Whatever you make with your own hands: home furniture, decorative crafts made of wood and metal, photo frames or simple handles for tools - all this requires finishing. Namely, grinding.
Therefore, any home workshop must have a grinding machine.
These devices vary in design and size. There are universal and highly specialized designs. As practice shows, it is cheaper and easier to make them yourself.
In this article we will look at several budget options for homemade disc and drum grinding machines.
To make homemade devices, you can use both purchased and used materials - it’s up to you.
An electric motor is usually used as a drive (for example, from a washing machine). You can also use alternative options - install an electric drill or grinder.
Types of grinding machines
Wood sanding machines are divided into the following types:
- design features;
- the nature of the tasks being solved;
- processing accuracy;
- permissible geometric dimensions of processed parts;
- power of installed engines;
- manufacturer ratings;
- cost with a set of attached equipment.
Modern manufacturers present three types of design of such machines: disk, belt, cylinder. Each of these species has its own highly specific subspecies. For example, belt sanding machines are available in the following versions:
- narrow-belt (allow grinding of wooden structures with complex geometric shapes);
- units equipped with a fixed table (capable of processing only wooden workpieces with flat rectangular surfaces);
- machines equipped with a freely moving table (they are used for grinding large-sized wooden structures - doors, panels, door slopes).
Belt Sanding Machine
The nature of the tasks to be solved determines the classes of this equipment. The main classes (sometimes called models) are:
- belt grinding machines;
- vibrating tools such as delta grinders;
- disc-type grinding machines (orbital and eccentric);
- specialized angle grinders;
- combined type grinding systems.
Despite such a variety of ready-made factory tools, home craftsmen prefer to develop and assemble a wood grinding machine with their own hands to carry out simple grinding operations.
I screw the boot to the body
First I attach the front part of the case, and then the boot and secure it with a few screws. Later I add thickness by cutting out another boot according to the template. I attach it with glue and leave it to dry, clamping it with clamps.
Principle of operation
The operation of a belt-type grinding machine is based on the principle of counter-movement of an abrasive belt located on two rotating drums and the processed wooden part. Both drums are located at a certain distance from the desktop surface. To ensure the required grinding quality, the following parameters must be correctly taken into account:
- size (number) of abrasive applied to the tape;
- the tension force of the belt on the rotating drums;
- the speed of its movement;
- the force of pressure on a moving wooden part.
Working with a belt sander
Incorrect selection of these parameters significantly degrades the quality of grinding. For example, if the pressure on the workpiece is insufficient or the rotation speed of the drive drum is too high, some places on the workpiece will remain unprocessed, that is, they will not be polished. On the contrary, if there is excessive pressure from the belt on the surface and insufficient speed of the belt, burns and changes in the color of the wood are possible. Therefore, when assembling a grinding machine with your own hands, it is necessary to provide for the possibility of adjusting these parameters.
Making a front panel
I mark the location of the motor shaft on a piece of plywood, then drill a large hole in its place. I attach the blank to the body and mark the dimensions. Using a band saw I cut out a 35x35 cm square.
Application areas of the machine
Each of the manufactured machines performs a predetermined list of technological operations.
The drum-type system produces high-quality sanding of flat wood pieces. Processing of chipboard, OSB or MDF, including those covered with veneer, is allowed.
Application of Drum Sanding Machine
Processing of large, long, non-standard wooden wood products (for example, molded structures) is carried out using profile grinding equipment. Finished workpieces are fed to the grinding unit via a conveyor chain.
To grind the surface of wooden products that have a complex geometric shape (decorative frames, artistic products), belt sanding machines equipped with a freely moving table are used.
I make trunnions
The purpose of the trunnion is to make the emphasis for the workpieces rotating. I cut out 2 hemispheres from hardwood and cut slots in them. I try them on the body.
DIY grinding machine
The desire to make wooden structures yourself is always faced with the need to equip your workshop with sawing and grinding machines. Modern manufacturers produce them in a wide range. Such machines have good performance and high reliability. The most important and quite significant drawback is their high cost.
Therefore, many craftsmen try to assemble a grinding machine from existing components. The most experienced ones try not to limit themselves to a machine capable of performing only one function; they immediately try to assemble a universal machine capable of performing several functions: cutting wooden blanks, grinding followed by polishing, removing old coatings and preparing surfaces for renovation.
Homemade grinding machine
This is possible because the basis of any home-made machine is a frame on which are mounted: an engine, drive and driven drums, a set of additional equipment (saws, cutters, grinding wheels, and so on).
I'm balancing the disk.
