Properly position the blade on the metal

Metal hacksaw is a hand tool that is used for cutting profile metal and pipes. The simplest metal hacksaw consists of a machine and a hacksaw blade. The machine in its turn consists of a frame into which on one side is inserted a handle which has a device for fixation of the blade and on the other side a device for fixation and regulation of tension of the blade. The tensioning device, on one side, has a groove for inserting and fixing the blade, and, on the other side, a screw with a rammer which is used for tensioning the blade.

Hacksaw blades for metal differ in width, length, thickness, distance between teeth and their height. The use of one or another blade depends on the thickness, hardness and shape of the material that needs to be cut. Blade manufacturers made sure you have the right blade for the material you need to cut, whether it’s aluminum, copper, bronze, or even plastic. The dimensions of the blade, namely the length, width, tooth size and steel grade can be found on the hacksaw blade you buy.

How to set the blade in the metal saw?

As shown in the first picture of the article: with the teeth downward (if the blade is single sided) and the teeth pointing forward from the handle. When you saw, you apply downward and forward pressure. exactly the same way the teeth of the hacksaw should be pointed, downward and forward. To install, loosen the tensioning screw, remove the old blade from the pins, put on the new blade and tighten until the blade tinkles when your fingernail clicks. The main thing is not to over tighten and tear the blade. You will find the optimum tensioning by experimenting.

The tensioning is achieved by means of the turnbuckle on the adjuster, i.e. twisting the turnbuckle to tighten the blade. So when tensioning the hacksaw blade you need to find the golden mean. Also, make sure that the blade is positioned straight, without tilting, because tilting will result in an uneven cut during cutting.

How to saw?

Since you were wondering about setting up the blade, it doesn’t hurt to have some advice about how to use the metal trimmer blade as well. Hold the handle of the hacksaw with one hand (right hand if you are right handed or left handed if you are left handed) and with the other hand grip the vertical edge of the hacksaw arch opposite to the handle. Put the blade on the trimmer blade. Guide the blade strictly in the direction of the cut line. Keep the angle of the trimmer blade small. The blade should almost lie on the part, usually at an angle of 30-45 degrees. That way there is less vibration, less noise, and a smoother trimmer blade. Cutting across the material, at a 90 degree angle, is worthwhile only in emergency cases, for example, when turning the cut line. The flatter you need the trimmer blade to cut, the smaller the angle.

Use light pressure the first few strokes so the blade cuts into the material and does not slide sideways off the cutting line. With a smooth, forward motion, press the hacksaw against the part as you move forward, and release pressure as you return to the starting position. Once the blade grips into the material, you can work at full force.

Move as far as possible from blade edge to edge without hitting the workpiece with the arc of the hacksaw. You don’t want to “tread on the spot”. that way you will quickly erase the blade in one area and have to throw it away, because you can’t use a damaged blade. Keep the arc of the hacksaw straight, do not let it bow in different directions. Cutting direction corresponds to the arc plane of the hacksaw, so chattering is contraindicated. Also, the blade breaks easily if the hacksaw jerks to the side. The material properties of the sheet are such that it holds very well under longitudinal tensile strength, but is very brittle in the bends.

Cutting with a hacksaw on a curved line

Metal hacksaw is also valuable because it allows you to cut along almost any curve line. In order to cut in an arc without stopping the forward motion of the hacksaw, align it perpendicular to the face of the workpiece material (t.е. angle of 90 degrees) and gradually turn the arc of the hacksaw smoothly so that the blade follows the planned line. Yes, the trimmer trimmer cut line is always sure to mark anything. pencil, marker, scratch nail. The main thing is to be able to see it when you work. Turning the blade should be done as gently and smoothly as possible or it will break; turning is an extreme for a metal saw blade.

If you need to make a sharp turn, say, by 90 degrees, you will have to practically “stomp on the spot”, continuing to saw and smoothly turn the arc of the hacksaw, periodically stepping back so as not to go far from the place of turn, while using the side of the material that is external to the part to turn the blade.

To cut the inner corner, you must first drill a straight line for the trimmer with a thin drill bit longer than the width of the blade, slide the blade into this groove and cut further with a hacksaw. In general, practice will show you how to do it. Nothing complicated here.

