What is a good technique for sharpening curved edge blades ?
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    Default What is a good technique for sharpening curved edge blades ?

    I can get a wood chisel razor sharp so that it cuts the little hairs on the back of a hand. The blade is straight and there is enough straight edge behind the edge so that the blade can be easily moved across a stone.

    But with a pocket or much larger type knife with a curved edge the sharpness is not there. I tried a diamond stone and ceramic rods. Moving the blade over a stone or moving the stone on a stationary blade. Is a jig the way to go?

    I decided to ask this because someone in a recent "Kershaw knife quality?" mentioned that he only goes to a sharpening service.

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    I am a devout guided sharpener user for the same reason I use guided cutting tools, it's just way more accurate and repeatable. I do a bit of work for a company called Edge Pro who makes these things. As for what abrasive to use it depends on the steel your sharpening. If it is hard enough then my personal favorite is resin bond diamond, but then I make those too so go figure. Many will say just learn freehand but whenever I sharpen a freehanded blade the angle varies by a few degrees along the edge, even on a 3" blade by a well-respected freehander. This is just my opinion, not saying it's the only way to go.

    Great way to sharpen scissors too.

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    A horizontal rotating lapping plate to set the bevel angle, since you can manoeuvre the blade around, while keeping the angle fairly constant. Followed by stropping to remove any final burrs.

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    You know about those cheap belt sanders with a sanding disk on the other end of the motor shaft? I use a fine grit stick on disk on there. I first sharpen one side of the blade with the edge down against the aluminum rest. Just draw it across the edge of the disk with a 'pull it out of the scabard' sort of action. Then, turn the blade over so the back of the blade is now against the rest and draw it across the edge of the disk again. It is relatively easy to keep the knife at a consistent angle while executing this swiping motion. It will follow any curve easily.

    Couple of swipes each side will fix a pretty scummy edge. Then you can hone it to finish if you wish.

    My kitchen knives are kept dangerous

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    Yeah, I generally only let a pro sharpen them, it's just better results. I've had a couple different kits. I have the best results with a guided kit with various grades of diamond stones attached to long rods, which let you set the angle of the stone to the blade. I can take a dull or nicked up knife and make it serviceable again... But I generally can't get to arm hair shaving sharp.

    Also, two of my last 4 knives have been this one: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    and I'm definitely not trying to sharpen the ceramic at home.... Though the oldest of the 2 is about 3 years old, and despite missing its tip, STILL doesn't need any actual sharpening, and the other one... Well, the other got flushed down a toilet at work a few months ago

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    IMO it's not all that different than deburing a part. Whatever your method (power or wet stone) just hold it at a consistent angle and keep the piece moving so you don't dwell in one spot. With curved blades, only a single point is making contact with the stone so you start at one end and curve it around as is goes across the stone. If it's beveled on both sides, I like to go back and forth between each side. The bevels will stay even and you get a finer edge than if you take several passes on one side before switching to the other.

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    How to sharpen a curved knife edge? I think it is called skill.

    I have a slow speed wheel with a water bath for knife sharpening. It works great. I had to put warning notes in the kitchen drawers.

    For scissors, unless they are really damaged, I sharpen them with an action that can best be described as attempting to cut a 1/16" drill bit with them. I try to cut the shank of that bit just behind the end of the flutes, where the shank is hard. This produces a perfectly sharp pair of scissors. And it does not remove any material: it just rearranges it into a sharp edge. You need to tilt the drill bit a few degrees to match the ground edges on the blades of the scissors.

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    These are my basic woodworking tools, the Witherby draw knife at the top is an example of fine toolmaking a century ago. Thankfully no idiot had taken it to a power grinder!
    Not your regular draw knife, it is curved on two planes, making it more of a challenge to maintain an edge that would cut God, if he should encounter the blade.
    The best edge I have made on the tool is with Japanese water stones about 1" wide, then a quick stropping. With its slow single bevel, it will remove the hardest wood with surprising ease.

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    I use a burnisher or steel when honing is needed. The inexpensive tool that you draw thru the Y that holds carbide hones.Will sharpen any blade including serrated ones. Never tried it on scissors. You can actually sharpen a cheap knife like a clam knife or cheap steak knives that cost about $10.00 for a set of 4. The cheapest I saw was a Chef Master for around $6.00. Bought one for the tackle box. Works great, I sharpen a filet knife with it. I sharpen hooks with a tool that has two chain saw files bonded together on a plastic base. Just use it on hooks and gets the hook sharper than new.
    Saying this I have sharpened wood working tools for 55+ years and have carborundum , diamond , Arkansas,
    ceramic stones and 600 grit wet sandpaper. Carborundum is pretty much junk, I only use it to sharpen an axe . I could care less if the stone loaded up with dirt.
    Metal working cutters etc. I use a 1x42 sander with 120 grit.
    mike

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    Quote Originally Posted by TeachMePlease View Post
    Yeah, I generally only let a pro sharpen them, it's just better results. I've had a couple different kits. I have the best results with a guided kit with various grades of diamond stones attached to long rods, which let you set the angle of the stone to the blade. I can take a dull or nicked up knife and make it serviceable again... But I generally can't get to arm hair shaving sharp.

