The double bench grinder it is a ubiquitous machine tool; It is possible to find it in almost any workshop and even private garages. Its primary use there is for sharpening cutting tools, removing burrs from freshly cut materials, and other manual roughing tasks. But how is it different from the angle grinder?
In this note we will see the main differences, their advantages and their most prominent uses.
What is a double bench grinder?
A bench grinder is a machine tool that is used on a workbench (and therefore not portable or hand-held).
When we say that this machine tool It is a double bench grinder, we mean that it allows us to place two grinding wheels or discs; one on each side of the motor, and that said wheels or discs can be different from each other and even work at different speeds and angles.
Some types of double bench grinder
For wet roughing jobs
This type of double bench grinder It offers two grinding wheels or stones: one, traditional, for coarse roughing, at the front. The other stone, finer, is special for wet sharpening work: wicks, knives, lathe and milling tools, chalicears, etc.
In general, the sharpening stone is presented perpendicular to the motor and between the shaft and it there is a geared motor that allows it to rotate more slowly, at a speed appropriate to the task to be carried out.
For fine adjustment or polishing work with emery cloth or sandpaper
Another interesting presentation is that of the double bench grinders which, in addition to the coarse grinding stone, offer a belt for emery cloth and sandpaper. In this way, this machine offers roughing and fine polishing in one place, since, after roughing and coarse polishing, we can continue with mirror polishing using a cloth wheel.
What are the components of the double bench grinder?
As with traditional bench grinders, in the double ones we have a motor, which is what allows the rotation of the double shaft; the I flip, which is the space where the stone is installed and can rotate freely; the spark guard, which protects the user from sparks and possible fragments that may be thrown away by the rotation and friction of the stone on the workpiece; the rest, which is made of thick sheet metal, where the hand and the piece to be worked can be supported; the stone guard, a piece of aluminum or steel that protects the machine and the user against any type of breakage of the stone (and also prevents sparks from spreading beyond the work area).
The modern spark arrester is made entirely of transparent acrylic, which in the event of a blow from a detached piece, does not break.
Some manufacturers include a small sheet metal container, which is placed in front and allows to have cold water or coolant on hand to cool the material that is being worked.
What jobs can I accomplish with a double bench grinder?
Roughing and sharpening of cutting tools
Traditional stone allows coarse roughing of raw material; also deburring semi-finished parts (such as those fresh from the saw, milling machine or lathe).
Another practical use is sharpening cutting tools such as bits, lathe and milling bits, knives, etc., making use of the fine wet sharpening stone.
Cleaning of materials
A highly required task in workshops and factories is cleaning metals prior to anodizing, blasting or welding. This process removes rust, paint and any other impurities or inclusions from metal surfaces, leaving them ready for alkaline cleaning prior to any surface treatment.
To achieve this, it is only necessary to remove the grinding stone and replace it with a metal bristle wheel (which is called card or brush in factories).
How different is it from traditional bench and angle grinders?
Traditional bench grinders (which we can find in any workshop or factory), have a shaft that joins both ends in solidarity. This allows that, with a single motor, it is possible to have two stones, one at each end.
The problem with this configuration is that if one of the stones is much smaller than the other, or if one or both stones are worn asymmetrically, the machine will experience unwanted vibrations. The other problem is that both stones will have the same angular velocity.
Angle grinders, on the other hand, are tools manual use that under no circumstances should be used to sharpen or work on parts held with one hand. Never make that mistake!
The double bench grinder circumvents all these problems by offering two different angular speeds at each end of the shaft. They also allow you to work in different positions, so while one operator works roughing, another can comfortably sit in front of the sharpening stone.