Why Bandsaw Blades Off Wheels
Installing blade guides
So that the saw cuts the material smoothly and the tape does not push through, guides are installed on a narrow beam along the blunt saw end. A common version of the device consists of three bearings located on the bar, one of which rests the canvas with its flat side, the other two support it from the sides. Sometimes on the sides, instead of bearings, they put limiters made of wood.
Align the guides at the pivot point so that there is no vertical deflection at the opposite end, for convenience, the position of the beam is marked with the canvas stretched out.
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 wood band saw 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.
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:
Types of saws depending on the work with the material
The following division into categories is made according to the processing material:
- for stone;
- for metal;
- for wood;
- for synthetics.
Working with hard materials (metal, stone) is carried out with a tool in which the working saw blade is reinforced with heavy-duty teeth from the corresponding alloys. The wrong choice of the saw blade leads to its breakage and deterioration of the edges on the workpiece being cut. Before buying a saw, determine the front of further work.
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.
The process of soldering the cutting strip
Soldering in the workshop is as follows:
- the places at the junction of the canvas are polished from both ends, a brass strip is placed between the surfaces;
- to make a strip, a piece of brass (0.3-0.4 mm) is cut along the width of the saw blade, moistened and sprinkled on both sides with borax powder;
- the sponges of the ticks are heated in an accessible way (gas burner or forge) to a bright red color, applied to the adhesion site and pressed;
- the strip heats up from hot sponges, brass melts and spreads, and borax works in the form of a flux, which prevents the oxidation of the solder when heated;
- the pliers are not removed until the joint has completely cooled and the solder has hardened, after they are removed, the adhesion site is moistened with a wet hardening sponge;
- inspect the joint, its hardness must correspond to the canvas;
- if the junction is solid, then the heating procedure with mites is repeated until a straw-colored adhesion appears, gradually cooled;
- a soft adhesion requires one more incandescent heating with tongs and a more abrupt cooling;
- so that the sponges of the mites are not soldered to the saw strip in the process, a solution of chalk with liquid glass is applied to their contact surfaces;
- for installation and tension on the lower and upper pulley, a handle is used, the correct position on the disks and rollers of the stop is checked by rotation, the correct passage is adjusted;
- turn on the unit for a short time and additionally adjust it if necessary.
Types of material for canvases
For cutting wood, strips of steels with high m carbon, blades with soldered carbide teeth and bimetallic strips are most often used. The bimetallic version provides for a flexible blade and hard teeth, for which two types of metal are used. The base of the strip is made of a springy material, a tool high-speed wire is welded to it using an electron-beam type of welding, from which a toothed profile is subsequently milled.
They produce blades that are universal in use and special saws used for specific steels. The area of use is selected taking into account the parameters of the teeth:
For cutting large workpieces, strips with large teeth are used, in particular, for processing sheet metal of significant dimensions, blades with enlarged elements are used. To avoid beating of the blade and resonance phenomena, teeth of different sizes are attached to the same strip (variable pitch).
The hardness of the cutting elements depends on this index of the steel. Most often, in the manufacture of teeth, metal is used with the designation M42 (this means the hardness of the edge according to the Vickers category. 950 units). To machine tool steel, this indicator is small, therefore, the hardness of the teeth is M71 (100 Vickers units), work of medium complexity requires the hardness of M51.
The geometric shape is determined by the sharpening angle and the profile of the cutting element. To cut a profile (channel, corner, T-bar, I-beam, pipes) to size, it is required to form teeth with reinforced backs. This is dictated by the special shape of the profile, during the cutting of which shock and vibration occur, leading to chips and cracks. To process viscous stainless steel or other materials with similar indicators, the teeth are made sharp, a significant gap is left between them.
The layout of the cutting elements is done depending on the size and massiveness of the material being processed. For example, to prevent pinching when cutting solid massive material, strips are used on the saw with alternating narrow and wide setting.
