Easily distinguishable in any mechanical workshop, carpentry, blacksmith or even in the home of many DIY enthusiasts, the grinder is a tool characterized not only by its usefulness, but also by its simplicity.
There are various types of grinder and it should be clarified that, depending on the country or geographical area, this tool also known as grinder, electric grinder, stone or emery stone. Whatever its denomination, it is another tool of abrasive machining that employs a tooth powered by an electric motor. This is the very principle of a grinding machine, but the fundamental differences between a grinder and one grinding machine reside in the fact that the grinder is a tool much simpler and in which, as it is not intended for the finishing of the pieces, the cutting effort is much higher than that of a grinding machine.
According to the general classification we can highlight four types of grinder:
- Angle grinder: it is basically an angle grinder.
- Bench grinder
- Pedestal grinder
- Belt grinder
Also exist special grinders, as the tube terminal grinder, which is used to clean tube ends and plate edges quickly and easily. They have two small grinding wheels that can be adjusted to the desired wall thickness and are used for metalwork, construction of appliances and heaters, shipyards, mechanical engineering and pipes, among others.
It is, in general, a machine of small dimensions and about 6 or 7 kg of weight, which is mounted on a work bench and that is used for sharpening tools (drill bits, chisels, lathe blades, screwdrivers, burins, chisels, etc.) and for removing burrs from small parts. It has two grinding wheels of different granulometry on each side, one fine for sharpening and another enough for reworking.
The main components of a bench grinder are:
one. Ignition switch
two. Tool holder (right)
3. Eye protection
Four. Eye guard clamp
6. Tool holder (left)
Bench Grinder Uses
The following table shows some examples and procedures for sharpening tools with a bench grinder.
Many bench grinders incorporate a pedestal as an optional piece, which does not mean that they can be “transformed” into a pedestal grinder. On the contrary, pedestal grinders As such, they are larger tools, intended for heavy work. They are used for cleaning welds and removing burrs from castings and other large parts.
They consist of a cast iron pedestal or base that is screwed to the floor and highlight the same components of a bench grinder, but the mounting of the grinding wheels is much more robust, they have light and a central command in the upper part. Some models incorporate a conduit finished in a cloth bag, where the particles detached from the machined material and from the grinding wheels are collected. They can also contain a container of water to cool the tools.
Depending on the power, size and speed of rotation of the grinding wheels and the spacing between them, there are pedestal grinders from 1/3 HP to 5 HP, corresponding to spindle speeds of 3600 RPM for the less powerful model and 1200 RPM for the 5 HP.
The belt grinders in its format Bank they are usually a combination of grinder and belt sander, as shown in the following figure.
However, there are also double belt grinders. In this kind of tools, the material cutting operation is performed by a abrasive belt, so the mechanism is ideal for irregular and even cylindrical parts, such as pipes or tubes.
Precautions with the use of grinders
Although they are provided with security guards and other effective elements, the grinders are tools dangerous that should be used with extreme caution. Before use, the instruction manual of the tool, as well as reviewing the advice that we already provide in a timely manner in Of Machines and Tools.
In addition, other additional care should be observed with the use of the wheels, such as those detailed below.
- The grinding wheels must be properly surrounded by protectors made of tough material.
- They should fit properly on the shaft, but in no case should they be too tight.
- Make sure that the shaft of the machine rotates in free play bearings and that it does not hit.
- When starting the grinding wheel, make sure you gradually reach the required number of revolutions.
- At the first start-up and especially when the grinding wheel is uncovered or poorly protected, be careful not to stand in front of it.
- Protect the grinding wheel against impacts.
- The grinding wheel becomes hot when sharpening. This heating should not occur too quickly. If a cold grinding wheel is subjected to very fast and strong stress, it can become dislodged, especially in winter temperature conditions.
- If the grinding wheel has to be pushed very hard on its sides, be sure to use coarse grain size. If lateral work is continuous, form wheels should be used.