It depends on the size! Kitchen shears are essentially two knives linked together, and like any other knives, they'll lose their edge after repeated use. Shears tend to have thicker blades than kitchen knives, but if your sharpener can accommodate them, it'll sharpen them. (This is easier if you can separate the blades of your shears, but it can even work with non-separable shears, if you're careful.) Take a close look at the blade edge, though: Many shears have a subtly serrated edge, which will be damaged by a sharpener that's only designed for straight blades.

The material the sharpener's body is made from makes a difference, as well. Nonstick rubber or plastic on the bottom helps keep the unit in place while you're using it; if the blade or sharpener slips, you could end up cutting yourself. Cheaper sharpeners also tend to be made of thin plastic, which is more likely to break if it drops off the counter. Some models even come with cut-resistant gloves as an additional safety element.

Although we did find that it left small scratches on the side of the blade, which could lead to a damaged knife with repeated use, an easy-to-use design combined with performance makes this a more than fair value.

The Mill 16’s new split case design meets truly massive machining needs, with wedge-style cutter bodies ranging from 300 to 500mm in diameter. And for those worried about hanging such humungous cutters off their machine spindles, there’s good news: the largest split case Mill 16 cutter body weighs only 20.4kg, roughly one-third that of competing designs, but still able to rotate at up to 2 800 RPM.

Style: Roller | Abrasive Material: Diamond and ceramic | Dimensions: 4.5 x 2.25 x 1 (for the block) and 3.25 x 2.25 (for the roller) | Best For: Most kitchen knives, but not serrated

The Chef'sChoice ProntoPro has the most advanced technology of any of the manual sharpeners we tested. Its diamond abrasive wheels sharpen both sides of the blade at the same time, and its three-stage sharpening process creates a two-facet, arch-shaped edge that the brand says will stay sharper for longer.

We purchased and tested 22 knife sharpener models—10 electric and 12 manual—to figure out which ones did the best job at restoring dull knife blades and which didn't. All were tested by our Lab team, which consists of testers with decades of experience in both professional and home kitchens, to compare their performance directly.

The flexible belt helps accommodate knives of all different sizes, though we found that it also leaves a lot of wiggle room for the blade, making it somewhat difficult to keep knives at the exact correct angle through the entire sharpening process. The Easy Edge theoretically can sharpen a serrated knife, but it only sharpens the flat edge and not the serrations themselves, so we recommend against it. This knife sharpener is simple to use and sharpens very well, but with its high price, it's probably best for someone who spends a lot of time in the kitchen or is a professional chef.

According to Blake Hartley, Executive Chef at Lapeer Seafood Market, a sharpening steel removes material from your knife by moving the edge alongside the steel to restore the V-shape of a blunt edge. A honing steel is not used to sharpen but to restore the bent edge so that it's straight again.

But there are more options with KCFM available than just PCBN Combining the semi finishing KY3500 silicon nitrate ceramic with KBK50 finishing wiper inserts is also a very productive, and cost effective solution for customers that don’t want to have a full load PCBN inserts in the cutter.

To discover the best knife sharpeners on the market, we collected an array of dull knives—plus several boxes of Band-Aids—and tested their performance slicing through paper, carrots, and tomatoes (and a baguette, for serrated blades), both before and after sharpening. We also measured each knife's sharpness scientifically, using an Edge-on-Up tool to record the exact amount of force needed to cut through a standard material.

The deterioration of the finishing occurs as soon as the inserts show slight wear. That causes an increase in cutter pressure, resulting in vibration, and feeding marks are observed. The result is down time due to frequent insert exchange.

The carbide itself is Kennametal’s KCK20 grade, which comprises a PVD AlTiN/AlTiCrN multilayer coating bonded to a wear-resistant substrate that’s said to prolong tool life.

Rebecca Treon, who also updated this piece, is a food writer, experienced home cook, and mother of two. Her work has been featured in BBC Travel, Huffington Post, Hemispheres, and Thrillist.

It really depends on how much you use them and how much abuse they take, but knives generally need sharpening once or twice a year. If a knife feels dull or has trouble cutting, sharpen it. Just note that every time you sharpen a knife, it removes a little bit of metal. After many repetitions, there won't be enough left to sharpen, and it'll be time to replace your knife.

Donna Currie is a food and recipe writer, cookbook author, and product tester for The Spruce Eats. She spends a great deal of time in the kitchen chopping, slicing, and dicing. Her kitchen is stocked with knives ranging from budget-friendly to high-end picks, and she knows how to keep them sharp.