Vertical band saw for wood
Vertical-type wood sawing machines are distinguished by the fact that the blade, which is in contact with the surface to be cut, is located vertically. The table saw for wood of this type can be used in small workshops for wood processing, as well as in home workshops for domestic needs. Such a tool easily handles materials of various widths and can work in any path. The dimensions of this type of wood band saw may vary. When choosing a vertical band saw, you must remember the following characteristics:
- moving speed of the web;
- web length;
- number of speeds;
- the ability to adjust the angle of inclination of the table;
- cutting depth;
- machine weight.
What materials are needed for manufacturing?
It should be noted that not the entire structure can be built from improvised means. Therefore, before making a band saw, you should assemble the necessary parts:
Wooden boards, chipboard, MDF or plywood. These materials are used for the frame and the saw stand, as well as the pulleys.
Channel and steel bar. These parts are used to manufacture the support frame and the axle on which the pulleys will be installed.
Sheet rubber. It is used to protect wood.
Strong belt that will keep the wheels spinning on the machine.
Polyurethane adhesive for joining some parts.
Fasteners: self-tapping screws, brackets, bolts, washers and rubber pads.
Electrical engine. You shouldn’t buy a very expensive model. Just decide how much power the machine should have.
Thus, a band saw can be constructed with your own hands. Drawings of this structure should be done, calculating each step as accurately as possible. Naturally, you can find all the schemes ready-made.
Instructions for the manufacture and assembly of the device
Now you should start producing the presented unit. To do this, you will have to carry out several stages:
If you decide to make a unit such as a band saw with your own hands, you should already have the drawings. They are the ones. recipe for success. It is worth starting with the construction of a table and a pedestal on which the mechanism will be fixed. To do this, you need a furniture board or wood.
Next, pulleys are made of plywood, which are subsequently pasted over with sheet rubber. Wooden elements must be sanded and epoxy coated.
Now you can make a frame for assembling the entire device. It can be C-shaped, which provides good tape retention. The support frame is made of a channel on which a steel axle is fitted.
Now let’s deal with the pulleys. They must be put on the axle using bushings, and at its different ends. Naturally, both pulleys need to be balanced.
In order for the tape not to vibrate, it is necessary to use a damper.
All movable parts must be connected to the electric motor.
You can also build a guiding mechanism with which the processed material will be fed. For this, metal corners are used.
Varieties of machines
Before you start making band saws, you should understand their types. There is such a classification of devices:
Which canvas should you choose?
Do-it-yourself band saws can be made from those materials that can be found at home. However, the canvas will have to be bought. Before that, it is worth deciding exactly what it should be. To do this, you need to know what you are going to cut. So, there are such canvases:
Bimetallic. They are used for cutting sufficiently strong alloys, stainless steel. At the same time, you can be sure that the tape will not burst.
Diamond. They are used when it is necessary to process marble, granite, quartz and other hardest materials.
Carbide. They can be used for cutting alloys that are quite difficult to work with.
Tool steel. Such canvases are most often used at home or in small workshops. They are best suited for working with simple materials.
Naturally, any equipment needs periodic repair and inspection. For example, sharpening band saws with your own hands is quite simple. The main thing is to know its technology. A special machine is used for work. All work consists of several stages:
Initial sharpening (eliminates cracks that have appeared, restores the symmetry and profile of the teeth).
Cleaning the blade from sawdust and dust.
Wiring (to restore the back and front corners).
Final sharpening. It removes all distortion and sharpens the teeth.
If you do not have experience sharpening saws, then all actions should be done as carefully as possible. The quality of the device depends on this procedure. If you are not confident in your abilities, then invite an experienced specialist.
Features of setting up the device
A homemade wood band saw must be carefully prepared for work. To do this, it should be tested and tuned. The cutting tape must be strictly at right angles. Any slight misalignment can stop the machine from running and become life threatening.
Note that the cutting band should be as tight as possible. Use the driven pulley for tuning. It is with his help that you can normally adjust your machine. It should also be noted that the welding of band saws used in the manufacture (it is quite simple to do it with your own hands) will provide good strength and stability of the machine.
What problems can arise during the manufacture of the device?
First of all, you need sophisticated equipment to do some of the work. For example, not every craftsman knows how to use a welding machine. Not everyone has a milling machine. Please note that the entire structure must be stable. In this case, one should not forget about the mass of the material that will be processed.
