Wicked Edge / Edge Pro

[wongKI]

With regard to convex grind, perhaps some form of flexible rod? I think having little joints with a small (1-5 degrees) range of motion one inch apart would do a great job of mimicking a convex edge.

 

[bladestamp]

With regard to convex grind, perhaps some form of flexible rod? I think having little joints with a small (1-5 degrees) range of motion one inch apart would do a great job of mimicking a convex edge.

This is really not necessary. There is a very simple, and highly controlled way of creating a convex edge using the system as is.

An alternative to the published (soon to be demo'd on video) method might be this; take a blank holder (without stones on, about $22/pair) glue a piece of mouse mat on, followed by your lapping film of choice.

BladeChemist, just realised you meant choose W.E over E.P, not W.E over learning to sharpen by hand.. My analogy is, unfortunately, meaningless. , at least in the context of your reply.

To go off-topic for a moment, I just heard the UK's biggest turkey farmer died on Thanksgiving. A bootifull irony.

 

[Medic1210]

Sure. The specs list the knife as 10" in length, 0.1875" thick with a high saber grind. The steel is 1095. 10" is a very comfortable length to work with in the sharpener. The high saber grind makes it easy to clamp and the thickness is well within the range of the clamp's maximum width of 0.33". It would be good to clamp this knife closer to the front third of the blade to adjust for the widening bevel along the curvature. This diagram shows how that adjustment works:

I guess I'm a bit confused, and am probably missing something, but doesn't this photo prove that as you get near the tip of a longer knife, the bevel angle changes? I mean, it shows the edge bevel going from 26 degrees to 17 something degrees near the tip. Am I missing something? I like this system, and am looking forward to using mine in a few weeks when I get home, but it seems pretty clear by these drawings that some folks' concern about bevel angle changing is valid.

Another way of looking at it is this. Since we're looking at a right triangle with this setup. If you keep the pivot locked in at 20 degrees, but sharpen a blade that's so small, the edge barely rises above the clamp, the edge bevel will be more obtuse, unless the marked angles are taken at the clamp itself. Then, if you replace the small knife with a hypothetical meat cleaver with a 25" wide blade (edge to spine), that puts the edge 24" above the clamp, the edge bevel would be more acute than 20 degrees. This is because, when you lengthen the long sides of a right triangle while keeping the base the same length, the two angles change (pivot angle gets larger and edge bevel gets smaller or more acute). Why would this be any different when going toward the tip of the knife? A long knife will mean you have to extend the stone along the guide rod, which means you're changing the length. When you change that length, you're changing the angles of the edge and pivot the same as you are when sharpening that hypothetical meat cleaver with the 25" wide blade. I'm not a geometry whiz by any means, so my logic may be flawed. Looking at Clay's drawings makes me think my logic is right though, because it shows a more acute edge bevel angle as the stones near the tip. This is not something you can look straight down the blade from the handle, as the box with strings suggests. This is something you have to look at from a constant angle that is perpendicular to the sharpening stone in order to see how the angle changes. If you take a right triangle, and stand it up straight, the only way to keep all angles consistent would be to lay the triangle over on its side, which means you'd have to sharpen an arched shaped blade. Since blades aren't circular shaped like that, you have to extend the stone to get near the tip. Anytime you extend the stone, you're increasing the length of the long sides of the triangle, which changes your angles.

Now, is this enough of an issue to matter for most folks? Doubtful. I know for me, I don't carry too many Junglass size blades. Most of the knives I'll be sharpening are pocket knives and kitchen knives. If my bevel appears to widen a bit near the tip, I won't lose any sleep. The 710 posted earlier in this thread shows this very thing, and it was sharpened on the EP. I could care less, it's still an impressive looking edge, wide beveled tip and all.

 

[atony]

I used the Wicked Edge on my Xm I just got, and it worked awesome. About 20min on the WE. 18per side, and this thing is laser sharp.

 

[bladestamp]

Anytime you extend the stone, you're increasing the length of the long sides of the triangle, which changes your angles.

Actually, no it doesn't

The angle changes at the tip because the tip curves. The curve puts the bevel in a new plane. While it is in a constant plane, (along the straight section)the angle does not change. It just doesn't, this has already been covered, and you can see in the diagram that it doesn't on the straight section.

On a tanto blade tip, the angle would be different (subject to the contents of the next paragraphs) but it would remain the constant along the entire length of the tanto section because it is in the same, constant plane (because it is straight). That angle will be greater or smaller depending on how far the tanto edge is from the clamp, in the same way that the angle is greater or smaller depending how high the blade is above the clamp. The angles marked on the W-Edge are based on the edge being 0.625" above the clamp. See spec page:

http://www.wickededgeusa.com/info/specifications.html

To get the bevel to remain exactly the same angle around a regular curving tip, you would need to place the blade in the clamp so that the distance from the pivot to the edge, measured vertically ("Distance A"), is the same as the radius of the curve described by the tip. To imagine this, just picture sharpening a semi-circular blade, with the guide rod pivoting round a point in line with the centre of the base. The bevel would be constant all the way round, like the side of a cone.

