How the blade is fitted in band saws
How to correctly sharpen a band saw
Immediately note that if there is no experience and skills to perform such work, it is better to entrust the sharpening of saws to professionals. Disturbance of geometry of cutting edge teeth, scale on metal or improper sharpening noticeably reduce blade life.
When you have decided to sharpen your bandsaw with your own hands, it does not hurt to first become familiar with key definitions you may need to know as you work. So, the correct formation of the cutting edge will require:
- setting. deflection of teeth from the plane of the main saw blade
- Tooth height. distance between top point and base;
- pitch. distance between teeth, usually varies between 19-25 mm.
- sharpening angle. depends on the instrument application; for example, recommended sharpening angle for table saws is 35°, for circular saws. 18-22, for sawing timber. not more than 15°.
Angle of sharpening is determined by the manufacturer, so when dressing the saw yourself it is recommended to adhere to these parameters.
Here is a detailed instruction that will help to correctly sharpen the closed circular saw without resorting to the services of specialists.
Sharpening band saws in wood is the first step in restoring the profile of the cutting edge. During the operation the arrangement of the teeth may change, so it makes no sense to sharpen the saw part until the correct geometry is achieved.
- classical. the teeth are alternately deflected to the right and left side;
- scraping. 1st and 2nd tooth are deflected to different directions, the third one stays straight. This profile is created for sawing hard materials;
- wavy. the most complicated version, reminding of a wave shape. each tooth is given an individual shape, and this type of reaming is usually done only in specialized workshops.
It should be noted that when setting, not the whole tooth is set, but about 2/3 of the upper part. The procedure is performed on a special band saw setter. The cost of such a tool is quite high, that’s why it is bought if several tools need to be adjusted. It can be the basis of a sharpening business.
Of course, it may not be possible to do everything correctly even on a parting machine at the first time, so at least the geometry of the profile must remain the same as before the beginning of the work.
This is the main stage in straightening the cutting edge and can be done in two ways.
Full profile saw sharpening is performed with an CBN wheel mounted in a special sharpening machine.
This is a fully automated operation used by professionals. The wood band saw blade sharpening machine is controlled electronically and the sharpening wheel sharpens the entire band in one pass. The disadvantage of this method is that the CBN wheel is adjusted individually to the profile of the saw, so for straightening different tools the sharpening element must be in stock.
Tooth sharpening is performed either by hand or with the help of specialized equipment.
Please note! This is the method used for self-sharpening band saws. A normal emery wheel or emery board can be used.
In the first case it is possible to restore the sharpness of the teeth in a short time, but the work requires certain skills. In the second. painstaking work: 4-5 movements on the edge of each tooth.
Diamond, CBN and corundum wheels are used for automatic sharpening. Important thing to realize is that this procedure only sharpens the teeth, and leaves the geometry created after setting the blade.
Why you need a band saw for wood?
When choosing a tool for even wood sawing, special attention should be paid to household wood band saws. Adjustment of saw blade speed and direction allows the saw blade to be used for a variety of applications. A choice of tooth size for a specific material adds to the saw’s capabilities. Blades with coarse teeth are good for soft types of wood, and fine ones for tougher types of wood. Other features of the band saw make it an indispensable helper for the home craftsman:
- Many band saws have the ability to be fine-tuned to the specific needs of the worker.
- Thin blades can be used to cut figured products, a variety of decorative elements.
- The band saw can work in any direction. both lengthwise and crosswise.
- The saw can be used to create identical and mirrored parts for furniture.
- Productivity of band saw is higher than at other kinds of tools.
- Band saws are notable for safety.
What will be needed to build a sawmill
For those who consider the construction of their own sawmill an uncomplicated matter, let us say at once that it is not easy to create a high-quality, workable unit. And it’s not even that you can’t do without certain financial expenses. as a rule, the budget of self-made sawmill is easily stipulated in the amount of 30-40 thousand rubles. rubles. Assembling a machine capable of producing quality lumber will require solving problems related to the stability of the work, the strength of components and parts, setting and adjusting mechanisms, making a device for sharpening the band saw and setting its teeth, etc. д. Don’t be afraid of difficulties? Then get acquainted with what materials and tools you’ll need for work.
