Takes a big man to admit he's wrong... especially when he's throwing it out in front of neatly 100K subscribers. You presented your original theory as best you could, and were willing to accept when someone tactfully pointed out not THAT you were wrong, but more importantly WHY you were wrong. You learned something. And you shared that lesson with the rest of us. Thank you!
Work With Nature • That he chose to make the correction is a breath of fresh air these days. I respect his correction far, far more than anyone that decides to "dig in" despite learning new information.
Simple Little Life , you did not lie to us, you were just wrong for a brief moment. it happens to everybody ! You are among the few though who will stay open to other opinions and just acknowledge their mistakes. *insert famous quote about how learning from mistakes make you better in life here*
this is true only when the edge you're sharpening is perfectly straight though, most knives curve back towards the tip and the heel. if you just look at the width of the sharpened edge, you would see that it's wider towards the tip than the belly : ) which means there's still some slight changes in the angle.
I’m sorry sir but I must correct you. A straight knive doesn’t have the same distance to to vertical pole where the pivot point is. So I doesn’t have the same stone attack angle along the blade. A curved blade in the form of a portion of a circle would would get the same sharping angle all along its edge.
Actually, both versions were correct - with caveats. For the straight portion of the edges, this update is correct simply because the flat surface of the sharpening stone actually starts to rotate counterclockwise (in relationship to it's pivot point) as you sharpen to the right of the pivot point. However, as you approach the curved portion of the blade, the stone will be rotating less (or even go back to neutral) and it will start removing more metal giving you a shallower bevel. One important part you missed is that the bevel is measured from the TANGENT of the edge. Along the straight portion, the tangent is the same and the surface of the stone remains in the same plane. However once you hit the curve, this changes at every point along the edge. In order to get the most consistent bevel, you want to place the pivot point as close as possible to a theoretical center of the curved edge's radius (this being a guestimate, as most blades to not have a uniformly circular curve to them).
Very good comment. In long chef's knives, in particular, I believe some draw a line from the heel of the blade to the point, and set the clamps such that the sharpening angle will achieve the set angle along that line, and average the set angle over the full length of the blade - which offers a good compromise. As an alternative, each section could be sharpened separately; but that would add re-positioning error, and take a lot more time.
Leave the previous video. The strings made me see it because I shared the same thought process as in previous video. But I can swear the further I go out to the side of the blade the angle of the edge changes. I am using Lansky Sharpening system. Next time I will have to pay attention to my sharpening. Thanks for doing all of those tests with the angles. Still amazed.
By the way, you didn't lie. Lie-a false statement made with DELIBERATE INTENT to deceive; an intentional untruth; a falsehood. Unless you meant to do it ;-) Still can't believe the slope doesn't change.
On the other hand, I feel the angle changes when I come to the end of the curved blade. I remember changing the slope in order to keep the same angle on the edge. I am still confused.
Remember, the angle does ONLY stay the same as long as the "probe" (or the blade) is straight. With a curved blade, the distance changes - and therefore the angle as well. Given that most blades aren't as straight as your piece of cold rolled steel... Well. You'll figure it out. So. Yeah. Under certain circumstances, the angle stays constant. With most blades, it won't.
@steffankaizer: go to the footage with the dentalfloss and imagine one piece ending not on the left side but on the right side of the metal bar simulating the tip of the blade, this means that the angle changes from the straight portion of the blade to the tip. (Because the blade "curves" towards the pivotpoint.)
but if the curve is a part of a circle that have the pivot point as center, the angle doesn't change (imagine you're sharpening a circle) sorry for my poor english.
How about doing this same experiment on a curved piece of steel? That straight tool steel remains the same distance from the pivot point but a curved piece will shorten that distance now moving the edge closer to the pivot point.
I’m sorry sir but I must correct you. A straight knive doesn’t have the same distance to to vertical pole where the pivot point is. So I doesn’t have the same stone attack angle along the blade. A curved blade in the form of a portion of a circle would would get the same sharping angle all along its edge.
I really appreciate that you made this followup video! Though, I'm not sure I'd say you lied (which implies that you knew better, and told us the wrong information anyhow)... it was just a mistake, and since you're human, that'll happen. I have a similar style sharpener, and I have found that the bevel size *can* be different from ricasso to tip, which I previously attributed to the "flaw" you described the first video. Now, after seeing this one, I think it must be due to the uneven wear on the stone, or the fact that sometimes I may not be holding the stone consistently flat. I'll have to play around with this some more. Good to have it settled!!
A straight knive doesn’t have the same distance to to vertical pole where the pivot point is. So I doesn’t have the same stone attack angle along the blade. A curved blade in the form of a portion of a circle would would get the same sharping angle all along its edge.
The sign of a great man is to recognize and admit when he is wrong. I was one of those who accepted and agreed with your explanation in the previous video, so I too stand corrected. :) Great work!
For curved blades, try to angle the blade in the clamp so it’s curve approximates a circle with its center at the upright. Not perfect but it will minimize that “walk-out angle “ effect.
If the length of the floss (hypotenuse) changes, and consequently, the length of the adjacent (horizontal distance between floss contact at knife edge, and pole the floss attaches to), changes, then shouldn't the angle formed between the hypotenuse and adjacent change as well? The angle formed between hypotenuse and adjacent is the sharpening angle if I understand correctly. As an extreme example, think of this: : If you have a knife 2 miles long, then the floss at the center will be only approximately 8 inches long while at either end, it'll be 1 mile, 8 inches long. With the length of the opposite remaining the same, the angle of contact between the stone and the middle of the knife, will certainly be greater than the angle of contact between the stone and either end of the 2 mile long knife. I'd think that the only way for the angle of contact, between stone and straight knife edge (sharpening angle,) to remain the same (in this system), is for the position of the pivot to be able to move and ALWAYS be perpendicular to the knife edge.
Speaking as a long time sharpener who owned a business doing it, you’ve put more time into learning angles than most sharpeners I know. Don’t beat yourself up friend, it’s intent that matters. Also, this isn’t life or death stuff, it’s Sharpening.
First video of yours I've seen, but admitting that you'r 100% wrong when someone explained a new way to look at the issue was enough for me to subscribe. Kudos. So many people refuse to ever admit that they are wrong. My father was one of them for the most part. He could argue and convince a calculator that 2+2=5.
You're like me, A real man can admit when they are wrong. I am always amazed how many people cannot, will not admit when they are wrong and will die on that hill.
Your integrity and willingness to correct an untrue statement earned you another sub with me. It means alot that not only did you admit you were wrong, but took the time to learn and explain why you were wrong. Keep it up.
Your analogy with roof is partially accurate. The pitch of a roof stays constant from the peak to the gutter when they are parallel. Most blade edges are not parallel with the spine. As with a chef's knife, the closer you get to the tip the angle gradually increases. Most blades aren't so big with large enough curve that this is very noticeable. You were correct in your previous video but the difference in the angle is very small and virtually unnoticeable.
I’m sorry sir but I must correct you. A straight knive doesn’t have the same distance to to vertical pole where the pivot point is. So I doesn’t have the same stone attack angle along the blade. A curved blade in the form of a portion of a circle would would get the same sharping angle all along its edge.
A video like this has far more value than most on here because you have taken the time to say 'I was wrong' and show why. Then we learn more from that. Thank you. Brendan.
I believe you were correct initially. When viewed on end, the angles all look the same because they all have the same height and the same APPARENT length of the base (from the base of the support to the "edge"). However, that's only an illusion. The "true" angle is the one where we are looking at the angle of the string, blade and support straight on (as if it were drawn on a sheet of paper). If we viewed the furthest string from the same straight on view as the middle string you would see that the angle is more acute. A simpler way to test the angles in your demo is to put a protractor against the blade and the string at each point and measure the angle. But, I love your search for the truth. Never lose that.
I'm still convinced the angle changes. Try the dental floss thing again, measure up from the spine of the blade to the dental floss. If it's a different height at each distance than the angle IS in fact different.
If the angle doesn't change how can you explain that the edge bevel is always wider once you get farther from the pivot arm? I used to use a lansky sharpener and that was always an issue.
Think of a pyramid. The tip being the pivot of your TSPROF. The base would be the blade edge. The distance would be less from tip to center point along the base versus tip to end points of the base. The angle however, of the face of pyramid consistent.
