Band saw device for wood
Sawmills of the belt type are similar in their design. Professional tools differ in size and weight compared to household saws for small workshop use and hand-held power tools. Structurally, band saws consist of several units:
- Frame or bed – the body on which all the main elements are fixed.
- Working surface equipped with a ruler and stop that helps to regulate the correct cut.
- Motor – drives the saw.
- The wood band saw blade slides onto the pulley and rotates at high speed.
- Control panel, lubrication system, protective cover – additional units that make the band saw operation safe and convenient.
There are many varieties of sawmills working with wood. Understanding how a band saw works in wood is important for working properly with it. The serrated cutting blade rotates thanks to the motor, which results in sawing of materials that come into contact with it. The performance of the band saw machine depends on the shape and height of the teeth located on the blade, on the power of the engine. Special sharpening of the teeth is necessary to clean the sawdust from the working blade and prevent the saw from jamming.
Types of band saws for wood
In a carpentry workshop, you cannot do without a quality band saw from a trusted manufacturer. When choosing a sawmill, you need to understand the differences between the best band saws for wood. By type, sawmills are divided depending on the location of the blade, they are:
How to choose a band saw for wood?
A good woodworking machine is not cheap, you need to approach the purchase of such a tool responsibly. Thinking about which band saw for wood to choose, you need to weigh and correlate the parameters of the tool and your own needs. According to the characteristics of the band-type sawmills, they are divided into several types, you should choose a saw for yourself, taking into account the important characteristics:
- Capacity based on estimated production volumes.
- Working blade characteristics.
- Machine manufacturer.
How to use a band saw for wood?
This device helps to quickly and accurately make any cuts in wood products. Practice and accuracy is required when working with this type of tool, knowing how to use band saws for wood, the result will be worth the effort.
- Choose the right type of band saw, paying attention to power, speed, blade length, table working surface parameters, electrical characteristics.
- The saw blade must be selected individually for each project, taking into account its width, thickness and run of teeth.
- Before work, check the movement of the working blade and adjust the guides.
- The working surface must be adjusted to the desired angle of inclination.
- Before work, it is necessary to make markings on wooden blanks.
- The saw can be turned on and wait until it picks up speed.
- Directing the workpiece along the guides, make a cut.
How to make such a tool yourself?
Before starting the assembly of the saw structure, prepare at least a simple drawing in order to clearly understand the dimensions and main components of the device. Most of the parts will be made of wood.
The frame is made of polished sheet glued with an overlap. The minimum thickness of the mechanism parts is 2.5 cm. It is not advisable to use furniture shields or wooden slabs, as they are not strong enough.
The frame is made in the shape of the letter C. To make the body rigid and durable, overlays are attached to the wood surface glued from six layers. Make sure that the fragments are located only at right angles to each other..
Next, we collect the movable part of the saw. We mount the profile to simplify the creation of the guide groove. This profile will tighten the saw blade to the desired degree..
To strengthen the corner joints, we install additional fasteners. Further, the design is being finalized in such a way that the frame moves freely in the grooves.
To create rollers of rotation, glue together several wooden boards and cut out round pieces. Additional parts are installed on the wheels, which will make working with the device less noisy and more productive. After fixing the wheels, the saw blade is tensioned to ensure its stable position on the pulleys. A sufficiently taut blade will make accurate and accurate cuts.
Hand-held band saw for wood
Small in size tools are not inferior in their properties to professional machines for large-scale production. A mini band saw for wood will serve faithfully for a caring master, and will definitely come in handy on the farm, with its help you can easily and simply perform various actions:
- cut dry branches in trees;
- get rid of old seedlings in the garden;
- prepare firewood for the winter period.
Horizontal band saw for wood
Saws, in which the cutting blade is located horizontally, are widely used by professionals and novice craftsmen for cutting a variety of wooden materials. The horizontal wood band saw works well with both transverse and oblique (angled) cuts. Machine tools for industrial use can work autonomously, electronic control systems in such devices calculate the size of the cut surfaces up to a millimeter. The horizontal band saw for wood has the following characteristics:
- the possibility of cutting at an angle;
- the ability to save the program for reuse (in machines with electronic control);
- engine power;
- web speed;
- desktop size.