As rails can be used steel angles with a shelf width of at least 50 mm, a channel or an I-beam. The main requirement for the rails is their straight geometry. We must keep in mind that any flaw in our miniature “railroad” will affect the quality of the cut, because the band will copy every irregularity, transferring it to the surface of the board. That is why the best option would be T, H or U-shaped bars. Unfortunately, angles are the most susceptible to distortion during manufacture and transport. The most ideal case is to use factory rails, for example, from narrow gauge railroads, which with some luck can be found at scrap metal recycling centers.
Rollers, which ensure longitudinal movement of the bandsaw, can be turned on a lathe and hardened. In some cases it is possible to use ordinary ball bearings.
Very good linear recirculating ball bearing and guideway assemblies are commercially available. This solution is not the cheapest, but there is no doubt about the reliability and durability of such a unit
Actually the frame, the saw carriage and the bed for placing the logs are made of square and rectangular profiled pipes. It is best to use rolled metal products with a maximum wall thickness. It gives the equipment the necessary strength, because the work of the machine is connected with alternating dynamic loads.
For the carriage height adjustment mechanism (traverse), you need steel tube guides with sliders and two long screws with nuts. For this purpose, you can use parts from decommissioned lathes and screw-cutting machines (unlikely, but what the hell), mechanical presses, or bars with threaded bars from the building store (the most affordable, but the least preferred option). You can also have parts made by a turner. you can’t do without a specialist, anyway. In addition, you will need a chain gear, which is often borrowed from the timing mechanism of car engines. Bicycle chains and sprockets can also be used.
As the drive wheels for the belt are best suited pulleys from old domestic harvesters brand “Kolos”, “Niva” and other agricultural machinery. By the way, shafts and rolling bearing housings can also be taken from there. Please note that the diameter of the guides should be at least 30 cm (optimally 50 cm), otherwise excessive mechanical stresses will lead to cracks at the base of the saw teeth.
Pulleys from decommissioned domestic agricultural machinery can be used in the design of the band saw drive
There are designs of homemade units with guide pulleys in the form of wheels from cars. For the skeptics, we note that such a home-made solution has many advantages, starting with the possibility of using a hub assembly and ending with the fact that the fine adjustment of the tension of the blade in the process of work can be made by pumping tires.
The band saw can be purchased new or used. It is best to have several blades in stock, which can be replaced by sharper ones as they become blunt.
As for the tools that will be needed in the process of work, every self-respecting owner should have them. In particular, you will need:
- welding machine;
- “angle grinder”, or, in professional terms, an angle grinder;
- A drilling machine or an electric drill;
- a set of drills for concrete and metal;
- a set of locksmith’s clamps;
- wrench set;
- Fasteners (bolts, nuts, washers of various sizes);
- measuring tools (ruler, caliper, tape measure);
- level (laser type is best).
Do not forget about the fact that you will need to prepare a solid, level base, so be prepared for concrete work. make a supply of sand, gravel and cement, prepare a concrete mixer, tampers, formwork and a long rule.
How to choose a blade for metal, wood or meat
Before you start choosing a band saw for the machine, you need to read the instruction manual. In it the manufacturer specifies the parameters of the product, its maximum and minimum width. For the length, there is always a range that cannot be changed, whereas the width can be adjusted.
Choose the product should be in accordance with the sphere of use. For example, the maximum width is suitable if it is not expected that the workpiece will have to be sawed along the radius.
When selecting the parameters for the band saw, it is necessary to determine the following criteria:
- What will be the amount of work;
- Consider the frequency of use;
- What kind of materials you have to work with;
- blade dimensions.
Note the teeth. Their shape and size are important.
Each material requires a different band saw blade. M-51 tools are suitable if you need to cut high-carbon steel. M-42 saw blade is needed for mild steel, bimetal blade. It is needed for working with medium-carbon steel.
SP models are designed for long-term work with heat-resistant steel. TST type tools are required for machining workpieces made of titanium, and they are designed to work with nickel alloys.
