Does the Wicked Edge system really keep a constant angle?

[polar8]

I was about to purchase a Lanksy sharpening system, but I'll be doing quite a few kitchen knives and I read that it's not a great system for longer blades since the angle changes along the length of the blade. This particular reviewer has provided an interesting mathematical illustration to prove this point:

http://www.amazon.com/gp/customer-r...f=cm_cr_arp_d_rvw_ttl?ie=UTF8&ASIN=B000B8IEA4

With the Lanksy system written off, I started looking at different options. The Wicked Edge system seems to be really popular, but as far as I can tell it's the same general concept as the Lanksy product.

Without having performed the calculations myself, what I think is happening is that both systems are subject to the angle changing along the length of the blade. But since the distance from the rod pivot to the blade edge is longer on the Wicked Edge than on the Lanksy, the effect isn't as noticeable. That said, the problem remains.

Am I missing something here?

 

[Rey HRH]

I've seen a picture posted here by an engineer type where you can see from the side the angle made by the rod as it moves along the knife edge and the angle does appear to hold. It was convincing enough for me.

I used the site's search engine "constant angle wicked edge" but I didn't find the thread with the picture I'm talking about.

Here are two threads alone that discuss the issue. Feel free to use the search function yourself.

http://www.bladeforums.com/forums/showthread.php/1339022-angles-on-clamp-style-devices?highlight=constant+angle+wicked+system

http://www.bladeforums.com/forums/showthread.php/1131476-Geometry-and-Kinematics-of-Guided-Rod-Sharpeners

 

[cbwx34]

The links Rey HRH posted, will tell you what you need to know, but short answer... the angle doesn't change on the WE based on the knife length. (Doesn't change on the Lansky either... the Amazon link is incorrect). It seems counterintuitive... the distance changes so the angle must change... but the angle you think changes isn't what the sharpening angle is. The other threads will explain it.

 

[EdgePal]

As long as the knife are fixed onnits position on the grinding table and the pivot point are fixed in the same tool - the angle do not change on the straight part of the edge. In principle can you sharpen a sword with a Lansky - if you xould use a longer stabile guide rod

The distance between the edge and the pivot point are short on Lansky, that is not helpful on long blades. But Lansky are not constructed to sharpen long blades, it is constructed to sharpen blades up to about 12 cm blade length.

Lansky have fixed angles and can not be adjusted to different blade width. If you use 15 degree angle on a 2 cm wide blade you will get 15 degrees. If you change to another blade that are 3 cm wide, and keep the 15 degree angle, this blade will get a lower angle becouse of that the distance between the edge and the pivot point is now longer - but the edge angle will be the same all along the edge on the straight part of the edge - and will start to change angle when you come to the belly and tip.

So, on a Lansky shall you clamp the tool closer to the edge then to the handle and try to messure that the middle of the belly curve have the same distance as the distance in front of the tool - out to the edge - then you will get nearly the same angle also on the belly and the tip.

That is also why my tools are asjustble for different blade width, that makes it possible to use a built in exact protractor that shows the correct degrees on all blade widths. The other problem. Small changes of the edge angle on the belly and the tip have I solve with a 3 dimensional pivot point on my tool Chef. The pivot point can be moved up and down (to get different degrees), forward and back (To adjust for different blade width), and sideways (to be able to getvthe same edge angle all along the edge, from the handle out to the tip).

All constructers of sharpening tools knows this problems and we try to solve them, each of us in our own way

Thomas

 

[Rey HRH]

Okay, on page 6 of this thread, Twindog shows pictures of the constant angle. http://www.bladeforums.com/forums/showthread.php/788007-Wicked-Edge-Edge-Pro/page5

I'm just copying the post below.

Clay and Frank Hillary are correct. You can model this yourself with string and a box (don't need no stinkin' cad program).

The left side of the box represents the vertical position of the knife. The front right corner represents the axis of the stone. The string shows the angles for three different stone placements on a long blade. When you tilt the box and look down the angles, you can see they are all the same. No matter how far you go down a straight edge, the sharpening angle remains the same. It doesn't change until the blade starts to curve.

 

[MichaelMyers]

The lansky does hold a constant edge throughout the length of blade that it covers provided that the sharpened length blade is straight or uniformly curved. The problem is when you clamp at the middle straight part and reach a curve near the tip. The angle will change at the curved part. You will need to reposition the clamp to the curved portion and sharpen the curve separately.