DIY wood band saw
It is difficult to make a band saw yourself. The wooden frame for the machine is assembled from scrap materials; any master can find the necessary assembly tool. The process of working on a homemade wood band saw can be divided into main stages:
- The frame for the machine can be assembled from old furniture, a preliminary drawing will facilitate the work, and will allow you to assemble the saw according to the required dimensions.
- The simplest homemade tape machine is held on a frame assembled from a rod and two supports. The distance between the supports should be thought out in advance, it should not be less than the size of the processed logs, it is better to make it a little larger.
- An old desk can be used for the work surface, its cabinets can serve as containers in which sawdust will be collected.
- Depending on the parameters of the motor, it is necessary to calculate the diameter of the pulleys for the belt drive.
- For the lifting mechanism, to which the cutting blade is attached, a massive spring is suitable, with the help of which the necessary pressure of the machine will be provided.
- The guides are necessary to ensure that the cut is carried out on an even mowing line..
- In order for the machine to be safe, it is better to close the pulley with a special casing..
- Wood varnishing or painting the machine will increase its service life.
How to unfold and fold a band saw
Folding and unrolling the saw band must be done carefully and carefully. We offer step-by-step instructions on how to do it correctly and safely. Remember to always wear protective gloves and goggles when handling the band saw and keep a safe distance from others to avoid accidental injury..
Unfolding the saw
Take the saw, folded in three loops, in your right hand..
Find the loop that forms the number eight and pull it down with your left hand..
At the same time, the two upper loops form a cross..
Hold the loop that was at the very top with your right hand. Another loop. left.
Hold the saw in front of you and slowly spread your arms while opening your wrists out and down..
Saw deployed.
Folding the saw
Grasp the saw ring with both hands with the teeth facing towards you. Squeeze the saw ring lightly.
Shake the saw so that the top of its ring bends down..
Bring your arms together, slightly turning the wrists inward so that a criss-cross occurs on the downward bend of the saw..
The saw makes three loops. With your left hand, grasp the bottom hinge and lift it up to fold all three hinges together..
The saw is folded. Use a wire to tie up the folded saw so that it does not suddenly unfold like a spring..
HOW TO UNFOLD AND UNFOLD THE BANDSAW
HOW TO UNFOLD AND UNFOLD THE BANDSAW
HOW TO UNFOLD AND UNFOLD THE BANDSAW
Folding and unrolling the saw band must be done carefully and carefully. We offer step-by-step instructions on how to do it correctly and safely. Remember to always wear protective gloves and goggles when handling your band saw and keep a safe distance from others to avoid accidental injury..
Unfolding the saw
Take the saw, folded in three loops, in your right hand..
Find the loop that forms the number eight and pull it down with your left hand..
The two upper loops form a cross..
Hold the loop that was at the very top with your right hand. Another loop. left.
Hold the saw in front of you and slowly spread your arms while opening your wrists out and down..
Saw deployed.
Folding the saw
Grasp the saw ring with both hands with the teeth facing towards you. Squeeze the saw ring lightly.
Shake the saw so that the top of its ring bends down..
Bring your arms together, turning your wrists slightly inward so that a criss-cross occurs on the downward bend of the saw..
The saw makes three loops. With your left hand, grasp the bottom hinge and lift it up to fold all three hinges together..
The saw is folded. Use a wire to tie up the folded saw so that it does not suddenly unfold like a spring..
How to unfold and fold a band saw
Folding and unrolling the saw band must be done carefully and carefully. We offer step-by-step instructions on how to do this correctly and safely. Remember to always wear protective gloves and goggles when handling the band saw and keep a safe distance from others to avoid accidental injury..
Unrolling the Saw Band
1. Take the saw, folded in three loops, in your right hand..
Find the loop that forms the number eight and pull it down with your left hand..