If the choice of band saw blade is made correctly, the following will happen:
Different band saws are used for cutting stone, metal, wood and synthetic blade. Their price depends on the purpose and type of blade. Zubr 350 band saw blade is used for woodworking.
Cutting of plastic, glass and wood is done with 1425 mm blades, it is worth buying a 1650 mm blade for meat. For sawing wood you can buy blades 2240 mm.
Wood band saw with your own hands
It is difficult to make a band saw yourself. The wooden frame for the machine is collected from improvised materials, the necessary tools for assembly can be found in any master. The process of working on a homemade band saw for wood can be divided into the main stages:
- The frame for the machine can be assembled from old furniture, the preliminary drawing will facilitate the work, and will make it possible to assemble the saw according to the required dimensions.
- The simplest bandsaw self-made 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 more.
- For the working surface, you can use an old desk, its drawers can serve as containers, which will collect sawdust.
- How much oil to fill in the gearbox: How much oil to fill the belt pulleys on a tractor or machine with oil?
- For the lifting mechanism, to which the cutting blade is fastened, a massive spring is suitable, which can provide the necessary pressure of the machine.
- The guide rails are needed to make the cut in a straight line.
- For the machine to be safe, it is better to cover the pulley with a special cover.
- A wood varnish treatment or paint job will extend the life of the machine.
Design of band saws
Metal band saw machine consists of the following parts:
- a strong frame;
- several pulleys (2 to 3);
- a vice with hydraulic clamping;
- the working drive;
- The system responsible for supplying coolant to the work area;
- a mechanism that controls the degree of tensioning;
- The control panel, through which the control is carried out;
- control systems that are responsible for operation and safety;
- lighting fixtures.
Bandsaw performance is directly related to motor power. This is what you need to pay special attention to when selecting. It is recommended to buy equipment with a large power reserve, this will save the power unit from rapid wear and breakdown.
Band saws for woodworking: instructions for use
Band saws for wood is a cutting tool that is used on band saws to cut wood. A band saw is a closed, flexible steel band and has teeth on one edge. Band saws are mostly used for longitudinal sawing of logs (on band saws) and for cross, slash and shape cutting on band saws (vertical layout) or jigsaws. For each application, there are advantages over alternative cutting methods. The use of band saws on band sawmills allows cutting with minimum loss of material and high cutting performance due to the small thickness of the tool. The use of band saws or jigsaws (usually of vertical configuration) allows the cutting of workpieces with large cross-section, as well as shaped cuts.
In general, band saws, compared to circular saws, have a lower cost, ease of operation and maintenance, can be repeatedly repaired and restored.
Basic technical parameters of band saws for wood
Thickness of the blade; 2. Width of the blade; 3. Teeth pitch; 4. Height of tooth (depth of recess); 5. Rear corner of tooth; 6. Front corner of tooth; 7. Dentition of teeth; 8. Dentition bar.
Guidelines for selecting a blade
Thickness of blade In theory the less is the thickness of blade, the longer is its life. This is due to the occurrence of bending stresses and the fatigue strength of the blade. In practice, however, there is a high risk of blade failure due to improper use, hard particles in the material (e.g. knots, frozen wood).
A thicker blade produces a straighter and smoother cut. The choice of the blade thickness depends on the geometry of the drive pulleys (diameter and width of the working part), the cutting conditions and the type of wood. A thicker blade is recommended for soft wood and a thinner one for hard wood.
Blade width The choice of blade width depends directly on how and on what equipment the saw is going to be used. When choosing a band saw blade for shape cutting it is necessary to keep in mind that the width of the blade will influence the minimum cutting radius due to the specifics of the cutting process.
Dependence of the blade width and the permissible cutting radius is given below:
For sawmills the band width should be chosen in such a way that it is wider than the drive wheels by the height of the tooth 1-3 mm. The choice of dimensions for wide saw blades is influenced by many factors. To the selection of their parameters it is necessary to approach comprehensively, therefore it is desirable to address to the experts of the company “Golden Fleece, Ukraine”.