Jason Horn, a commerce writer for The Spruce Eats, updated this roundup to include data from our extensive tests of 22 sharpeners—10 electric and 12 manual—by both freelance testers and in our Lab in Birmingham, Alabama.

If you're the kind of person who has an opinion on the proper angle for knife sharpening and knows what a burr is, you'll want a Chef'sChoice 130. Its three stages use a diamond abrasive to prepare the blade, steel to set the cutting edge, and lastly a flexible stropping disc for the final perfection of the knife. This model significantly improved sharpness in our tests.

Whether you’re working with a manual or electric sharpener, there are typically at least two grit options that go from coarse to fine. Coarser grit will shave off more metal to remove nicks, chips, and other damage, and it will get a very dull knife ready for finer sharpening. Finer levels of grit further refine the edge, giving it a high level of sharpness. Some sharpeners offer only two different grits, while others have a third (or even a fourth) level, which is similar to a honing steel used for a gentle touch-up. To sharpen a blade effectively, it’s ideal to use at least two different grits.

In our tests, the ProntoPro was absolutely able to improve the sharpness of both straight and serrated blades, though its slots were too narrow to accommodate a thicker knife (like a cleaver). Overall, we love how easy the ProntoPro was to operate, and the instructions were very clear on what sharpener section to use and how to use it.

Style: Electric | Abrasive Materials: Diamond, steel | Dimensions: 10.6 x 6.4 x 6.3 inches | Best For: Straight or serrated edge blades

Each knife sharpener will have its own specific directions, and you should always follow those, but in general, you insert the blade into the slot and pull it through with even pressure several times. It's important to make sure the full blade passes over the abrasive, all the way from heel to tip. Then, you repeat the process on the other side of the blade (though some sharpeners work on both sides at once), first using the coarsest slot and then each of the finer ones.

An assortment of insert edge preps, geometries and corner radii as well as several complementary grades are available to ensure performance in a variety of machining conditions, from heavy roughing to semi-finishing and fine finishing to Ra 3.2 microns or better.

Wedge style and screw-on style cutters in fine, medium and coarse pitch cover all cast iron roughing and semi finishing applications

During testing, we were also impressed with this sharpener's safety features. Its non-stick bottom won't slide around on the counter, and the attached handle lets you steady the device with your off-hand for even more control. It also comes with a pair of cut-resistant gloves for ultimate safety. It doesn't work for serrated knives (few sharpeners do), but it's a great value nonetheless.

German company Wüsthof has been making world-famous knives for more than 200 years, so it makes sense that its sharpening tools are also high-quality. The Easy Edge features a spinning belt that runs at three separate speeds for coarse honing up to final polishing, along with a one-touch program with indicator lights for each stage. An integrated suction fan also keeps dust out of the way.

The material a knife sharpener's abrasives are made out of is the main thing that affects how well it can sharpen knives. It might include steel, ceramic, or even diamond. Essentially, the harder the material used, the more effective the sharpener will be. If you have a ceramic knife, a ceramic abrasive won't be able to sharpen it. You'll need to look for a diamond sharpener. (Diamond also works well on steel blades but does tend to increase cost.)

A honing steel is a long rod, often included in knife sets, along which you run both sides of the blade before you start slicing and dicing. It helps maintain the integrity of the blade, straightening out some of the microscopically uneven spots on the edge without actually removing any metal. Used regularly—as in every few times you use the knife—it can help stave off dullness, but you'll still need to sharpen your knife on occasion.

Carrie Honaker, who updated this roundup, is a food writer who has wielded many knives over the years. As a restaurateur and avid home cook, she knows the importance of caring for your knives to maintain steady, sharp edges. Her work has appeared in many publications, including Bon Appetit, Allrecipes, and Wine Enthusiast.

Style: Manual | Abrasive Material: Diamond | Dimensions: 9.25 x 2 x 2 inches | Best For: Straight or serrated edge blades

Everything from professional models and more affordable options to manual and electric sharpeners were included in the test, along with various types of blades. Each sharpener was rated on ease of use, design, effectiveness, and value.

Making a change Kennametal is pleased to announce that it is building on that success by expanding the Mill 16 platform by introducing new cutter body styles, new insert geometries and grades, and a split case design for large diameter bodies that reduces spindle bearing loads.

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The heart of the Mill 16 is an octagonal, double-sided insert with 16 effective cutting edges. The face of each cutting edge contains an aggressive chip-breaker for positive cutting action and increased chip flow. The wedge clamp on either side of the insert’s top face is likewise chamfered to improve chip evacuation.

