Clamp-style sharpening tools use a clamp with several holes with predefined angles. The stone is mounted on a rod and is pulled through these holes, so that the angle remains consistent. Another system is the crock stick setup, where two sticks are put into a plastic or wooden base to form a V shape. When the knife is pulled up the V, the angle is held so long as the blade is held perpendicular to the base. Several cutlery manufacturers now offer electric knife sharpeners with multiple stages with at least one grinding stage. These electric sharpeners are typically used in the kitchen but have the ability to sharpen blades such as pocket or tactical knives. The main benefit of using an electric sharpener is speed with many models that can complete the sharpening process in one to two minutes. The disadvantage is that the sharpening angle is fixed so some specialized knives, like a Japanese style Santoku, may need additional attention to sharpen to the ideal angle.
Practice holding the knife at a 20 degree angle. Most straight blades need to be sharpened at a 20 degree angle. To find the angle, hold the directly in front of you so it's straight up and down. This is 90 degrees. Tilt the knife halfway towards the table so it's at a 45 degree angle. Tilt the knife halfway again so it's about an inch (2.5 cm) above the table. This should be a 20 degree angle.[4]
Start off on the rough grit side of the stone. Check the grit on your stone, or the packaging that came with the stone, to identify which is which. In general, whetstones and diamond stones each have different grits on either side. The rough grit side is used to grind the steel down, while the fine grit side is used to sharpen or hone the knife. The grinding process comes first, so you start on the rough grit side.
Made in the USA means a lot! It sharpens quickly, whether you need to remove a lot or just a "tune up" on the blade edges. Because it's manufactured flat, it is excellent for planer blades and chisels. The ability to sharpen dry or with only water creates less of a mess than other types of sharpening stones. The no-hassle guarantee is a definite plus, though I would be surprised if you ever needed it.
A: You can sharpen your knives by hand using a stone or you can use a manual powered 1-stage, 2-stage or 3-stage sharpener or you can use a multi-stage electric powered sharpener. The choice is yours. Many people prefer not just the affordability but the precise control they have with an oil or water stone. While others opt for the more predictable results they get from an electric powered sharpener. It’s really a matter of taste.
You've acquired a good chef's knife, you're using it almost daily to make tasty dinners for the family, and it's stored in a nice knife rack or a magnet for safekeeping. So why stop there? Keeping that knife's edge fine will make cooking not only safer but, let's face it, much more fun. Whether you've spent £150 on a high-end knife or under a tenner on a dinky paring knife, keeping it sharp is crucial. 
J. Kenji López-Alt is the Chief Culinary Advisor of Serious Eats, and author of the James Beard Award-nominated column The Food Lab, where he unravels the science of home cooking. A restaurant-trained chef and former Editor at Cook's Illustrated magazine, his first book, The Food Lab: Better Home Cooking Through Science is a New York Times Best-Seller, the recipient of a James Beard Award, and was named Cookbook of the Year in 2015 by the International Association of Culinary Professionals.
Hobby microscope view of a 220 grit diamond sharpening stone. Tiny diamonds are electroplated to a perforated metal carrier strip and bonded to a plastic backing. The feature identified with the red line across it measures about 0.08 mm across. The dark area at upper right is a void designed to allow for swarf created during sharpening to be cleared from the diamonds. This relatively coarse stone would be used to reshape a damaged blade edge which would be refined by finer grit stones.
After you have completed a few passes over the stone on both sides, you can move to the final stage. This time it is P1 pressure, just enough pressure for you to control the knife. Ensure your stone is wet and now repeat the motions but with very very light pressure. You really need to focus here and ensure you are reaching the edge of the edge and again, just a few sweeps on both sides of the knife.

In addition, the most prized of the natural Japanese Water Stones are quarried in the Narutaki District north of Kyoto, Japan and are commonly available as either bench stones or pocket stones in grits ranging from 120 to 12,000. On the other hand, synthetic water stones are made from Aluminum Oxide and commonly available as either bench stones or pocket stones as well in grits ranging from 220 to 8,000 and, although this is the same abrasive material used to make India Oil Stones, the difference between the two is that the binder that holds the abrasive together enables Water Stones to be much softer than India Oil Stones which, in turn, promotes faster cutting because the worn abrasive material breaks away more quickly and is replaced with fresh, sharp, abrasive material more quickly. In addition, because water stones do not become glazed or loaded with swarf like oil stones can, new abrasive particles are constantly exposed as the stone wears so it continues to cut consistently. Plus, they can be lubricated effectively with water (rather than oil which can ruin some water stones) which combines with the fine particles of abrasive from the surface of the stone to form a slurry which polishes the bevel as the stone cuts. However, it should also be noted that Water Stones do become uneven significantly faster than other types of whetstones although, their softness does make them easier to true again.