Tooth pitch The pitch of a tooth is commonly understood as the distance between the tips of the teeth. For wood band saws the most common pitch is in “mm”. Carbon steel tool blade saws have a wider range of uses, and can be used for cutting metal, wood, plastic, and other materials, The pitch designation on these saws refers to the number of teeth per inch (25.4 mm.).
You should choose the pitch depending on the wood to be cut. Common tooth pitch is 22,2 mm. This is a universal pitch that allows you to process any type and size of wood all year round. It is necessary to pay attention that a small amount of teeth involved in cutting can cause damages of materials being sawed and saw’s teeth, and a big amount. filling of hollow space with chips that will lead to blade overloading and overheating, and in the worst case. to its breakage.
Tooth height The height of the tooth is the distance between the tip of the tooth and the base (depression) line. A larger hollow area makes it easier to cut soft wood because it allows more chips to be removed from the kerf.
Tooth geometry Depending on the hardness of the wood to be cut, the tooth geometry varies. When cutting soft wood a higher rate of feed is used and the amount of chips increases, so the front tooth angle should be 10-15°, the back angle 30°, which increases the volume of the chip cavity and allows more chips to fit in. Conversely, when cutting hard, frozen or exotic wood, the feed rate is low, but more tooth strength is needed. This is achieved by a smaller 30° back angle and a 7-10° rake angle. Thus, a carbide-tipped saw has a reinforced tooth and a reduced sinkhole, all of which contribute positively to the durability of the carbide-tipped saw. Most wood saws are made with a “Hook” tooth design. Have a front angle of 10°. 30° back angle and a large depression. This tooth shape is considered universal and provides good penetration into wood of different hardness, excellent chip evacuation from the cutting zone, thereby reducing the blade load and increasing blade life. The geometry of the tooth allows it to be sharpened as efficiently as possible, which increases the life of the blade.
Blade parameters depending on the wood to be cut.
Setting Setting (kerf). the slope or angle of the tooth in relation to the plane of the blade to allow the blade and the tooth edge to move freely. There are several types of setting. It is so called “standard” setting, when teeth are alternately bent to the left, to the right and “sinkhole” setting, when teeth are to the left, to the right, to the center. The second type of setting is used on most wood saws. Depending on the type and width of wood to be cut, the teeth need to be set closer to the center, taking into account that the softer the wood, the wider the set is.
Blade parameters depending on the wood to be cut.
In the table we used average data based on the most common recommendations. The settings should be made according to your equipment and the conditions of use.
Recommendations for use
How to Change a Bandsaw Blade
Rules for the installation of a band saw blade on the machine. During the installation of the band saw blade and during setting of the machine it is necessary to switch off the machine. Exercise caution when you handle the band saw blade and do not touch the cutting parts of the tool while it is in place and use gloves when installing the band saw blade. Handle with the blade with utmost care, under no circumstances throw it, because it can lead to chipping of teeth and breakage of the blade. Before putting a new (sharpened) blade on the machine it is necessary to pay attention to the technical condition of the equipment. Namely:. Condition of rollers or guiding blocks. Need to remove all debris, dirt, sawdust from them. Rotation should be smooth without jamming or seizing. If necessary, the pulleys and/or bearings should be replaced;. Check condition of track rollers. There should be no backlash in bearings and roller mountings;. Pay attention to machine sheaves. They should be in one plane, clean and have no backlash on the axis of fastening. Check drive pulley belt. It should be the same thickness, the presence of cracks, breaks are unacceptable. After completing the above requirements, you can proceed to install a new or sharpened blade on the machine. Work on changing the belt blade should be done with protective gloves and goggles.
