Sharpening: grind angles and "hair-popping"

[AlphalphaPB]

(raises hairless arms)

I've started to get the hang of sharpening blades. I'm not using a sharpening system, just a set of 3 natural Arkansas oilstones. I'm using honing oil, since the stones were impregnated with oil at the factory.

In my attempts to get "hair-popping" sharpness, I've noticed a few things, that I'm not quite sure about:

1. I only have production knives, and it seems that the cutting edges on the right side of the blade (the side you don't normally see when you're slicing) are at a shallower angle than the left side. I think so because the sharpened edge is wider than on the other side by one or two millimeters. Is this generally true? Right now I'm sharpening the right edge at a higher angle than the left.

2. How is "hair-popping" defined? I think my early attempts to achieve this failed because I wasn't shaving properly. I held the blade perpendicular to my skin, and not much hair was coming off. I realized that shaving razors are at an angle to the skin, so I tried angling the blade, and *pop* there goes all my hair. Hehe. Now I gotta test on my legs. But when I run my finger along the edge, it feels a little "rubbery", like the blade is sticking to the skin. Does this mean my technique is bad, and there's little imperfections in the edge?

3. I noticed a good way to "see" the wire-edge when sharpening is to hold the knife so that it's facing a light source. Places with a wire-edge will cast a very small shadow along their length, so you can tell where you need to sharpen some more. This also lets you see where the angle of sharpening is inconsistent.

4. I read in a thread here that Spyderco blades are ground at 20 degree angles, I was wondering if particular companies have their own consistent grind angles.

Wow, long post. Sorry for the long-windedness. I'm just a happy newbie sharpening all the blades in the house.

 

[ZENGHOST]

Originally posted by AlphalphaPB
4. I read in a thread here that Spyderco blades are ground at 20 degree angles, I was wondering if particular companies have their own consistent grind angles.

I'm not sure about the rest of your questions, but I believe that according to the video that comes with the Sharpmaker, Sal Glesser states that Spyderco comes with a 30 degree grind (15 per side). And I think that different companies do have angle preferences for their factory edges.

 

[Cliff Stamp]

AlphalphaPB :

... the cutting edges on the right side of the blade (the side you don't normally see when you're slicing) are at a shallower angle than the left side.

This is rarely intentional, and is usually just a sign of sloppy work on the grinding.

How is "hair-popping" defined?

In general it just means "really, really sharp", it shaves very smoothly. Personally I would define this as the ability to cut through fine hair without the blade touching the skin, but opinions differ.

I was wondering if particular companies have their own consistent grind angles.

Yes, but they should be pretty much ignored by the serious user.

-Cliff

 

[JayBird]

Cliff,

It's time for me to raise something I brought up in a thread a few weeks ago. One can have a burr that aligns with the edge and is both difficult to detect and fragile. It can also be very sharp, for a little while. Some people advise using progressively lighter strokes with the Sharpmaker. I guess I don't understand the intent of doing this when a finished and proper edge will see some pretty hefty loads. And such an edge, if created right, made in good steel, etc. will still shave after such loading.

I seem to always be battling the "burr aligned with edge" problem.

Also, I've sharpened my Native to 40 degrees, making the factory bevel a secondary. What do my fellow forumites think about the advantages / disadvantages of this?

 

[Cliff Stamp]

JayBird :

I seem to always be battling the "burr aligned with edge" problem.

Burrs are in general mainly an issue with soft steels with high alloy carbides, which is unfortunately really common right now. The straight up burr is the worst as it is deceptive and many miss that it is there. It is mainly a problem if you strop to remove to remove burrs, as any honing on a rod or stone will fold the burr to one side or the other if it doesn't remove it. The advice with the Sharpmaker is to remove such a burr, not create one, but isn't as trival as is stated. Experience is the key, as you have to apply enough pressure with the hone to cut off the burr, but not enough to fold it over again. This is different for different steels, and different abrasives.

I've sharpened my Native to 40 degrees, making the factory bevel a secondary. What do my fellow forumites think about the advantages / disadvantages of this?

Dual edge profiles, basically approximate convex ones, and offer a strong combination of high shallow durability (direct impact), and cutting ability. They also offer much quicker sharpening as you only touch up the secondary bevel. You do lose some cutting ability, but it is very small. You have to be cutting some very thin material to even notice it at all. Just be sure to touch up the 15 degree bevel from time to time to prevent excessive edge thickening.

-Cliff