    Also, two of my last 4 knives have been this one: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    and I'm definitely not trying to sharpen the ceramic at home.... Though the oldest of the 2 is about 3 years old, and despite missing its tip, STILL doesn't need any actual sharpening, and the other one... Well, the other got flushed down a toilet at work a few months ago
    Stropping with leather and green rouge is the secret to arm shaving sharpness. Very fine diamond paste should work also.

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    I looked at the edge of some pocket knife blades with a inspection microscope and didn't care too much about the quality of the sharpening job.

    The angle from the horizontal to the grind of the edge is 10 degrees.

    That does not correspond with a Tri-Angle ceramic stick sharpening set that I have. It was sold as a universal system:

    The tri-angular ceramic sticks are inserted into a block making a V shape with each stick at 20 degrees from vertical.
    There is another way to hold the sticks flat. The sticks are triangular in cross section and are 1/2" wide on each edge.
    They can be laid into a v-groove making a flat surface to run a blade by hand. But the V block method is a question below.

    The difference in angles reminds me about my Veritas wood chisel holder used for sharpening. The angle of tilt can be altered at the
    last few runs on the stone to produce a micro-bevel. I never used that myself because once I got the edge sharp, why change the angle?
    Unless the edge can last longer with a micro-bevel.

    QUESTIONS:
    Is there a correct angle?
    Is the design correct with a 20 degree rough angle and then a 10 degree bevel on the edge?
    Are all blades made with different bevel angles? Then the sharpening methods must be altered for different angles?

    OBSERVATION:
    The knife is a Uncle Henry. The blade has grind marks from manufacturing. Going across the blade from the back to the edge, is there only one angle or more?
    Is it undesirable to sharpen knives like this to be razor sharp?

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    All blades are made with varying angles, as are all hand sharpened blades. A 10-degree primary bevel with a 20-degree micro bevel is a big jump, the angle you want depends on the steel and what you will be doing with your knife. A 21-degree micro bevel is as universal as it gets, but that doesn't mean it is right for your knife and needs. Like what works best for your machining it is going to take time for you to figure it out, no one can tell you what will work best for you. A 10-degree primary bevel is pretty shallow, think Japanese kitchen knives that don't cut anything hard and you don't mind maintaining. If you want generic toughness then just go with 20 degrees per side.

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    Quote Originally Posted by DavidScott View Post
    All blades are made with varying angles, as are all hand sharpened blades. A 10-degree primary bevel with a 20-degree micro bevel is a big jump, the angle you want depends on the steel and what you will be doing with your knife. A 21-degree micro bevel is as universal as it gets, but that doesn't mean it is right for your knife and needs. Like what works best for your machining it is going to take time for you to figure it out, no one can tell you what will work best for you. A 10-degree primary bevel is pretty shallow, think Japanese kitchen knives that don't cut anything hard and you don't mind maintaining. If you want generic toughness then just go with 20 degrees per side.

    This coincides with what I was taught many moons ago, 15°-20° on your pocket knife, so it's maybe not quite as sharp, but will hold up to daily abuse, and 10° on your kitchen knives. Of course, now that both my pocket knives and my kitchen knives are ceramic (mostly), I don't sharpen any of them. Maybe one day I'll buy a nice set of Wusthof knives....

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    Quote Originally Posted by TeachMePlease View Post
    This coincides with what I was taught many moons ago, 15°-20° on your pocket knife, so it's maybe not quite as sharp, but will hold up to daily abuse, and 10° on your kitchen knives. Of course, now that both my pocket knives and my kitchen knives are ceramic (mostly), I don't sharpen any of them. Maybe one day I'll buy a nice set of Wusthof knives....
    My wife's paring knife is 21 degrees and still takes a beating. Mine, for the most part, are 12 degrees with a 16-degree micro bevel. My one ceramic knife is a cheap Kyocera paring knife and it is 21 degrees per side, anything finer or if I try a micro bevel I can't avoid microchipping. I do love ceramic because it will hold an edge many times longer than any steel knife I have. I consider new knives dull, that is how sharp I like to keep mine. The ones my wife uses are another matter.

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    Many years ago I used to resharpen Buck Folding Hunters for a couple of friends. Many considered it nearly impossible to duplicate the factory edge but I had great success roughing with an oilstone, final honing with hard Arkansas, and then buffing on a wheel with white rouge.

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    I'm trying to figure out a good way to sharpen a straight edge bread knife while in the kitchen.

    The blade is so flexible, there is really no way to manipulate it against a stone while just holding the handle.

