The confusion behind these knife sharpeners...
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- Опубликовано: 28 сен 2024
- So many folk think that the angle that you are putting on an edge changes the further the sharpening stone gets away from the pivot point of the knife sharpener. THIS IS WRONG. THE ANGLE DOES NOT CHANGE. Watch the video to see what you're missing.
Here is another video where I demonstrate how the angle that you are putting on an edge does not change: • The REAL TRUTH about k...
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Great roof demonstration for those who don't get it!
Guided systems only allow you to follow the set angle.
Hand sharpening allows you a choice. Follow the angle
(like a guided system), OR raise your elbow in the curve
to follow the bevel. (latter looks better/stronger tip)
Blade placement in a guided jig has a few options:
1) Clamping the straight part of the edge parallel
with the clamp. (may give you a wider bevel tip)
2) Drawing a straight line from tip to heal with a sharpie
and aligning that marker parallel with the clamps.
(tip & heel more of a balanced bevel thickness)
3) I've seen some guys clamping a knife with the tip
right in the center (with one off center clamp),
so when the knife flips the tip is always center
mass. (This one I am experimenting with myself.)
Hope this helps and I'm not intruding. Great channel btw!
What people fail to see is that the crosssection of the triangle perpendicular to the blade never changes. The angle changes if you look at the triangle inline with the guide rod. However the sharpening stone rotates to stay perpendicular to the blade so the angle never changes.
Indeed 👍
I can’t believe the ridiculous things people say, regarding the obvious. Which proves they have no experience whatsoever.
I agree. Some of the heated (and I mean heated) debates I’ve had with some folks is crazy!
Many people don't have a great grasp of geometry, so it's not surprising
What’s interesting to consider is that the angle of the edge remains the same for a perfectly straight blade, but also do a perfectly round knife (where the imaginary center of the circle made by the blade is the pivot point of the jig)
It is interesting to think about that. One of those things that doesn’t seem to make sense but also sort of does…maths….👍
only if the round knife edge has a consistent radius that it's center point is the axis of the lever.
I can't wait to see the trolls on this one... 😂
They’re already coming in 😆👍
Hey I finally broke down and bought one of these. I think I need more practice but I keep making the tips of the knives dull. The rest of the knife is perfect. Just the tips are messed up! Thanks for these videos!
Could be the stone passing too far past the tip of the knife; if you’re finishing the tip and the tip is in the middle of your stone you’ve gone to far out over the tip. This is a super common issue when starting. Check out KnifeKrazy’s tip for the tip video. Hope this helps.
The roof is a great analogy! It’s easy to get hung up on 2-dimensional thinking. Bevel filing jigs also wouldn’t work otherwise. All the bevels would “smile” but they don’t: they are even.
Good lesson
Thanks!
What happened to the knife build along?
January isn’t over 👍
Mostly for folks who never worked with their hands building stuff and fixing things. Good PSA anyway!
Hahaha! Exactly. I am blown away by how right some of these folks think they are. They complicate the crap out of a simple way of looking at what’s actually happening. Thanks! 👍
The angle of the secondary bevel will change slightly if the blade curves. This can be mitigated by re-clamping closer to the "center" of the curve or belly of the blade. I like these sharpeners on certain blades but not all blades. That being said, the slight change in bevel angle will be consistent and your edge will still be really nice assuming the thickness of the edge is consistent. I don't know what Jeremy used to sharpen the knife I purchased from him but it is the sharpest edge I've ever received out of the box, hands down👍
Thank so much! I appreciate that and I feel the same way. If there is a lot of curve to the blade that angle will change but it will be consistent from side to side. Also, with most blades the angle will become more obtuse toward the point of the blade which can be advantageous for a lot of tasks. I can’t say for sure what I used to sharpen your knife either but I think it was this K03 if I remember correctly. Cheers 👍
What you said makes sense.
Thanks. I hope it clears things up for others. I used to think the angle changed too until someone shared with me the roof analogy. Cheers👍
i remember you had a similar inital thought about potential angle change years back in video. another great explanation of the subject
Thank you very much! I appreciate the continued support. Cheers 👍
This video is correct in that, in a straight knife, the angle between the mid-plane of the knife bevel and the plane of the sharpening stone does not change. The roof example is a good analogy. However, what does change is the contact area between the stone and the edge bevel. At the center, the contact area is a regular rectangle. As you go further from the center, the sharpening stone gets tilted sideways compared to the plane of the edge bevel so the contact area gets elongated and becomes trapezoid and larger.
