Angle grinders (angle grinders) are irreplaceable hand tools. With their help, you can saw, grind, cut almost any material from wood to stone. But often there are tasks that require the use of a machine park.
For example, when cutting pipes, profiles or metal profiles, the task of cutting a long string into segments of a certain length is quite common. In this case, it is important that the ends of the segments are strictly perpendicular to the center line.
When cutting ceramic tiles or bricks, it is even more difficult to maintain the perpendicularity of the cut by holding the grinder by hand. When cutting thin and sticky material, the slightest deviation of the tool from the cutting line can lead to jamming and tool breakage.
In such situations, it is quite natural to want to not buy a separate machine - this, as a rule, is not economically feasible.
You can expand the scope of your favorite hand tool by rigidly securing it in some way.
Materials and tools
The first question that a home craftsman faces when designing a rack for a grinder is what to make it from. The answer to this question is elementary: what is, we will do from that. If you have water pipes at hand, they will come in handy for making hinges and guides. If there is a metal corner, we will assemble a frame from it.
The main and most difficult part of the pendulum saw is the hinge assembly. It carries the greatest loads, while the pendulum arm should not be able to freely deflect to the left or right. Consider the design of this node with the greatest care. Roller bearings are ideal. Pick up a pair of suitable sizes - and already "around them" build the rest of the structure.
It is best to mount the pendulum arm with ball or roller bearings. This will provide the best precision and rigidity. But if there are no suitable finished products, it is quite possible to spy on the options for homemade designs of this unit.
If there are no ready-made bearings, match pairs of metal tubes and steel pins of suitable diameters. This will make it possible to make not too high-quality, but home-made bearings. For a "plywood" machine as a suspension of the pendulum arm, good canopy hinges used to fasten doors and gates will do.
In any case, the pendulum arm itself is best made from a metal corner or a metal profile. But the holder in which the angle grinder will be fixed will probably be made of a wooden bar.
For a reliable and tight fixation of the grinder in the holder, it is better to glue the stock with a soft and durable material. For example, leatherette. And it is most convenient to press the angle grinder to the holder with flexible metal ties with a screw assembly. These are widely used in plumbing and car service.
The bed is best made from a thick sheet of metal. Compromises are possible, up to thick plywood fixed to a timber frame. It is good to provide on the desktop the possibility of fixing the abutment corners at some standard angles to the cutting axis. This will create a "miter saw".
Do not forget that now you will not be able to control the turning on of the grinder on the machine in the usual way. We can replace the operator's hand on the control keys with the same cable ties for pipelines. But the keyboard control post (which we will fix on the bed), the socket for connecting a fixed angle grinder to the circuit and a wire with a plug of sufficient length to connect the entire machine to the network should be saved.
If we have metal blanks at our disposal, it is best to connect them by welding. If you do not have such an opportunity, it is better to contact the familiar masters of this business. Bolted connections loosen over time and negate all the advantages of a metal frame.
Of course, the grinder itself will be useful in the manufacture of the machine. Cutting with its help blanks for the rack, you can feel like Munchausen pulling himself out of the swamp by the pigtail.
Manufacturing options
Honestly, the do-it-yourself racks available in many designs should rather serve as food for thought. It is worth taking a closer look at the design, typical dimensions of standard elements and general design principles. Then apply them in our particular case.
The fact is that the dimensions of the structure and individual nodes will entirely depend on what you have at your fingertips. For a large angle grinder (for example, UShM-230), it may be necessary to make a holder larger than indicated in the drawing. This will entail the need to replace bearings, and so on.
The general principles are clear enough. The simplest and most used machine is the transformation of a hand grinder into a stationary pendulum saw. This design consists of a frame, a stand and a pendulum arm pivotally attached to the stand.
Consider manufacturing options depending on the materials available.
Rectangular bed
Very stiff in itself, this profile allows the construction of a rigid and sturdy bed. More importantly, the pendulum arm made from this material does not flex very much during operation.
But the bed frame is only half the battle. On top of the frame it is necessary to impose a "table top" - a plate on which the processed material will be placed under the grinder.