Using foil from a cut aluminum can as a backing and a dial indicator, I balanced the disc.
This is important because if the disc is not balanced, you will have uneven wear on the sandpaper.
Calculation of grinding machine power
Before you begin assembling the machine, you must calculate its power. To correctly make such an assessment, it is necessary to determine the following parameters:
- power consumed by the electric motor;
- rotation speed of the selected engine;
- the area of contact of the entire surface of the part with the moving abrasive belt;
- grinding ratio;
- coefficient of friction between the back side of the belt used and the surface of the drums.
Based on data on these parameters, the power of the future unit can be determined.
I'm assembling the case
To cover the engine and raise it above the tabletop, I make the side parts of the housing. I screw them to the mount using self-tapping screws, smearing the edges with wood glue.
How to make a belt sander
The basis of the machine is a powerful frame that can withstand the weight of all equipment and perform the function of damping the resulting vibration. The frame of the bed is best fastened by welding. A plate is attached to the top. Chipboard with a thickness of at least 22 mm is chosen as such a plate.
An electric motor is mounted on the frame. The engine power must be no lower than the calculated one. The number of revolutions must be at least 1500 rpm. A gearbox is attached to the anchor to transmit rotation to the drive drum. The required diameter directly depends on the engine speed. It determines the speed of the belt at the moment of friction against the surface of the part.
The following relationships can be given as an example. When the belt speed is 20 m/sec, the diameter should be 20 cm. To prevent the slipping effect, rubber covers are placed on the drums. It is more expedient to make the platform for installing the drums at a slight slope. This will create smooth contact of the tape with the surface being treated while moving.
If you plan to process parts made of different types of wood, it is advisable to provide the possibility of changing the rotation speed of the drum. The above technique shows that it is quite easy to assemble a grinding machine with your own hands.
What to make the bed out of
The frame to which all other elements of the machine are attached is a powerful bed. It must have a large margin of safety and have good weight and size characteristics. It is made from sheet steel more than 5 mm thick.
The most acceptable dimensions of a homemade frame are considered to be the following dimensions: 500x180x20 millimeters. For a bed of this size, the optimal dimensions of the working platform are 180x160x10 millimeters.
For the convenience of further work, it is necessary to mark the work site. Three holes are made for its fastening. Then it is secured to the frame with three bolts.
Selecting and installing a motor for the machine
Calculations and operating experience of this type of units show that the engine must have a power of at least 2.5 kW. The shaft rotation speed must be 1500 rpm or more. The speed of movement of the abrasive belt largely depends on the engine rotation speed. This seriously affects the quality of processing. In turn, the speed of the belt affects the diameter of the drums.
Motor for grinding machine
As a finished device, you can use the motor that is installed on washing machines. You can also select an engine from other household units, for example, a powerful pump or other device suitable in terms of power and speed.
Master and slave drums
The drive drum is firmly fixed to the electric motor pulley. The driven drum is fixed on a separate axis. To ensure its free rotation, bearings are attached between the shaft and the drum.
DIY sanding belt
Abrasive belts for such machines have a fabric base. Calico or a fabric of similar density is used as a base. Abrasive chips are applied to the surface of the material on one side using special glue. Depending on the grain size of this crumb, it is divided into large, medium, small and zero.
In principle, such a tape can be made independently. Select the required fabric and apply abrasive powder of the required fraction to it. By applying glue to the surface of the material and sprinkling it with this powder, you can obtain a sanding belt of the required size. However, it should be recognized that modern industry produces such a wide range of such consumables that it is better to use the factory one.
Selecting the disk shape
Using a piece of chipboard, I draw a circle the size of sandpaper. Then I find the middle of the disc and mark the locations for the screws to secure the disc to the hub.
Using a Forstner drill bit, I drill out the recess for the T-nuts. Then I attach the hub to the disc and cut off the extra length of the bolt.
Sanding machine from a hand sander
Very often, to carry out simple grinding operations, homemade wood grinding machines are made using ready-made grinding machines.
A mounting system for a grinding machine is being manufactured. It is mounted on a pre-prepared frame. Grinding wheels intended for processing wooden workpieces are attached to its shaft. Instead of such a machine, you can use an ordinary electric drill. This design allows sanding of simple wooden parts of limited size.
Making a motor mount
Using a compass, I transfer the dimensions of the engine onto the plywood. Using a band saw, I cut the plywood into pieces, then clamp the motor and tighten it with clamps.
Assembling the table mount
To be able to replace the sandpaper, I make the table mount dismountable using a spline connection.
