I bought this knife sharpener for my son as a Christmas present years ago and recently (but cautiously) used it on my cutlery (Henkel and Wusthof). Frankly, I had been a little lazy and let my knifes lose a bit of their edge. I did not feel like getting out my stones and oil to do a proper job, so I borrowed my son's sharpener. It really works great, which I hate to admit, as it feels like a cheat and it is a fraction of what I spent on stones. I realize that I need to buy one for myself, so I looked around to see if there is anything better and I could not see anything that looked better. This one is adjustable, which is what I need. I looked at the 1 star ratings and there was a common theme that the knife edge chatters as the blade is pulled across. It can, if you don't use it properly! If your blade is very dull, you will need to pull with a very light, steady, and quick motion. You never need to push down hard as you pull. Even pressure. Don't be a brute! Finesse is what is needed. I am going to buy another one for me.
That’s not to say that you need one of these knife sharpeners—as we note below in the next section, you may prefer another type of sharpener, one that arguably produces an even better edge. But the simple, foolproof sharpeners we’ve picked here will satisfy most people, and they all do the job quickly. That means you’ll be far more likely to use one of these, and that means you’ll always have sharp, safe, effective, and enjoyable knives at hand.
Technically, the name whetstone can be applied to any form of sharpening stone, regardless of what cutting fluid is typically used with it. However because whet sounds like wet, many hear the word and assume that it refers to a stone that is used wet with water. Actually, water stones, oil stones diamond stones and ceramic stones are all forms of whetstones. So, while all water stones are whetstones, not all whetstones are water stones.
Soaked stone for about 20 minutes, then when attempting to sharpen the blade, A red slurry ends up all over the blade. Even a couple sprays from a water bottle and a wipe with a microfiber appears to take material off the surface. Since it is not coming off evenly across the stone surface, it is now uneven and the stone appears to be unusable at this point.

Before you start sharpening, soak the stone in water for around five to 10 minutes, until it absorbs the water and a liquid film appears on the surface. After soaking, splash some water on top, and re-splash during the process if it ever gets too dry. You'll get a dark, splotch of steel and stone building up on the stone while you're sharpening the blade. This is totally normal so just splash the stone with some water to clean it off and allow it to perform more efficiently. 
If you decide to use this device to sharpen a knife, you can simply attach the blade guide against the belt, creating a barrier against which you can lean your knife as you sharpen it. Leaning your knife against the guard holds it at a specific angle so that your blade can be sharpened to a specific angle. The angle is adjustable from 30 degrees down to 15 degrees. You can also choose to use this machine to sharpen tools, such as axes. If sharpening those types of blades, you will want to go with a freehand approach instead of using the guide.
This knife sharpener has three sharpening slots with three different cutting materials: tungsten carbide, ceramic, and diamond. The diamond slot is used for ceramic knives, while the other two slots for sharpening and honing steel knives. This can also sharpen serrated knives. This sharpener is easy to use and has a handle that keeps your hand safely away from the knife blade.
A hybrid manual-electric sharpener, the Chef’sChoice Hybrid 210 uses a motor and abrasive wheels to grind the new edge and employs a manual stage to hone it. This sharpener is eminently affordable. However, our top pick, the ProntoPro 4643 multi-blade-angle manual model (as well as its $30 to $40 single-blade-angle kin) produces a better edge and doesn’t make us worry about breakdowns the way the Hybrid 210’s lightweight motor does.

Most sharpening stones are made of aluminum oxide, Novaculite, and silicon carbide. They are commonly known as India, Arkansas and Crystolon stones. Crystolon and India are man made while Arkansas stones are natural. Arkansas stones have a fine to coarse texture while India stones are preferred for fine sharpening. Crystolon are mainly used for initial coarse sharpening. Some sharpening stones are mixed with diamond abrasives to produce the optimal cutting edge.
This knife sharpening system comes with a firm grip, to ensure a fine finish. This device does not slip around when sharpening your knife. You just need to hold it firm and it will adhere to the surface. This ensures that you get the desired results. The carbide surface is optimized to handle any type of knife. It doesn’t matter how blunt or damaged it is, it will give you a fine edge, for precision cutting.
It takes time to sharpen a knife correctly. I spent about 30 minutes on an already fairly sharp knife. I then spent two more sessions of about 10 to 15 minutes each. I took it a bit further with a 6000 grit stone and this puts a nice polish on it. Instead of cutting through an onion, it glides or slips through it. It was truly shocking to me to use a really sharp knife. It may take a bit of time to get it right the first time, since this was my first time with a water stone, but it was well worth the effort. I have been trying to figure out the best way to get a really sharp knife.

Begin by sharpening the knife from the front side. Sharpening is completed when the knife has an even burr. Only use a flat-surfaced stone to finish the back surface of the blade. Sharpen the blade from the edge to the spine. Do not sharpen at too great an angle between the blade and the stone. The stone used to finish the cutting edge of the blade should contact the edge evenly.

For this guide, we limited our focus to manual and electric sharpeners. Such models are by far the most popular choices for sharpening knives, and for good reason. When well-designed, manual and electric sharpeners are effective, extremely quick and easy to use, and durable. (By the same token, when poorly designed they’re cumbersome, flimsy, and ruinous to blades.)
By employing separate sharpening slots, the ProntoPro 4643 is capable of sharpening both older European-style knives (such as from Wüsthof and Henckels) and Japanese-style knives (such as from Mac—which makes our favorite chef’s knife—and Shun). The difference is in the angle of the bevel that forms the cutting edge: Traditional European knives have roughly 20-degree bevels, while Japanese knives have roughly 15-degree ones. If you own both types of knife, or if you do a lot of heavy work in the kitchen (like chopping up chicken carcasses), you’ll appreciate this feature, as a 20-degree bevel is best for tough jobs. Note, though, that Wüsthof and Henckels have stopped making 20-degree knives, having switched to 15-degree or 12-degree designs exclusively in 2011; the reason is that for all but the heaviest tasks, these more-acute bevels cut better and, with the ongoing improvements in steel alloys, hold their edges for just as long.
Once you've sharpened one side, you need to flip over, but don't swap the hand gripping the blade – think of it a bit like going backhand with a tennis racket (see above). Lead with the heel this time, rather then with the blade, but repeat the process in three parts. After five strokes on each third of the blade, it's time to check your knife. It's not an exact science, and it all depends on how blunt your blade was to start with (mine was very blunt indeed). But if you sharpen fairly regularly, it should just take a few strokes. 

Chefs and meat cutters frequently pause and “steel” their cutting edges. Steeling doesn’t sharpen an edge; it straightens it. That’s necessary because the thin edge actually bends or warps while you’re cutting. If you could see the edge under a microscope, it would look wavy, and it would feel dull while cutting. Steeling the knife straightens out all those waves to restore a straight, even cutting edge. So when your knife begins to seem dull, don’t sharpen it—steel it first. Every time you grab a knife for the first time to begin cutting, steel it before you even get started. But it’s important to do it right or you’ll just make the edge worse. And don’t act like one of the Iron Chefs on TV and do it all up in the air—you’ll eventually wind up in the ER. Rest the end of the steel on a cutting board and do your steeling the safer and more accurate way. It’s very important that you steel at an angle between 20 and 30 degrees. Photo 1 shows you how to figure that out.