The picture below shows another way to use a hacksaw for metal. For this method, you need to reset the blade by turning it 90 degrees.

Metal hacksaw blades

Blade for hacksaw for metal is one of the most undurable elements from whole range of consumables for tools. Of course much depends on the technology of working with metal and skills of using a hacksaw, but first of all you need to be able to make a correct choice of blade. Today, we’ll talk about the choices and types, and learn how to easily change a hacksaw blade.

Hand Hacksaw blades for metal. Home Craftsman

For cutting pipes of profile and thick sheet metal, as well as for cutting slots, grooves, trimming and cutting blanks on the contour and other works use hand or mechanical hacksaws. Manual hacksaw consists of a machine (frame) and an interchangeable hacksaw blade inserted into it. On one end of the frame there is a fixed head with a shank and a handle, and on the other end there is a movable head with a tensioning screw and a nut (wingnut) for tensioning the blade. The heads have slots in them, into which the hacksaw blade is inserted and secured with pins.

Hacksaw frames are made either in one piece (rarely for a single hacksaw blade of a certain length) or sliding, allowing the attachment of hacksaw blades of different lengths. To extend the hacksaw, the knees are bent until the rivet is out of the cutout and shifted. The rivet is inserted into the other notch, and the knees are straightened.

For work in cramped conditions and for small jobs a hacksaw with a single-sided clamp is used. As the blade in such a hacksaw is not stretched, it should be handled with care and with incomplete length. The advantages of such a hacksaw are its compact size and small dimensions, as well as the possibility to use fragments of the blade.

Hacksaw blades for hand hacksaws are thin, narrow bands with two holes and teeth on one of the ribs. Part of the blade (where the teeth are) is hardened and the opposite part is not hardened thanks to which the breakage of the hacksaw blade during working decreases. The most commonly used blades are of length 250 and 300 mm, height 13 and 16 mm, thickness 0,65 and 0,8 mm. Each tooth of the bandsaw blade has a wedge (cutter) shape with a rake angle usually equal to 0° and an angle of sharpening equal to 50°. For cutting metals we mostly use a hacksaw blade with a pitch of 1,3-1,6 mm which has 17-20 teeth on a length of 25 mm. The thicker the workpiece to be cut, the coarser the teeth should be,

and vice versa, the thinner the workpiece, the shallower the teeth of the hacksaw blade should be. For metals of different hardness blades with number of teeth are used: for soft metals. 16, for medium hardened steel. 19, for cast iron, tool steel. 22, for hard, strip and angle steel. 22.

When cutting with a hacksaw in the work at least two or three teeth simultaneously cut metal. To avoid the saw blade jamming in the metal, the teeth are set apart. When working with a set blade, the width of the cut is slightly larger (about 1.5 times larger) than the width of the blade, which makes the job much easier. The teeth can be set along the blade (wavy) and along the tooth (crimped).

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The hacksaw blade must be inserted into the slots in the heads of the hacksaw so that the teeth are oriented forward. In this case insert the end of the blade first into the fixed head until the holes are in line and secure the position by inserting the pin. Then insert the second end of the blade into the slit of the mobile head, fix it with the second pin. The blade is tightened by tightening the wing nut. The tension on the blade must not be too great otherwise the cut will be slanted and the blade will break easily. If the tension is too great the webbing can also break with the slightest twist. Check tension by turning the blade 1/8 of the way around its circumference, using two fingers in the center of the length of the blade.

When working with the hacksaw, the workpiece (or product) to be cut must be firmly clamped in a vise so that it does not shift during cutting, as this would cause breakage of the thin, brittle blade. Make sure that the hacksaw blade runs its full length. This will ensure even wear of the cutting teeth and therefore increase the durability of the blade. Start cutting with careful movements in order to get a kerf. When it is deep enough, the hacksaw is given a full swing by pressing the frame. Before the end of the cut, the tension is reduced.

A new blade in the hacksaw is first used for cutting soft metals (copper, brass, aluminum, etc.).), and when it is a little dull, for steel and cast iron.