Not everyone can figure out the drawing. Please note that the disadvantage of such a device is a fairly wide kerf. In general, if you want to build such a unit yourself, stock up on the necessary tools, material and patience.
Why do band saws break?
You can only answer this question by asking additional questions. The first step is to find out:
Question. What kind of flywheels do you use?
It has long been noticed that even leading manufacturers often use the wrong drive handwheels when working with band saws, which causes numerous problems with bandsaws.
Incorrect handwheels are ripping the blade off the line. For example, a 48cm wheel has 1.5m in circumference. With a nominal blade speed of 1.5 km per minute, the flywheel scrolls 1000 rpm. This is roughly 16.66 turns per second. Multiply 16.66 RPS x 1.5m (okr) = 25 meters of blade per second pulled during the cut. If you use a four-meter canvas, then in a second it makes a full revolution 6.24 times. Each time the blade passes through two flywheels. 2 x 6.24 is approximately 12 times per second the web is rewound through the wheel. It’s 1.5 km per minute!
When the flywheels are the cause of the band saw breakage, the most common reason is that the flywheels are out of the circle by 0.38 mm or more. Now multiply the two flywheels x 0.38, and we get 0.76mm of web deflection (stretching) during a full revolution. That is, the blade is stretched by 0.76 mm in the cutting zone and another 0.76 in the free zone. And this load on the saw occurs at least 12 times per second! The saw just can’t take it!
Many pulleys have a 0.38mm deflection and are fitted with a V-belt in the groove. Such a V-belt serves as a shock absorber, and it is due to such a belt that the flywheel can work even with a deviation of 0.38 mm.
The shock absorber must be changed at regular intervals. If the belt wears out from the inside (which cannot be seen and predicted), then it collapses and stops absorbing the load. Then, for no reason (at first glance), the tape blades begin to tear.
Question. Did the saws swell or wobble before breaking?
If so, then this is another reason why band saws can break, and the next step is to diagnose the cause of the bulge or waves, or, in other words, the geometry of the plane of the blade. During operation, the saw is under very great pressure, in addition, it gets very hot. all this needs to be clarified. Good saws and properly configured sawmills create minimal stress.
Question. What guides do you use?
It is believed that roller guides are best for cuts larger than 20 cm wide. Whereas for cuts less than 15 cm wide, sandwich guides are best.
It is very important that the sandwich rails are of good quality. Otherwise, the blade will constantly hit the guides during each turn of the flywheel.
Most band sawmill owners have iron flywheels, but for those with belt flywheels, roller guides are better suited due to the offset of the flywheels.
Question. Which tensioner are you using?
It is best if the tensioner is able to change the saw tension depending on the situation. When the saw stretches and heats up during the cut, the spring or air tensioner will release the tension, and when the saw passes over the kerf free zone, it cools down and the tensioner will increase the tension again.
The hydraulic tensioner only provides constant tension without changing it. This is not to say that it does not work, many of you have been using hydraulics for a long time and successfully, but it can be one of the reasons for the breakdown of the saw.
Question. Saws tearing from the front or back?
This is a very important point. The place of the first breakage is most often discolored, and the last one shows bright steel. The saws on the face side are torn due to excessive stress. This can be due to tension during the cut, too much tension on the saw, poor flywheels, or tension during sanding.
When the saw breaks from the wrong side, most often the problem is that it gets damaged from something on the back. It might be a bearing that needs to spin freely, but it hits the saw, wearing out the bolts and guide.
All this causes the saw to heat up, the rear of the saw crystallizes and micro-cracks form. To determine this, bend the saw sharply and inspect the back, you will see many cracks. All machines using these rear bearings should be inspected regularly.
Question. Saws tear after the first cut or after sharpening?
If the saw breaks during the first start, check if it is too dull.
Some people complain that after sharpening, the saw breaks in the sinus area. This can be caused by starting a dull saw or by over-sharpening the saw in the bosom. If after sanding, there is residue on the back of the sinus, then you have put too much effort. You need to grind the saw lightly so that the grinding wheel cuts, and does not melt the steel
Why do band saws break?
