Knife sharpening machine vs manual expert knife sharpening system

1.1. Belt sanding and grinding machines without cooling

Of all the power-driven devices, belt sanding machines and grinders stand out from all the rest due to their maximum efficiency. The wide range of different grinding belt materials extends the range of use, from aggressive metal removal, profiling, and all the way to sanding and polishing.

In this way, sharpening on a sanding endless belt can be considered an advanced, modern, and efficient processing method. The repetition of standard sharpening angles is achieved through machine attachments and accessories.

Advantages of belt sanding machines and grinders

• The belt grinder can be used for sharpening various knives, chisels, and other tools, roughing, deburring, and sanding with a reverse rotation due to the frequency converter.
• When sharpening low-cost kitchen, chef, household, and carving knives on a belt sanding or grinding machine, the use of two abrasive belts followed by a polishing step is acceptable if a high level of precision is not required.
• More expensive knives can be sharpened using up to 5-6 different belts, but the need to replace the belts and partially readjust them also takes time to complete the process
• The use of the grinder significantly expands the range of use compared to a belt grinding machine and is designed for mass production or commercial knife sharpening

Disadvantages of belt sanding and grinding machines 

• The need to monitor the temperature condition of the blade and cutting edge if an automatic cooling supply is not in use
• When using a grinding machine there are no ready-made solutions and there will be many issues: vibration, heating of the belt and blade cooling, the question of size and placement of the device itself, storing accessories, etc.
• On a belt-grinding machine, you can make a quick honing of the geometry, and the equipment has a certain level of diversity, but such machines are suitable mainly for roughing, removing chips, or at most for an inexpensive sharpening
• The need to acquire a high level of skills, as well as significant financial costs

Even with sufficient precision of belt sanding machines and grinders due to the special use of endless belts, it is still not possible to achieve results comparable to professional sharpening with a manual mechanical sharpening system of the Apex type. Trying to produce very thin bevels without cooling or to finish the cutting edge on the belt is not a good idea for quality steel and expensive knives, as it can simply affect the knife maker's image.

1.2. Electric water-cooled knife sharpeners

The main features and advantages of this class of sharpening machines are capability, versatile use, and high precision, which are ensured by a number of the following parameters:

• Variability and versatility

The sharpener can be set up for sharpening a number of different cutting tools, and knife blades of different types and sizes thanks to the accessories. A number of sharpening wheels on different bonds also makes it possible to work with steels of different hardness. Such sharpeners are used in various workshops. Some manufacturers have separate models specifically designed for sharpening kitchen and chef knives for use in large restaurant and hotel kitchens.

• Consistency and precision of sharpening angle adjustment

A high level of consistency and precision of knife angle adjustment is a feature of quality machines of this kind. In the design of higher quality and more expensive machines, the engine and the shaft are placed under the metal part of the body, on which the universal support is mounted. This technical solution provides much greater rigidity of fixation of the universal support (slide) with the possibility of adjusting the height above the tooling. This support slide is the basis for all types of sharpening work. Knife blades are clamped in suitable jigs, which are guided along the guide. This technique ensures a smooth feed and a consistent sharpening angle.

• Low RPM and quality control

The low speed of 100 - 200 rpm enables gradual gentle machining during the sharpening process, which enables precise control of the result of the work.

• RPM support and adjustment

Leading manufacturers' sharpeners are equipped with special electronic speed support, which ensures constant sharpening quality even under high loads. Some sharpeners are equipped with speed adjustment.

• Water cooling

Cooling of this type of machine depends on the use of special grinding wheels designed for sharpening with water mainly for stainless steels. Cooling is also required because of the high torque and the already mentioned large contact area.

• Safety and low noise

All waste abrasive material is collected in a tray with water and no dust gets into the air. Also, there are no sparks, which can be dangerous under certain conditions. In addition, high-quality machines produce almost no noise.

• Relative portability

The sharpening machine is easy to transport due to its relatively low weight for work outside the workshop. At the same time, such a machine and its accessories still require a certain workplace, which should be taken into account before purchase.

Drawbacks of water-cooled sharpeners

• The cost of quality sharpeners and components is quite high
• Rather high costs for the purchase of grinding wheels of different grit sizes
• Recommended for commercial use

1.3. Electric water-cooled sharpening stations

Equipment of this type can be found at a number of manufacturers. Still, a significant difference compared to even a professional wet sharpener will be the unit's equipment which provides greater ease of use, and thus the speed of obtaining the result. There are also a number of models that combine elements of a wet grinder and belt sander. If we consider that such devices are equipped as standard with water cooling, then they are significantly superior to any other equipment that does not have it.