Hold the handle with the right hand and keep the front end of the hacksaw horizontally with the left hand. Do not work with a hacksaw without a handle, as the sharp saw blade can injure the user. In this case it is necessary to press with the left hand, which is in the front, and the right hand only moves the hacksaw; when moving backwards (towards yourself) no pressure is applied, because this would cause the teeth to blunt quickly. Before the end of the forward motion the tension is reduced. The pressure on the hacksaw depends on the hardness of the metal and the size of the part to be cut (hard metals require more pressure than soft ones).

To decrease the friction of the bandsaw blade against the walls of the workpiece it must be lubricated with mineral oil.

If the tension of the blade is low or the setting is one-sided the blade can run away from the marking mark. In this case the attempt to bring the blade back to the right cutting direction by turning the hacksaw usually ends up with the blade breaking. In case the blade retracts, you should start cutting in a new place, or better, if possible start a new cut from the opposite side by turning the workpiece over. It is also not recommended to continue cutting in case of breakage of at least one tooth of the blade. Continued work with such a blade will lead to chipping of other teeth. It is best to change the blade and start cutting in a new location. When replacing the blade with a new one, keep in mind that the old, worn blade gives a narrower kerf and you must start cutting in a different place with the new blade.

When cutting solid workpieces, the kerf is long and difficult to cut, so the hacksaw must be tilted back and forth for easier work. This does not cut across the entire width and makes cutting easier.

Cut facets start at the edge not the corner. Cut strip metal along the narrow edge. Thin material is cut on a wide edge, as the teeth cling and the blade can easily break when plunge-cutting. usually a small kerf with a three-edged file is used to ease plunge cuts and guide the blade sideways with the left thumb.

Very thin material is clamped between wooden bars 15-30 mm thick and cut together with the bars.

When making a long cut the blade should be turned through 90° and you have to cut very carefully, because the own weight of the hacksaw blade breaks easily. If the saw blade is normally mounted, a narrow and long cut cannot be made because the frame prevents this from happening.

Hacksaw blades

Metal hacksaw is a hand tool that is used for cutting profile metal and pipes. The simplest metal hacksaw consists of a machine and a hacksaw blade. The machine, in its turn, consists of a frame into which on one side is inserted a handle with a device for fixing the blade, and on the other side a device for fixing and adjusting the tension of the blade. The tensioning device has on one side a groove for inserting and fixing the blade, and on the other side a screw with a ram, which is used for tensioning the blade.

Metal hacksaw blades differ in width, length, thickness, distance between teeth and their height. Which blade you use depends on the thickness, hardness and shape of the material you are cutting. Blade manufacturers make sure you have a blade just right for the material you want to cut, be it aluminum, copper, bronze or even plastics. You can find the blade dimensions, specifically the length, width, tooth size and steel grade, on the hacksaw blade you buy.

How to install a blade in a metal saw?

As shown in the first picture of the article: with the teeth downward (if the blade is one-sided) and the teeth pointing forward from the handle. When you saw, you apply downward and forward pressure. that’s how the teeth of the hacksaw must point, down and forward. To install, loosen the tensioning screw, remove the old blade from its pins, put on the new one, and tighten it until the blade tinkles like a string when you snap your finger nail. The main thing here is not to overdo it or tear the blade. Find the optimum tension by experimenting.

The tensioning is carried out with the turnbuckle on the adjuster, that is you will tighten the blade by twisting the turnbuckle. So when tensioning the hacksaw blade you need to find the golden mean. Also, make sure that the blade is set straight, without twists, because twist will cause uneven kerf while cutting.

How to saw?

Since you were wondering how to set up the blade, it doesn’t hurt to have some advice on how to use the metal saw blade. Hold the handle of the hacksaw with one hand (right hand if you are right handed or left handed if you are left handed) and with the other hand hold the vertical edge of the arc of the hacksaw opposite to the handle. Place the blade on the trimmer cutter fishing line. Guide the blade strictly in the direction of the cut line. Make the angle of inclination of the hacksaw small. The blade should rest almost flat on the workpiece, usually at an angle of 30-45 degrees. This way there will be less vibration, less noise, and a smoother cut line for the trimmer. Cutting across the material, with a 90 degree angle, is worthwhile only in urgent cases, such as when turning the cutting line. The flatter you want the trimmer blade to cut, the smaller the angle.

