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I have no idea when the first guided sharper came to be, but I'm guessing it's more like burr removal was perfected a couple thousand years before the first one.
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Angle sharpener vs freehand
- Thread starter RugerNurse
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I agree. One of the reasons I started to get back into freehand sharpening was that I spend all day, almost every day, in front of a screen of some kind. Computer, phone, TV . . . . I needed something else to do, something that didn't involve electronics or a half hour trip to the range. So I dug out some stones, and old pocket knives. After a day of shuffling words into the right arguments, there's something soothing about getting out of my head and focusing on the steel and the stone.
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Do the people you cohabitate with find it as unnerving as my wife does?
Early on in our marriage when we had a small apartment I was sharpening at the kitchen table after she'd gone to bed.
*shiiiiiiiick* *shiiiiiiiiiick* *shiiiiiiiiick*
Moment's later she comes out and says, "can you stop doing that? that's the creepiest sound when I'm trying to sleep."
.... *shiiiiiiiick* *shiiiiiiiiiick* *shiiiiiiiiick*
I wasn't so sure the marriage was going to work out after that, but we bought a house and I threw out the draft papers for divorce.
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Mrs. McGee thinks it sounds like a wheezing cat. Other than that, she's not bothered by it. The fact that I do it in another room while she's watching TV might have something to do with that, though.
Well look; the reality is that we are not machines and thus there is always going to be variability when it comes to freehanding and unless you are a real pro, your edge will just not be as clean, as uniform, and as a result probably not as sharp as a guided system.
That being said it is important that we recognize that guided systems do have their shortcomings as well. With many systems, there is a practical blade length limit so clamping in that 12 inch kitchen blade is not going to work out that well. There might be some limitations with how tall the blade needs to be or issues with transportation of such a large cumbersome system.
Free hand is going to be faster to set up and more easily transported. You will be able to use regular plates or stones on anything including wood working tools, hatchets, axes, scissors, etc that just aren't going to work on a guided system.
The trade off is that the guided system is going to produce a better more uniform edge.
For me it is important to have both. Free hand for cheaper knives, kitchen blades, axes, hatchets, etc and for more expensive pocket knives in PM steels I will turn to the KME for the uniform clean high performance edge that I can get on a PM steel that will actually make good use of such an edge.
That being said it is important that we recognize that guided systems do have their shortcomings as well. With many systems, there is a practical blade length limit so clamping in that 12 inch kitchen blade is not going to work out that well. There might be some limitations with how tall the blade needs to be or issues with transportation of such a large cumbersome system.
Free hand is going to be faster to set up and more easily transported. You will be able to use regular plates or stones on anything including wood working tools, hatchets, axes, scissors, etc that just aren't going to work on a guided system.
The trade off is that the guided system is going to produce a better more uniform edge.
For me it is important to have both. Free hand for cheaper knives, kitchen blades, axes, hatchets, etc and for more expensive pocket knives in PM steels I will turn to the KME for the uniform clean high performance edge that I can get on a PM steel that will actually make good use of such an edge.
I switch hands to do the opposite bevel when sharpening. That just seems easier for me and gives me more control.
I discovered them through straight razors. I usually go for something a little coarser for knifes but they are a great stones. Such a wide range and with speed too, they are a must have for anyone that likes natural stones.They are beautiful stones. You'll love it.
I'm trying to warm up to the BB side on a couple of natural combos but it's still a work in progress.
How does the guided system correct for a curve in the blade? I know that the only knife I have tried to touch up that was sharpened on one was problematic for me in that regard. I didn't know what was going on but knew that there was a transition area that wasn't smooth and that's when my friend told me he used a guided system and reclamps. Is this the way it is with all of the systems?
Yeah that can certainly be a limitation with clamping guided systems. Blades with a pronounced curve can be difficult to maintain the same angle throughout without re-clamping the the blade or changing the angle of the stone holder section by section.
It is another trade off. Pocket knife sub 5 inch blades with a moderate belly should be fine but if you are dealing with a very pronounced persian style blade and particularly one that is long you are going to have some issues likely with a clamp system keeping a consistent bevel thickness from heel to tip
So an even bevel of a precise angle is a myth with a guided system unless of course the blade is straight.
I would think the longer the arms on a guided system the better because it would produce a more even bevel with a blade that wasn't straight?
Its a bit more complex than that. There are a lot of factors that go into this. Where you clamp matters, how the blade was ground originialy matters and I have found many times that the edge was ground more obtusely in some parts than others which was no fault of my KME which was performing as intended but there was a much thicker edge bevel required in some places to apex properly. Your blade shape matters, your clamp size matters etc
The long and short of it is: If what you are after is a perfectly even edge bevel from heel to tip than you may need to play a bit more than just setting your blade up in the clamp, finding the angle you want with an angle cube, and grinding away.
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Just for fun I did a quick study of the geometry of one of those pivoting sharpening jigs. I played a little fast and loose with the blade setup, but it makes the math easier.
Looks like by the time you reach 2 blade lengths distance from the post, the angle on the entire length of the blade is going to be within a degree of your goal angle.
Here I used 15 degrees to be the goal angle.
Edited to Add: There's a special case where a completely straight bevel is always coplanar to the pivot point, and the stone will always adjust to meet the bevel.
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G
garry3
C
c7m2p3
Technically, the only blade shape that would match the sharpening jig perfectly is a blade shape of a single radius (semi circular).
