Used Bench Grinders for Sale — 251

Bench grinder – a standard machine in all operational facilities

A bench grinder consists of a base frame made out of cast steel, a covered electric motor, one or two grinding discs with a protective device, and a support plate. The engine is mounted onto the base frame and drives the central shaft. With smaller bench grinders, the grinding disc is directly attached to the shaft. Bigger bench grinders have a belt drive. The support plate, upon which the workpiece is placed, acts as a guide and is located in front of the grinding disc. The grinding disc is either located on a stable worktable or screwed onto a separate column. It is screwed into the floor, which means that the machine has a very stable stance.

Increase the efficiency: double wheeled bench grinders

Double wheeled bench grinders have two wheels that are powered simultaneously and connected by a rigid shaft. This provides several advantages. First of all, the installation of the grinding disc is left to the operator. In general, course and fine grinding discs can be installed onto one double wheeled bench grinder. Workpieces that are ground can be prepared and then subsequently processed. Turning on the bench grinder uses up the most amount of energy. Once it has been set into rotation, a large amount of the energy required to turn the wheels comes from its own momentum. The braking effect of grinding on one of the rotating grinding wheels is offset on a double wheeled bench grinder by the rotational energy of the two grinding wheels. Therefore, they are particularly energy efficient.

The types of double wheeled bench grinders

A double wheeled bench grinder from Flott

Double wheeled bench grinders are machines used for manually grinding components. They are usually (there is one exception) only suited for large products and work that is not technically demanding. The most common uses for a bench grinder include regrinding chisels, deburring injection-moulded and die cast products, milling flame-cut or cut components, and cleaning tools. Grinders can be required to clean tools if they are, for example, covered with adhesive resin or varnish. Double wheeled bench grinders can also be equipped with polishing discs or brushes, instead of grinding discs. The size of these machines ranges from small table-top bench grinders, with hand-sized grinding discs, up to large double bench grinders, whose grinding discs are up to a meter in diameter.

Bench grinders used for precious stones are the exception in terms of precision. These operate with a much higher rotation speed have an automatic water supply. Grinding precious stones requires a lot of experience and a good eye. With the right skills, the operator of a bench grinder for precious stones can work to a level of precision within a fraction of a millimetre.

Working with a double wheeled bench grinder

In order to properly handle a bench grinder, new workers should receive a safety briefing from an operational expert. It is very important to note, that one should not wear gloves when working with a bench grinder. The problem is that the gloves can get caught by the rotating discs and the momentum would pull the worker's hands towards the disc. This could lead to bad injuries. Close-fitting clothing is required, because loose t-shirts or jumpers could also come into contact with the grinding disc and cause the same problem. The same goes for hair; long-haired workers can only work with a bench grinder when wearing a hair net or another form of protection.

The course side of the grinding disc quickly removes a lot of material from a workpiece. Workers with little experience should practice grinding waste material before processing high-end products and tools. The material that is taken off is mainly caught by the cover. However, there is a still a lot of waste material that flies around uncontrollably. Therefore, it is important to wear eye protection (this is the minimum safety equipment required). Depending on the type of workpiece, sometimes it is also important to wear a mouth guard. Grinding dust from galvanised sheet metal is very toxic. Due to the health risks, it is important to undertake the necessary safety precautions when working with a bench grinder.

Before and during the work, the technical conditions should always be inspected and monitored. The frame, the engine's cover, and the protective cover for the grinding disc could have rips, holes or defects. The electric cable and switches on the control board all have to be undamaged. Before starting the bench grinder, it is recommended to check the state of the entire machine and that the grinding discs are fixed into place.

The bench grinder should run steadily and reliably. During operation, the rotation speed should not oscillate. A damaged engine can be recognised by the development of sparks or turbulent operation. If this occurs, the bench grinder should be immediately switched off and unplugged.

Noisy bench grinders are often the due to the fact that they are unbalanced. This is commonly due to the material only being ground on one side. This cannot be avoided on bench grinders and occurs sooner or later on all grinding discs. The roundness of the grinding disc can be fixed using a straightening tool. This should not be neglected because an imbalance in the grinding disc can quickly lead to damages in the bearings. To repair these would be much more complicated than straightening the grinding disc.

Working with a bench grinder is always very loud. Therefore, ear protection is useful and is usually a requirement.

Cleaning a bench grinder

Because of the abrasion that occurs between the grinding disc and the workpiece, bench grinders produce a lot of grinding dust. Therefore, it is necessary to thoroughly clean the workspace after every work step. Compressed air guns are not suited for this task, because they distribute the debris and fine dust all over the place. Metal dust is particularly dangerous because it is conductive, which means that it can cause damage to electric components or cause short circuits. The ideal cleaning process for bench grinders is just rinsing and vacuuming. Sweeping and manually wiping the grinder with a damp cloth is much better than cleaning the bench grinder with compressed air.

Suppliers of bench grinders

Normal table-top bench grinders are very cheap and available in all building supply stores. It is only useful to buy these machines used, when they are from a well-known brand. The biggest tool manufacturers all have bench grinders and double wheeled bench grinders in their product range. This includes the companies AEG, METABO, FEIN, BOSCH and MAKITA. It is possible to order individual components from these companies. Therefore, if there are small defects, it is easy to repair the machines.

Large bench grinders are available from the companies REMA, GREIF, GISAG, HIMMELWERK and LES.