Jason Wisser that would seem to only work if the edge was straight and parallel to the pivot point right? The pyramid does help me to understand that. I can see that definitely on a straight blade the angle is consistent. But on a curved blade I'm not sure
Brian Sandoval you are correct The blade would have to be set up properly. The angle would indeed change on a curved blade however the change would so minimal that it wouldn't affect anything. A quick test I just did showed that the change would be roughly .3 degrees for every 12 inches of travel. Most knives are straight until they curve to the tip. So the curved portion on 6 inch blade may only be 1.5-2 inches long. So that last edge may be about .025 - .035 degrees different than the straight edge of the blade. I don't think that would affect the sharpness of the blade at all. As a matter of fact I bet any blade sharpened by hand on a stone varies more than this.
The angle changes. If you have a paper guillotine blade or something with a similar geometry, just set it on your jig, calibrate the angle in the center of the blade to be the same as the chisel grind of the blade . Then paint it with marker and grind it trough the hole lenght. You will see that the angle changes.
I think you were correct to begin with ! If the angle changed on that gauge the angle changed on the steel ! Its about removing material from the edge, a line of floss perpendicular to the blade will give the best results for consistent bevel and edge. I think the issue comes from looking at the knife differently, meaning that there are two angles to consider. You simply cannot ignore the fact that the angle of the floss changes, in the top view, when removing material. You will remove more material in the direction of the floss!
Nope. You even looked at the demonstration. In that demonstration, that straight "blade" would have the exact same bevel angle from heel to toe. Gauges are like computers, they do exactly what you tell them to, not what you want them to do. You're actually talking about the grind angle, or the angle of the lines ground on the bevel. The bevel angle does not change here
@@theboathaaa7654 I watched the video again and we agree that if you have an edge to follow moving the stone left and right on the edge is the same angle along that existing edge. Building an edge with 180 grit stone is where the issue is. The more you move the stone in and out, off center, the more compound angle or curve you put into your edge. This edge would still have the angle of the center plus an addition one. I have the TSPROF and learned this, the hard way, by sharpening a set of display knives that had no edge.
The angle DOES change. HOWEVER, the change is related to the ratio between the length of the blade being sharpened and the length of the sharpening arm (file). If the blade is long compared to the arm the angle difference is more pronounced. If the arm is much longer compared to the blade the angle difference become more negligible. The difference is caused by the change in length of the radial arm (the distance between the pivot and the edge). If the blade is curved outwardly the angle difference become less pronounced and more pronounced in a curved inwardly. All that said, for all intents and purposes the angle VIRTUALLY does not change due to the much longer arm than any kind of knife it is designed to sharpen.
I ran across this video completely unplanned. It was just on the sidebar after I watched another video by another TH-camr. I'm so impressed with the integrity shown here that I've subscribed. We need more people (not just on TH-cam, but in our society) who have the courage and principles to simply say "I'm sorry; I was wrong."
‘Lie’ is a strong word. I don’t think you were lying. You just made an error. I appreciate the video. Thanks for clearing up the error and clarifying! You weren’t lying. Carry On! :))
Jeremy.... This is why I love your channel. Number 1. A lie is an intentional act of deception. You made an error based on some factual mathematical data. Not a lie... an error. Number 2. You unlike many had the integrity to come back and post a correction admitting your error. Well done! By the way... because of you I am now a TH-cam advertisement watching zealot.... Keep posting those awesome videos!!!
I say keep it up, but changing the title is not enough. If possible, I would recommend you edit the original video with a plain text disclaimer right at the beginning stating "The conclusions reached in this video are INCORRECT - please see subsequent video for factual conclusions". Just my two cents. Awesome job correcting the mistake!
What about an actual blade with a curve? Im curious to see that. The edge of the tool steel stayed the same. But a curve on a blade would be closer to the pivot point by 3/4 to 1" at least. How would that change the angle?
But if you have a big curve on the blade of the knife toward the end of the blade the edge will become wider . Any thoughts maybe I am full of it lol . The hapstone or similar knife sharpeners you just reposition the blad to keep this from happening . Any thoughts ?
You are correct. If you have a straight edge the angle is the same. But when you have a curve the angle changes relative to the curve. It's still the same angle compared to the straight portion but not to the curve. However that's not a bad thing. It makes a more consistent cut. It makes the edge finer compared to the curve. It weakens the tip. But the edge and point are finer. Better than the alternative of a steaper angle on the curve.
yup, any blade with a curve needs the 'dental floss' test. Also, I think an even better test would be to make a 'mock' sharpener, but have the sharpening pivot system much closer to the 'mock' blade. this will give a shorter angle, and therefore illustrate the angle on a larger scale (even though if a change was found, it would most likely be negligible from a regular knife standpoint)
Guys calm down. a blade is not straight. this video is about a STRAIGHT edge. Of course if the blade is not straight the angle changes. This video is about the theory
Dave Erving Evader Knives you said it youself, it's the compound angle that your stone is against, so a curved blade would cause the angle to change. I have a lansky sharpener and that's what it does on curved blades. I'm no expert but sure makes sense to me. Please correct me with simple explanation if you disagree.
This demonstration of integrity is heartening. Comments made by people who don't understand distal taper as a curved blade nears the tip, and how incredibly difficult it is for a knife maker to keep that constant, not so much. What I'm still waiting for is a rational argument explaining why variability in edge bevel size negatively effects cutting capability in any way other than the potential for binding.
Simple Little Life, please measure the lengths of the floss, and understand, they all originate at a single point. Therefore, you are viewing all three "Different Length" strings from "3 Different Angles". Then run a calculation of the height of "Y", length of "X" to find the angle & length of the hypotenuse. You will find your angles do change. WHY? You are measuring from 1 anchor point, to three separate locations, of different distances. Length of hypotenuse changes, therefore, the angle does in fact change. EX 1. X=4.5, Y=9, Angle=63.435(10.062") EX 2. X=4.5, Y=11, Angle=67.751(11.885") That is a 4.316 degree difference, with an increase of 1.793 inches from the pivot point. So, I declare, "You DID NOT LIE"!
You still don´t get it sir. It is not about the angle of the arm, it is about the angle of the edge and the stone. That the angle of the arm changes is obvious but irrelevant to the results. Whit a curved tip it will change becous the 90 degrees from the edge changes but on at straght edge it stays true.
HoutmeyersP nope is wrong...the slope of the roof idea suits...if I run a string from my lightung rod in the dead center of my roof to the corners and to the center does that mean that my roof slope is different angle thought out..if that were the case your roof would be dropping in the center as its angle would be steeper then the corners since they are all equidistant from the edge..
Andreas Persson I am not sorry to inform you that "Only On A Blade With A Very Specific Curve/Radius Would The Angle Remain The Same"! If one changes the distance between the pivot & contact with the knife edge, one has in fact changed the angle of contact. Therefore, the angle of the edge has in fact changed. Your explanation only holds true, "If And Only If, The Pivot Point Slides To Remain 90 Degrees From The Edge. If you don't believe it... Take a 12 inch piece of flat stock, swab dykem to top & edge, scribe the edge ( center line ), center it on your jig, and file/sharpen your way to the scribe mark. Once done, look at the shiny area. It will get wider as you move farther from the center.
Steven Smith sorry no..you are thinking of the wrong angle....take the pivot point and move it to be in direct line with any point on the blade and measure the angle...if the bevel and truly changed your blade bevel would be a wave as it went from shallow at one end to steeper angle to shallow again..the triangle in question is not edge to pivot to point of sharpener...it is base of blade/underside to top of spine to edge...the pivot point is immaterial to bevel angle..if that were the case bevel jigs would not work...
Dude.. the first video is correct and the second video is the lie. The angle becomes more acute the farther you move away from the center point. Trust your eyes, you saw the angle gauge move. Trust geometry, math doesn’t lie. Sharpen a blade, you can see the bevel angle lessen at the tip. The roof concept is wrong. If you use a constant angle sharpener like Lansky or Wicked Edge, the ANGLE CHANGES and you have to compensate for those changes to maintain a truly constant bevel.
That's what I call integrity. We all make mistakes. It's how we respond or deal with them when we are confronted. You did the exact right thing. Thanks for making this clear.
Thats it... i can't take it anymore!!! My world is crushed.. im not sure but i might just end it all!! How can i go on??? I cant even think about trying to finish my 2nd knife ever. 😭😭😭😭😡😡😡
I like the fact that you corrected the first video and admitted it! We all make little errors, you didn't "Lie" you just miscalculated the first time then found your error. What happens with the sharpeners is that more of the sharpening stone or sandpaper or whatever is sharpening the blade is in contact with the blade at the further edges of the knife, but the angle is the same. At any rate I am not going to go into the geometry, but will say, good job! Thanks, you made a subscriber of me today...