Algorithm of belt blade replacement:. Disconnect power;. Release the tension of the web (using the screw that regulates the tension to loosen the movable pulley and bring it close to the drive pulley);. Open band guards;. Remove the web from the sheaves;. Remove chips from the rails and sheaves Unfold the new blade (Do not drop it) Fit the blade (check the direction of the teeth, the teeth should be facing the direction of rotation of the drive sheave). Set the blade on the pulleys; the main working load should pass through the center of the saw along the whole length. Make sure that the blade is in the same position over the whole length of the sheave. To do this it is necessary to set the band saw blade on the slats and turn them by hand several times, if necessary leveling the blade. Also keep in mind that the tooth must extend beyond the edge of the pulley to the full height plus 1-3 mm;. Insert the blade into the guides. If the machine has block guides it is necessary to have a gap of about 0,1-0,2 mm between them and the body of the saw;. Close the protective guards;. Set the tension on the webs (watch out for crushing points);. Turn the machine on (run it for a few minutes to allow the blade to settle finally on the pulleys);
Parameters of band saws
This equipment brings a lot of positive points if you need to process wood. At home, it is necessary when running a small furniture manufacturing business.
Some types of saws allow additional work with the following materials:
The high density of these materials requires the use of equipment that includes parts and consumables made of reinforced steel. If you use standard steel, when processing metal or stone, the disk and teeth deform in a short period of time, so you need to prepare for work in advance.
Take into account not only the type of material to be worked, but also the production scale. The stamina and power of the machine you buy depends on it. For one-time use you can buy a cheap band saw or make it from local tools, but intensive work requires a serious and expensive machine.
Blade tooth size and pitch
When choosing a saw, one must pay attention to the size of the machine itself. Requirements are described in the manual when purchasing the machine, but there are some nuances that are not specified there.
The following additional recommendations should be kept in mind when selecting a saw:
- For longitudinal sawing choose wide saws, which are characterized by smooth and high-quality sawing.
- Where thin workpieces are handled, tools with a small blade thickness are used. This is an important parameter, because a thick saw when working with thin material damages it.
- Shaped and contour cutting requires an individual selection of the cutting element, but if it is not possible to buy several versions of the saw, then it is better to choose the middle variant. Considering an output width in the range of 14 to 88 mm, it is advisable to buy saws with an average blade size of 35-40 mm.
Quality of cutting is affected not only by size, but also by pitch of teeth on the cutting blade. On it depends on how fast the work will be, the presence or absence of damage.
When selecting, the following features of the work should be considered:
- Large tooth pitch used exclusively for thin sheet material.
- Dense setting of teeth on the blade is used when processing large blades.
- A moderate version with a variable toothing pattern is used for synthetic materials. To prevent the saw from clogging with waste, the cutting speed is increased.
Tooth arrangement and sharpening
Tooth setting affects material quality, vibration, lack of deformation of the material being cut and has a direct impact on the service life of the machine. Choosing the right profile is important in working principles. There are several different cutter profiles:
- Profile with wavy teeth is used for cutting thin material or small workpieces.
- Standard tooth arrangement used for high volume, contour cutting or vertical machine mounting. Teeth are positioned on either side of the central segment of the blade, but there are variants with additional teeth positioned in the center.
- The most expensive type of profile is a pairwise (variable) setting of teeth. This type of saw is the most durable of the presented range, effectively copes with cutting even rough and dense varieties of wood, reduces the load on the frame of the cutting element, which significantly increases its service life.
When choosing a blade, it is important to check that the teeth are well sharpened, that the steel is uniform throughout the blade, and that the cutting edge is smooth. If you focus your attention on these indicators then you can buy a consumable that has not been used before.
Check with your salesperson about the capabilities of the saw. For example, some instances are created with allowance for re-sharpening, and it is important to ask how many times the teeth are allowed to be re-sharpened. Do not sharpen the segments on a saw that is not designed for this purpose. This is an unnecessary load that will dull the teeth or break them.
Operation of the band saw blade
A sharpened pencil will break immediately, unlike a sharp but slightly blunted pencil, and the same principle applies when preparing a band saw blade.
