Water-cooled grinders
Water-cooled grinders
EXPERT KNOWLEDGE WET GRINDERS
Functionality
The way wet grinders work is relatively simple. The machine typically consists of a rotating grinding stones mounted in a housing.
The sanding process begins by filling the system with water, which reduces friction, binds the resulting sanding dust and prevents overheating.
During the sanding process, the workpiece is pressed against the rotating sanding disc, which removes material. This generates heat, which is reliably dissipated by the coolant, minimising cracking and Material damage to the sanding piece. This continuous cooling flow is a key advantage of water-cooled grinders over dry grinding processes and ensures a smooth, precise and, above all, gentle grinding process.
In addition, many wet sanders offer a wide range of accessories for more precise adjustment of the grinding angle or for stabilising the workpiece. This ensures controlled and even sanding.
The motor in water-cooled grinders
- Performance and Speed
Engine power in water-cooled grinders usually varies between 120 and 200 W, depending on the Use and the machine. Speed is usually relatively low to avoid overheating and sparking. Typical speeds are 90-150 revolutions per minute (rpm). - Smooth running and low vibration
The motor of water-cooled grinders must run very quietly, as vibrations can have a negative impact on the precision of the grinding process. Asynchronous motors (inductive motors), which are known for their quiet running, are often used. - Protection against water and dust
As water is used to cool the workpiece in a water-cooled grinder, the motors and electrical components are specially protected against moisture and dust. This is usually done by specially encapsulating the motor and using seals that prevent water from entering the motor. - Torque
Water-cooled grinders need sufficient torque, especially at slower speeds, to sharpen even hardness materials. These machines are designed to be strong enough to grind consistently even at low speeds. - Durability
Motors are often built to last, as sanders are often in continuous use in workshops and professional uses. High-quality bearings and robust materials contribute to the service life of the motor.
Wet sanders are available in different price ranges. Sizeable differences in quality can be found in the motors, grinding stones and available accessories. When buying, be careful not to compare apples with pears. A supposedly cheap machine that gives up the ghost after a short time is not a sustainable purchase.
What accessories are available for wet grinders?
For water-cooled grinders with vertical disc alignment, there is usually a wide range of accessories that make the sanding process more efficient and precise.
Grinding angle setting aid
The angle gauge is a device that enables both the existing angle on the cutting edge of the workpiece to be removed and the precisely defined grinding angle to be maintained. To set the bevel angle for Sharpening jigs on Water-cooled grinders, the grinding wheel diameter and the desired bevel angle are set on the angle gauge and transferred to the machine by tracing the grinding wheel. Straight with tools such as knives or chisels, a constant grinding angle is absolutely crucial for the sharpness and durability of the cutting edge.
Tool holders
These holders stabilise workpieces and allow an even sanding process, particularly helpful with Lengthy blades or irregularly shaped tools with curves, bends, cranked irons and the like.
Honing stone and dressing tool
The whetstone makes the grinding wheels sanding discs flat again if grooves or unevenness have occurred due to frequent use. This restores a flat surface for precise sanding work and increases the service life of the grinding wheels sanding discs. The dressing tool is suitable for removing dirty or clogged areas on the surface of the whetstone. It therefore improves the sanding performance and ensures an even, clean sanding result.
Honing systems and Polishing pastes
Honing systems and Polishing pastes are used to polish ground blades to a high lustre and produce the finest cutting edges. Traditionally, a leather honing disc is mounted in addition to the grinding wheels sanding discs, often supplemented by a leather honing disc with a Profile. After the grinding process, they remove the resulting burr and polish the cutting edge.
Water recirculation systems and drip collectors
These systems collect and return excess grinding fluid. They minimise fluid consumption and keep the work area clean.
DICTUM offers various sets and accessory packages for water-cooled grinders that are tailored to specific tools and ranges of application. There is also a basic version for the in-house DICTUM SM250 model as well as for the Tormek T-4 and Tormek T-7 /T-8 with the most common accessories.
Grinding wheels sanding discs materials
- Silicon carbide:
This material is particularly hard and is known for its high stock removal rate. It is used for grinding wheels sanding discs with coarser grits. - Aluminium oxide:
This abrasive is considered particularly pure and is used for finer grits. - Diamond:
Diamond discs are suitable for particularly hard materials such as HSS. Diamond grinding discs do not need to be dressed, have a long service life when used correctly (low pressure when grinding) and enable precise grinding results. However, they are more expensive than conventional grinding wheels sanding discs. - CBN (cubic boron nitride):
Like diamond grinding discs, CBN discs are also designed for particularly hardness. The CBN grinding wheels available from DICTUM can be used without cooling (in dry grinding).
Grits of the Grinding wheels sanding discs
The Grit of a Grinding wheels sanding discs determines how fine or coarse the material removal is:
- Coarse Grit (60-80):
Coarse grit Grinding sanding wheels discs are ideal for initial stock removal or coarse pre-grinding. They remove material quickly and are suitable for blunt tools or for removing rust. - Medium grit (200-400):
These discs produce a smooth surface and are ideal for sharpening cutting tools followed by polishing on a leather disc. - Fine grits (over 1000):
These grits are used for polishing or fine grinding.
Advantages and disadvantages
Advantages:
- Heat reduction:
The use of water or grinding fluid prevents overheating, which extends the life of the blades. - Excellent sharpening results:
Wet grinding enables precise machining and excellent sharpness. - Versatility:
Most water-cooled grinders can be used on a wide variety of tools. - Dust reduction:
The use of liquid minimises dust and ensures a clean working environment.
Disadvantages:
- Increased space requirements compared to hand sharpening:
Water-cooled grinders require different amounts of space, depending on the model and intended use. Typical models such as the Tormek T-8 have a compact footprint of around 270 x 270 mm with a height of 330 mm, while smaller machines such as the Tormek T-4 measure around 240 x 205 x 260 mm and are designed straight for small hobby workshops. The actual space required varies depending on the accessories that also need to be stowed away. - Slow material removal:
The low speed of wet sharpening machines means that material is only removed slowly. Dry sharpening, e.g. on a slow-speed machine, definitely offers advantages here. - Cleaning and care:
The machines must be cleaned and maintained regularly to keep them in good condition. There should be a sink for cleaning the water tank in the immediate vicinity. - Acquisition costs:
High-quality water-cooled grinders can be relatively expensive. However, their versatility and durability can make them a lifelong companion.
