Lansky Kit + Ka-Bar BK2. Edge angle?

[atod]

I purchased the Lansky Diamond Stone Kit and tried it out tonight. The spec's for the Ka-Bar BK2 indicate it has a 20 degree edge, however when using the Lansky the edge appeared to be almost 30 degrees! I have attached pictures showing the setup with 20 degree setting which appears to small angle for existing edge.

I'm wondering if the thickness of the spine is changing the angle. Does anyone know? Has anyone used the Lansky kit on the Ka-Bar?

Thanks

 

[Belker]

Just looking at your picture, and applying some basic geometry, it is apparent that blade thickness and blade width (dependent on the amount of blade width inserted into the jig) will both have a minor effect on the angle of the stone. Using two accurate measurements with a ruler and some trigonometry, you could easily estimate the actual angle of the stone. Or, you could not worry about the exact angle and simply make your knife sharp. I would, given the situation, consider picking the slot in the jig that most closely matches the angle already on the knife. (If having a specific angle is very important to you then you'll have to do the math and set up the jig using a ruler.)

 

[atod]

I sent a message to Lansky. Hopefully they have advice to offer. I would really like to keep the 20 degree angle. I think the main issue is the thickness of the spine and first V angle off the spine. I'm wishing I picked up free hand stones at this point...

 

[Obsessed with Edges]

I just posted a reply in another thread which is pertinent here:

Keep in mind, the 'spec' angles as marked on the Lansky clamp (or Gatco, or DMT, or etc.) won't likely be accurate anyway. I recently starting taking some measurements of blade-in-clamp, and using trig functions to calculate actual angle. One thing that surprised me, the marked angles on the Lansky clamp are based on the hypothetical 'edge' of the blade being flush to the front of the clamp. If the blade extends even slightly beyond that (as it must, in order to actually reach it with the hones), the actual angle will be less than what is marked. I've been using my Lansky on several traditional pocketknives lately. Most of the blades are ~ 1/2" - 5/8" wide, and I use the small notch in the end of the clamp to hold these blades. That means my edges are roughly ~ 3/8" or so beyond the clamp's front edge. As it turns out, the actual angle produced on these blades, when using the '17' setting (lowest), is closer to 15 degrees per side, or slightly less. The same generally holds true with the clamp's other settings. With blades that are very wide at all (3/4" up to something like a large chef's knife or meat cleaver at 2-1/2" or more), the actual angle will be much, much lower than indicated by the clamp's markings.

So, long story short, if you really are concerned about hitting a specific angle measurement, you'll need to measure and/or calculate for it. Relying solely on the clamp's marked settings will lead you astray.

 

[Monofletch]

I freehand with my Lansky stones all the time. In fact, I think it's easier to sharpen bigger knives (like my BK2) with them freehand!.

 

[brady.kevin07]

I freehand with my Lansky stones all the time. In fact, I think it's easier to sharpen bigger knives (like my BK2) with them freehand!.

I agree. Just mount the stones in a vice and go at it freehand. or depending on your budget you can use a sanding block and sandpaper to freehand sharpen

 

[Hard H2O]

Is there a reason you have the blade clamped so far into the clamp?

On the GATCO i never have that much blade in the clamp.

 

[Hard H2O]

I do not worry about actual angle measurements. If you like the factory angle on the blade, whatever it is, then use the sharpie trick to find that angle on the Lansky.

I never leave a factory angle alone. I always decrease it a notch or two. I have yet to meet a blade that couldn't support, and benefit from, a finer angle.

 

[Obsessed with Edges]

I do not worry about actual angle measurements. If you like the factory angle on the blade, whatever it is, then use the sharpie trick to find that angle on the Lansky.

I never leave a factory angle alone. I always decrease it a notch or two. I have yet to meet a blade that couldn't support, and benefit from, a finer angle.

Pretty much sums up my philosophy too. Out of curiosity, I've recently started measuring & calculating for my angle on my Lansky, usually after I've already re-bevelled, just to see where it ends up. More often than not, it usually seems to finish up a little below 30 inclusive (28 or so) on my traditional pocketknives, or somewhat less on wider blades. That produces a bevel width that just seems to 'look right' for a given blade, and these edges perform very nicely too. They're also a good starting basis for convexing. Much wider than that, and the convex usually turns out a little too blunt (for me, anyway).

 

[Hard H2O]

I do not measure the angles. i use the slots on the GATCO that work for a given blade. I test before, during, and after sharpening. If it slices good for me I am good to go.

I believe the real test is in the using. Different knives have different thicknesses, steels, grinds, uses... Even the way the same knife is used and sharpened will vary between owners.

I do not think you can say to sharpen to a certain angle on any blade until you have it and tested it yourself.

That works for me.

Good Luck.