The two upper loops form a cross..
Hold the loop that was at the very top with your right hand. Another loop. left.
Hold the saw in front of you and slowly spread your arms while opening your wrists out and down..
Saw deployed.
Folding the saw band
1. Grasp the saw ring with both hands with the teeth facing towards you. Squeeze the saw ring lightly.
Shake the saw so that the top of its ring bends down..
How to Fold & Unfold Band Saw Blades | Tricks of the Trade
Bring your arms together, turning your wrists inward so that a crisscross forms on the downward bend of the saw.
The saw makes three loops. With your left hand, grasp the bottom hinge and lift it up to fold all three hinges together..
The saw is folded. Use a wire to tie up the folded saw so that it does not suddenly unfold like a spring..
HOW TO UNFOLD AND UNFOLD THE BANDSAW
HOW TO UNFOLD AND UNFOLD THE BANDSAW
HOW TO UNFOLD AND UNFOLD THE BANDSAW
Folding and unrolling the saw band must be done carefully and carefully. We offer step-by-step instructions on how to do it correctly and safely. Remember to always wear protective gloves and goggles when handling your band saw and keep a safe distance from others to avoid accidental injury..
Unfolding the saw
Take the saw, folded in three loops, in your right hand..
Find the loop that forms the number eight and pull it down with your left hand..
The two upper loops form a cross..
Hold the loop that was at the very top with your right hand. Another loop. left.
Hold the saw in front of you and slowly spread your arms while opening your wrists out and down..
Saw deployed.
Folding the saw
Grasp the saw ring with both hands with the teeth facing towards you. Squeeze the saw ring lightly.
Shake the saw so that the top of its ring bends down..
Bring your arms together, turning your wrists slightly inward so that a criss-cross occurs on the downward bend of the saw..
The saw makes three loops. With your left hand, grasp the bottom hinge and lift it up to fold all three hinges together..
The saw is folded. Use a wire to tie up the folded saw so that it does not suddenly unfold like a spring..
Band saw welding machines
The most durable connection is created on special resistance welding machines. Depending on the method used, they are divided into 3 types:
- Resistance welding units. Their advantages include compactness and low cost. However, they have low performance.
- Flash welding equipment is more bulky and more expensive. Has a high performance, can connect belts from any material.
- Automated reflow systems are used in large factories.
Saw band welding machine
What to look for
Various defects can occur when welding band saws.
- The edges of the ends to be welded may be unevenly joined. This happens if the clamping of the clamps was very strong, which affected the displacement.
- Large amount of metal on the surface of the weld. So there was too much current.
- Lack of penetration of the web is a low current and a small clamping force.
By the way, the quality of welding can be checked manually, you just need to fold the saw into a ring so that the joint is located at the very top. If the arc has the correct shape, and the joint is not cracked, then the welding process was carried out correctly. If cracks appear in the welding zone, it means that the blade was quickly cooled during the annealing process. If a curved shape in the form of the letter “V” appears at the welding site, then this means that the joint is too soft. This was influenced by the slow annealing.
In addition, we suggest you watch a video – how to properly weld a band saw.
Welding technology
The method of welding band saws on a machine is not very complicated. But you need to know some of the nuances of the technological process. First of all, the saw must be prepared.
- The saw ends to be welded must be trimmed so that the joint planes are parallel to each other and perpendicular to the cutting edge. Cutting can be carried out on a guillotine or with a chisel with a hammer.
- If the saw for wood breaks down at the place of preliminary welding, then the joint must be removed, stepping back from its edge by 5 mm on each side.
- It is imperative to cut the blade between the teeth..
- The ends are treated with a solvent to remove contamination.
- Sharpened on a grinder to create a rough surface and remove burrs and uneven cut.
- After preparation, the saw is inserted into the apparatus, where it is welded.
Welding of band saws on special welding machines
The essence of the butt-welding of band saws is that an electric current is passed through the butt-connected and compressed with a certain force of the saw ends, leading to heating, melting and welding of the end edges of the blade. The current is supplied through electrodes connected to the terminals.