If the frame is made of metal, sheet metal is the best material for the workbench. However, a thick sheet of plywood or chipboard is also quite suitable. Just do not forget that directly under the grinder's disk in the tabletop, a rather wide slot must be provided, which ensures the through passage of the disk through the material being cut.
The upright is a very busy pendulum saw assembly. The use of a metal profile will create a strong and rigid structure.
When using metal as the basic element of the machine, preference should be given to welded joints. Of course, metal profile products can also be bolted together.
But such connections do not provide the required rigidity.
Carriage made of pipes and shock absorbers
If there are water pipes, a pair of car shock absorbers and a metal corner or profile in stocks, you can make a wonderful cross-cut (aka "cut-off") machine with a transverse horizontal carriage feed.
The pendulum unit is still required to bring the tool into the cutting plane. But the carriage, movable along the pendulum arm, allows you to significantly expand the range of material sizes. Now it is possible to cut quickly and accurately not only pipes, profiles and beams.
The horizontal carriage travel allows for neatly cutting sheet materials as wide as we can design the carriage overhang.
Complex rail assemblies with spring-loaded bearings are usually designed to ensure smooth yet accurate carriage travel. But you can use car shock absorbers. They have a very robust and precise construction. If you remove gas and liquid, you get excellent guides.
The rear shock absorbers of VAZ cars have a stroke of almost 200 millimeters. This will allow, for example, when fastening on the UShM-230 carriage, to organize a cutting line up to 400 mm long. But even if you have a compact grinder with a disc only 150 mm in diameter, you can still cut sheets up to 200 mm wide. This more than covers most of the daily tasks.
When designing a “guide-carriage” assembly based on automobile shock absorbers, it should be taken into account that the shock absorber bodies themselves are rather thin and easily wrinkle. Such "guides" should be fixed to the upper arm of the pendulum with semicircular clamping brackets. This is where water pipes come in handy.
Wooden elements
If it is not possible to make the basic elements of a pendulum saw from metal, do not despair. Many structural elements can be made from wood. First of all, these are the frame, the pendulum arm and the angle grinder holder.
The frame can be made from any suitable lumber. Very good frames are assembled from hard and heavy wood bars of significant cross-section. They are both durable and quite heavy. This ensures the stability of the entire machine.
The frame, assembled from an oak bar with a section of 100x100 mm, is certainly impressive. But it is too expensive. Thick blocks of larch or even birch are quite suitable for the base of the desktop.
But for the manufacture of the pendulum arm, you can just use the noble types of wood, traditionally used in furniture production. Oak would be quite appropriate here.
When constructing a machine from wood, do not forget about the overall rigidity of the structure. Significant dimensions of the bed allow to ensure the strength and rigidity of this part when made from not the highest quality materials.
The pendulum arm has a long, elongated design. If made of wood, its geometry can be unstable with changes in temperature and humidity.
For this structural element, it is better to use the so-called furniture board, consisting of several wooden elements glued together.
Plywood parts
An interesting solution to the problem of stiffness can be the use of plywood in a wooden structure. The multidirectionality of the veneer layers in this material imparts a certain dimensional stability to plywood products. The fact that the product consists of many thin layers connected with strong adhesive provides strength.
Plywood is great for making beds and work tables. When designing, it should be borne in mind that plywood is very strong and stable in the plane of the product. But the plane itself can undergo deformation. Therefore, plywood products should be mounted on rigid frames.
A good example of a design is a multi-layer plywood assembly with intermediate gluing and bolting.
The result is very strong, rigid and stable structures.
Safety engineering
As with any electrical tool, electrical safety guidelines must be followed. Do not work in rooms with high humidity. When installing the machine on the street, it is advisable to build at least a temporary shelter over the workplace to protect it from precipitation.
Like any cutting tool, angle grinder, even fixed in the machine, requires strict adherence to safety precautions. Working without a protective cover around the disc is completely unacceptable. And also the use of protective glasses or a transparent shield is mandatory.
Many people neglect gloves - and in vain. Sparks flying out from under the saw stone only seem small and harmless. Crumbs of abrasive and processed material fly like bullets and can penetrate deep into the skin.
You can find out more about how to make a metal stand for a grinder with your own hands.