 

[HotSteel]

Is there a reason you have the blade clamped so far into the clamp?

On the GATCO i never have that much blade in the clamp.

I agree with this. It looks like if you had less blade in the clamp the angle would be less.

 

[HoosierQ]

Keep in mind also that the angly will be continuously variable the entire length of the edge because the geometry of the setup...the triangle formed by the vertical portion of the clamp, the line from the spine to the edge, and the length of the stone and the guide wire will be changing as you move up and down the blade. So the only place the angle will match the stated angle is straight ahead from the clamp...and then only if you have the clamp set just right relative to the width of the blade. Lansky is a good system for learning but no for precision. When I was still using it I used to move the thing up and down the spine to even things out, mark blades so I'd always clamp the thing in the same place, etc.

A Lansky will get a knive sharp...real sharp. Just don't expect to have a lot of control over your edge geometry...especially on big knives.

 

[Obsessed with Edges]

Looking at the pics in the OP, it appears there's at least an inch or so of blade extending beyond the end of the clamp. For the reasons explained in my earlier post (see post #4), the actual angle at the edge will be significantly lower than the '20' setting would imply. The angle settings on the Lansky clamp are as measured at the very front edge of the clamp. Extending the edge beyond that will further reduce the real angle. (I verified this with my own Lansky). The relatively large amount of blade inside the clamp isn't the issue here. With an inch of blade extending beyond the clamp's end, it's more likely the desired 20 degree angle would be found using the '25' slot on the clamp. In fact, I explained it in more detail in my post here -->: http://www.bladeforums.com/forums/s...aterstone-or-Arkansas?p=10964842#post10964842

Edit (Did some calculating based on the following):

Some clamp dimensions, to form the 'triangle' used to calculate the real angle:
Vertical side: Height of the front edge of the '20' slot (where the guide rod will rest), above the inside face of the clamp, is ~ 1.2" Add half of the blade's thickness to that.
Base of triangle: Length of the clamp, measured from the plane extending down from the front edge of the '20' slot, to the end of the clamp's jaws, is ~ 3.5". Add amount of blade width beyond the clamp to that.

With the guide rod in the '20' slot as pictured in the OP, and assuming ~ 1/4" blade thickness, and ~ 1" of blade extended beyond the clamp's front edge, the real angle at the edge will be ~ 16.4 degrees per side.

 

[Hard H2O]

This may be true but will it affect the edge in use? How much of a variance will there be? What is the tolerance on the angle for a useable edge.

The key is to get the two sides of the edge bevel to match in as refined of a line as the user desires. If the angle is off a little bit here or there it is not going to matter one bit.

I sharpen all of my cutlery on my GATCO. From small paring knives and folders up to my 10" chef. I clamp once near the midpoint and never reclamp. I sharpen using the professional kit with the extra fine and ultimate finishing hones added to the kit as well as a stropping step.

Even on the 10" chef any variance on the angle is negligible. If anything the angle is smaller at the heel and tip and that increases the slicing and dicing power.

There is slop between the rods and the guide. As you use the systems the stone naturally finds the flat on the edge. Even if you are a little off on clamping between sessions the stone will sit flat on the edge due to the clearance between the rod and the guide.

Even in freehand sharpening you are going to have variance in the angle side to side and heal to tip. There is no way a freehand sharpener can hold steady enough to have a perfectly machined edge bevel every time. The first time I used the GATCO I was amazed at the symmetry and straightness of the edge geometry.

Good Luck.

Keep in mind also that the angly will be continuously variable the entire length of the edge because the geometry of the setup...the triangle formed by the vertical portion of the clamp, the line from the spine to the edge, and the length of the stone and the guide wire will be changing as you move up and down the blade. So the only place the angle will match the stated angle is straight ahead from the clamp...and then only if you have the clamp set just right relative to the width of the blade. Lansky is a good system for learning but no for precision. When I was still using it I used to move the thing up and down the spine to even things out, mark blades so I'd always clamp the thing in the same place, etc.

A Lansky will get a knive sharp...real sharp. Just don't expect to have a lot of control over your edge geometry...especially on big knives.

 

[atod]

Hi Folks,

I ultimately went with the Spyderco Triangle Sharpening system and Ultra Fine Stones as well. It sharpens the Ka-Bars factory 20 degree angle (using the Spyderco 40 degree setting) perfectly. I have the BK2 pretty much razor sharp cutting through paper. Thanks for all the feedback.

 

[greggcz200]

I bought a bk 2 a few weeks back and have used it alot on site at work and on weekends away anf sharpened it for the first time on my lanskey last night and also noticed it wasnt a 20 deg edge mine was 25. doesnt really make a difference to me i could still shave me leg after sharpening and slice paper with ease so that keeps me happy. The bk2 is now my favourite knife !