The first movements should be done with a little effort so that the blade cuts into the material and does not slide sideways away from the cutting line. Make smooth, forward movements, press the hacksaw against the material as you move forward and release pressure as you return to the starting position. When the blade grips the material. you can work with all your might.

Move as much as possible from blade edge to edge without hitting the workpiece with the arc of the hacksaw. There is no need to tread on the spot. this way you will quickly erase the blade in one area and have to throw it away, because it is impossible to use a defective blade. Keep the arc of the hacksaw straight and do not let it drop to either side. Cutting direction corresponds to the arc plane of the hacksaw, so chattering is contraindicated here. Also, the blade will break easily if the hacksaw jerks to the side. The material properties of the blade are such that it holds very well under longitudinal tensile stress, but is very brittle in flexure.

Cutting with a hacksaw on a curved line

The metal saw is also valuable in that it allows you to make a cut in almost any curved line. In order to cut along the arc, without stopping the forward motion of the hacksaw, align it perpendicular to the face of the workpiece material (t.е. angle of 90 degrees) and gradually turn the arc of the hacksaw smoothly so that the blade follows the planned line. Yes, the trimmer trimmer line cut is always sure to mark with anything. pencil, marker, scratch nail. The main thing is to be able to see it when you work. Turning the blade must be done as gently and smoothly as possible or it will break; turning is an extreme for a metal saw blade.

If you need to make a sharp turn, say 90 degrees, you will practically have to stomp on the spot. while continuing to saw and smoothly turning the arc of the hacksaw, periodically stepping back so as not to go far from the place of turning, while using the side of the material that is external to the workpiece to turn the blade.

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To cut the inside corner, you must first drill a straight line for the trimmer with a thin drill bit longer than the width of the blade, slide the blade into this groove and cut further with the hacksaw. Well, practice will tell you how to do it. Nothing complicated here.

The figure below shows another way to use a metal hacksaw. For this method you need to reset the blade by turning it 90 degrees.

Metal hacksaw blades

Hacksaw blade for metal is one of the most short-lived elements of the entire range of consumables for tools. Of course much depends on the technology of work with metal and the skill of using a hacksaw, but first of all it is necessary to know how to choose the right saw blade. Today, we will talk about the choice and types, and also learn how to change hacksaw blades with ease.

Types of hacksaw blades

GOST R 53411-2009 “Metal hacksaw blades” establishes two types of such tools. for machine and manual cutting. The first we will not touch, and the latter are available in three basic sizes:

  • Single, with a distance between the fastening holes 250±2 mm, with a total length of the cloth not exceeding 265 mm;
  • Single, with a distance between the fixing holes of 300±2 mm, with a total length of the blade not exceeding 315 mm;
  • Double, with the distance between the fixing holes 300 ± 2 mm, with a total length of the blade not more than 315 mm.

In this case, the thickness of the leaf s single version. 0,63 mm, double. 0,80 mm. Height with single row of teeth is 12,5 mm, and with double row. 20 mm.

GOST also regulates the teeth pitch P, mm and their quantity z which are 0,80/32, 1,00/24 and 1,25/20 respectively for the first type of blades. Owners of “longer” hacksaw blades can also take advantage of hacksaw blades with the parameters 1.40/18 and 1.60/16.

According to the grade of the material used for the production of hacksaw blades for metal, they are made of tool steels:

Range of Russian-made hacksaw blades is limited by this fact, but specialized trading networks have widely spread so called diamond blades with surface spraying by titanium nitrides or other high-temperature metals. Such blades can be easily distinguished by their color: usual steel blades are dark gray, and sprayed blades can have different coloring. from bright orange to blue (depending on manufacturer).

There are also blades with a so-called tungsten-carbide coating, but they are extremely sensitive to bending stresses despite their very high hardness. Therefore, when cutting metal, their durability is insignificant.

High durability of metal saw blades is ensured by proper heat treatment. On blade surface we distinguish two zones with different hardness values: directly by the teeth it ranges from HS 6467 for alloy tool steels to HS 7378. for high-speed steels (for diamond blades this parameter reaches HS 8284), and in other zone. HS 4446. Considerable difference in hardness confirms high sensitivity of the product to bending stresses, therefore the standard limits the maximum force applied to the hand hacksaw as well. It should not exceed 60 kg for blades with a tooth pitch less than 1.4 mm and 10 kg for blades with a tooth pitch greater than 1.4 mm.

