- Joined
- Nov 20, 2016
- Messages
- 144
I am using the KME sharpening system and I am very happy with it. I have getting scary sharp polished edges with it. But as I get more into sharpening I get a bit more OC. And I did some angle measurements. I found angle variations in a couple of areas.
!. I use the wood stand that KME produces. Very handy. But there is slop in the fitting that fits on the post. That slop can produce up to a 2 degree variation depending if it is pulled back away from the knife or pushed forward. Actually the weight of the knife would naturally pull it forward. So if I clamp the wood base to my workbench, then zero out the angle cube on the wood base, and I put a steel ruler in the clamp (like its a knife). I would expect it to read 0 degrees. And it does if I pull the sharpener back away from the clamp. But if I let the sharpener slack towards the ruler, which it does on its own, I get a reading of about 2 degrees. I put a diamond block on the sharpening arm and let it rest on the ruler. Pushing back and forth on the wood grip gets me a 2 degree variation. Now this sharpener was made to work from your hand and the base is an accessory. And your hand will never be level. It just means that if you want an accurate edge angle you have to be careful how you get your zero point and then to keep the sharpener in that position when you adjust for the final angle.
2. Again with the ruler in the clamp. If I set the angle cube on the sharpening arm (I have glued an old steel ruler on the back of it so the cube will stick to it) and then zero it out. Then swing the sharpening angle from side to side, like I was sharpening a real knife. The variation in angle, caused purely by the geometry (not the slop issue above) is about 2 degrees on each side of the center position ( over 5") on the ruler. Interestingly, with my Spyderco Native 5 blade this only about 2 1/2" and is curved the whole length, I get about 0 variation in angel from point to heel. BTW my setup is to draw a line from the beginning of the edge to the point. then I measure the midpoint on that line. Then I put the knife as deep as I can, before I run our of the rubber cushion, and match the angle of the line centered on the center marks of the jaws and blade. I think the good news is that this system is perfect for my spyderco but for a longer straighter knife there will be a variation of angle. But it will be the same on both sides so for sharpness it will work fine but the angle will vary as you go along the blade..... depending on the blade shape.
So the bottom line for me, now knowing this, I will try to fix the sharpener from any wobble. Get a zero on the cube with a ruler clamped in the jaws. then set my knife and get the sharpening arm at the edge angle that I want relative to that zero point. After that it can wobble on the stand as much as it wants. For straighter blades, all of mine have a curve over the last 1/3 to 1/4 of the blade. I checked them and get variations running from .2 to .8 degrees. probably not a big deal.
But on my Wustoff Classic 20cm Chefs knife, zeroing out in center, clamped like described above, I get 1 degree variation at the hip and 2.5 degree variation near the point. And you can see the variation in the grind thickness.
But it all gets hecka sharp.
By the way I would guess that any fixed pivot swing arm sharpener would have the same results.... right?
Any thoughts? Am I wrong with my conclusions?
!. I use the wood stand that KME produces. Very handy. But there is slop in the fitting that fits on the post. That slop can produce up to a 2 degree variation depending if it is pulled back away from the knife or pushed forward. Actually the weight of the knife would naturally pull it forward. So if I clamp the wood base to my workbench, then zero out the angle cube on the wood base, and I put a steel ruler in the clamp (like its a knife). I would expect it to read 0 degrees. And it does if I pull the sharpener back away from the clamp. But if I let the sharpener slack towards the ruler, which it does on its own, I get a reading of about 2 degrees. I put a diamond block on the sharpening arm and let it rest on the ruler. Pushing back and forth on the wood grip gets me a 2 degree variation. Now this sharpener was made to work from your hand and the base is an accessory. And your hand will never be level. It just means that if you want an accurate edge angle you have to be careful how you get your zero point and then to keep the sharpener in that position when you adjust for the final angle.
2. Again with the ruler in the clamp. If I set the angle cube on the sharpening arm (I have glued an old steel ruler on the back of it so the cube will stick to it) and then zero it out. Then swing the sharpening angle from side to side, like I was sharpening a real knife. The variation in angle, caused purely by the geometry (not the slop issue above) is about 2 degrees on each side of the center position ( over 5") on the ruler. Interestingly, with my Spyderco Native 5 blade this only about 2 1/2" and is curved the whole length, I get about 0 variation in angel from point to heel. BTW my setup is to draw a line from the beginning of the edge to the point. then I measure the midpoint on that line. Then I put the knife as deep as I can, before I run our of the rubber cushion, and match the angle of the line centered on the center marks of the jaws and blade. I think the good news is that this system is perfect for my spyderco but for a longer straighter knife there will be a variation of angle. But it will be the same on both sides so for sharpness it will work fine but the angle will vary as you go along the blade..... depending on the blade shape.
So the bottom line for me, now knowing this, I will try to fix the sharpener from any wobble. Get a zero on the cube with a ruler clamped in the jaws. then set my knife and get the sharpening arm at the edge angle that I want relative to that zero point. After that it can wobble on the stand as much as it wants. For straighter blades, all of mine have a curve over the last 1/3 to 1/4 of the blade. I checked them and get variations running from .2 to .8 degrees. probably not a big deal.
But on my Wustoff Classic 20cm Chefs knife, zeroing out in center, clamped like described above, I get 1 degree variation at the hip and 2.5 degree variation near the point. And you can see the variation in the grind thickness.
But it all gets hecka sharp.
By the way I would guess that any fixed pivot swing arm sharpener would have the same results.... right?
Any thoughts? Am I wrong with my conclusions?
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