The sharpening angles of a knife

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Sharpening angles

Knowing the sharpening angles of a knife is essential to make the correct choices of angle of the wire according to the type and destination of the knife.

Working and using a sharp knife is the best way to do a clean job and give a nice feeling in using it.

When you first try a quality knife and sharpen this feeling is established in your memory and you will never go back, you will only look for more quality and sharp knives.

As soon as you feel that after a certain period of use the knife no longer cuts as before and this is inevitable if you use it, you will be forced to sharpen it again because you will be annoyed to hear your knife in those conditions.

At this point you can decide to sharpen it yourself or bring it to sharpen but if sharpening a knife needs knowledge and to develop a certain dexterity it is an operation that I recommend to learn how to do.

Today there are several ways and systems to do this as well as sharpening kits that make this easier and more accessible.

Ps. NEVER use those sharpeners you find in kitchen product retailers if you care about your knife.

L’ affilatura e gli angoli di affilatura di un coltello

After you have built your knife one of the last operations to do is sharpen your blade through rubbing using:

  • levigatrice a nastro,
  • pietra affilatrice (quindi una superficie molto ruvida e dura),
  • carta vetrata (quindi con una superficie morbide con particelle dure),
  • cinghia del rasoio.

The lower the sharpening angle between the blade and the stone/tape/paper/etc. and the more sharp the knife will be but less resistant to blows that can chime the wire.

Sharpening angles

 

Come vedi dallo schema:

  • Le lame molto affilate si affilano a 10 – 15 gradi.
  • Le lame normali si affilano a 20 – 25 gradi.
  • I coltelli che hanno bisogno di un bordo duro (come quelli per tagliare) si affilano a 30 – 35 gradi.
  • Per un taglio estremamente duraturo le lame vengono affilate oltre i 30 gradi.

Sharpening angles

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In general, the harder the material to cut, the larger the angle of the blade.

The grain of the stone (composition) determines the thread of the blade (the finer the grains are the more sharp), the same applies to the type of steel of the blade because some metals take and maintain the thread better than others.

For this reason, the intended use of the knife is used to better understand which steel to use to build it.

Sharpening angles

LA PIETRA ABRASIVA (o affilatrice)

The actualsharpening is carried out with the abrasivestone, usually composed of aluminum oxide or silicon carb.

There are also diamond stones (within the matrix of the stone is dispersed diamond dust), very expensive but more effective.

The grain of the stone can be more or less fine, ranging from 100 grits (grossolana) to 1200 grit (extra fine). A stone with grain greater than 300 can effectively sharpen any type of knife.

On the market there are stones with double grain, coarse and fine ranging from 240 to 10,000. They sell the bases to lock them during the sharpening operation.

Sharpening angles

Choose a largestone, at least 3-5 cm wide and 20 cmlong.

In general, you can divide the stones for sharpening knives into 3 categories:

  • naturali
  • sintetiche
  • diamantate

Each of these types of stones depending on how it is used can then be then divided into:

  • a secco
  • ad acqua
  • ad olio

Natural stones were the first stones to be used for sharpening knives, but today they are surpassed in effectiveness and practicality by synthetic stones.

As each natural stone is a unique piece completely different from any other natural stone in the world (in fact, each natural stone differs in shape and structure) are indispensable for knife enthusiasts, as they give the knife enthusiast the knife with them sharpened a micro-sewing of the unique blade.

Le pietre naturali vengono solitamente “fatte”:

  • a olio che ha il solo compito di lubrificare,
  • ad acqua che oltre a lubrificare ha il compito di trattenere parte della limatura di ferro che contribuisce alla ri-affilatura.

Synthetic stones are made industrially by manipulating materials with particularly high hardness.

They are stones often made from ceramics, silicone dioxids, aluminum oxides and carbonitrites.

Being made with industrial processes, synthetic stones are much more uniform in both shape and structure than natural stones;

Synthetic stones, being made with industrial processes, are much more uniform both in shape and structure than natural stones; this means that, especially in the final stages of sharpening, when using stones with grains greater than 1000 grits, you get much more homogeneous results and especially knives with micro-sects very similar to each other as opposed to what happened with naturals.

Synthetic stones are usually “made” or dry or water that has, in this case, the purpose described above.

Sharpening angles

 

The diamond stones are relatively recent and are also made in the factory. In practice they are metal plates to which zircons are tied on the surface (the zirconium is ideal for quickly sharpening any type of steel).

In fact, the diamanta stones are often used to make portable field sharpeners.

Usually the diamond stones are “made” dry or water that, in this case, serves to lubricate and remove the iron filing, which would otherwise decrease the capacity of the stone itself.

Sharpening angles

Altri sistemi

Today there are apart from the stones a set of tools for those who do not have the skills or patience to acquire it and learn a valid resharpling technique that prevents you from ruining a knife.

Grip sharpening tools use a support with several holes, with predefined angles such as the Lansky sharpening stand where the stone is mounted on a rod to be tucked into holes to keep the sharpening angle constant.

Another system is the crock stick, where two chopsticks are placed on a plastic or wood base, so as to form a V-shaped angle.

When the knife is placed above the V, the angle is held until the blade is perpendicular to the base.

There are also even more professional systems that allow you to make excellent sharpening by controlling the angles and symmetries of the wire.