You're not lying. You were mistaken. Lying is intentionally giving bad information. It's ok to be wrong. Congrats on showing integrity and it's earned you a new sub!
The fact that the stone arm can rotate in it's pivot to stay flat against the blade is what makes your "roof pitch" argument valid. It also allows for more possibility of rounding as the stone approaches parallel to the edge. Again, this only applies to a straight blade. A curved blade causes a more obtuse angle at it's point, the same way a domed roof top would not have a single pitch. This is another reason the EdgePro is a superior machine. It allows the unclamped knife to slide along the sharpening table to compensate for this phenomenon.
As a matter of practicality, it's too much attention to an infinitesimal question of geometry that doesn't affect the performance of either your knife sharpener or knife. Don't beat yourself up about it. The service you provide is still invaluable.
Practically I agree with you 100%. Technically it will make a difference. Although I have yet to meet someone who can actually feel the difference. The bigger part is sharing something on TH-cam. You kinda get held up to the letter of the law on some stuff. By people who really couldn’t even tell the difference. 😆👍
LOVED this video, all but for one thing. You did not LIE to us. You passed on incorrect information, that is different than a lie. A lie is intentional deception. You did not intend to deceive, you passed on what you believed. And I believed it exactly the same way that you did. I will be pointing my viewers to this video to explain this same phenomena.
So basically the lateral distance from the fixed point don't matter. But if you put anything with a curved blade in (almost all knives), then the part of the blade closest to the fixed point is a more obtuse angle. So if you set it up at 15° then the blade will be 15°, but the tip will gradually get blunter the closer it gets to the fixed point. If you were sharpening an ulu, and set the angle to 20°, then your final edge profile from end to end would be something like 23°,22°,21°,20°,21°,22°,23°. It may not be that extreme a change, but you get the idea.
If a knife edge was straight, like the steel or the top plate of a wall frame you are correct. But the more curve on your knife edge the bevel must change just like when the ridge to the top plate is not parallel. I notice it more on my Santoku, Deba and Cooks knives which all have rounded cutting surface. But a winding bevel is common in many chefs knives, fine edge at the front for detailed work and a flatter bevel where the heavy work is done for edge durability. I am tempted to demonstrate this using a similar knife sharpening system and an exaggerated curve cut out of MDF.
For a flat blade or one that is close to flat, yes. however, when you have a curved blade, the angle does change because your angle is from a fixed point that is not the centroid of the curved section. If you put the pivot point at the center of the curve, it won't be same angle at the flat section of the blade. The angle may need to change slightly depending on what portion of the blade you are sharpening to maintain the right amount of angle.
In my opinion, leave it all out there, it shows you are a great guy who is not afraid to admit a mistake. This shows more about you as a person than any skill video could. Big thumbs up from me.
You didn't lie to the audience, lying is an intentional attempt to deceive another. You were simply wrong, or incorrect, and learned from the experience. It's awesome that you came right back and provided the correct information as well as the caveat of the previous information being wrong. Interesting topic definitely since it highlights how easy it is to assume one perspective as an obvious answer.
As a retired machinist I know exactly what you are talking about. So many times in trying to solve machining problems with compound angles it is easy for your brain and eyes to switch planes without you realizing you are now looking from the wrong perspective.
The angle DOES change. It might not be much, but it changes. It's basic trigonometry: Consider the triangle defined by the piece of dental floss, the imaginary line from the point the floss is attached to the tool steel to the vertical post, and the segment of the post to the top (or the other end of the floss). It looks like the tool steel is perpendicular to the post. It doesn't really make any difference if it's not, because the correction would be a constant, but it makes the explanation easier. That makes these 3 triangle right triangles. The angle of the floss to the tool steel has to change, because the ratio of the distance on the post (which doesn't change) to the length of the floss (which does change) is the sine of that angle. If the sine changes, the angle has to change! The change in the angle is probably insignificant, but it does change.
As a Mechanical Engineering Technologist I can confirm you are correct in your analyses. You can perform the same procedure using disks tilted to a fixed degree, as in a table saw. The disk / saw blade will cut the wood evenly as you elevate the blade into the wood. The angle stays the same on all parts of the wood.
I'll use a little bit of math to explain this: The angles ARE the same and here is why: The sum of angles in a triangle (any type) is 180 degrees. Let's say that those are Right-Angled Triangles so the angles between a and b1 and between a and b2 (I tried to represent the triangles in the pictures below) are always the same, 90 degrees, but this method can be applied to any type of triangles, the only difference are the formulas, however it will give the same result. p1 and p2 are the angles at the pivot points. (h1 and h2, each represent the hypotenuse of their corresponding right-angled triangle) (a is the altitude and is the same for each right-angled triangle) (b1 and b2, each represent the base of their corresponding right-angled triangle) - h1 and h2 are the dental floss strings and their lengths are not identical; - b1 and b2 are the distances from the metal bar to the base of the vertical round bar that has the pivot point on top; b2 and b1 are also not identical, but as the length of the dental floss string increases, the length of the base also increases, in a direct proportional ratio. - x1 and x2 are the angles that will be compared first triangle |p1\ | \ | \ a h1 | \ | \ |__b1______\x1 second triangle (we know for a fact that h2 is longer than h1 and b2 is longer than b1) | p2 \ | \ | \ a h2 | \ | \ |____b2____________\x2 Solution: Because these triangles are Right-Angled Triangles we can use the following formula: h1(^2) = a(^2) + b1(^2) h2(^2) = a(^2) + b2(^2) h1(^2) - b1(^2) = h2(^2) - b2(^2) ---> h1(^2) = b1(^2) + h2(^2) - b2(^2) (********) Now the formulas for x1 and x2 angles are: cos (x1) = b1/h1 cos (x2) = b2/h2 Now, let's assume that the angles x1 and x2 are identical, then: b1(^2) b2(^2) ---------- = ----------- h1(^2) h2(^2) then: b1(^2) * h2(^2) = b2(^2) * h1(^2) (***) Because the lengths of the dental floss strings are in a direct proportional ratio with the lengths of their corresponding triangle base legs, then: h2 h1 ---- = ---- ---> b1(^2) * h2(^2) = b2(^2) * h1(^2) (***) b2 b1 Both results from both (***) above are identical so the assumption that the angles are identical is TRUE. If angle x1 = angle x2 then angle p1 = angle p2 (in degrees). This applies to all types of knives even if the knives are curved or just straight. The surface of the knife that is getting sharpened increases as you move the sharpening stone left or right in relation to the pivot point and that is because the sharpening stone has a width that cannot be ignored. If length of a , as I shown in the pictures (the height of the pivot point) changes, as the stone is moved left or right, then the angles will be different. End of solution*** Cheers!
I have not watched your initial video but based on what you were saying, I believe you were right the first time. The angle can only be the same if it is at equal distance to the vertical supporting beam and form a circle. It looks like a cone in 3d. The further you are away the smaller the angle, although not by much in term of knife length. The rate of angle changes also dropped the longer the grinding arm.
The angle does change. Your initial observation is correct. However. The angle does not change with how far the stone moves on the blade on either side of the center line. The angle changes with the curve of the blade, which in effect retracts or extends the contact surface depending on the blade curving towards or away from the center point of the hone arc of movement.
You didn’t lie to us. You just made a mistake. That happens mate. You’re honest enough to recognise you error, apologize and get it explained and fixed. You have my respect for that. Thanks mate!
When you lined up the floss your eye wasn't level with the flat edge of the bar stock. Looking directly in-line with the flat edge of the bar stock the angle does change. Sorry, I think you were right the first time...
It’s confusing but the angle does not change. Think of the pitch of a roof as the floss strings. Doesn’t matter what angle you pivot across the roof, the angle is always the exact same when you measure it perpendicular to the eve of the roof. Same here. With a straight blade, the angle never changes. That’s a fact.
What is said in this video is absolutely true. The angle doesn't change on straight edges. It does change however on curved edges. There the change depends on the curve as well as on the size of your sharpener, more accurately the length of the hypotenuse. Since the length of the catheti that is upright stays constant, the angle at the edge changes. Think of the exact same triangle that was shown with the strings in this video. It was the projection of a view perpendicular to the edge of the blade from the real triangle that is made by the apparatus itself. Now change that perspective a little bit with the curve of a blade and in your mind make that projection again. The new projection is a triangle that is inbetween the big one from the apparatus and the formerly projected one for the straight edge, with the same height on the upright catheti. Now there you also immediately notice that the change of the angle of this triangle depends on its size, obviously. So what would you get on a knive with a 90° curve? No, it wouldn't be dead flat. Even on the 90° point you would only get the angle difference that is made up by the triangle from the apparatus, meaning the difference in the length of the arm. That would be exactly the triangle that was shown in the last video. So the angle change on a curve is really minimal, since most curves aren't even close to 90°.
