about that "too sharp" nonsense.

Is there a 'too smooth' for edge polish? I guess that's really what I was asking, as far as how fine a grit to go with, and if it was dependent on the knife steel. I don't like very highly polished edges, they don't slice well at all, but I am wondering where a good balance lies for the finish of the microbevel. If I can drop the angle, stay coarse, and keep a durable edge, that'll be great. I thought that thinner edges needed a bit of polish to reduce stresses.:foot:

Also, would polishing the relief on a carbon steel help reduce corrosion there, I'm guessing it would.

 

[db]

A very polished edge is good for some things but for the most part on a edc I don't really care for them much either. The finish I've been useing lately is the Spyderco medium bench hone. It's a good balance between push and slice. What do you have or use to sharpen? I've found that you can effect how it will cutt by pressure used, heavyer can give a coarser edge and lighter can give more of a polish.
Polishing the relief can help with corrosion a little. I know for a fact that a polished relief does help with stuff sticking to it. I get much less sticky tape goo if I polish it.

 

[Cliff Stamp]

Is there a 'too smooth' for edge polish? I guess that's really what I was asking, as far as how fine a grit to go with, and if it was dependent on the knife steel.

You can sharpen a knife past the ability to take a polish at which point nothing further happens as the edge just keeps chipping due to the coarse structure. In general though you need fairly acute edges to see this meaning far less than fifteen degrees per side.

Polish does reduce slicing ability both in terms of initial cutting ability and especially edge retention. Rather than looking at one sort of mixed finish I would suggest looking at sharpening different areas of the blade to differnet grit finishes. That way you get two excellent finishes rather than one ok one.

Also, would polishing the relief on a carbon steel help reduce corrosion there, I'm guessing it would.

Yes, but generally this isn't significant compared to the inhernet corrosion resistant of the steel. Note that as soon as you use it significantly the polish is removed anyway.

-Cliff

 

[bbcmat]

Cliff:

What is a "short" pass on the final step - can't picture it. Edge into stone? Forward or lateral movement - or a combination of both? Short as compared to what?

THx

MAT

 

[Cliff Stamp]

The blade doesn't travel very far on the stone, I use strokes of about half a cm or so on edges which tend to be prone to burr formation. This means that you have to do the edge in sections. This isn't always necessary.

-Cliff

 

[Ben Dover]

Cliff, I didn't want to experiment on my better blades, so I pulled an old Schrade and a couple of Bucks out of the box and tried your advice. I don't have an X coarse, but I do have a coarse diasharp.

It took a while with the Buck Stockman, but I went through the coarse diasharp until it would shave. I then went through the waterstones, from 1,000 to 8,000, and stropped with CrO. I haven't tried it on newsprint yet, but it push cuts computer paper two inches out easily. The Schrade only took about 20 minutes, and a little Buck "Gentleman" took about 10 minutes

:jerkit: :jerkit: I'm trying to work up the nerve to start on my Benchmade 710-D2!:jerkit: :jerkit:

Thanks for the advice!

Ben

 

[Cliff Stamp]

... I went through the coarse diasharp until it would shave.

That is the critical part that causes most problems. Not enough work is done on the coarse stone and thus the finer stones actually have to finish its work and they are much slower. Now you just have to get them to push cut single ply toilet paper.

-Cliff

 

[omniphile]

I don't wish to sidetrack this important thread, but while on the subject of high sharpness, there is something that always made me curious. In the movie The Bodyguard there is a scene where Whitney Houston is holding a samaurai-type sword stationary edge upwards, and Costner takes a scarf off her neck and throws it in the air. Under its own weight is falls across the blade edge and cleanly slices it in two. Is this degree of sharpness actually achievable or is it just Hollywood hype?

 

[hardheart]

I read that was how swordsmiths in Japan tested their edges, with a piece of silk, that had to be where they got the idea for the scene.

 

[thombrogan]

It'd need to be a heavy scarf. Or any scarf choosing death over dealing with Kevin Costner and Whitney Houston...

 

[omniphile]

OK. I tend to agree with thombrogan!

But that is very interesting factoid, hardheart. It kinda makes you (or me, anyway) appreciate the skill of the "old tradespeople". In these days of science and super high technology, its easy to forget just how talented the tradespeople of old really were.

I also just realised that I shouldn't pose a "hypothetical" without people knowing what I'm talking about. I posted a small excerpt of that scene at http://www.phile.com.au/Short.wmv (its 450 Kb) in case anyone was interested.

Cheers and thanks
Phillip

 

[jdennen]

The sharpest knife I had ever seen until I got my Spyderco R2 was a factory sharpened Native, which can push cut newsprint about 1.5" from where you hold it.

The first Native 1 that I owned was extremely sharp. I traded it and bought another Native1. This one was very dull! I looked at it under a magnifier and one edge looked perfect and the other was all chopped up. I re-profiled it using the 30 and the 40 setting on the Sharpmaker. It took forever. In fact, I just ordered the diamond rods for it. The knife is now fairly sharp. Ironically, the sharpest knives that I’ve seen lately (strictly for paper) have been Gerbers. The have a fine consistency and glide through the paper. They don't stay that way, but no knife does. Up to that point, I would have said that MT, PT and BM were the sharpest. Once I re-profiled my 710, it would cut for a long time before getting dull. D2 has a coarse consistency and you have to polish the serrations off before it will not rip paper instead of cutting it

 

[gunmike1]

The first Native 1 that I owned was extremely sharp. I traded it and bought another Native1. This one was very dull! I looked at it under a magnifier and one edge looked perfect and the other was all chopped up. I re-profiled it using the 30 and the 40 setting on the Sharpmaker. It took forever. In fact, I just ordered the diamond rods for it. The knife is now fairly sharp. Ironically, the sharpest knives that I’ve seen lately (strictly for paper) have been Gerbers. The have a fine consistency and glide through the paper. They don't stay that way, but no knife does. Up to that point, I would have said that MT, PT and BM were the sharpest. Once I re-profiled my 710, it would cut for a long time before getting dull. D2 has a coarse consistency and you have to polish the serrations off before it will not rip paper instead of cutting it

The last Spyderco I got before the R2 was an Endura Wave, and it couldn't push cut at all because of a large, visible burr. A few passes on the sharpmaker at 20 degrees cut the burr off and had it very sharp. Even Spyderco puts out some blades that aren't sharp, which you expect for a production line item, but they seem to be consistently among the sharpest knives out of the factory.

 

[thombrogan]

Thanks to everyone's inspiration, the back-bevels on my zdp Delica are now at the bottom of the opening hole and will be halfway past it, or higher, when the first burr is raised.