These are expensive tools but allow you to have professional sharpenings like the Wicked Edge Generation 3 Pro.

There are home solutions such as the base of the ceramic cup but these are strategies to use if you have nothing available, it is not a method that I recommend if you have stones or other systems.

L’acciaino

Everyone has been seen using this tool in shops and supermarkets and some believe that kitchen knives are sharpened with steel

Actually this tool only serves to correct and maintain the sharpening.

This tool realigns the molecules that make up the sharp edge, which have been moved by continuous shocks, “restoring” the sharpening.

If a knife is of quality and is made with a very hard material with a high rockwell hrc that keeps the sharpening for a long time the use of the steel can also be superfluous because it does nothing.

It’s better to waste half an hour every two to three weeks, to sharpen the knives we use most often, rather than sharpening them with the steel every time we use them to ruin them.

A good steel, which must have a very fine grain, can cost like a knife and can not replace a real sharpening with the abrasive stone.

If the material of the knife is not particularly hard, then it may be necessary to frequent use the steel to maintain a decent level of sharpening.

One more reason to buy quality knives.

 

Breve guida per affilare con le pietre

The secret of proper sharpening is the maintenance of thesharpening angle during the operation.

For this purpose there are special plastic guides that allow you to maintain a constant angle.

Some quality knife brands provide them with the knife so even the angle will be optimized according to the sharp ness of the knife.

L’affilatura

1) Place the abrasive stone on a stand that does not allow it to slide on the support plane. Usually the stones are provided with a special rubber support.

2) Choose thesharpening angle for, for example, for kitchen knives that are common to maintain a 15-20 degree angle but follow the pattern you’ve seen before based on the type of knife and its type of use.

With higher angles the blade stays sharp for longer, but cuts less.

Larger angles are used for knives (such as cleaver) that have to cut hard objects such as animal bones.

Depending on the type of cut you need to apply it can be a good advice to have multiple knives with different sharpening angles to make the wire last.

To maintain the sharpening angle, use your thumbas as in the figure below as a reference: if the blade is smaller than 13-15 cm, it only takes one inch, for larger knives use both of them.

3) Apply a continuous, circular or alternating movement to the blade on the stone, being careful to keep the sharpening angle constant and to keep the blade always in contact with the surface of the stone.

To calculate the exact slope of the blade, rely on the following table:

measure the l width of the blade, and take from the table the height at which you need to place the blade on your thumb.

Important!! Always count alternating rotations or movements and repeat the same number from both sides.

The number of movements varies depending on the hardness of the steel of the blade, it takes at least 50, up to 100 for the hardest steels.

Sharpening angles

So the real key to a nice sharpening of the knife is a suitable and constant angle on the bevel of the blade.

This is easy to say, but difficult to make freehand, some make supports, use montetes, plastic supports.

There are 2 problems that you have to overcome and check:

  • Trovare l’angolo corretto per il suo impiego.
  • Creare quel angolo sulla pietra affilatrice costante.

Ecco una guida generale:

10 to 15 degrees
This is the extreme. Razor blades and scalpels are in this group. Even quality knives with high-tenor steel can take this thin angle of sharpening and hold it for a long time.

15 to 20 degrees
Corners in this series are great for knives that serve to slice or in domestic work although many commercial kitchen knives are factory sharp at about 22 degrees.

25 to 35 degrees
Many types of knife can fit well in this series. Usually sharpening at this angle is good for both openers and fixed blades in general, survival/bushcraft knives and general uses;

35 to 40 degrees
A cleaver sharpens well to 35 degrees (some sharpen it even at 25 degrees). So all those heavy work knife models, like Bowie, Machete, Accept, etc.

 

Controllo della lama per verificare l’affilatura

The blade is sharp enlated when the dross chip is formed on the edge of the blade.

You can feel it by gently passing a finger on the blade, in a cross direction (notalong the blade!), passing from one side of the cutting edge to the other (be careful not to cut yourself!): on the one hand the blade will seem rougher than on the other.

Remove the dross chip by gently passing on the blade a pumice stone, or an abrasive stone fineter than 600 grits or on a leather belt.

Once you have removed the dross chip, you can check if your blade is a perfect blade.

A perfect blade has the following characteristics:

– it is perfectly smooth: take a pen with plastic cap and slide the cap on the blade: you do not have to feel any step or obstacle;

does not reflect thelight: look at the blade in front: the light must not be reflected by the blade at any point.

Also follow these 5 ways to see if the blade is sharp.

Conclusioni

Learning to sharpen requires a lot of practice, a lot of practice.

Learning to sharpen requires a lot of practice, really a lot and therefore do not expect to get great results right away but try and try again and if you follow all the instructions calmly and precisely you will get a good sharpening.

In the house people always have knives that they don’t use because they don’t cut anymore ask people to give them and sharpen them, exercise.

With time and experience, you’ll get a blade with incredible cutting ability!

Make a good sharpening!

Andrea

 


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Andrea F

Maker and Enthusiast of Knifemaking. Other: Engineer / Professional Blogger / Bass Player / Instructor of Boxing / Muay Thai / Brazilian Jiu Jitsu / Grappling / CSW / MMA / Self Defence / FMA / Dirty Boxing / Silat / Jeet Kune Do & Kali / Fencing Knife / Stick Fighting / Weapons / Firearms. Street Fight Mentality & Fight Sport! State Of Love And Trust!

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