It is not everyday on this platform that an established youtuber will put himself out there, provide an extremely convincing argument, then be open minded enough to consider other insights and retract their previous stance. I have a lot of respect for you and the example you are setting... I hope I can be as open minded and responsive as you have been in similar situations
Yes, and the angle also changes as you wear away metal (which is the whole point of sharpening) and if using water stones, wear away the stones. The result is a slightly convex bevel, more pronounced near the tip. (As well as for most knifes, it won't be sharp at the heel end, because a diagonal stone cannot create a full bevel there, but will butt against the ricasso.)
I think the angle does change. It's just like a hip rafters on a house. It's on the same plane but you have to cut the angles on hip rafters different than on common rafters. Say your common rafters are a 5/12 pitch, you have to cut your hip rafters using a 5/17 on the rafter square.
Integrity is everything. Great work. So many people put their opinions out there but refuse to correct themselves when wrong. Your knife work is great. Your integrity as a You Tuber is to be commended. Thanks for the honesty and humility.
God this satisfied a question I had in my mind... For a Blade with Straight and constant radius "convex" curved portions (at the tip), position the blade so that the centre of the radius is coincident with the swivel post axis, then the straight and constant radius curve portions will all will have an approximate correct angle... (blades with reflex won't work as well.) Don't forget that sharpening a knife and designing it to its intended purpose is as much art as geometry...
I'm with Wes, you didn't lie,,, you miss informed us... big difference... I appreciate you correcting the info. I was convinced as well. I use a wicked edge and the bevel is always wider the further away from the middle of the blade.. keep up the great videos....
You're correct -- as long as the rod holding the stone can ROTATE as it moves. If you think of the board on a roof, when the board hangs "normally" (i.e., 90 degrees from the peak) the board is "flat" within itself in the vertical direction; but as it moves it off further to the side from the normal position, the board has to rotate "within itself" in order to stay flat on the roof (and thus flat at the "edge"). Think of it this way: it you went very FAR from the "normal" position, the board would end up lying almost "sideways" on the roof in order to be flat (and be flat at the edge), but one side of the board is higher than the other side of the board -- to match the pitch of the roof. The board has "rotated" in order to stay flat -- just as the stone has to "rotate" (vs the stationary rod support vertical pole) in order to stay flat on the edge as you move out. Now, it's interesting to consider that if your "knife" was in the shape of a circle which went completely around the center support (where the stone's rod is attached to the stationary "angle" point), then the angle would always stay the same as well (as long as the edge was everywhere "level," i.e., perpendicular to the center stationary pole. So the system would work perfectly with a "circular" knife -- although the stone would touch the blade at only a single point as it passed (well, actually, a single "line" spanning the bevel). But what about "in between" those two examples? Well, it wouldn't be perfect anymore, would it. Think of an extreme example: some part of the knife curves back around to come quite near the central post -- in that case the stone would be nearly vertical, and obviously at the wrong angle. The conclusion is: curved parts on a blade may or may not be at the correct angle, depending upon how closely they match a rotation which, when it leaves the straight part of the edge, has, as its axis of rotation the center pole that holds the rod holding the stone. Practically speaking, curved parts of the blade are going to have their angle at least a little messed up. Finally, it's interesting to note that around time 3:40, just as in fact you were saying "that angle does not change," the angle indicator on your instrument was moving up and down, and changing quite a bit! This might be, in fact, because your instrument doesn't allow for your stone to rotate on its own axis (that's how it appears in the video).
I've always wondered about this Thx for demonstrating what happens when the sharpener is pushed out further than what looks normal to our eyes 👀 because I actually stopped using my lanksky because of how it looked on the wide strokes, now it's time to take it out again Thx again
You were right the first time SLL. The angle of the bevel changes the longer the stroke is or further away from the pivot point you get. If the hypotenuse of the triangle gets longer then the angle must be shallower to compensate. Trust me, Im an engineer. Thats the why the bevel (or ground edge) is smaller at the base of the knife and wider at the tip. Any who...knives shorter than 8" it makes no real practical difference, but it is confusing to think about.
Agreed with another poster, it takes a big man to admit when you are wrong. Especially for a man with as much knowledge as you. Thanks for all the hard work on this and I think I am a little bit smarter for it, seeing the original and follow up vids. Keep up the good work!!! Thanks again and God bless!
I applaud you for making a video and correcting the misinformation. I don’t think you lied, in your previous video relayed to this, but making this video to give the correct information is awesome!
You are correct when you were talking about a straight blade but when you get to a Skinner I think you will find out that the actual angle does change because distances change, it might not be much but i would bet a lot of money that it does ,when you get to where the curve starts in the blade the sharpener will lower as it gets farther back from the initial straight part of the blade, take your piece of steel and radius the end and attach your dental floss where the point of the knife would be and it will no longer line up with the other 2
You were right the first time in that the bevel is fatter , also as the knife changes its height the angle does change and the edge becomes steeper as he grind point approaches closer to its axis
LOL ! Thank you for clearing this up. I did my own test, just to satisfy my curiosity. I created the same setup you had. I then cut a wood "wedge" (like.a doorstop) and placed the wedge on the flat bar (blade). I then adjusted the height of the pivot, to match the angle of my wedge. Then, it was easy to confirm. Any where I moved the arm across the bar, the wedge slid in perfectly. The wedge provided a bread visual. If you ever repeat this, cut a wedge. You won't need a second camera, and the proof will jump out at you, like it did me. Just a thought.
![[LIVE] : ONE ลุมพินี 78 | คู่เอก "ปกรณ์ vs ฟาบิโอ"](http://i.ytimg.com/vi/LSOmgl0Th2c/mqdefault.jpg)
Takes a big man to admit he's wrong... especially when he's throwing it out in front of neatly 100K subscribers. You presented your original theory as best you could, and were willing to accept when someone tactfully pointed out not THAT you were wrong, but more importantly WHY you were wrong. You learned something. And you shared that lesson with the rest of us.
Thank you!
Teach this to Justin Trudeau.
Glad to know that u care enough and were determined to research the issue and tell us thx for being a great youtuber
AGREED!!
Amen!
Well he was not lying it was a falsehood. To correct it is his obligation.
Work With Nature • That he chose to make the correction is a breath of fresh air these days. I respect his correction far, far more than anyone that decides to "dig in" despite learning new information.
I like your take and like your honesty even more. Thanks
Really appreciate your integrity.
It takes a good man to admit he is wrong. Better man to find out why. You are A-1 in my book.
Simple Little Life , you did not lie to us, you were just wrong for a brief moment. it happens to everybody ! You are among the few though who will stay open to other opinions and just acknowledge their mistakes. *insert famous quote about how learning from mistakes make you better in life here*
I think the angle changes when the blade tapers to the point. So if this is true there has been no lies. It all depends on the shape of the blade.
this is true only when the edge you're sharpening is perfectly straight though, most knives curve back towards the tip and the heel. if you just look at the width of the sharpened edge, you would see that it's wider towards the tip than the belly : ) which means there's still some slight changes in the angle.
I was thinking exactly the same thing...
I was thinking the same which was my main concern
This.
I’m sorry sir but I must correct you.
A straight knive doesn’t have the same distance to to vertical pole where the pivot point is.
So I doesn’t have the same stone attack angle along the blade.
A curved blade in the form of a portion of a circle would would get the same sharping angle all along its edge.
@@max88nielsen you are wrong
Actually, both versions were correct - with caveats. For the straight portion of the edges, this update is correct simply because the flat surface of the sharpening stone actually starts to rotate counterclockwise (in relationship to it's pivot point) as you sharpen to the right of the pivot point. However, as you approach the curved portion of the blade, the stone will be rotating less (or even go back to neutral) and it will start removing more metal giving you a shallower bevel. One important part you missed is that the bevel is measured from the TANGENT of the edge. Along the straight portion, the tangent is the same and the surface of the stone remains in the same plane. However once you hit the curve, this changes at every point along the edge. In order to get the most consistent bevel, you want to place the pivot point as close as possible to a theoretical center of the curved edge's radius (this being a guestimate, as most blades to not have a uniformly circular curve to them).