Types of cutter blades

GOST R 53411-2009 “Metal hacksaw blades” specifies two types of such tools. for machine and hand cutting. We will not touch the first ones, and the 2nd ones are available in three main sizes:

  • Single, with a distance between the fastening holes 250±2 mm, with a total length of the blade less than 265 mm;
  • Single, with the distance between the fixing holes 300 ± 2 mm, with a total length of the blade less than 315 mm;
  • Double, with the distance between the fixing holes of 300±2 mm and a total length of the blade of less than 315 mm.

By all this the thickness of blade s of single execution is 0,63 mm, double. 0,80 mm. The height with a single row of teeth is 12.5 mm and with a double row of teeth 20 mm.

GOST also regulates the pitch of teeth P, mm and their quantity z which for the first type are 0,80/32, 1,00/24 and 1,25/20 respectively. Owners of “longer” hacksaw blades, apart from those mentioned above, can also use hacksaw blades with the parameters 1.40/18 and 1.60/16.

According to the grade of material used for the production of hacksaw blades for metal, created from tool steels:

That is the only range of Russian-made hacksaw blades, but specialized retail chains has widely spread so called diamond blades with surface spraying by titanium nitrides or other high-temperature metals. Such blades can be simply distinguished by their color: ordinary iron blades are dark gray, and sprayed blades can have different colors. from bright orange to blue (depending on the manufacturer).

There are also blades with so-called tungsten-carbide coating, but they are very sensitive to bending stresses despite their very high hardness. That is why their durability is negligible when cutting metal.

The highest durability of metal saw blades is ensured by an appropriate thermal treatment. Two zones with different hardness values are distinguished on the surface of the blade: specially for teeth it ranges from НRС 6467 for alloy tool steels to НRС 7378. for high-speed steels (this parameter reaches НRС 8284 for diamond blades), and in the other zone. НRС 4446. Significant hardness difference confirms the higher sensitivity of the product to bending stress, so the benchmark is also limited and the greatest effort applied to hand hacksaw. it should not exceed 60 kg when working with blades with tooth pitch less than 1,4 mm and 10 kg for blades with tooth pitch over 1,4 mm.

Using a tool. patience and work will get the job done!

Metal hacksaws do not require any special skills in operation. All you have to do is keep an eye on the condition of the blade and change it in time. By the way, the tool, because of the small teeth, is suitable for work not only with metal, it will also show itself perfectly in. Plastic, chipboard, PVC, laminate, and even ceramic and plexiglass. That way you get a fairly straight cut edge.

The biggest difficulty that beginners face when cutting metal and other materials with a metal hacksaw is the wiggling of the blade from side to side. If this happens, check your fasteners. wiggling might mean the thumbscrews aren’t tight enough. By the way, do not rely on the effort of your hands alone. use at least pliers to increase pressure. Unlike a joiner’s hacksaw you will not be able to sharpen the blade after it has blunted, you will only have to replace it with a new one.

setting, blade, metal, hacksaw

Clamp the blade with the teeth down and away from the handle. Tension the blade during its change so that the slightest blow makes it jingle like a string. Take care not to overdo it!

The optimum tensioning can only be found experimentally. The blade of the hacksaw must rest on the workpiece when you work. Work at an angle of up to 45°. so you get less vibration and noise, and the cut will be smooth. You should not put too much pressure on the blade the first time you move it. excessive force is useless, the blade will just start sliding around. Increase pressure on forward movements, do not use any pressure at all when returning the saw to its initial state. And when the blade has cut a good edge you may work with all your might.

Blade for metal hacksaw. How to choose and install? |

Hacksaw blade for metal is one of the most nondurable elements in the whole range of consumables for tools. Of course much depends on the technology of work with metal and the skill to use a hacksaw, but first of all you need to be able to make the right choice of blade. Today, we will talk about the choice and types, as well as learn how to easily change a hacksaw blade.

