Can finally produce a hair popping edge from the wicked edge. After very close examination of the secondary bevel on my zt0450 (as in the one created by sharpening) it looks to me that near the choil it starts out thin, gets a little thicker, then thins out again at the belly. The other side is almost the opposite starting out thinner, gets a little thicker, then gets thick at the belly and near the tip. If I wanted perfect edge geometry would I have to grind away the “smaller” edge? Does perfect edge geometry really matter that much? Would it be okay to slowly match the geometry when sharpening? I try to be as careful as possible when sharpening to maintain the same pressure and strokes on both sides. Before you guys suggest the sharpie method I always do this. The variations in the thickness of the edge are very very slight but I’m very anal about this and I’m not to sure if this makes much of a difference. I know that blade thickness can change the size of the grind especially near the tip where the blade gets thicker which I’m aware of. Tell me if I am just over thinking this, have a bad techniques, the initial sharpening was done uneven, or if it doesn’t even matter and just get the edge the same thickness over time. Any input is greatly appreciated.
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Edge geometry on a wicked edge (we130)
- Thread starter LarryT
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^^Yes... need pix. Are you using strokes going away from the bevel and from choil to tip? If you're starting at the choil, there may be an issue with the very beginning of your stroke on the WE. That's the stoke I use most often on my WE. It's the most natural feeling stoke for me to use when sharpening and if I'm not careful, I can start the stroke with the stone at an odd angle to the blade (not flat against the bevel). Correcting that is a matter of me slowing down and watching what I'm doing. Also, working *carefully* from tip to choil for some of the strokes might help even out your bevel.
If it was mine, I'd probably go after just that area a few times until I got it worked in with the rest of the bevel. I assume you use some kind of lighted magnification to see what you're doing? If not, I highly recommend it. Work slowly, check your work often, and you should be able to repair it with your WE.
Of course... without pix I may be totally out in left field here. You might be talking about something very different than what I'm imagining.
If it was mine, I'd probably go after just that area a few times until I got it worked in with the rest of the bevel. I assume you use some kind of lighted magnification to see what you're doing? If not, I highly recommend it. Work slowly, check your work often, and you should be able to repair it with your WE.
Of course... without pix I may be totally out in left field here. You might be talking about something very different than what I'm imagining.
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What do you mean with thickness? Are you talking about shouder to shouder thickness or are you talking about bevel height (wide bevel)?
Every sharpening system or almost every one has a pivot point that you use the shaft with a radius distance between the blade bevel and the pivot. Don’t matter if is Wicked Edge or Edge Pro, both works with similar way since you have a clamped blade. This distance also determines the set angle. I use the sharpening system marks only as reference.
If you have a precise angle cube you can confirm what I’m talking about, just lay the stone on the closest point from the pivot and measure the angle then lay the stone on further point from pivot and measure again.
If you are talking about it I believe it’s natural a little difference between tip choil angles that make the bevel look wider or not.
Even the same blade on exactly same position that you grind 3, 4... 9 times will make the angle change (will be higher) because the edge of the blade is near to the pivot.
On the same angle set:
Closest the pivot = higher angles
Further the pivot = lower angles
Just to try illustrate a draw:
Personally, I dont care about a minimal angle change. I like a very well defined bevel.
Looking closest to some knifes I have, even the factory edge isn’t perfect.
A picture would help.
Now, if you are talking about shouder to shouder thickness my guess is can be a blade factory grind issue or a non well centered blade on the clamp and then I'll leave it to my friends from the bladeforums help you.
Edit. Everything you see inside the “circle” in Wicked Edge Picture is in higher angles that what you see outside.
Everything you see in circle line is in the same set angle.
Every sharpening system or almost every one has a pivot point that you use the shaft with a radius distance between the blade bevel and the pivot. Don’t matter if is Wicked Edge or Edge Pro, both works with similar way since you have a clamped blade. This distance also determines the set angle. I use the sharpening system marks only as reference.
If you have a precise angle cube you can confirm what I’m talking about, just lay the stone on the closest point from the pivot and measure the angle then lay the stone on further point from pivot and measure again.
If you are talking about it I believe it’s natural a little difference between tip choil angles that make the bevel look wider or not.
Even the same blade on exactly same position that you grind 3, 4... 9 times will make the angle change (will be higher) because the edge of the blade is near to the pivot.
On the same angle set:
Closest the pivot = higher angles
Further the pivot = lower angles
Just to try illustrate a draw:
Personally, I dont care about a minimal angle change. I like a very well defined bevel.
Looking closest to some knifes I have, even the factory edge isn’t perfect.
A picture would help.
Now, if you are talking about shouder to shouder thickness my guess is can be a blade factory grind issue or a non well centered blade on the clamp and then I'll leave it to my friends from the bladeforums help you.