Very good comment. In long chef's knives, in particular, I believe some draw a line from the heel of the blade to the point, and set the clamps such that the sharpening angle will achieve the set angle along that line, and average the set angle over the full length of the blade - which offers a good compromise. As an alternative, each section could be sharpened separately; but that would add re-positioning error, and take a lot more time.
Leave the previous video. The strings made me see it because I shared the same thought process as in previous video. But I can swear the further I go out to the side of the blade the angle of the edge changes. I am using Lansky Sharpening system. Next time I will have to pay attention to my sharpening. Thanks for doing all of those tests with the angles. Still amazed.
By the way, you didn't lie.
Lie-a false statement made with DELIBERATE INTENT to deceive; an intentional untruth; a falsehood. Unless you meant to do it ;-) Still can't believe the slope doesn't change.
On the other hand, I feel the angle changes when I come to the end of the curved blade. I remember changing the slope in order to keep the same angle on the edge. I am still confused.
He is wrong, the angle changes
Remember, the angle does ONLY stay the same as long as the "probe" (or the blade) is straight. With a curved blade, the distance changes - and therefore the angle as well. Given that most blades aren't as straight as your piece of cold rolled steel... Well. You'll figure it out.
So. Yeah. Under certain circumstances, the angle stays constant. With most blades, it won't.
thats wrong as well. it would need to have a radius shorter then the distence to the pivotpoint or an inside curve for the bevel angle to change
@steffankaizer: go to the footage with the dentalfloss and imagine one piece ending not on the left side but on the right side of the metal bar simulating the tip of the blade, this means that the angle changes from the straight portion of the blade to the tip. (Because the blade "curves" towards the pivotpoint.)
MadHatter123456 is right. This is the big true.
but if the curve is a part of a circle that have the pivot point as center, the angle doesn't change (imagine you're sharpening a circle)
sorry for my poor english.
@Jo Jo: Thats right, but i would guess that the curve to the tip of most blades has a different radius.
How about doing this same experiment on a curved piece of steel? That straight tool steel remains the same distance from the pivot point but a curved piece will shorten that distance now moving the edge closer to the pivot point.
808keith no it actually doesn't one end is much further away from the pivot point then the center.
I’m sorry sir but I must correct you.
A straight knive doesn’t have the same distance to to vertical pole where the pivot point is.
So I doesn’t have the same stone attack angle along the blade.
A curved blade in the form of a portion of a circle would would get the same sharping angle all along its edge.
This is wrong. The opposit is true
Brother, I have found that half of the stuff I though I knew over the last 60 years is up for debate. Your honesty is refreshing! Thank you.
I really appreciate that you made this followup video! Though, I'm not sure I'd say you lied (which implies that you knew better, and told us the wrong information anyhow)... it was just a mistake, and since you're human, that'll happen.
I have a similar style sharpener, and I have found that the bevel size *can* be different from ricasso to tip, which I previously attributed to the "flaw" you described the first video. Now, after seeing this one, I think it must be due to the uneven wear on the stone, or the fact that sometimes I may not be holding the stone consistently flat. I'll have to play around with this some more. Good to have it settled!!
correct, in my youth, a LONG time ago, he would have said he "misspoke" .
The reason for that is the curve on the blade.
Yes the stone would have to remain constant in the plane of angle, that is actually what changes, that is, the angle of the stone
Maybe you are incorrect sir, the curve of the blade is a constant along the plane of the angle
A straight knive doesn’t have the same distance to to vertical pole where the pivot point is.
So I doesn’t have the same stone attack angle along the blade.
A curved blade in the form of a portion of a circle would would get the same sharping angle all along its edge.
The sign of a great man is to recognize and admit when he is wrong. I was one of those who accepted and agreed with your explanation in the previous video, so I too stand corrected. :)
Great work!
For curved blades, try to angle the blade in the clamp so it’s curve approximates a circle with its center at the upright. Not perfect but it will minimize that “walk-out angle “ effect.
If the length of the floss (hypotenuse) changes, and consequently, the length of the adjacent (horizontal distance between floss contact at knife edge, and pole the floss attaches to), changes, then shouldn't the angle formed between the hypotenuse and adjacent change as well? The angle formed between hypotenuse and adjacent is the sharpening angle if I understand correctly. As an extreme example, think of this: : If you have a knife 2 miles long, then the floss at the center will be only approximately 8 inches long while at either end, it'll be 1 mile, 8 inches long. With the length of the opposite remaining the same, the angle of contact between the stone and the middle of the knife, will certainly be greater than the angle of contact between the stone and either end of the 2 mile long knife. I'd think that the only way for the angle of contact, between stone and straight knife edge (sharpening angle,) to remain the same (in this system), is for the position of the pivot to be able to move and ALWAYS be perpendicular to the knife edge.
One side is constant om the 90 degrees triangle. The hight of the pivot point. The other change and therefore So does the angle.
Speaking as a long time sharpener who owned a business doing it, you’ve put more time into learning angles than most sharpeners I know. Don’t beat yourself up friend, it’s intent that matters. Also, this isn’t life or death stuff, it’s Sharpening.
First video of yours I've seen, but admitting that you'r 100% wrong when someone explained a new way to look at the issue was enough for me to subscribe. Kudos. So many people refuse to ever admit that they are wrong. My father was one of them for the most part. He could argue and convince a calculator that 2+2=5.
You're like me, A real man can admit when they are wrong. I am always amazed how many people cannot, will not admit when they are wrong and will die on that hill.
Your integrity and willingness to correct an untrue statement earned you another sub with me. It means alot that not only did you admit you were wrong, but took the time to learn and explain why you were wrong. Keep it up.
Thank you very much! I really appreciate that. 👍
@@Simplelittlelife It means even more that you just replied to a video that is over 2 years old. Lol. Thanks.
Your analogy with roof is partially accurate. The pitch of a roof stays constant from the peak to the gutter when they are parallel. Most blade edges are not parallel with the spine. As with a chef's knife, the closer you get to the tip the angle gradually increases. Most blades aren't so big with large enough curve that this is very noticeable. You were correct in your previous video but the difference in the angle is very small and virtually unnoticeable.
I am an old retired machinist, you are now correct. I have heard over and over about this angle change bs, I just ignored. Put a straight edge on it.
Thanks for the correction. The angle does however change when you have a curved blade.
I’m sorry sir but I must correct you.
A straight knive doesn’t have the same distance to to vertical pole where the pivot point is.
So I doesn’t have the same stone attack angle along the blade.
A curved blade in the form of a portion of a circle would would get the same sharping angle all along its edge.
A video like this has far more value than most on here because you have taken the time to say 'I was wrong' and show why. Then we learn more from that.
Thank you. Brendan.
Kudos for having the balls to admit an error, and to put the record straight :)
I believe you were correct initially. When viewed on end, the angles all look the same because they all have the same height and the same APPARENT length of the base (from the base of the support to the "edge"). However, that's only an illusion. The "true" angle is the one where we are looking at the angle of the string, blade and support straight on (as if it were drawn on a sheet of paper). If we viewed the furthest string from the same straight on view as the middle string you would see that the angle is more acute. A simpler way to test the angles in your demo is to put a protractor against the blade and the string at each point and measure the angle. But, I love your search for the truth. Never lose that.
On a straight blade, the angle will never change when you measure it correctly; perpendicular to the edge. Just like the roof on a house.
Change the title and keep it up, just put some observations pointing to this video and you are just fine.
Leave them both up. Transparency. I appreciate your candor. Bravo.
I appreciate the feedback. Thank you. 👍
No man, it wasn't a lie, it was an honest mistake. And it takes guts to recognise mistakes. Thanks.😎👍
Thank you.
Refreshing to have someone admit they were wrong and put effort into correcting the mistake!
I'm still convinced the angle changes. Try the dental floss thing again, measure up from the spine of the blade to the dental floss. If it's a different height at each distance than the angle IS in fact different.
If the angle doesn't change how can you explain that the edge bevel is always wider once you get farther from the pivot arm? I used to use a lansky sharpener and that was always an issue.
Think of a pyramid. The tip being the pivot of your TSPROF. The base would be the blade edge. The distance would be less from tip to center point along the base versus tip to end points of the base. The angle however, of the face of pyramid consistent.
Jason Wisser that would seem to only work if the edge was straight and parallel to the pivot point right? The pyramid does help me to understand that. I can see that definitely on a straight blade the angle is consistent. But on a curved blade I'm not sure
Brian Sandoval you are correct The blade would have to be set up properly. The angle would indeed change on a curved blade however the change would so minimal that it wouldn't affect anything.