Of course we're assuming you can clamp the blade orthogonal to the post.
Also, G garry3 , your intuition is correct- the further the knife is away from the pivot point, the most it reduces the variation in the bevel angle.
The problem, of course, is that there is always variation, because the blade isn't always equidistant from the post.
Edited to Add: There's a special case where a completely straight bevel is always coplanar to the pivot point, and the stone will always adjust to meet the bevel.
Technically, the only blade shape that would match the sharpening jig perfectly is a blade shape of a single radius (semi circular).
Of course we're assuming you can clamp the blade orthogonal to the post.
Also, G garry3 , your intuition is correct- the further the knife is away from the pivot point, the most it reduces the variation in the bevel angle.
The problem, of course, is that there is always variation, because the blade isn't always equidistant from the post.
Edited to Add: There's a special case where a completely straight bevel is always coplanar to the pivot point, and the stone will always adjust to meet the bevel.
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^All this is great info. Again, the long and short of it is; your blade shape will almost never allow the edge to be totally equidistant from the post BUT even more than that, knives are RARELY ground at the same angle from the factory from heel to tip and will often match a given angle at say, the heel but that will not be the angle you have by the time you get to the tip.
The answer to all this is that clamp systems are really quite fantastic and allowing you to pick an angle and repeat it sharpening after sharpening while also allowing one to achieve more consistent angle bevels than most people could ever dream of achieving with a freehand stone. It is, however, not excalibur in that variations of space in which to clamp the knife, naturally occurring flats on the knife face to clamp, blade shape, blade grind, and a host of other factors come in when it comes to the real world and getting that instagram ready edge may not always be feasible.
The answer to all this is that clamp systems are really quite fantastic and allowing you to pick an angle and repeat it sharpening after sharpening while also allowing one to achieve more consistent angle bevels than most people could ever dream of achieving with a freehand stone. It is, however, not excalibur in that variations of space in which to clamp the knife, naturally occurring flats on the knife face to clamp, blade shape, blade grind, and a host of other factors come in when it comes to the real world and getting that instagram ready edge may not always be feasible.
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It's true that you can get angle variation with these jigs, but it's not what most people would think, and not what I used to think either. Namely, if you have an absolutely straight edge, there is no angle variation with a fixed angle system. It's very counterintuitive, but I've confirmed it via 3D modeling/simulation.
Just for fun I did a quick study of the geometry of one of those pivoting sharpening jigs. I played a little fast and loose with the blade setup, but it makes the math easier.
Looks like by the time you reach 2 blade lengths distance from the post, the angle on the entire length of the blade is going to be within a degree of your goal angle.
Here I used 15 degrees to be the goal angle.
What throws you off is that you're thinking of it as a triangular arrangement formed by the plane of the apex, the pivot, and the contact point, whereas it's really just a 2D plane. I made the same mistake.
Where you do get variation is with curved blades. Namely, as the blade curves toward the center of the jig, the angle increases, and if it curves away from the jig, the angle decreases. In practice this usually works out pretty well, because drop point and clip point blades tend to get thicker towards the tip, so having a slightly steeper angle reduces the change in bevel width you'd get if the sharpening angle didn't get steeper.
Ya i think you actually were the one that brought this to my attention in other threads and its good info to know and helps keep in perspective when you are clamping your blade it to minimize the effect of the curve.
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I hate to say I don't believe you, but I really can't believe it's physically possible to change the distance of the contact point from the guide pole and maintain the same angle when the guide pole is at a fixed height.
It's the reason why the curved blades experience this, as I've highlighted above.
a flat edge also changes the distance from the jig as you follow the edge out to the tip.
Can you define this 2D problem for me? The way I see it, it's 3D by default. There's distance from the guide pole (1D), radius (rotation of the guide pole) (2D) and guide pole adjustment height (3D).
Edit: alright, I drew it out. You're saying it stays in the same plane because the sharpening stone can rotate and therefor can stay coplanar with a straight edge.
I think if that's the case, I can believe it, and it's because I neglected that the stone can rotate.
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The way I feel about it is that if you can't do it freehand, then you can't do it at all.
It's not that you don't have the knowledge, or that there's something wrong with using specialty equipment for greater precision and consistency. There's nothing wrong with that. It has a valid place. It's just that what really matters to me is being able to do it with my own two hands. If you can't do that, then you're not really capable of sharpening a knife. You might have a complete understanding of all the concepts involved, but when it comes down to it, you can't actually do anything with that knowledge on your own.
It's not that you don't have the knowledge, or that there's something wrong with using specialty equipment for greater precision and consistency. There's nothing wrong with that. It has a valid place. It's just that what really matters to me is being able to do it with my own two hands. If you can't do that, then you're not really capable of sharpening a knife. You might have a complete understanding of all the concepts involved, but when it comes down to it, you can't actually do anything with that knowledge on your own.
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I couldn't believe it myself!
I can't give you a mathematical explanation for it, but I put together this short video showing the simulation of what actually happens:
How about numerous self guiding blades like Scandi grind knives, single bevel knives, planes and straight razors? Free hand sharpening is a really simple way to keep the bevels straight and uniform. Guided systems struggle with those blades. Thin and flexy kitchen knives are a major problem for guided systems. Some spine shapes like rhombic and hammered spine are hard to clamp. Guided systems work well on a rather narrow field of blades.