Types of hacksaw blades

GOST R 53411-2009 “Metal hacksaw blades” specifies two types of such tools. for machine and hand cutting. We will not touch the first ones, and the latter are produced in three basic sizes:

  • Single, with the distance between the fixing holes 250±2 mm, with a total length of the blade not more than 265 mm;
  • Single, with a distance between the fixing holes of 300±2 mm, with a total length of the blade not exceeding 315 mm;
  • double, with the distance between the fixing holes 300±2 mm, with a total length of the blade not more than 315 mm.

Herewith the thickness of single version blade s is 0,63 mm, double version. 0,80 mm. The height with a single row of teeth is 12.5 mm, and with a double row of teeth it is 20 mm.

GOST also regulates the values of tooth pitch P, mm and their number z, which are 0.80/32, 1.00/24 and 1.25/20 respectively for the first type blades. Owners of “longer” hacksaw blades can also use the 1.40/18 and 1.60/16 hacksaw blades in addition to the above mentioned ones.

According to the grade of material used for the production of hacksaw blades for metal, they are made of tool steels:

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Range of Russian-made hacksaw blades is limited by this fact, but specialized trading networks have widely spread so-called diamond blades with surface spraying of titanium nitrides or other high-temperature metals. Such blades can be easily distinguished by their color: standard steel blades are dark gray, and sprayed blades may have different coloring. from bright orange to blue (depending on manufacturer).

There are also blades with the so-called tungsten-carbide spraying, but they are extremely sensitive to bending stresses despite their very high hardness. Therefore when cutting metal their durability is insignificant.

High durability of metal saw blades is ensured by appropriate heat treatment. Two zones with different hardness values are distinguished on the blade surface: directly at the teeth it ranges from НRС 6467 for alloy tool steels to НRС 7378. for high-speed steels (for diamond blades this parameter reaches НRС 8284), and in the rest zone. НRС 4446. Significant hardness difference confirms the high sensitivity of the product to bending stresses, so the standard also limits the maximum force applied to the hand hacksaw. It must not exceed 60 kg when working with blades with tooth pitch less than 1,4 mm and 10 kg for blades with tooth pitch over 1,4 mm.

Principles of blade selection

The durability of the hacksaw blade is also affected by the quality of the coating. For domestic tools, the most common coating is Chem.Ox.Prm., less common are tools with nitro enamel coating like HC-25 or HC-132. Keep in mind that under prolonged stress, when the saw heats up, the enamel can give cracks.

While choosing qualitative hacksaw blades it is necessary to pay attention to the evenness of tooth pitch: in qualitative products this parameter must not exceed 45% of the pitch of the teeth at the length of 10 mm. Quality of the product can be estimated by the parameter of equal height of the teeth: difference in the adjacent peaks must not exceed 0,100,15 mm, what is checked with the help of micrometer or depth gauge.

How to mount a blade on a metal saw?

The mounting method is determined by the design of the mounting system on the hacksaw itself. In the case of a threaded clamp, the saw blade is put on the corresponding tab, slightly tightened, and then secured with a wing nut. With sudden changes in the load on the hacksaw such a fastening will have to be checked periodically. With hacksaw blades with a lever-arm type device simplifies installation and replacement: simply pull out the lever on the opposite side to the handle of the hand saw, put the blade on, and return the lever to its original position.

When properly tightened, the blade should make a slight buzzing sound and vibrate slightly. When working, such blades must not change their direction of travel under load.

For single-sided blades it is important to position the blade in the correct direction. Their inclination must be away from the handle. Most workers make the main working movement in the direction from themselves, when the metal cut is performed. Reverse motion is designed only to return the hacksaw to its original position. When attempting to cut metal and while idling, a tooth geometry unadapted to such stresses will pull the tooth away from the base, and the blade may break as a result. This phenomenon is particularly characteristic of diamond blades.

Recently so-called bimetal blades (designation. BIM) have become popular when a strip of high-speed steel is welded on the main band of hardened constructional steel like steel 45. Quality has a major issue here: the metal grade of Chinese-made saw blades is most often not guaranteed (nor is the quality of the welding), so when working with hard metal it is not uncommon for bimetal blades to delaminate.

Hacksaw Blade for Metal. How to choose and install? |

Metal hacksaw blades are one of the most nondurable items in the tool’s consumable range. Of course much depends on the technology of work with metal and the skill to use a hacksaw, but first of all you need to be able to make the right choice of blade. Today, we will talk about the choice and types, and learn how to easily change hacksaw blades.