Blade tearing is a common occurrence during metalworking. But, despite the regularity, sometimes it is difficult to quickly determine the cause of the breakdown. There is no universal reason for the gap, other than a combination of inattention and non-compliance with recommendations. The first decision that comes to mind in such a situation would be to replace the tool with a new one from another manufacturer. However, you should not arrange a witch hunt ─ in case of complex problems, replacing the canvas will not solve the problem, but only hide the symptom and postpone its re-manifestation. Saws will break, and labor productivity will decline until the very cause of the deviations is found and eliminated.
To make it easier to determine the cause of the tape break, it would not be superfluous to determine the types of the break itself. There are two types:
- rupture of the band saw along the weld;
- tearing the web over the body.
Weld quality is the primary cause of saw burst at the seam. Insufficient cleaning of the joint, excessive or insufficient overlap of the edges of the ring, non-observance of the welding and annealing conditions ─ lead to premature opening of the saw. If welding was carried out in a service center, its free restoration is considered a rule of good taste.
The rupture of the canvas along the body occurs as a result of non-compliance with the modes of its use. The quality of the instrument has long ceased to be the cause of this phenomenon. Most modern manufacturers have used techniques and technologies that exclude the possibility of producing saws that are easy to break.
There are several types of band saw breaks along the body:
- Straight web break.
- the break line goes at an angle from the sinus to the back.
- Break with warped or bend edges.
A break perpendicular to the mowing line of the blade indicates excessive stress on the body during operation. Quite often, it happens instantly, without any visible signs. The main reason for this is that the flow rate is too high. It should be understood that a saw installed on a horizontal machine bends (as a result ─ experiences loads) in at least four places (pulleys, two guides). Excessive feed provokes additional overloads at the cut site, and as a result, increases the likelihood of breakage. In addition, the following factors contribute to the breaking of the band saw: too large a tooth pitch (the load is accentuated on one section of the blade, instead of spreading as much as possible, this is especially true when cutting a profile). Too high tension of the band blade (exceeding the stiffness of the blade at the cut point can lead to its breakage, in addition, regular over-tightening of the blade negatively affects the quality of the pulleys). It is important to understand that the rupture of the web usually occurs only with a combination of the above problems, therefore, in case of malfunctions, it is worth checking all possible causes ─ there may be several.
In case of axial rupture, the cause should be sought in the minor but regular loads that the blade experiences during operation. Small cracks in the back or sinus of the tooth on the eve of rupture are common. This phenomenon can be caused by too small a tooth pitch ─ in this case, the interdental sinus will quickly become clogged with waste chips, experience overload and, at best, become blunt, at worst ─ regular loads will lead to cracks in the sinus and rupture of the case. Particularly careful attention should also be paid to the installation of the saw itself and the elements of the machine (especially carefully ─ the condition of the pulley substrate, the pulley itself and the guide blocks that clamp the blade). The fact is that the cause of axial rupture can be the regular beating (or even abnormal friction) of the tool against the elements of the machine. The blade should be installed so that its front and rear surfaces do not come into contact with the sides of the pulley, and are not squeezed by the guide blocks too much. Another reason is the discrepancy between the radius of the pulley and the thickness of the saw. given its size, it bends too much over the pulleys, which leads to destruction. The problem will disappear after replacing the saw with a narrower one.
Rupture with deformation occurs when there is too much lateral pressure on the saw body. This breakdown is the result of operator carelessness. It occurs when the workpiece starts to move during cutting. The reason for this may be insufficiently strong fixation of the material in the vice or moving elements of the turntable. Turning on the machine while the blade was in direct contact with the workpiece can also lead to this type of accident. Therefore, it is always important to check the correct position of the frame and the reliability of fixing the workpiece and moving parts of the machine before starting it.
It should be remembered that in most situations, replacing the saw will not solve this problem. Their complete solution and, as a consequence, a decrease in the cost and an increase in the quality of the cut is possible only with a complete diagnosis of the conditions for using the band saw.
For more detailed recommendations on the selection and use of band saws for metal, see here.