This explains the common observation when using these systems, being that less material gets removed at the ends then in the middle for the same amount of passes. The rate of abrasion is proportional to the pressure (not force) applied. As the contact area increases towards the ends of the knife, the pressure (in Newton per square meter or pounds per square inch) decreases and so less abrasion occurs.
Such a FANTASTIC example! I've been trying to explain, in words, this concept for a long time to my coworkers. Now I can show them this video, OR make me a cardboard roof with a thumb tack and tongue depressor. I think I'll just show the vid. Thanks Brother
People just need to be right no matter how wrong that they are.
Isn’t that the truth. 😆👍
Yeah....but....but....... the world is flat.
For anyone who believes that, I have no rebuttal or argument to their point of view. You simply can’t fix stupid.
Aye, I have the economical Lansky fixed angle system from the hardware store. Through actually using it recently (I'm more for freehand usually) I arrived at the same conclusions as expressed here.
I used the system for tidying up a scandi type bevel and for this purpose it worked very well.
Right on. I do admire folks who can sharpen efficiently freehand on stones. I can end up with a decent edge but usually it ends up taking me way too long and I end up have to correct multiple times that I end up removing a lot more material than I need to. I should probably just get a few junker knives and practice over and over with them until I get the technique down. Also more than one way to get a sharp knife and at the end, the sharp knife is all that matters. Cheers 👍
@@Simplelittlelife I doubt that I'm efficient but I like to play around with the handheld diamond sharpeners, ceramic rods and sharpening steels. As long as I'm not mashing an edge I'm thinning it down. If it gets too thin it's quick to reprofile backwards. So I'm gunning for optimal convexity whereas with the fixed angle you get an optimally crisp final bevel. I believe the convex will always slice better and the v-edge will always be stronger and retain its edge longer - that's providing shared geometry along the initial slicing edge. Those shoulders I knock off most of my knives with a steel are speed bumps to cutting but they provide stability to the edge. So the style of sharpening I employ expedites the necessity for future sharpening.
I would be a bit curious to see what the change in angle is when you have a curved blade like a chef knife. I'm guessing it's likely under 2 degrees if you have it clamped in a relatively parallel orientation.
Less than 1° typically, and even then, if it’s fixed and sharpened on both sides it will be perfectly symmetrical side to side as the angle changes along the curve.
On long blades, with long pivot points and sweeping curves the difference is minimal. With short blades with tighter curves and shorter pivot point length, it can be quite noticeable.
It is going to take the shape of an arc or circle because it is on a pivot point, it would make a perfect blade on a circle, but its negligible the amount of change in the angle on a regular knife. Now if you were to use it on a 3 foot long blade you would start to see the blade getting thinner on the ends
wrong...
Nope. The blade itself is what makes it not arc in a radius but rather just remove the steel at the angle that the pivot arm is set to. In order to make an arc you would have to grind away the extreme ends of the blade farthest from the pivot point and remove way more material there than closer to the pivot point. We only sharpen until we achieve the burr that we want, progress through the grits doing the same thing and stop when it’s sharp. That why the angle is the same along the whole length of the sharpening. You could make any blade radius even on a whet stone if you just started grinding material away like an idiot. It’s amazing what dumb people can accomplish. But your argument is wrong. Unless you’re using this like a dumb person.
Not disrespecting anyone but think of this way, if you took a 2 foot piece of steel that’s 1/4” thick and put it on the sharpener and sharpened one side only before you get all the way to the other side you would see an arc developed in the steel where the ends are steeper than the middle, it’s just science, it’s going to follow the arc of the center point, but like I said on thinner steel and being sharpened from both sides and only 6” long you’re not going to see any difference
@@jamesbrandon8520 I'm sorry you think this way... I know its hard, but you are 100% wrong
@@jamesbrandon8520it doesnt matter the length of blade at all, as long as the blade is on the same plane, ie being straight. If the blade curves towards or away from the pivot then the angle will change because it is no longer on the same plane. Its only realy noticible on smaller blades with tight curves
I discovered your channel and immediately subscribed. You clearly know your stuff. You have great camera presence combined with excellent communication skills. I just finished turning my garage into a forge and your videos are really helping. Your knife sharpening videos are brilliant. Is there a mid-range, fixed-pivot sharpening system that you would recommend? Thanks from Nova Scotia!