A large number of models of machines for resistance welding of band saws are produced. The most advanced of these provide an automated weld and anneal cycle that eliminates the possibility of operator error in timing the electrical impulse during welding and annealing. In the simplest devices, the welding and annealing times are controlled by the operator..
The simplest machine for welding band saws is shown in the photo below. It consists of a body (1), a welding transformer (2), a clamping mechanism with electrodes and clamping levers (3), a start button (4). The clamping mechanism, in turn, consists of a fixed (5) and a movable (6) clamps. The latter has a free play necessary for upsetting – the movement of the ends of the saw towards each other with the formation of a welding bead. Under the action of a spring that creates upset pressure, the ends of the saw are pressed against each other with a certain force.
Band saw welding machine
Band saw welding machine
The band saw welding process includes the following operations:
- saw cutting;
- stripping the ends to be joined;
- installation of the blade in the welding machine, selection of the current mode, setting the required effort and upsetting stroke;
- welding of the blade;
- annealing the saw;
- seam stripping.
Blades are best cut with guillotine shears, but can be cut with a cut-off wheel or chiselled. If the blade has already been welded before, when re-welding it is necessary to cut about 5 mm from each end..
In any case, the following conditions must be met when cutting:
- the junction should be located between the tops of the teeth;
- when cutting, an allowance for upsetting should be left (approximately 1.5 mm for each end of the tape);
- the cutting line must be flat, perpendicular to the back of the saw.
The latter is necessary so that the saw blade of the welded saw does not have a bend at the junction (along the mowing line of the back).
There is a fairly simple way to accurately cut the band to be welded. It consists in placing the saw as shown in the figure below (middle image) and trimming or deburring both ends of the blade at the same time (complete). With this processing of the ends, even if the cutting line is not perpendicular to the back of the saw, its ends will nevertheless dock as expected, and the evenness of the blade after welding will be ensured.
Simultaneous processing of the ends of the saw band
The saw ends are cleaned of dirt and degreased with acetone or alcohol. The edges to be joined are cleaned with an abrasive. They must be even, without burrs..
Installing the blade into the device
The prepared saw is installed in the clamping mechanism (one end in the fixed clamp, the other in the movable one) so that its edges meet in the middle of the free space between the clamps. In this case, their complete coincidence must be ensured..
Corresponding control knobs set the upsetting force and stroke, welding mode. All these parameters depend on the dimensions of the saws to be welded. The larger the cross-section of the saw, the more welding current is required and the higher the upsetting force.
In the instructions for the welding machines there are tables containing all the necessary settings, depending on the size of the saw to be welded. Often, welding modes are set without specifying a specific value for the welding current and voltage. To weld a specific saw, you just need to set the control handle to a specific position (I, II or III, for example).
The welding process is started by pressing a button or turning the handle. In this case, the current is supplied to the clamps, and from them to the ends of the saw, as a result of which the metal melts in the joint zone. Under the action of the spring, the movable clamp begins to shift towards the stationary one by the amount of the upsetting stroke, as a result of which a welded bead is formed in the joint zone, connecting the ends of the saw.
Welding band saws
In addition to the value of the current strength, the most important parameter is the time of supply of the current pulse. Welding machines that have an automatic welding mode turn off the power supply after a certain time (usually 1-2 seconds). When working on machines that do not have an automatic mode, the welding time must be controlled by the operator..
The whole difficulty of welding band saws lies in the difference in the sizes of their blades and the materials from which they are made. Therefore, often after the first welding, which ended unsatisfactorily, the welder is forced to experimentally select suitable modes. It is better to do this on unnecessary scraps of the canvas. After the optimal mode has been selected, it is advisable to write down its parameters so that the correct mode can be applied to all saws with the same parameters..
It is very important to keep the electrode surfaces in contact with the saw clean. The presence of foreign substances between the blade and the electrodes increases the resistance of the circuit and disrupts the welding mode.