This may not actually be possible because you only have so much blade depth to play with, the clamp won't adjust for height and blade curves aren't all perfect arcs.

With a tanto it's easier, you place the blade so that Distance A is the same as the distance to a point on the tanto section that is 90 degrees to the guide rod. You can use an imaginary point if the the blade is not large enough.

This is probably where the Edge Pro has it beat. It's easier to place the curving edge at the correct angle to the stone, and constantly move it to maintain that angle around the tip.

 

[Medic1210]

Actually, no it doesn't

Actually, yes, it does. You can check this for yourself by drawing a simple right triangle on a piece of paper. For simplicity sake, make the sides 3, 4 and 5cm, with the base of the triangle being 3cm (feel free to use inches if you're paper is large enough). Now, on this same drawing, without changing the length of the base, increase the length of the long sides (4 and 5) to whatever length you want, but at least double the length of the vertical side to 8 or longer. If you do this as an overlay of your original triangle, you will clearly see the pivot angle (where the base meets the longest side) increases, and the edge angle (where the long sides meet) decreases. With the WE system, the base of the right triangle does not change during sharpening, yet the length of the other two sides do change, which is why you have to extend the stone further on the guide rod to sharpen longer blades. Anytime that distance increases, it's the same as your right triangle drawing. You cannot see this angle change if you're only looking down the length of the knife as shown in the example with the box and strings. You have to view this angle perpendicular to the angle of the sharpening stone/guide rod, because it's no different than leaning the triangle over.

 

[bladestamp]

We are covering old ground, but here goes. (Before I start, open a new tab with Clay's graphic at post #70, it's clearer, and you can toggle between the pages as I ramble on.)

OK, what you have done in your example/model is increase the distance between the pivot and the blade edge ("the longest side" = the hypotenuse). Of course that changes the angle. That is why the system is adjustable. That's why a deeper blade changes the angle and it has a depth key.

Your model is looking at the wrong plane (or rather, you are confusing 2 planes). We are not dealing with a 2D shape, it is a 3D prism. The length of the sides of the 2D triangle you have described (at the ends of the prism) do not change at all during sharpening. The base of your triangle (we'll call B) represents the bar with the angle markings on. The vertical side (V) represents the clamp (with the depth key adjustment). The hypotenuse (H) is the long side, and is also the new plane in which the stone is held.

To change the bevel angle (the new plane, and the sloping face of the prism) you adjust the length of V & B but once it's clamped down, they can't change, so the angle doesn't. The stone is kept in that constant plane by being in contact with the edge of the blade. That's where the angle could change, with the curve of the blade.

Also, if the user applies uneven pressure, or twists the stone forcibly while sharpening then they will change the bevel angle, but if they have such poor motor skills they probably shouldn't be playing with knives. (Not you, mate!).

To put your example into practice on the W-Edge, it is like taking an EDC blade out of the clamp, putting in a Kukri and saying "see, the angle has changed". It has, because you have increased V, and therefore H, without altering B.

Now, when you sharpen, the stone is staying in the same plane (because it is in contact with the edge). The length of the rod increases, but this is not the hypotenuse of your triangle. Your triangle is in another plane. Imagine your stone is 18" square. You wouldn't need to lengthen it, it would just move about in that plane and the blade edge would sharpen against it over a wider area, and that is the plane we are interested in.

 

[Medic1210]

I understand that. My example above was in response to the comment stating that changing the long side of the triangle doesn't change the angles. The problem isn't in the straight edge. It's where the blade curves toward the tip that is where the hypotenuse and plane change. Longer knives with more curve will have more of an effect than short knives. Most of this discussion has been whether or not the bevel changed near the tip of the knife. Clay's last drawing shows it does, in fact change. Moreso on long knives. That's why knowing this, I'm still happy with my purchase of the WE, because I'm not a 'big' knife person. Most of my pocket knives are 4" blades or less. I will sharpen some kitchen knives too, but really don't care about thinning the bevel near the tip. I am really looking forward to getting home in a few weeks and playing with my new WE, which I just received confirmation Friday that it was shipping. They also told me the extra fine ceramics were back ordered, but should ship by Dec 7, so they should be there by the time I get home anyway, so no worries. I have a lot of knives in need of better edges, and I can't wait to try my new system out.

 

[bladestamp]

I think we are all agreed, then! I can't wait for mine either.

All this stuff is interesting but let's face it, if the main part of the blade on my hunting knife is 25º and the tip blends to 22.6º, am I really gonna give a toss? It might help, actually.