A quick test I just did showed that the change would be roughly .3 degrees for every 12 inches of travel. Most knives are straight until they curve to the tip. So the curved portion on 6 inch blade may only be 1.5-2 inches long. So that last edge may be about
.025 - .035 degrees different than the straight edge of the blade. I don't think that would affect the sharpness of the blade at all. As a matter of fact I bet any blade sharpened by hand on a stone varies more than this.
The angle changes. If you have a paper guillotine blade or something with a similar geometry, just set it on your jig, calibrate the angle in the center of the blade to be the same as the chisel grind of the blade . Then paint it with marker and grind it trough the hole lenght. You will see that the angle changes.
I think you were correct to begin with ! If the angle changed on that gauge the angle changed on the steel ! Its about removing material from the edge, a line of floss perpendicular to the blade will give the best results for consistent bevel and edge. I think the issue comes from looking at the knife differently, meaning that there are two angles to consider. You simply cannot ignore the fact that the angle of the floss changes, in the top view, when removing material. You will remove more material in the direction of the floss!
Nope. You even looked at the demonstration. In that demonstration, that straight "blade" would have the exact same bevel angle from heel to toe.
Gauges are like computers, they do exactly what you tell them to, not what you want them to do. You're actually talking about the grind angle, or the angle of the lines ground on the bevel. The bevel angle does not change here
@@theboathaaa7654 I watched the video again and we agree that if you have an edge to follow moving the stone left and right on the edge is the same angle along that existing edge. Building an edge with 180 grit stone is where the issue is. The more you move the stone in and out, off center, the more compound angle or curve you put into your edge. This edge would still have the angle of the center plus an addition one. I have the TSPROF and learned this, the hard way, by sharpening a set of display knives that had no edge.
Leave the video up every day is a school day!
You know what this is the first video I have seen of yours but I followed you because someone willing to admit they was wrong is what the world needs
Thank you, I appreciate that. 🙏👍
Excellent. Thanks.
Nice to see somebody correcting a mistake in public. I trust that you didn’t “lie” with intent. Thank you for the honesty and recognizing the mistake.
One of the few that admits he's wrong. Hats off
This is the first video of yours I've ever seen, but the fact that you made another video to admit you were wrong is enough to earn my subscription.
+Grant Baugh thank you so much! I really appreciate it👍
The angle DOES change. HOWEVER, the change is related to the ratio between the length of the blade being sharpened and the length of the sharpening arm (file). If the blade is long compared to the arm the angle difference is more pronounced. If the arm is much longer compared to the blade the angle difference become more negligible. The difference is caused by the change in length of the radial arm (the distance between the pivot and the edge). If the blade is curved outwardly the angle difference become less pronounced and more pronounced in a curved inwardly. All that said, for all intents and purposes the angle VIRTUALLY does not change due to the much longer arm than any kind of knife it is designed to sharpen.
Yes, see my post above.
I ran across this video completely unplanned. It was just on the sidebar after I watched another video by another TH-camr. I'm so impressed with the integrity shown here that I've subscribed. We need more people (not just on TH-cam, but in our society) who have the courage and principles to simply say "I'm sorry; I was wrong."
Not a lie if it is not intended, just a mistake
‘Lie’ is a strong word. I don’t think you were lying. You just made an error. I appreciate the video. Thanks for clearing up the error and clarifying!
You weren’t lying.
Carry On! :))
Keep the other video, it's better to have both sides to prove your point
Matthew Katchmar keep the video or better yet make a third video to combine the two ideas. Compared back to back in the same viewing.
Gary, this is a great idea!
Jeremy.... This is why I love your channel.
Number 1. A lie is an intentional act of deception. You made an error based on some factual mathematical data. Not a lie... an error.
Number 2. You unlike many had the integrity to come back and post a correction admitting your error. Well done!
By the way... because of you I am now a TH-cam advertisement watching zealot.... Keep posting those awesome videos!!!
I say keep it up, but changing the title is not enough. If possible, I would recommend you edit the original video with a plain text disclaimer right at the beginning stating "The conclusions reached in this video are INCORRECT - please see subsequent video for factual conclusions". Just my two cents. Awesome job correcting the mistake!
HoutmeyersP ...and you'd be wrong. Don't bet your life so frivolously when you don't know what you're talking about.
HoutmeyersP wrong...the bevel triangle on a blade on a table is....table forms base...up the spine is the height....angled down to the edge...
What about an actual blade with a curve? Im curious to see that. The edge of the tool steel stayed the same. But a curve on a blade would be closer to the pivot point by 3/4 to 1" at least. How would that change the angle?
I was wrong aswell thank you for pointing that out.
I cherish your humility. It is one of the important facets of learning & progress. Pride almost always causes more damage than humility.
But if you have a big curve on the blade of the knife toward the end of the blade the edge will become wider . Any thoughts maybe I am full of it lol . The hapstone or similar knife sharpeners you just reposition the blad to keep this from happening . Any thoughts ?
You are correct. If you have a straight edge the angle is the same. But when you have a curve the angle changes relative to the curve. It's still the same angle compared to the straight portion but not to the curve. However that's not a bad thing. It makes a more consistent cut. It makes the edge finer compared to the curve. It weakens the tip. But the edge and point are finer. Better than the alternative of a steaper angle on the curve.
yup, any blade with a curve needs the 'dental floss' test. Also, I think an even better test would be to make a 'mock' sharpener, but have the sharpening pivot system much closer to the 'mock' blade. this will give a shorter angle, and therefore illustrate the angle on a larger scale (even though if a change was found, it would most likely be negligible from a regular knife standpoint)
Guys calm down. a blade is not straight. this video is about a STRAIGHT edge. Of course if the blade is not straight the angle changes. This video is about the theory
Those of us that know it changes on the sweep tilt the sharper up in the sweep to compensate so the apex stays the same.
Dave Erving Evader Knives you said it youself, it's the compound angle that your stone is against, so a curved blade would cause the angle to change. I have a lansky sharpener and that's what it does on curved blades. I'm no expert but sure makes sense to me. Please correct me with simple explanation if you disagree.
This demonstration of integrity is heartening. Comments made by people who don't understand distal taper as a curved blade nears the tip, and how incredibly difficult it is for a knife maker to keep that constant, not so much. What I'm still waiting for is a rational argument explaining why variability in edge bevel size negatively effects cutting capability in any way other than the potential for binding.
Simple Little Life, please measure the lengths of the floss, and understand, they all originate at a single point. Therefore, you are viewing all three "Different Length" strings from "3 Different Angles".
Then run a calculation of the height of "Y", length of "X" to find the angle & length of the hypotenuse. You will find your angles do change.
WHY? You are measuring from 1 anchor point, to three separate locations, of different distances.
Length of hypotenuse changes, therefore, the angle does in fact change.
EX 1. X=4.5, Y=9, Angle=63.435(10.062")
EX 2. X=4.5, Y=11, Angle=67.751(11.885")
That is a 4.316 degree difference, with an increase of 1.793 inches from the pivot point.
So, I declare, "You DID NOT LIE"!
You still don´t get it sir. It is not about the angle of the arm, it is about the angle of the edge and the stone. That the angle of the arm changes is obvious but irrelevant to the results. Whit a curved tip it will change becous the 90 degrees from the edge changes but on at straght edge it stays true.
HoutmeyersP nope is wrong...the slope of the roof idea suits...if I run a string from my lightung rod in the dead center of my roof to the corners and to the center does that mean that my roof slope is different angle thought out..if that were the case your roof would be dropping in the center as its angle would be steeper then the corners since they are all equidistant from the edge..
Joseph Rector "If And Only If" the pivot point remains at 90 degrees from the stone. If it is static, the angle does in fact change!
Andreas Persson I am not sorry to inform you that "Only On A Blade With A Very Specific Curve/Radius Would The Angle Remain The Same"! If one changes the distance between the pivot & contact with the knife edge, one has in fact changed the angle of contact. Therefore, the angle of the edge has in fact changed.
Your explanation only holds true, "If And Only If, The Pivot Point Slides To Remain 90 Degrees From The Edge.
If you don't believe it... Take a 12 inch piece of flat stock, swab dykem to top & edge, scribe the edge ( center line ), center it on your jig, and file/sharpen your way to the scribe mark. Once done, look at the shiny area. It will get wider as you move farther from the center.
Steven Smith sorry no..you are thinking of the wrong angle....take the pivot point and move it to be in direct line with any point on the blade and measure the angle...if the bevel and truly changed your blade bevel would be a wave as it went from shallow at one end to steeper angle to shallow again..the triangle in question is not edge to pivot to point of sharpener...it is base of blade/underside to top of spine to edge...the pivot point is immaterial to bevel angle..if that were the case bevel jigs would not work...