Annealing is necessary in order for the metal, which has acquired increased hardness and brittleness as a result of welding, to return its original (or close to it) structure, i.e. became plastic and viscous again. Annealing is performed in the same clamps as welding, but in the absence of upsetting force and in a different current mode.
Heating up to the annealing temperature (about 600 ° C) and slow cooling is sometimes carried out by pressing, holding and releasing the button that supplies the annealing current to the electrodes, while the button for supplying the annealing current is periodically pressed to slow down the cooling. If the apparatus is not equipped with a pyrometer, the temperature is controlled by the color of the metal – when it reaches the annealing temperature, it should be cherry red. Do not heat up to orange or yellow, indicating a higher temperature. The gradual cooling during annealing can take about 3-5 minutes. Some canvases require two bake cycles. Sometimes welding and annealing are combined in one process, increasing the cooling time of the seam after welding by periodic inclusions of the heating current..
Cleaning the canvas
When scraping, the sag in the area of the weld seam must be removed from the blade and the correct geometry must be given to the interdental cavity at the joint. You can clean it with almost any abrasive tool. The main thing is that the treated surface is flat and flush with the adjacent areas. When stripping, the circle must be guided along the seam, and not across it.
Cleaning the saw band after welding
Cleaning the saw band after welding
Quality control of welding and annealing
When welding band saws, the following defects may occur.
- The welded edges of the web are offset relative to each other (the surfaces of the ends of the web are not in the same plane). This happens when the upsetting stroke is too large or the current strength is insufficient..
- Ejection of melt onto the surface of the web. Observed when the current is too high.
- Lack of penetration. Occurs due to low pressure and low stroke of settlement or too little current.
In well-welded saws, the weld seam should protrude above the surface of the blade at least 1.5 mm.
The quality of annealing can be checked as follows – bend the fabric around a circle with a bending radius of 20-25 cm and look at its behavior. If the bending arc is close in shape to a circle, and the seam does not crack, then the welding and annealing were performed well. If the curved blade takes a V-shape, then the metal in the weld zone is too soft due to excessive annealing. Cracks in the weld zone indicate insufficient annealing (too fast cooling).
How to Fold a Bandsaw Blade into 3 Rings
Saw band annealing
During the welding process, the joint of the saw band becomes strong but brittle. One hammer blow destroys the joint at once. The thing is that under the influence of a high current, the metal changes its structure. To return it to the state of plasticity and viscosity, it is necessary to carry out an annealing operation. This process is carried out all on the same welding machine, without removing the blade from the clamps. The current regime simply changes and the upsetting force is removed..
A large current is applied to the electrodes, and the joint itself is heated to a temperature of 60C. Many machines have a pyrometer that monitors the temperature in the welding zone. It will be used to control the annealing mode. After heating, the current is turned off and the saw slowly cools down. If the ambient temperature is below zero, then during the cooling process, it is necessary to periodically turn on the current supply so that the cooling goes slower. Typically, the temperature drop lasts 3-5 minutes.
Some canvases require double annealing, it all depends on the metal grade. Some experienced operators combine welding and annealing. That is, the web is heated to the temperature at which welding is performed, then the tool is slowly cooled. Here it is important to increase the cooling time, for which periodically turn on the supply of current to the electrodes.
How to weld a band saw with your own hands
Welding technology
Regardless of the type of saw welding is carried out according to a single method, carried out in stages.
Welding technology
Regardless of the type of saw welding is carried out according to a single method, carried out in stages.
How to weld a band saw
Band saws, both for wood and metal, are made from a cutting blade connected in a ring. Since during operation they are subjected to cyclic tensile and bending loads, the joint in terms of strength should ideally not be inferior to the material of the canvas. Therefore, special equipment is used for welding strip plates..
Welding process
After preparation, the ends of the blade are inserted end-to-end into the clamping device of the band saw welding machine. It is necessary to make sure that the edges are the same height and are located in the middle between the movable and rigidly fixed clips. According to the attached table, current, force, shrinkage stroke are established. Depending on the choice of the operating mode, automatic or manual, the welding time is determined. In the first case, it lasts a few seconds, in the second, it is controlled by the operator..