Kennametal’s Mill 16 face mill is designed to tackle tough cast iron applications. The Mill 16 has a fine-pitch and medium-pitch cutter body equipped with a single-screw, wedge-style clamping system. This reduces setting time in the tool crib and ensures rigid, no-fail tool placement, the company says. Each pocket on the cutter body is numbered, as are each of the insert’s cutting edges, promoting accuracy and ease of use when indexing to a new cutting edge.

And there is even more good news. All cutters use the same innovative, multi edged design insert. An insert with 16 cutting edges that provides lowest cost per cutting edge. The Mill 16 product line is covering all heavy roughing and semi finishing applications.

Finishing up consistently with KCFM To an engine manufacturer, flatness and finish is everything. Without it, leaks are sure to occur, leading to expensive warranty claims and unhappy customers. The same can be said for those making transmissions, hydraulic manifolds, pump bodies, and anywhere a smooth sealing surface is needed. Unfortunately, the material used to make many of these components – cast iron – can be challenging to machine.

We did not expect a knife sharpener at this low of a price to work as well as it does, but the Longzon 4-in-1 really delivers. As the name suggests, the manual sharpener has four slots—three successively finer ones for standard knives and an extra-wide one especially for sharpening scissors and shears. Some manual sharpeners take a little practice to use correctly, but the Longzon's design and included directions make things simple. There's even a QR code link to video instructions if you're more of a visual learner.

It doesn’t matter which knives you buy—they'll all need to be sharpened periodically. Besides making it easier to cut and chop, keeping knives sharp is also safer for your fingers: Dull knives can drag or skip while cutting, which can increase your chance of injury. How often you need to use a knife sharpener depends on exactly how often you use the knife, what you cut, and what surface you cut on, but professionals typically recommend sharpening once or twice a year.

The answer to that the carbide grade KC514M. A TiAlN PVD coating that is both tough and wear resistant. Designed for light to medium machining. KC514M can be applied with or without cutting fluids.

Electric sharpeners are typically bigger than manual ones, and the number of grit options that any sharpener offers will also affect its size—one with two slots will be smaller than one with three or four. The slot width also matters, as narrower ones can't handle thicker blades, while wider ones might offer too much wiggle room to hold the perfect angle. One thing you don't have to worry about is blade length: Any of the slot-style sharpeners we tested can handle a short paring knife or 12-inch chef's knife with equal ease.

Electric sharpeners are typically easier to use than manual ones, but they're also quite a bit more expensive. The Presto EverSharp is one of the most affordable electric knife sharpeners we tested, but it still did a fantastic job of honing dull knives—straight and serrated—to a nice, sharp edge; It even performed better on our tests than its slightly more expensive cousin, the Professional EverSharp, despite only having two sharpening stages.

"Keep knives in a covered, safe environment when not in use," says Hartley. "Do a weekly light hone with steel or stone, always wiping away particles with a clean dry towel. Don't feel like you have to work fast—with a process like this, form is everything. Work out the proper form first, and then the speed will come."

Overall, the Chef'sChoice 320 made light work of sharpening the knife and creating a good edge during our tests. Directions were very specific and told you which knives to sharpen at which stage and how long to sharpen them.

The tool is available in diameters ranging from 50 to 250mm. Kennametal has rated the maximum axial depth of cut (Ap1) at 5.5mm, although depths to 9mm or greater are possible. According to the company, low cutting forces facilitate machining at 100 per cent radial engagement. All cutters have internal coolant supply capability.

Every once in a while, there’s a new method for doing an old task. In this case, sharpening knives. Rather than manually scraping a knife against an abrasive surface, or dragging a knife through grinding wheels or stones, this simple device keeps the knife still while the sharpener rolls along next to the knife, shaping it at a precise angle.

PCBN and ceramic grades are perfect for mass production and stable conditions. But in many cases there is also the need for fine finishing on rather unstable conditions, such as weak workpiece clamping, limited spindle speed, or long overhang.

The electric Chef'sChoice 130 Professional Sharpening Station is simple to use and works well on many different sizes of blades, while the manual Longzon 4-in-1 offers similar quality with a low price tag.