Being wrong isn't lying. Coming back and saying you were wrong then explaining the how and why... makes us all better.
Dude.. the first video is correct and the second video is the lie. The angle becomes more acute the farther you move away from the center point. Trust your eyes, you saw the angle gauge move. Trust geometry, math doesn’t lie. Sharpen a blade, you can see the bevel angle lessen at the tip. The roof concept is wrong. If you use a constant angle sharpener like Lansky or Wicked Edge, the ANGLE CHANGES and you have to compensate for those changes to maintain a truly constant bevel.
That's what I call integrity. We all make mistakes. It's how we respond or deal with them when we are confronted. You did the exact right thing. Thanks for making this clear.
Thats it... i can't take it anymore!!! My world is crushed.. im not sure but i might just end it all!! How can i go on??? I cant even think about trying to finish my 2nd knife ever. 😭😭😭😭😡😡😡
I like the fact that you corrected the first video and admitted it! We all make little errors, you didn't "Lie" you just miscalculated the first time then found your error. What happens with the sharpeners is that more of the sharpening stone or sandpaper or whatever is sharpening the blade is in contact with the blade at the further edges of the knife, but the angle is the same. At any rate I am not going to go into the geometry, but will say, good job! Thanks, you made a subscriber of me today...
You're not lying. You were mistaken. Lying is intentionally giving bad information. It's ok to be wrong. Congrats on showing integrity and it's earned you a new sub!
You didn't lie, you misunderstood the problem. Then you figured it out and corrected yourself. Admirable.
The fact that the stone arm can rotate in it's pivot to stay flat against the blade is what makes your "roof pitch" argument valid. It also allows for more possibility of rounding as the stone approaches parallel to the edge. Again, this only applies to a straight blade. A curved blade causes a more obtuse angle at it's point, the same way a domed roof top would not have a single pitch. This is another reason the EdgePro is a superior machine. It allows the unclamped knife to slide along the sharpening table to compensate for this phenomenon.
I like your integrity and honesty. Rare bread that you will find.
As a matter of practicality, it's too much attention to an infinitesimal question of geometry that doesn't affect the performance of either your knife sharpener or knife. Don't beat yourself up about it. The service you provide is still invaluable.
Practically I agree with you 100%. Technically it will make a difference. Although I have yet to meet someone who can actually feel the difference. The bigger part is sharing something on TH-cam. You kinda get held up to the letter of the law on some stuff. By people who really couldn’t even tell the difference. 😆👍
LOVED this video, all but for one thing. You did not LIE to us. You passed on incorrect information, that is different than a lie. A lie is intentional deception. You did not intend to deceive, you passed on what you believed. And I believed it exactly the same way that you did. I will be pointing my viewers to this video to explain this same phenomena.
So basically the lateral distance from the fixed point don't matter. But if you put anything with a curved blade in (almost all knives), then the part of the blade closest to the fixed point is a more obtuse angle. So if you set it up at 15° then the blade will be 15°, but the tip will gradually get blunter the closer it gets to the fixed point. If you were sharpening an ulu, and set the angle to 20°, then your final edge profile from end to end would be something like 23°,22°,21°,20°,21°,22°,23°. It may not be that extreme a change, but you get the idea.
If a knife edge was straight, like the steel or the top plate of a wall frame you are correct. But the more curve on your knife edge the bevel must change just like when the ridge to the top plate is not parallel. I notice it more on my Santoku, Deba and Cooks knives which all have rounded cutting surface. But a winding bevel is common in many chefs knives, fine edge at the front for detailed work and a flatter bevel where the heavy work is done for edge durability. I am tempted to demonstrate this using a similar knife sharpening system and an exaggerated curve cut out of MDF.
For a flat blade or one that is close to flat, yes. however, when you have a curved blade, the angle does change because your angle is from a fixed point that is not the centroid of the curved section. If you put the pivot point at the center of the curve, it won't be same angle at the flat section of the blade. The angle may need to change slightly depending on what portion of the blade you are sharpening to maintain the right amount of angle.
In my opinion, leave it all out there, it shows you are a great guy who is not afraid to admit a mistake. This shows more about you as a person than any skill video could. Big thumbs up from me.
I like your clear explanation and humility. On your old video, you should do a quick intro for it and re-post it... or take it down.
You didn't lie to the audience, lying is an intentional attempt to deceive another. You were simply wrong, or incorrect, and learned from the experience. It's awesome that you came right back and provided the correct information as well as the caveat of the previous information being wrong. Interesting topic definitely since it highlights how easy it is to assume one perspective as an obvious answer.
As a retired machinist I know exactly what you are talking about. So many times in trying to solve machining problems with compound angles it is easy for your brain and eyes to switch planes without you realizing you are now looking from the wrong perspective.
It's nice to see intellectual honesty and integrity.
Great to se a youtuber actually admit hes wrong that takes a honest person.
Wish you all the best my good sir
The angle DOES change. It might not be much, but it changes.
It's basic trigonometry: Consider the triangle defined by the piece of dental floss, the imaginary line from the point the floss is attached to the tool steel to the vertical post, and the segment of the post to the top (or the other end of the floss). It looks like the tool steel is perpendicular to the post. It doesn't really make any difference if it's not, because the correction would be a constant, but it makes the explanation easier. That makes these 3 triangle right triangles. The angle of the floss to the tool steel has to change, because the ratio of the distance on the post (which doesn't change) to the length of the floss (which does change) is the sine of that angle. If the sine changes, the angle has to change!
The change in the angle is probably insignificant, but it does change.
A couple people get it, sadly, not many. Maybe the third video will get it right.
As a Mechanical Engineering Technologist I can confirm you are correct in your analyses. You can perform the same procedure using disks tilted to a fixed degree, as in a table saw. The disk / saw blade will cut the wood evenly as you elevate the blade into the wood. The angle stays the same on all parts of the wood.
I'll use a little bit of math to explain this: The angles ARE the same and here is why:
The sum of angles in a triangle (any type) is 180 degrees. Let's say that those are Right-Angled Triangles so the angles between a and b1 and between a and b2 (I tried to represent the triangles in the pictures below) are always the same, 90 degrees, but this method can be applied to any type of triangles, the only difference are the formulas, however it will give the same result.
p1 and p2 are the angles at the pivot points.
(h1 and h2, each represent the hypotenuse of their corresponding right-angled triangle)
(a is the altitude and is the same for each right-angled triangle)
(b1 and b2, each represent the base of their corresponding right-angled triangle)
- h1 and h2 are the dental floss strings and their lengths are not identical;
- b1 and b2 are the distances from the metal bar to the base of the vertical round bar that has the pivot point on top; b2 and b1 are also not identical, but as the length of the dental floss string increases, the length of the base also increases, in a direct proportional ratio.
- x1 and x2 are the angles that will be compared
first triangle
|p1\
| \
| \
a h1
| \
| \
|__b1______\x1
second triangle (we know for a fact that h2 is longer than h1 and b2 is longer than b1)
| p2 \
| \
| \
a h2
| \
| \
|____b2____________\x2
Solution:
Because these triangles are Right-Angled Triangles we can use the following formula:
h1(^2) = a(^2) + b1(^2)
h2(^2) = a(^2) + b2(^2)
h1(^2) - b1(^2) = h2(^2) - b2(^2) ---> h1(^2) = b1(^2) + h2(^2) - b2(^2) (********)
Now the formulas for x1 and x2 angles are:
cos (x1) = b1/h1
cos (x2) = b2/h2
Now, let's assume that the angles x1 and x2 are identical, then: b1(^2) b2(^2)
---------- = -----------
h1(^2) h2(^2)
then:
b1(^2) * h2(^2) = b2(^2) * h1(^2) (***)
Because the lengths of the dental floss strings are in a direct proportional ratio with the lengths of their corresponding triangle base legs, then:
h2 h1
---- = ---- ---> b1(^2) * h2(^2) = b2(^2) * h1(^2) (***)
b2 b1
Both results from both (***) above are identical so the assumption that the angles are identical is TRUE. If angle x1 = angle x2 then angle p1 = angle p2 (in degrees).
This applies to all types of knives even if the knives are curved or just straight. The surface of the knife that is getting sharpened increases as you move the sharpening stone left or right in relation to the pivot point and that is because the sharpening stone has a width that cannot be ignored.