Before starting welding, you need to check the cleanliness of the electrodes, as dirt creates additional resistance. After turning on the device, current is applied to the ends of the tape. Where they meet, the metal begins to melt. At the same time, the movement of the movable clamp begins by the amount of the specified shrinkage. As a result, a weld seam is created in the form of a bead..
If the material of the band saw blade is unknown or it is not in the table, the current parameters are selected experimentally on unnecessary scraps. When a satisfactory result is achieved, the settings are recorded for use in the future when working with similar products. Thus, an additional table is compiled, where non-standard settings values are entered..
If the use of special machines is not available, you can weld the saw at home. To do this, it is enough to have a simple welding machine and a vice. After preparing the canvas according to the method indicated above, its ends are clamped in yews. To create a strong connection, it is recommended to use a filler metal rod for welding. After the suture is applied, the fabric is turned over, the operation is repeated on the other side.
Band saw welding machines
The most durable connection is created on special resistance welding machines. Depending on the method used, they are divided into 3 types:
- Resistance welding units. Their advantages include compactness and low cost. However, they have low performance.
- Flash welding equipment is more bulky and more expensive. Has a high performance, can connect belts from any material.
- Automated reflow systems are used in large factories.
Soldering
When contact welding is not available, high-temperature brazing with silver solders with a special borax-based paste flux is used. To secure the ends of the web, a simple home-made device is used. Heating by a gas burner.
Soldering is carried out according to the standard procedure. Flux is applied to the beveled ends of the saw. After clamping in the fixture, the junction is heated to the melting temperature of the solder placed next to it. Under the action of capillary forces, it will begin to tighten into the joint. After the solder appears over the entire mowing line of the joint, heating stops. After cooling, the saw is removed and cleaned of sagging.
Preparing the canvas
To make the ends to be connected even, the blade is cut with a guillotine. In its absence, you can use an angle grinder or chisel. When re-welding at the place of the destroyed old seam, 5 mm are cut off at the ends. the cutting line must be strictly between the teeth. At both ends, leave a draft allowance of 1.5 mm. With an abrasive tool, irregularities and burrs are removed. After cleaning the ends from dirt, they are degreased with a solution of industrial alcohol or acetone.
Annealing
The metal in the welded area becomes brittle under the influence of high temperature. To return to its previous properties, it is subjected to annealing using the same butt welding machine for band saws without removing the blade. The settings set the zero stroke value and change the current mode.
After the current is applied, the connection point heats up to 600˚C. The temperature is controlled by the readings of the pyrometer. If it is absent, they are guided by the color of the metal. A cherry red hue is considered normal. The appearance of orange or yellow means overheating. When the required temperature is reached, the current supply is interrupted. The optimal annealing time is 3 – 5 minutes. To prevent rapid cooling of the metal at low ambient temperatures, the current is switched on cyclically for short periods of time..
Depending on the metal, it is sometimes necessary to anneal twice. Combining operations is possible to improve performance. Immediately after welding, current pulses are periodically started to increase the cooling time. After manual welding, annealing is carried out using an oven and oil.
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Sharpening of cutting tools. circular saws, band saws, cutters, drills, knives.
- sharpening band saws
- saw blade sharpening
- sharpening of all types of cutters
- sharpening drills
- sharpening of flat knives and replaceable profile knives.
Band saws for metal. prices
Sawing recommendations
To get the best results when cutting wood, you must first of all follow the band saw manufacturer’s recommendations and keep it in good working order. But the results are more dependent on the tool used. band saw.
Band saw blades for metal, band saws for metal. HOW AND WITH WHAT THEY ARE EATED!
In this article, I will tell you in detail about band saws for metal, all the advantages and disadvantages, how to use them, how to choose the tooth pitch, what kind of saws there are, and much more. Here’s a bunch of technical information. so first things first.