Edit. Everything you see inside the “circle” in Wicked Edge Picture is in higher angles that what you see outside.
Everything you see in circle line is in the same set angle.
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An easier way to visualize the angle of the sharpening arm relative to the blade is to superimpose a roof, like the image below.
As the point of reference, use the case where the "rectangular knife blade" (shown in green) is perpendicular to the sharpening arm (the blue line).
Now pivot the sharpening arm either left or right from that point, along the rectangular blade, relative to this (i.e. the 3 yellow lines), maintaining the same pivot point in all cases.
Note that the yellow and the blue lines are all parallel to the fixed slope of the roof, so the angle is the same in all cases (even though the "radius" changes). You are just pivoting along the same inclined plane represented by the slope of the roof. The angle (of the sharpening arm relative to the blade) would only change if the width of the knife got narrower (e.g. rounding in toward the tip) or wider.
As the point of reference, use the case where the "rectangular knife blade" (shown in green) is perpendicular to the sharpening arm (the blue line).
Now pivot the sharpening arm either left or right from that point, along the rectangular blade, relative to this (i.e. the 3 yellow lines), maintaining the same pivot point in all cases.
Note that the yellow and the blue lines are all parallel to the fixed slope of the roof, so the angle is the same in all cases (even though the "radius" changes). You are just pivoting along the same inclined plane represented by the slope of the roof. The angle (of the sharpening arm relative to the blade) would only change if the width of the knife got narrower (e.g. rounding in toward the tip) or wider.
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I didn’t understand the roof plane. To keep the same angle increasing or decreasing the radius, shouldn’t you sharpening at 0 degrees?
When you rise (in Wicked Edge you actually spread) the arm to touch the apex you create a geometrical triangle shape between the pivot point, the blade apex and the vertex where is the 3th.
In Wicked Edge we can visualize the 3 point being as pivot the joint ball, the base in which the clamp is mount and the blade apex where the stone touch it.
What I mean is if you put a blade that measure from spine to edge something like 1” and take a measure (from apex to pivot, then put another blade on it measuring 7” from spine to edge you will see the angle difference. Ok, it was a bit exaggerated, but just to illustrate.
Even if you measure the sides lines from green blade until the pivot you will see that the center ones are smaller than the outsides lines that go from the same blade to the same pivot.
When you rise (in Wicked Edge you actually spread) the arm to touch the apex you create a geometrical triangle shape between the pivot point, the blade apex and the vertex where is the 3th.
In Wicked Edge we can visualize the 3 point being as pivot the joint ball, the base in which the clamp is mount and the blade apex where the stone touch it.
What I mean is if you put a blade that measure from spine to edge something like 1” and take a measure (from apex to pivot, then put another blade on it measuring 7” from spine to edge you will see the angle difference. Ok, it was a bit exaggerated, but just to illustrate.
Even if you measure the sides lines from green blade until the pivot you will see that the center ones are smaller than the outsides lines that go from the same blade to the same pivot.
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If you showed a cross section of the roof for each yellow line it would be clear that the angle does change. As the yellow line from the yellow dot (pivot) to the green line (blade edge) gets longer, you are moving a longer horizontal distance for the same vertical drop, which means a lower angle.
I think I see your point re: cross section. If we think of any of the yellow lines (or the blue line) as the hypotenuse of a right triangle, with vertex P at the pivot point, vertex B at the blade edge intersect point, and vertex A as an imaginary point below the roof which joins vertex P and B in a right angle, we have triangle APB like the crude diagram below (use your imagination to draw the hypotenuse PB).
P
|
|
|
|____________________
A....................B
As you pivot left or right along the green "rectangular blade edge" from the blue line to any of the yellow lines, two sides of the triangle (sides PB and AB) increase in length. But since the height AP stays the same as you pivot, the angle at vertex P has to change, as does the angle at vertex B (even though the angle at vertex A stays constant at 90 degrees). I was imagining a similar triangles argument because the slope of the roof is constant but now that I think about it some more, in light of EconProf's comment, that doesn't work. AP would have to change too, in order for that to work.
Figuring out how much the angle changes...that's a thought exercise. I think you could split it into 2 separate triangle solving problems: a horizontal triangle that you solve first, then take the results from that and reflect it into a vertical triangle. Does that sound right?
P
|
|
|
|____________________
A....................B
As you pivot left or right along the green "rectangular blade edge" from the blue line to any of the yellow lines, two sides of the triangle (sides PB and AB) increase in length. But since the height AP stays the same as you pivot, the angle at vertex P has to change, as does the angle at vertex B (even though the angle at vertex A stays constant at 90 degrees). I was imagining a similar triangles argument because the slope of the roof is constant but now that I think about it some more, in light of EconProf's comment, that doesn't work. AP would have to change too, in order for that to work.