Types of hacksaw blades

GOST R 53411-2009 “Metal hacksaw blades” establishes two types of such tool. for machine and manual cutting. We will not touch the first ones, but the latter are produced in three basic sizes:

  • Single, with the distance between the fastening holes 250 ± 2 mm, with a total length of the leaf not more than 265 mm;
  • Single, with the distance between the fixing holes 300±2 mm, with a total length of the blade not more than 315 mm;
  • Double, with the distance between the attachment holes 300±2 mm, for total length of blade not more than 315 mm.

In this case, the thickness of the web s single version. 0.63 mm, double. 0.80 mm. Single tine row is 12.5 mm in height, double tine row is 20 mm.

GOST also regulates the pitch of teeth P, mm and their quantity z, which for the first type of blades are respectively 0,80/32, 1,00/24 and 1,25/20. Owners of more “long” hacksaws, in addition to the above, can also use hacksaw blades with parameters 1,40/18 and 1,60/16.

According to the grade of material used for the production of hacksaw blades for metal, they are made of tool steels:

Range of Russian-made hacksaw blades is limited by this fact, but in specialized trading networks so-called diamond blades with surface spraying by titanium nitrides or other high-temperature metals are widely spread. Such blades can be distinguished very easily by their color: ordinary steel blades are dark gray, but the sprayed blades can have different colors from bright orange to blue (depending on the manufacturer).

Blades with so-called tungsten-carbide coating are also common, but although very hard, they are extremely sensitive to bending stress. Therefore, their durability when cutting metal is negligible.

High durability of metal cutter blades is ensured by an appropriate heat treatment. On the blade surface there are two zones with different hardness values: directly near the teeth it ranges from HS 6467 for alloy tool steels to HS 7378. for high-speed steels (for diamond blades this parameter reaches HS 8284), and in other zone. HS 4446. Considerable hardness difference confirms high sensitivity of the product to bending stresses, therefore the standard also limits the maximum force applied to a hand hacksaw. It must not exceed 60 kg when working with blades with tooth pitch less than 1.4 mm and 10 kg for blades with blade pitch over 1.4 mm.

Principles of blade selection

Durability of hacksaw blades is also influenced by the quality of coating. For domestic tools, the more common coating is Chem.Ox.Prm., the tools with nitro enamel coatings like NTs-25 or NTs-132 are encountered less often. It should be remembered that the enamel can crack under prolonged loads when the saw is heated.

When choosing a high-quality hacksaw blade you should pay attention to the evenness of tooth setting: in high-quality products this parameter must not exceed 45% of the pitch of the teeth on a length of 10 mm. Product quality can be estimated also by the parameter of equal height of the teeth: the difference in the adjacent tops must not exceed 0,10 0,15 mm, which is checked by means of micrometer or depth gauge.

How to mount the blade on a hacksaw for metal?

The method of installation is determined by the design of the mounting system on the hacksaw itself. In the case of the threaded clamp, the saw blade is put on the corresponding tab, slightly tightened, and then secured with a wing nut. Such fasteners have to be checked periodically if the load on the hacksaw changes sharply. With hacksaws that have a lever-type device, the installation and replacement process is simplified: simply pull out the lever, located on the side opposite to the handle of the hacksaw, put on the blade, and return the lever to its original position.

When properly tightened the blade should make a slight ringing and slightly vibrating noise. When working such a blade should not change its direction of travel under load.

For single sided blades it is important to position the teeth in the correct direction. Their inclination should be away from the handle. Most workers make their main work movement away from themselves, which is when they cut the metal. Reverse motion is intended only for returning the hacksaw to its original position. When attempting to cut metal and while idling, tooth geometry unadapted to such loads will pull the tooth away from the base, and the blade may break as a result. This phenomenon is especially common with diamond blades.

Recently so-called bimetal blades (designation. BIM) have become popular, when a high-speed steel strip is welded on the basic band of hardened constructional steel like steel 45. Quality has everything to do with it: the metal grade of Chinese-made saw blades is most often not guaranteed (and neither is the quality of the welding), so when working with hard metal it is not uncommon for bimetal blades to delaminate.

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