Sawing equipment types
The band saw for wood differs from other types of sawing equipment in that it can process not only boards, but also solid logs, lumber of considerable width. Depending on the equipment and the type of teeth used, the band saw can be used for working with metal, stone or plastic, aerated concrete, mineral wool slabs, etc. It is also possible to use band saws in the food industry: for cutting large fish and meat.
For work with wood, carbide band saws with high m carbon are used in the composition of the steel band. For cutting steel billets, non-ferrous metals and some types of wood, bimetallic band saws are used.
According to the principle of operation of the mechanism, the following types of units are distinguished:
- with a toothed blade;
- toothless friction;
- with an electric spark device
By the type of location of the sawmill, band saws are divided into:
- horizontal;
- vertical.
The larger the pitch of the band saw (the distance between the teeth of the band), the larger the size of the workpiece can be processed by the equipment.
Band saws for wood
The band saw is used for cutting straight and curly lines. The main structural element, with the help of which the sawing is performed, is a steel flexible tape closed in a ring. One edge of the belt is equipped with teeth.
Sawing wood on a band sawmill
Most often, a log appears on the sawmill, from which boards, beams and other sawn timber are made. Before proceeding with sawing on a band saw, it is necessary to calculate the amount of material for the sawmill, make longitudinal markings in such a way as to get as little waste (slab) as possible at the output, select a blade for the band saw with the desired pitch and inclination of the teeth. The log must be well secured to the sawmill, making sure that it passes freely between the guides and meets the band saw band at the intended point.
Cutting with a band saw is not technically difficult, but it requires experience and practiced skill. The correct selection of a band saw blade for wood makes the process much easier..
Sharpening and welding equipment
Pre-sharpening band saws for wood reduces friction during operation. The need for sharpening is determined visually by the quality of the cut. Before sharpening the band saw, select a stone depending on the characteristics of the blade.
The work uses special circles for sharpening band saws. The most qualitative method is considered to be the method of full-profile sharpening with an elbor disk. Improper preparation of the band can lead to breakage, requiring welding of the saw band.
Saw band annealing
During the welding process, the joint of the saw band becomes strong but brittle. One hammer blow destroys the joint at once. The thing is that under the influence of a high current, the metal changes its structure. To return it to the state of plasticity and viscosity, it is necessary to carry out an annealing operation. This process is carried out all on the same welding machine, without removing the blade from the clamps. The current regime simply changes and the upsetting force is removed..
A large current is applied to the electrodes, and the joint itself is heated to a temperature of 60C. Many machines have a pyrometer that monitors the temperature in the welding zone. It will be used to control the annealing mode. After heating, the current is turned off and the saw slowly cools down. If the ambient temperature is below zero, then during the cooling process, it is necessary to periodically turn on the current supply so that the cooling goes slower. Typically, the temperature drop lasts 3-5 minutes.
Some canvases require double annealing, it all depends on the metal grade. Some experienced operators combine welding and annealing. That is, the web is heated to the temperature at which welding is performed, then the tool is slowly cooled. Here it is important to increase the cooling time, for which periodically turn on the supply of current to the electrodes.
Stripping
The main requirement for cleaning is to remove the bead of metal and impart the correct geometry to the cavity between two adjacent teeth at the welding point of the blade. Cleaning can be done with any abrasive tool. It is important that the canvas does not lose its evenness in the plane, and the joint metal is flush with the adjacent areas. Therefore, it is recommended that the stripping is carried out not across the junction of the saw blade, but along.
Welding band saws
Band saws are used in many wood cutting applications. Essentially, it is a flat cutting blade with a serrated cutting edge on one edge. For its technical purpose, this fabric is welded into a ring. Welding place – two extreme ends of the tool. A band saw welding machine is used to join the joint edges. This is a special equipment, it is highly specialized, it is used only for welding band saws.
Welding technology
The method of welding band saws on a machine is not very complicated. But you need to know some of the nuances of the technological process. First of all, the saw must be prepared.
