Grind The grind of a blade refers to the shape of the cross - section of the blade . It is distinct from the type of blade ( " e . g . " , clip point or drop point knife , sabre or cutlass , axe or chisel , etc . ) , though different tools and blades may have lent their name to a particular grind . Grinding involves removing significant portions of metal from the blade and is thus distinct from honing and polishing . It is notably done when first sharpening the blade or when a blade has been significantly damaged or abused ( such as breaking a tip , chipping , or extensive corrosion ) A well maintained blade will need less frequent grinding than one which is not treated well . The terms " edge angle " and " included angle " can be important when talking about grinding . The edge angle is measured between the surface of an edge and a line running from the point of the cutting edge to the centre of the back edge . The included angle is the sum of the edge angles . All other things being equal , the smaller the included angle the sharper the blade and the easier it is to damage the edge . An appropriate grind will depend upon what the blade is to be used for and the material from which the blade is made . Knife manufacturers may offer the same model of knife with different grinds on the blade and owners of a blade may choose to reshape it as a different grind to obtain different blade properties . A trade off exists between a blade ' s ability to take an edge and its ability to keep an edge . Various grinds are easier to maintain than others or can provide a better shape over the life of the blade as the blade is worn away by repeated sharpening . In material science terms , harder steels take sharper edges , but are more brittle and hence chip more easily , while softer steels are tougher , and are used for knives such as cleavers which must be tough but do not require a sharp edge . In the range of hardnesses used for knives , the relationship between hardness and toughness is fairly complex and high hardness and high toughness are often possible at the same time . As a rough guide , Western kitchen knives generally have a double - bevel ( approximately 15° on the first bevel and 20 – 22° on the second ) , while East Asian kitchen knives are made of harder steel and are ground at 15 – 18° , being either wedge - shaped ( double - ground ) or chisel - shaped ( single - ground ) . Process . A sharp object works by concentrating forces which creates a high pressure due to the very small area of the edge , but high pressures can nick a thin blade or even cause it to roll over into a rounded tube when it is used against hard materials . An irregular material or angled cut is also likely to apply much more torque to hollow - ground blades due to the " lip " formed on either side of the edge . More blade material can be included directly behind the cutting edge to reinforce it , but during sharpening some proportion of this material must be removed to reshape the edge , making the process more time - consuming . Also , any object being cut must be moved aside to make way for this wider blade section , and any force distributed to the grind surface reduces the pressure applied at the edge . One way around this dilemma is to use the blade at an angle , which can make a blade ' s grind seem less steep , much as a switchback makes a trail easier to climb . Using the edge in this way is made easier by introducing a curve in the blade , as seen in saber s , scimitar s , and katana , among many others . Some old European swords ( most memorably Hrunting ) and the Indonesia n style of kris have a wavelike shape , with much the same effect in drawing or thrusting cuts . When speaking of Japan ese edged weapons , the term refers to the grind of the blade : an edge with more niku is more convex and / or steep and therefore tougher , though it seems less sharp . Katana tend to have much more niku than wakizashi . If it is required to measure the angles of cutting edges , it is achieved by using a blade edge protractor ( or goniometer ) see CATRA Hobbigoni Typical grinds . It is possible to combine grinds or produce other variations . For example , some blades may be flat ground for much of the blade but be convex ground towards the edge .