Metal band saw blade: Features of use
The absence of excessive vibrations while cutting and the type of chips are key factors in selecting the correct cutting conditions. For optimum cutting results, each saw blade tooth needs to cut a certain chip thickness. In practice the feed rate should be selected according to the recommendations of the equipment manufacturers or the type of chips that are cut. If the chips are thin or dusty, increase the feed rate of the blade or reduce the cutting speed. A faintly curling chip is an indication of a correct cutting action. Thick or bluish chips are an indication of excessive feedrate or slower than necessary cutting speed.
optimum chip shape:
a) Thin, decaying. increase feed or decrease blade speed;
b) thick, blue-black. reduce feed, check emulsion feed;
Tightly twisted. the recesses between teeth are clogged; use a blade with a larger tooth pitch; reduce feed rate or increase blade speed;
c) free, spiral-shaped. the parameters are chosen correctly.
It is also important not to overheat cutting material of the band saw blade, hence the intensive watering of the blade, cutting zone and sawn workpiece. If vibrations occur, reduce feed rate. Check cut surface quality; burrs and cavities may be caused by wrong pitches, machining regimes or blade wear.
Resting of the band saw blade
The blade resting allows to redistribute the fatigue stresses which appear during the working process, to keep the characteristics of the tool material and to increase the life time. When working intensively throughout the day, it’s best to work with two blades, one before lunch and one after. At the end of the working day always loosen the tension of the blade, or better yet take the blade off the machine, and turn it inside out and hang it on the hook.
Lifetime of a band saw blade
For most manufacturers’ blades (provided the manufacturing process is followed. from blanks to packaging and the conditions of storage of the finished blade) the blade life is within 140.160 hours of machine operation.
Removal of the blade during breaks in the machine for relaxation somewhat extends the life of the blade.
Resistance of band saws
Bimetal band sawing performance is in the range of 10-25 cm/min when cutting high-alloy and tough materials, and 40-60 cm/min when cutting structural steels. There is a definite relationship between performance and durability for each tool, which is shown in Table 1. (The data are given for workpieces with a diameter of 100 mm, cut by 27×0.9 saws)
In addition to the resistance of the saw tooth to wear it is worth mentioning the resistance of the blade itself to cyclic alternating loads occurring during the motion of the saw in the bandsaw mechanism.
In most manufacturers’ saws (if the technological process of sawing is observed. from the raw material to packaging and to the conditions of storage of the finished saw blade) the service life of the blade is within the limits of 140.160 hours of machine operation. Removal of the saw during breaks in the equipment for relaxation, slightly increases the life of the blade.
The durability of the saw tooth is significantly affected by the properly selected tooth pitch of the band saw. The tables below show the dependency of the blade pitch on the diameter of the material to be cut. It should be noted that when cutting with a bundle, the wall thickness should be considered the total thickness of the metal that the saw tooth will pass through.
The main causes of premature blade failure
A) Teeth splinteringSaw pitch too fine.Saws pitch too coarse.Workpieces are not securely clamped.Saw speed too low, causing excessive plunge.Feed pressure too high, causing the saw to cut into the material unnecessarily.Saw blade tension is too low, causing the saw to slip.Saw slips (stops) under load, causing the saw to cut into the material unnecessarily.The saw blade cleaning brush is missing, not working or worn out
B) Cracks in the tooth flanks. Difficulty in saw blade guidance and sheave movement due to soiled sheaves or reduced clearance in guidance system.The clearance between the rails is too great.Guides are too far away from the workpiece.The side guides are jamming the saw in the area of the tooth hollows.Loose side guides tilt the sawDue to improper saw blade tensioning.
B) Cracks on the back side of the saw.Upper support bearing in rails is worn outThe feed pressure is too high.Side guides too worn.The blade is pressed against the shoulder of the sheave.
D) Saw run-out (vibration).Saw pitch too high.Missing teeth (broken).Feed pressure too low or too high.
E) Teeth blunted prematurely.Saw speed too high for the material.Saws pitch too fine or too coarseSaw blade not parallel to feed direction.Defects in the side guides.Guides not secured properly or worn.
F) Unpendicular cut.Saw blade not parallel to direction of feed.Large clearance in guides.Table surface is not perpendicular to the saw.Vise not perpendicular to saw.Weak saw tension.Side guides not secured properly.
G) Chips burnt through.High feed rate.Brush saw blade not working.Blunt saw.no cooling.