- The saw ends to be welded must be trimmed so that the joint planes are parallel to each other and perpendicular to the cutting edge. Cutting can be carried out on a guillotine or with a chisel with a hammer.
- If the saw for wood breaks down at the place of preliminary welding, then the joint must be removed, stepping back from its edge by 5 mm on each side.
- It is imperative to cut the blade between the teeth..
- The ends are treated with a solvent to remove contamination.
- Sharpened on a grinder to create a rough surface and remove burrs and uneven cut.
- After preparation, the saw is inserted into the apparatus, where it is welded.
Welding machine
There are several types of band saw welding machines, which mainly differ from each other in performance. The simplest apparatus is a small-sized machine, which includes a transformer, electrodes, clamps (one stationary, the other movable – it is supported from behind by a spring). The electrodes are connected to the clamps, so the current from the transformer is fed directly to the junction of the saw band parts.
The mobility of one of the clamps creates conditions for adjusting the gap between the ends of the web. It is very important that the end result of welding is a neat weld bead that is strong and reliable. After all, the band saw is subjected to repeated cyclic bending and tensile loads..
So, the band saw is installed in the welding machine. One end of it is clamped into a fixed clamp, the other into a movable one. It is very important that the cut ends are tightly joined together. After that, with the help of special handles, the clamping force is set, that is, the movable clamp is shifted towards the fixed one. The value of the welding current must be set. These two parameters, the upsetting force and the current value, directly depend on the dimensions of the section of the canvas. The larger it is, the more current must be, the more clamping force must be applied..
It should be noted that manufacturers of welding machines made sure that consumers did not look for current and clamping parameters. In the instructions for each device, a table of the dependence of the section of the band saw on the parameters of current and settlement is attached. So there should be no problems with the choice of welding modes..
Band saw welding process
If the band saw is installed, the welding mode is selected, it remains only to press the start button of the welding process. In this case, the current from the electrodes is supplied to the clamps, and through them, in turn, to the ends of the welded parts of the band saw. They begin to melt, that is, they become soft. In this case, a spring-supported movable clamp pushes one of the edges of the web towards the other. This forms a welded bead.
It should be noted that in addition to the correctly selected welding mode, there is one more parameter that affects the quality of the final result. It’s welding time. In simple machines, it is controlled by a worker who welds the band saws. If welding is carried out on automatic models, then the welding time takes 1-2 seconds.
By the way, the cleanliness of the electrodes also affects the welding quality of the band saws. Therefore, the machine must be kept clean. Even the smallest contamination of the ends of the electrodes is the resistance to the passage of current through them, which reduces the indicator of the latter. This means that the current value at the ends of the saw sections to be welded also decreases..
It should be noted that welding band saws with your own hands is not the easiest process. The difficulty lies in the fact that canvases have to be joined with different sections and with different materials from which they are made. That is, for each criterion, you need to correctly select the welding mode. Which is very difficult and sometimes impossible to do. Therefore, often the first welding of an unknown saw leads to an unsatisfactory result. After that, the operator begins to select the welding mode by the “poke” method. Exposes different modes in turn and looks at how well the welding took place, how much the joint meets the strength requirement. Experienced operators, therefore, create a table for themselves in order not to repeat their mistakes in the future..
What to look for
Various defects can occur when welding band saws.
- The edges of the ends to be welded may be unevenly joined. This happens if the clamping of the clamps was very strong, which affected the displacement.
- Large amount of metal on the surface of the weld. So there was too much current.
- Lack of penetration of the web is a low current and a small clamping force.
By the way, the quality of welding can be checked manually, you just need to fold the saw into a ring so that the joint is located at the very top. If the arc has the correct shape, and the joint is not cracked, then the welding process was carried out correctly. If cracks appear in the welding zone, it means that the blade was quickly cooled during the annealing process. If a curved shape in the form of the letter “V” appears at the welding site, this means that the joint is too soft. This was influenced by the slow annealing.
In addition, we suggest you watch a video – how to properly weld a band saw.