    I'v come up with ways to hang the edge over the counter and run the stone over it, and ways to spread my fingers over the blade like a pianist.

    But I would like to come up with a good way to restore the edge while still in the kitchen. I suppose one of those disc type draw sharpeners might do....

    The bread knife works well for slicing tomatoes when it's sharp, And it's tomato time!

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    Quote Originally Posted by CalG View Post
    I'm trying to figure out a good way to sharpen a straight edge bread knife while in the kitchen.

    The blade is so flexible, there is really no way to manipulate it against a stone while just holding the handle.

    I'v come up with ways to hang the edge over the counter and run the stone over it, and ways to spread my fingers over the blade like a pianist.

    But I would like to come up with a good way to restore the edge while still in the kitchen. I suppose one of those disc type draw sharpeners might do....

    The bread knife works well for slicing tomatoes when it's sharp, And it's tomato time!
    Hang the edge over a cutting board and use a small hand held stone. Just watch your fingers or better yet wear one of those cut resistant kitchen gloves.

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    I read this book when I was a young man and the answers to all the mystery and frustration were revealed. The book is called “the razor edge book of sharpening” by John Juranitch. Read the book, I give you my word that it will serve you well.
    Mike

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    Quote Originally Posted by rons View Post
    I can get a wood chisel razor sharp so that it cuts the little hairs on the back of a hand.
    MAPP gas torch is faster Ron.

    But with a pocket or much larger type knife with a curved edge the sharpness is not there. I tried a diamond stone and ceramic rods. Moving the blade over a stone or moving the stone on a stationary blade. Is a jig the way to go?

    I decided to ask this because someone in a recent "Kershaw knife quality?" mentioned that he only goes to a sharpening service.
    That's just nuts. Probably working the entire lot of that kit - any of which CAN work - AGAINST itself?

    Brookstone used to sell a handy trio of stones as kept an Xacto frisket knife, a tiny Puma on-up to carvery knives razor sharp.

    Get you a decent "India" stone, Ouchita, and a hard Arkansas.

    Only other thing you need is a light cleansing or honing oil. Stones MUST be kept clean and FLAT, not with grooves wore into them - plus about an hour of practice with but the ONE set, not some of each - to get the hang of it. More is better, but that will come as you go, anyway.

    It sorta "grows on yah" as you get the hang of different angles for different blades and their specific use absorbed into "muscle memory".

    A few sheets of rag bond paper make a better sharpness test than shaving yer hands like you were going Kalifornikyah pub-crawling for strange trade, nail polish, lipstick, high heels, and all.

    Or so the grown-ups thankfully warned me off of 'fore I had need of discovering some things in life really ARE a pain in the ....anatomy?


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    Quote Originally Posted by CalG View Post
    I'm trying to figure out a good way to sharpen a straight edge bread knife while in the kitchen.

    The blade is so flexible, there is really no way to manipulate it against a stone while just holding the handle.

    I'v come up with ways to hang the edge over the counter and run the stone over it, and ways to spread my fingers over the blade like a pianist.

    But I would like to come up with a good way to restore the edge while still in the kitchen. I suppose one of those disc type draw sharpeners might do....

    The bread knife works well for slicing tomatoes when it's sharp, And it's tomato time!
    "Flexible"? A "bread" knife? Something else, actually.

    Non-serrated blade, just use a "rifle".. One of those straight-grooved round-rod cousins of a file.

    Half-moon large serrations, nine-inch or more, and stiff as a power-hacksaw blade as any PROPER "bread" knife has to be? More to life than "wonderbread". Just buy a new one very 30 years or so, cut anything breadish from a fresh Baguette, Batard, crusty Puglia round, to rock-hard ten year old Russian black..

    Maybe more than 30 years?

    Neither of my French nor German ones seems to want to go dull yet, even with the odd radiator hose attacked. Mind - at what good ones cost? Ignore anything under about $100-$140, but last a very long time they assuredly will do, so that's cheap, not dear.

    A "Heathcotes" is about the cheapest decent bread knife, all crusts, ages, and shapes you are likely to find. Serrated one side only, so they can be "sort of" sharpened.

    Tomaters one cuts with a ceramic blade, Russel "Green River", heavy Chinese or more presentable Japanese chef's knife, "Ginsu" or "Santoku", either one - so long as razor-sharp. Sharpening is dead-easy for any of those, BTW,

    Go for the heavier and homelier ones Asian Great'G'Mums as have been preparing food since early girlhood use AND NOT the "pretty" ones "as seen on TV". Them's overpriced and junk as well.

    The ceramics - ten bucks or less - do the job well and are basically disposable. Just drop one on a tiled floor a few times if you doubt me!



    Too acidic for the ancient Case "Old Forge" HCS razors of a wasted youth or the newer German Damascened or carbide-edged toys, tomatoes are.


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