If length of a , as I shown in the pictures (the height of the pivot point) changes, as the stone is moved left or right, then the angles will be different.
End of solution***
Cheers!
I have not watched your initial video but based on what you were saying, I believe you were right the first time. The angle can only be the same if it is at equal distance to the vertical supporting beam and form a circle. It looks like a cone in 3d. The further you are away the smaller the angle, although not by much in term of knife length. The rate of angle changes also dropped the longer the grinding arm.
The angle does change. Your initial observation is correct.
However. The angle does not change with how far the stone moves on the blade on either side of the center line. The angle changes with the curve of the blade, which in effect retracts or extends the contact surface depending on the blade curving towards or away from the center point of the hone arc of movement.
You didn’t lie to us. You just made a mistake. That happens mate.
You’re honest enough to recognise you error, apologize and get it explained and fixed. You have my respect for that.
Thanks mate!
When you lined up the floss your eye wasn't level with the flat edge of the bar stock. Looking directly in-line with the flat edge of the bar stock the angle does change. Sorry, I think you were right the first time...
It’s confusing but the angle does not change. Think of the pitch of a roof as the floss strings. Doesn’t matter what angle you pivot across the roof, the angle is always the exact same when you measure it perpendicular to the eve of the roof. Same here. With a straight blade, the angle never changes. That’s a fact.
Leave the old video.
You show that sometimes we are wrong. Cool that you made this video with your new knowledge....
Watched it many times
You nailed it. Linking the videos is the right thing to do. I know that I am watching the right channel when you can be wrong then admit to it.
What is said in this video is absolutely true. The angle doesn't change on straight edges. It does change however on curved edges. There the change depends on the curve as well as on the size of your sharpener, more accurately the length of the hypotenuse. Since the length of the catheti that is upright stays constant, the angle at the edge changes.
Think of the exact same triangle that was shown with the strings in this video. It was the projection of a view perpendicular to the edge of the blade from the real triangle that is made by the apparatus itself. Now change that perspective a little bit with the curve of a blade and in your mind make that projection again. The new projection is a triangle that is inbetween the big one from the apparatus and the formerly projected one for the straight edge, with the same height on the upright catheti.
Now there you also immediately notice that the change of the angle of this triangle depends on its size, obviously.
So what would you get on a knive with a 90° curve? No, it wouldn't be dead flat. Even on the 90° point you would only get the angle difference that is made up by the triangle from the apparatus, meaning the difference in the length of the arm. That would be exactly the triangle that was shown in the last video.
So the angle change on a curve is really minimal, since most curves aren't even close to 90°.
It is not everyday on this platform that an established youtuber will put himself out there, provide an extremely convincing argument, then be open minded enough to consider other insights and retract their previous stance. I have a lot of respect for you and the example you are setting... I hope I can be as open minded and responsive as you have been in similar situations
Mind blown... I always thought the angle would change! Great clarification vid. Thanks.
1st, I value your humility.
Question re those sharpeners: If an edge is not straight (recurved), the angle DOES change...correct?
Yes, and the angle also changes as you wear away metal (which is the whole point of sharpening) and if using water stones, wear away the stones. The result is a slightly convex bevel, more pronounced near the tip. (As well as for most knifes, it won't be sharp at the heel end, because a diagonal stone cannot create a full bevel there, but will butt against the ricasso.)
I think the angle does change. It's just like a hip rafters on a house. It's on the same plane but you have to cut the angles on hip rafters different than on common rafters. Say your common rafters are a 5/12 pitch, you have to cut your hip rafters using a 5/17 on the rafter square.
Integrity is everything. Great work. So many people put their opinions out there but refuse to correct themselves when wrong. Your knife work is great. Your integrity as a You Tuber is to be commended. Thanks for the honesty and humility.
God this satisfied a question I had in my mind...
For a Blade with Straight and constant radius "convex" curved portions (at the tip), position the blade so that the centre of the radius is coincident with the swivel post axis, then the straight and constant radius curve portions will all will have an approximate correct angle... (blades with reflex won't work as well.)
Don't forget that sharpening a knife and designing it to its intended purpose is as much art as geometry...
I enjoyed your nice clear demonstration, thanks. I think a lie is a deliberate attempt to mislead, it's a different thing from being mistaken.
I'm with Wes, you didn't lie,,, you miss informed us... big difference... I appreciate you correcting the info. I was convinced as well. I use a wicked edge and the bevel is always wider the further away from the middle of the blade.. keep up the great videos....
You're correct -- as long as the rod holding the stone can ROTATE as it moves. If you think of the board on a roof, when the board hangs "normally" (i.e., 90 degrees from the peak) the board is "flat" within itself in the vertical direction; but as it moves it off further to the side from the normal position, the board has to rotate "within itself" in order to stay flat on the roof (and thus flat at the "edge"). Think of it this way: it you went very FAR from the "normal" position, the board would end up lying almost "sideways" on the roof in order to be flat (and be flat at the edge), but one side of the board is higher than the other side of the board -- to match the pitch of the roof. The board has "rotated" in order to stay flat -- just as the stone has to "rotate" (vs the stationary rod support vertical pole) in order to stay flat on the edge as you move out.
Now, it's interesting to consider that if your "knife" was in the shape of a circle which went completely around the center support (where the stone's rod is attached to the stationary "angle" point), then the angle would always stay the same as well (as long as the edge was everywhere "level," i.e., perpendicular to the center stationary pole. So the system would work perfectly with a "circular" knife -- although the stone would touch the blade at only a single point as it passed (well, actually, a single "line" spanning the bevel).
But what about "in between" those two examples? Well, it wouldn't be perfect anymore, would it. Think of an extreme example: some part of the knife curves back around to come quite near the central post -- in that case the stone would be nearly vertical, and obviously at the wrong angle. The conclusion is: curved parts on a blade may or may not be at the correct angle, depending upon how closely they match a rotation which, when it leaves the straight part of the edge, has, as its axis of rotation the center pole that holds the rod holding the stone. Practically speaking, curved parts of the blade are going to have their angle at least a little messed up.
Finally, it's interesting to note that around time 3:40, just as in fact you were saying "that angle does not change," the angle indicator on your instrument was moving up and down, and changing quite a bit! This might be, in fact, because your instrument doesn't allow for your stone to rotate on its own axis (that's how it appears in the video).
I've always wondered about this Thx for demonstrating what happens when the sharpener is pushed out further than what looks normal to our eyes 👀 because I actually stopped using my lanksky because of how it looked on the wide strokes, now it's time to take it out again Thx again
You were right the first time SLL. The angle of the bevel changes the longer the stroke is or further away from the pivot point you get. If the hypotenuse of the triangle gets longer then the angle must be shallower to compensate. Trust me, Im an engineer. Thats the why the bevel (or ground edge) is smaller at the base of the knife and wider at the tip. Any who...knives shorter than 8" it makes no real practical difference, but it is confusing to think about.
Good man ! Shows a lot of integrity to correct yourself and make sure you give your viewers the true info.
Agreed with another poster, it takes a big man to admit when you are wrong. Especially for a man with as much knowledge as you. Thanks for all the hard work on this and I think I am a little bit smarter for it, seeing the original and follow up vids. Keep up the good work!!! Thanks again and God bless!
It was a lie but your truth change once you received more information that gave you a new truth. Great work.
I applaud you for making a video and correcting the misinformation. I don’t think you lied, in your previous video relayed to this, but making this video to give the correct information is awesome!
You are correct when you were talking about a straight blade but when you get to a Skinner I think you will find out that the actual angle does change because distances change, it might not be much but i would bet a lot of money that it does ,when you get to where the curve starts in the blade the sharpener will lower as it gets farther back from the initial straight part of the blade, take your piece of steel and radius the end and attach your dental floss where the point of the knife would be and it will no longer line up with the other 2
Wow. A youtuber who is willing to say that he was wrong about something. I didn't even see the original video but I am impressed.
You were right the first time in that the bevel is fatter , also as the knife changes its height the angle does change and the edge becomes steeper as he grind point approaches closer to its axis
LOL ! Thank you for clearing this up. I did my own test, just to satisfy my curiosity. I created the same setup you had. I then cut a wood "wedge" (like.a doorstop) and placed the wedge on the flat bar (blade). I then adjusted the height of the pivot, to match the angle of my wedge. Then, it was easy to confirm. Any where I moved the arm across the bar, the wedge slid in perfectly. The wedge provided a bread visual. If you ever repeat this, cut a wedge. You won't need a second camera, and the proof will jump out at you, like it did me. Just a thought.