Figuring out how much the angle changes...that's a thought exercise. I think you could split it into 2 separate triangle solving problems: a horizontal triangle that you solve first, then take the results from that and reflect it into a vertical triangle. Does that sound right?
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Great video. Now I got it what you want to say. But I don’t want to be clod, I’m just open my mind and on dental floss footage or even on the “sharpening motion” the camera is set in level with the bar, isn’t he changing the 3D spatial perspective of a “triangle” (maybe a pyramidal shape) into a 2D view?
I mean when the rod is align in right in front of the jig there is a triangle, when he move to the right or left near the edge border another triangle is created and the hipotenuse isn’t the same, unless you look at the same sided perspective.
If you look too to bottom not even a triangle you see and not even so it’s not there.
This remind me the movie contact when the aliens send a plan and “we” saw the plan 2D when in fact it is in 3D.
M’I still wrong?
I mean when the rod is align in right in front of the jig there is a triangle, when he move to the right or left near the edge border another triangle is created and the hipotenuse isn’t the same, unless you look at the same sided perspective.
If you look too to bottom not even a triangle you see and not even so it’s not there.
This remind me the movie contact when the aliens send a plan and “we” saw the plan 2D when in fact it is in 3D.
M’I still wrong?
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It's oversimplified case. The angle at B is not sharpening angle at B. You have to review in 3D and add an extra vertex. Your roof example shows that sharpening angle is the same everywhere, but angle P-B-A is not the same everywhere. In terms of airplanes, the sharpening stone not only pitches but also rolls.
However, the roof is a bad example for knives. It works for straight line cutting edge only. If the blade has a different shape, sharpening angle comes closer to angle P-B-A.
I clamped very big knife (20") with 30 dps in the middle. I got 25 dps in far point.
Of course, it's the weird example. My point is, don't trust anyone who admits the sharpening angle does not change in far point. It's BS.
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Sounds to me like what you are experiencing is probably an uneven grinding technique. To answer your question, if you have the angles set the same w/ an angle cube, then yes you will grind the 'thinner' sections of the edge to even everything up, and yes you can do this over time w/ repeated sharpenings (if it's sharp no reason to waste metal right?
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My point is:
On left we have a sidedly view.
On blue is the clamp
White is the blade
Yellow is the stone
Grey is the arm.
The hipotenuse have a length when straight the arm to the clamp, when you move the arm to left with a straight blade, the hipotenuse have another length, so the triangle formed by the same system with same angle setting point in different blade points have different triangles with different hipotenuses and different angles.
On right we have a frontal view which make my earlier point.
On blue we have the clamp
Red over white next to the clamp we have the blade and same for the white.
Yellow is the stone
Grey is the arm
Wider blades makes the angle change. Even on a recurved blade when we have the concave part closest the clamp and the convex part far from clamp. This case is the same when you reach the tip part of the blade when is curved forward to the spine to form the tip itself. At the same angle setting point we have different angles at the blade.
On left we have a sidedly view.
On blue is the clamp
White is the blade
Yellow is the stone
Grey is the arm.
The hipotenuse have a length when straight the arm to the clamp, when you move the arm to left with a straight blade, the hipotenuse have another length, so the triangle formed by the same system with same angle setting point in different blade points have different triangles with different hipotenuses and different angles.
On right we have a frontal view which make my earlier point.
On blue we have the clamp
Red over white next to the clamp we have the blade and same for the white.
Yellow is the stone
Grey is the arm
Wider blades makes the angle change. Even on a recurved blade when we have the concave part closest the clamp and the convex part far from clamp. This case is the same when you reach the tip part of the blade when is curved forward to the spine to form the tip itself. At the same angle setting point we have different angles at the blade.
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You’re right,,, this applies only to the straight part of the blade... not when it curves.
It does change when a blade curves (and can quite dramatically).My point is:
On left we have a sidedly view.
On blue is the clamp
White is the blade
Yellow is the stone
Grey is the arm.
The hipotenuse have a length when straight the arm to the clamp, when you move the arm to left with a straight blade, the hipotenuse have another length, so the triangle formed by the same system with same angle setting point in different blade points have different triangles with different hipotenuses and different angles.
On right we have a frontal view which make my earlier point.
On blue we have the clamp
Red over white next to the clamp we have the blade and same for the white.
Yellow is the stone
Grey is the arm
Wider blades makes the angle change. Even on a recurved blade when we have the concave part closest the clamp and the convex part far from clamp. This case is the same when you reach the tip part of the blade when is curved forward to the spine to form the tip itself. At the same angle setting point we have different angles at the blade.