How To Adjust the Wheel & Blade Guides When Installing a New Blade on a Metal-Cutting Bandsaw
The cheap model hit the top thanks to its high-quality assembly from reliable components. It works with different types of materials, including metals, has a rotary vise and cut length limiter. The belt drive protects the motor from overload, extending its service life. For convenience, it has an additional work table. Vibration and noise during operation are practically not felt.
JET J-349V 50000333M
A compact band saw indoors takes up little space, easily handles metal profile workpieces with a diameter of up to 12.5 centimeters, so it is most often chosen for small workshops. It has smooth speed control and low vibration. The saw blade is securely and easily attached, giving an even cut. The equipment can be moved independently without resorting to lifting mechanisms.
Selection and operation of equipment
When choosing a band saw for metal, you need to consider these factors:
- Saw thickness. it should be between 0.9 and 1.1 mm. The smaller the thickness, the lower the feed should be. The standard thickness is 1 mm.
- The width of the saw is from 14 to 80 mm, most often blades with a width of 31-41 mm are used. Wide band saws handle thicker metal more easily.
- Tooth pitch is the distance between sharp edges of adjacent teeth. The shorter the distance, the more precious the work. A long distance is suitable for working with hard metals, in which case a low speed is used. When regrinding, it is necessary to ensure that the step remains the same.
- Tooth shape. the best shape is considered if the rake angle of the tooth has 10 degrees, the clearance angle and the height of the tooth have little effect on the result.
- Number of teeth. the more teeth, the smoother the cut of thick-walled metal workpieces.
- Notch size. large teeth are chosen for deep cuts, medium. for shape cutting, small. for thin metal sheets.
General rules for the operation of equipment:
- Ensure that the teeth are always sharpened and correctly set.
- Do not work on a faulty machine, otherwise the result will be ruined.
- There must be sufficient light in the work area.
- Follow the shape of the grinding wheel.
- Thanks to individual adjustment, you can achieve impressive results from a conventional machine.
Proma PPK-115 25330742
The metal saw has a rigid structure, high performance and three speed settings. The belt drive protects the motor from overload. Due to its light weight and parameters, it is easy to move around the room. During operation, it is almost silent and gives out a low level of vibration, which increases the level of comfort of work.
Jet MBS-56CS 50000320M
This model of band saw is considered reliable for medium-sized production, it produces cuts at three different speeds. The robust design minimizes vibration, allowing precise and accurate work. Replacing the belt is quick and easy, no tools required. The machine is equipped with automatic engine shut-off and hydraulic feed system. Transportation is carried out using the wheels of the machine.
METALMASTER BSG-220 00000014719
Thanks to the three-phase motor, the machine can be kept on for cooling. The metal saw has two speed modes: 45 and 90 m / min. There is a removable pallet that collects chips during operation, so little time is spent on cleaning. The saw frame is raised manually and lowered by its own weight. During operation, the model does not make noise and vibrates weakly. There is a strain gauge that shows the tension of the blade, which results in a high quality cut.
TRIOD BSM-115/230 211015
This small vertical band saw is designed for cutting not only metal but also wood. Quality assembly guarantees a long service life. Sawing is done vertically or at an angle. Reliable vise eliminates the movement of the workpiece during operation. During operation, the speed is regulated from 20 to 50 meters per minute. The machine has a special tray for storing tools. Even a beginner can handle a saw.
Recommended cutting data
High speed is fraught with the fact that the machine can make a lot of noise and vibrate, and the blade from overloading at best becomes dull, at worst. bursts or deforms. Therefore, you need to control the feed according to the chip shape:
- Thick, curly, elastic. perfect shavings. Feed rate and speed are matched correctly.
- Thick, hard, short or fragile. reduce saw speed and pace. Check coolant.
- Thick, hard, elastic and short. slightly reduce the feed rate, check the correct tooth pitch.
- Thick, hard, elastic and long. slightly increase feed rate, check blade teeth.
- Slim, straight, elastic. increase feed rate.
- Powdery. decrease saw speed and increase feed rate.
- Thin, tightly curled. reduce feed rate and use a coarser tooth pitch.