Wedge style and screw-on style cutters in fine, medium and coarse pitch cover all cast iron roughing and semi finishing applications

We found it quite fun to use—like rolling a toy car across a table. The set we tested included a block with magnetic sides angled at 15 or 20 degrees, along with the rolling sharpener. Simply attach the knife to the block at the chosen angle. Place the block on a flat surface, then roll the sharpener back and forth next to the knife. The sharpening disk contacts the edge of the knife and neatly sharpens it at the chosen angle with very little effort, while keeping the knife solidly in place. Then, attach the knife to the block facing the opposite way to sharpen the other side of the knife (unless of course, you have a custom knife that’s only angled on one side). The sharpener has a diamond grinding disk on one end and ceramic honing disk on the other. At first glance, this looks like it might not work for wider blades, like cleavers or similar knives, since the roller isn’t very tall. But that’s an easy fix. Simply set a cutting board next to the knife and place the roller on top of the board so it can reach the blade edge. Because this is manual sharpening, it’s easy to feel when the movement becomes smooth and the sharpening is done. If the first run was done with the coarser diamond disk, it can be honed with the ceramic disk. It only takes a few honing strokes on each side to get the job done.This was incredibly easy to understand and use. And we’d say it’s nearly foolproof so it’s great for beginners as well as experienced users who like the idea of manual sharpening. Even better, since one hand needs to hold the block while the other holds the roller, hands go nowhere near the knife blade so it’s also pretty safe to use.While the block only has two angles, they are the most common ones for most kitchen knives, aside from some unique or custom blades. This sharpener is available in two different finishes—oak or walnut—if you have a preference. Replacement disks are available, as well as extra grits, including both coarser and finer disks. Sets are also available with different sharpening options. While this is a fairly expensive tool, Horl says that the coarse diamond disk is likely to never wear to the point it needs to be replaced, so this is a one-time buy that will keep kitchen knives sharp without a lot of fuss.

A brand-new knife has (in theory) a perfectly straight blade, ground down to a precise cutting edge at a specific angle. As you use it, the metal on the edge gets damaged on a microscopic level, causing uneven spots that can get caught on foods and create a ragged tear rather than a clean cut. A sharpener does for a metal knife basically the same thing that sandpaper does for a wooden board: It shaves off a layer of uneven material to make the surface smooth and even again. Different models of sharpener use different materials and methods to remove metal, along with different methods of holding the knife in the correct position while doing so.

Sharpening a knife to the finest possible point is a true art that takes a lot of practice and technique. The Chef'sChoice 320 takes out a lot of guesswork, thanks to its firm-fitting sharpening slots that hold the knife at just the right angle. This machine uses just two different textures of diamond abrasive to hone blades and works with standard or serrated knives, but we missed a third, coarsest abrasive that other models use to make sharpening faster.

This process is essentially the same with both a manual and electric sharpener, but the motorized abrasives in an electric model will do more of the work for you. The most important thing is to try to use the same amount of pressure and the same angle with each pull through the slot—different models of sharpener make this easier or harder, depending on their design. Unless the directions specify otherwise, it should take three to five pulls through the coarse slot, and then just a couple through each finer slot, to sharpen the knife. If it's not as sharp as you like, try a few more pulls through the finest grit slot, and if that doesn't work, try the whole process over again.

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The super positive KCFM – Kennametal Cast Iron Finishing Milling – with the new KBK50 full top PCBN (polycrystalline cubic boron nitride) grade was developed to address these issues. Now customers can produce much more parts per edge in a reliable and consistent manner, so the cost per component will decrease.

Style: Electric | Abrasive Materials: Diamond, steel | Dimensions: 12 x 6 x 6.25 inches | Best For: Straight or serrated edge blades

Sharpening a knife blade removes tiny bits of metal, and those will need to be removed from the sharpener once in a while. Many models have a compartment in the bottom to collect metal filings, which you can simply dump into the trash and wipe clean with a wet cloth. (If there's no compartment, turn the unit over and lightly tap to get the filings out.) You can also clean the abrasive parts with a cloth or a soft brush dampened with water; make sure to let everything dry completely before using again. Unless the directions say otherwise, it's not a good idea to use soap or any kind of oil to clean a knife sharpener, as you can damage the abrasive.

With these new additions the portfolio will fit any of your cast iron face milling applications. From fine pitch wedge style cutters for highest productivity and very powerful machines to medium and coarse pitch cutters with screw-on inserts when horsepower is limited. From machining of small components to very large components.

It works with serrated knives—something many other sharpeners can't do—but we found the instruction manual a bit lengthy and dense. However, if you follow it properly, including looking for a burr (which, for the record, is a very thin lip of metal that hangs over the cutting edge and indicates it's time to sharpen the other side of the blade), you'll have great success.

Style: Electric | Abrasive Material: Sapphirite | Dimensions: 9.9 x 7.2 x 4.8 inches | Best For: Straight or serrated edge blades

And keep in mind machining time reduces drastically since PCBN can be applied with 3 times higher cutting speeds compared to carbide inserts.