Wrong about the left... right about the right.
I don't think there is any dispute--including any of the older threads cbw posted links to--that the discussion is only applicable to a straight blade edge. That's the one thing everyone agrees with. But I think there's an additional condition, which is that the straight blade edge has to be perpendicular to the centerline of the sharpener's pivot axis. Correct me if I'm wrong, but if the blade's straight edge is not perpendicular to the pivot axis (i.e. if the blade's edge is skewed) it has the same effect as a tapering or curving blade (or the same effect as increasing/decreasing the width of the blade as in brasileiro's drawing on the right).
cwb: thanks for the old links, but there were a lot of potentially useful photos/drawings that suffer from the Photobucket deletion syndrome.
However, I think the bottom line is that my roof example and explanation was correct (it's essentially showing the same thing as the dental floss examples from the old threads, but using a different visual aid). And my followup regarding non-similar triangles, while mathematically correct, is conflating a different geometric plane that isn't the plane that the sharpening stone face travels over and is therefore not relevant to the sharpening angle question.
The plane of the sharpening stone's face that contacts the blade edge--even though the rectangular stone itself becomes slightly skewed as it is pivoted right or left of the sharpener's pivot centerline--is kept coplaner with the roof plane (assuming the roof plan represents the desired sharpening angle) because the sharpening stone on its rod (for both the WE and the EP) can rotate slightly as you pivot left or right of centerline such that the stone face is always scrubbing co-planer with the roof plane, regardless of its amount of pivot from the centerline.
Do I have this right?
cwb: thanks for the old links, but there were a lot of potentially useful photos/drawings that suffer from the Photobucket deletion syndrome.
However, I think the bottom line is that my roof example and explanation was correct (it's essentially showing the same thing as the dental floss examples from the old threads, but using a different visual aid). And my followup regarding non-similar triangles, while mathematically correct, is conflating a different geometric plane that isn't the plane that the sharpening stone face travels over and is therefore not relevant to the sharpening angle question.
The plane of the sharpening stone's face that contacts the blade edge--even though the rectangular stone itself becomes slightly skewed as it is pivoted right or left of the sharpener's pivot centerline--is kept coplaner with the roof plane (assuming the roof plan represents the desired sharpening angle) because the sharpening stone on its rod (for both the WE and the EP) can rotate slightly as you pivot left or right of centerline such that the stone face is always scrubbing co-planer with the roof plane, regardless of its amount of pivot from the centerline.
Do I have this right?
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Skewing the blade... if you mean tipping the blade up or down in a clamp... the angle will still stay the same along the straight part. If you think about it, the pivot doesn't see "parallel" or "perpendicular", it just sees "straight" or "curve". (Confusing as heck, but trying to keep it simple). The easiest way to see it is in the Wicked Edge. You can mount a straight edge at an angle, and then just tip the whole Wicked Edge unit until the blade is "parallel" again. (Assuming this is what you mean by skewed). Not saying it will be the same angle if you mount a blade straight then tip it (because you may be raising or lowering the height like in the right diagram shown earlier)... only that whatever the angle is will stay the same along the straight portion. If you by skewing you mean angling it to the left or right as you look down on it (thinking W.E. again), again I'm not sure a pivot would "see" the difference... if that makes sense.
I think the rest you got right.
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Ok. I believe we are having friendly talk about what I didn’t understand. Now I do. Thanks for patience and for clarification. Thanks for the draws, for the links and videos.
Sorry by my mistakes and if my words offend someone of you guys apologize.
Sorry by my mistakes and if my words offend someone of you guys apologize.
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Started reading but broke off when the whole "the angle changes the further you move from the pivot" thing started again; there is no angle change along the way.
As for the stuff OP asked about: if it's mirrored unevenness you may have clamped the blade at an slight angle.
It also is possible that the main-bevel isn't ground evenly, or that you removed more metal at the points where it has a higher grind(greater thickness behind the edge)
Also did you measure your angles with an anglecube of some sort and fine-tune?
As for the stuff OP asked about: if it's mirrored unevenness you may have clamped the blade at an slight angle.
It also is possible that the main-bevel isn't ground evenly, or that you removed more metal at the points where it has a higher grind(greater thickness behind the edge)
Also did you measure your angles with an anglecube of some sort and fine-tune?
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If you mean me... I wasn't offended, and you didn't do anything wrong. This comes up all the time. It's so counterintuitive to the way it seems it should be. If you read my post in one of the other threads... I was the same way when I first heard that "the angle didn't change"... that's why I stuck like a 3 ft. long ruler in the W.E... to prove it did. Which of course it didn't.
This round seemed to have quickly settled... maybe all those Photobucket pictures that disappeared... were just confusing people.