The advantages of electric water-cooled sharpening stations lie in their technical characteristics and include the following points:

• Reliable and efficient equipment designed for catering, gastronomy, industrial meat packing plants, sanding workshops, etc.
• This type of equipment allows you to sharpen a variety of cutting tools, such as meat-cutting knives, carving knives, chef knives, table knives, and many others
• Relative variability of sharpening angle adjustment
• Depending on the model and the complexity of the design, an aspirator is available as standard, and water cooling significantly reduces all emissions into the environment during sharpening and polishing to protect the respiratory organs of the operating staff
• Relatively small dimensions
• Does not require special training of operating staff
• Low power consumption and relatively low noise 

The disadvantages of electric sharpening stations lie in the financial aspects:

• Rather high retail cost and long payback period for individual use in a private workshop
• Cost requirements for scheduled maintenance of equipment and purchase of consumables

1.4. Electric CNC automatic machines

CNC machines capable of automatically sharpening knives of any size and shape can be referred to as the highest category of technological devices, which have high productivity, but along with all the positive points they have some negative aspects.

The advantages of CNC machine tools:

• Perfectly sharpened knives allow you to make more precise and efficient cuts
• Quality sharpened knives reduce the risk of accidents
• Individual measurement of blade parameters before the sharpening program is possible - each individual knife is scanned at the measuring station, which allows you to sharpen knives of different shapes and sizes
• Production capacity ranges from about 400 knives per 8-hour shift, with direct personnel involvement of about one to two hours per work shift
• The option of purchasing with an integrated standard aspirator and water cooling, as with the smaller units, significantly reduces the amount of fine dust that gets into the environment during sharpening and polishing. This protects the operator's respiratory organs
• The industrial machine room remains practically clean. This increases the operational safety of the mechanical components. The filtered grinding and polishing abrasive is collected in a tray. From there it can be easily disposed of in an environmentally friendly way

Disadvantages of CNC machine tools:

• Large size and higher power consumption
• High acquisition cost and long payback period
• The need to train the staff
• The need for debugging when changing technical tasks, such as sharpening the angle
• Relative noise level

1.5. Professional manual mechanical sharpening systems of the Apex type

One of the most technologically advanced groups of knife sharpeners is the mechanical or manual expert sharpening systems of the Apex type, which were named after devices developed by a talented engineer a couple of decades ago and have become synonymous with the name of such sharpeners. These manual sharpening systems can be divided into three main sizes: compact, medium-sized, and full-size desktop sharpening systems.

All sizes of sharpeners in the professional expert segment have the following three distinctive parts in their design:

• guide rod with abrasive holder
• Sharpening angle adjustment unit, where the guide with the abrasive holder is mounted
• Semi-automatic turning mechanism with frame and clamps for fixing the blade of the knife

The following technical features of such a series of devices greatly expand the range of sharpening capabilities and give the sharpeners certain advantages in terms of quality of knife service in comparison with other devices:

• Turning mechanism with vertical position change in relation to the sharpening angle adjustment unit
• Some devices use a special toothed rack or a more complex rack lift to adjust the sharpening angle
• Some turning mechanisms have the option of horizontal displacement relative to the base of the sharpening device
• Some models have a unit for adjusting the position of the base of the unit over the working surface for use in combination with some natural abrasives
• There are devices with a removable clamping frame, which gives additional convenience of visual control of the knife
• Some manufacturers in the program have additional accessories for sharpening blades with complex geometry

Besides, there are sharpening systems that can be upgraded and combined with accessories of different models of the same brand in order to create a sharpener for your needs or to sharpen a knife of a certain size or shape of the blade.

The obvious advantages of using such a system are:

• High consistency of the sharpening angle due to the fixed position of the knife and the angle of the sharpening stone in relation to the knife blade, resulting in correct secondary bevels and a sharp cutting edge
• The abrasive guide with an abrasive holder makes the work easy
• The use of special-type bars makes it possible to shape the secondary bevels with ease, to perform precise finishing of the secondary bevels, as well as to reprofile the blade if the cutting edge is damaged
• Stepless adjustment of the sharpening angle and adjustable blade clamping allow working with blades of different types and sizes

Compact systems are used wherever you need a lightweight and compact tool and a focus on small and medium-sized knives above all else. The main advantage is the size of the clamps and the size of the clamping frame. Sharpening a knife, especially a small one with a thin blade, will be much easier to do with such a device. Such sharpeners will definitely find their place in the household kitchen.

Medium-sized sharpening systems, as compared to full-size sharpeners, are most often distinguished by a different angle range and a holder for abrasive stones of a certain standard, Some also have a turning mechanism. Medium-sized sharpeners can be used in workshops for sharpening small series of various knives with some limitations.

Full-size devices are obviously the most efficient, since they can cover the widest possible range of sharpened knives of different lengths and geometries and are recommended for experienced users, master sharpeners, and knife makers who maintain a personalized approach to customers.

The main disadvantages of professional manual mechanical sharpening systems such as the Apex are as follows:

• These are complex devices that require high skills of the sharpener
• High financial costs for the purchase of the device, related accessories, and consumables.
• Sharpening time per blade is often the longest compared to other semi-automatic and automatic sharpening systems.
• The price for the maintenance is determined individually.

Those who are going to use such sharpeners should understand up front that with experience and properly selected abrasives, you will get a much higher output quality of such systems compared to all the others.