Cutting metal with a hacksaw - cutting metal. Cutting metal with a hacksaw - Knowledge Hypermarket List the rules for safe work with a hacksaw

The blade is inspected, paying attention to the absence of cracks, bends, and also to the set of teeth.

Check the serviceability of the frame (body) of the hacksaw: tight fit of the handle, free rotation of the wing nut, movement of the sliding part and tension pin, the presence of pins.< >Install the sliding part of the hacksaw according to the size of the blade, leaving the pin extended for tension by 10-12 mm. Install the blade in the slot of the heads so that the teeth are directed away from the handle (Fig. 74). At the same time, the end of the web is inserted first in the fixed head until the holes coincide and the position is fixed with a pin tab. Then insert the second end of the web into the slot of the movable pin and fix it with a pin. Pull the web, screw the wing nut without much effort, without resorting to pliers, a vice and other tools

Rice. 75. Position of hands when working with a hacksaw

Stand at the vise when cutting with a hacksaw should be straight, free and stable, half-turned in relation to the vise jaws. The left (supporting) leg must be set slightly forward.

The instructor demonstrates the correct holding of a manual hacksaw in three steps; 1) take the hacksaw in the right hand so that the handle rests on the palm (Fig. 75, a); 2) the handle is covered with four fingers, overlaying thumb on the handle from above (Fig. 75, b); 3) fingers of the left hand take rake angle hacksaw blade, lamb and tension bolt (Fig. 75, rff.

The hacksaw blade is installed on a wide plane of a wooden block, creating at the beginning of cutting a slight downward slope of the front of the hacksaw. To obtain the exact direction of cutting according to the markup, it is necessary to put the nail of the thumb of the left hand at the risk, firmly press the hacksaw blade against it (Fig. 76, a), and right hand to carry out cutting (Fig. 76, b). Continuing to cut cutting edge canvases are gradually transferred to a horizontal position (Fig. 76, c).

Rice. 76. Work with a manual hacksaw: a - installation of a hacksaw blade at risk; b - acceptance of work at the beginning of the cut; in the reception of work in the cutting process

Movements when working with a hacksaw should be smooth, without jerks and on such a scale that all the teeth of the blade participate in the cutting. The rate of movement when cutting with a hacksaw should be 30-60 strokes per minute. When finishing cutting, you should loosen the pressure on the hacksaw, reduce the pace of movements in order to avoid breaking the blade and injuring your hands. After finishing work, the hacksaw, turned by the blade to the vise, is placed on a workbench with right side vise.

When cutting a metal bar square section first mark the place of cutting, for which they measure the length of the workpiece with a measuring ruler, applying risks with a scriber. After that, using a square with a wide base, risks are drawn on the upper and two sides of the square. Next, the bar is clamped in a vice so that the risk is located on top.

Rice. 77. The position of the hacksaw blade at the initial cutting of workpieces various profiles: a - round; b - square; c - rectangular; g - pipes; d - angular

To preserve the teeth of the blade, cutting begins at the back edge of the part, tilting the hacksaw away from itself until the beginning of the cut is formed with low pressure (Fig. 77, b). The slope is gradually reduced until the cut reaches the leading edge and the hacksaw blade takes a horizontal position. In this position, increase the pressure on the hacksaw, continuing to cut the bar

Cutting metal with a manual hacksaw without turning the blade

For cutting metal bars of circular cross section, the cutting points are marked with a scriber. The bar is clamped horizontally in a vice, extending the cut end to the left side of the vise jaws so that when working with a hacksaw, its head does not touch side surface vise. If the cutting plane is too far from the vise jaws, the bar will vibrate when cutting, making it difficult to cut. The bar must be secured in a vise securely.

On the workpiece (at risk), a small cut is made with a trihedral file so that the hacksaw blade at the beginning of cutting does not slide over the surface of the bar. Then they take a hacksaw, take working position, lubricate the canvas with boiled oil with a brush, insert the cutting edge of the hacksaw blade into the cut and start cutting (Fig. 77, a).

At the beginning of cutting, the pressure on the hacksaw blade should be less, and as the blade approaches the center of the bar, the pressure is increased.

During cutting, the hacksaw blade sometimes "leads" to the side, this creates an oblique slot (due to the weak tension of the blade or the incorrect position of the hacksaw and its direction). If the blade has "pulled" to the side, it is necessary to turn the bar and start cutting g of the opposite side opposite the slot. At the end of the cut, you need to loosen the pressure on the hacksaw and reduce the pace of movement.

to the end using the entire length of the hacksaw blade and all the time controlling the position of the blade and its direction in relation to the risk. At the end of the cut, the pressure is released.

Cutting strip metal(Fig. 77, c), as a rule, should be performed on the narrow side of the strip, provided that the cutting is performed by at least three teeth of the hacksaw blade. The fewer teeth are simultaneously involved in the work, the less pressure on the hacksaw blade.

Cutting workpieces with a thickness less than the pitch of the teeth of the blade should be carried out with a hacksaw in vertical position, with a slight pressure on the tool. In this case, you need to work with a hacksaw slowly using the entire length of the hacksaw blade.

When cutting pipes, the cutting points are marked using a template. The template is made of thin tin, curved around the circumference of the pipe.

A measuring ruler from the end of the pipe marks the length of the segment. The edge of the template is brought to the mark, applied with a scriber to the risk along the entire

pipe circumference.

For cutting, the pipe is clamped horizontally in a vise. To avoid crushing the pipe, it is clamped in gaskets (Fig. 77, e) For cutting, a blade with fine teeth (tooth pitch 1 mm) is selected, a cut is made with a trihedral file at risk and cutting is started. As the hacksaw blade deepens into the pipe wall, the hacksaw is slightly tilted towards itself. Having cut the pipe to the thickness of the wall, take out the hacksaw, turn the pipe away from itself by 45-60 ° and continue cutting, combining the rotation of the pipe with cutting along the entire circumference of the pipe. The rate of movement when cutting pipes should be 35-45 strokes per minute with little pressure on the hacksaw. At the end of the cut, the pressure on the hacksaw must be loosened.

Before cutting the corner, it is marked on the planes of the shelves. The corner shelf must be installed in a vice (Fig. 77, e). The corner must be cut along the narrow edge of the shelf, where less cutting force is required. Therefore, cutting will be much easier.

Having cut through the first shelf to the inner plane of the second shelf, the angle is set to the cutting position of the first shelf, continuing cutting to the end. At the end of the cut, it is necessary to loosen the pressure on the hacksaw.

The correctness of the cut is checked with a ruler, and the angle of 90 ° - with a square.

Cutting metal with a manual hacksaw with a turn of the blade

Rice. 78. Techniques for cutting metal with a manual hacksaw with a turn of the hacksaw blade

The work is performed in the following sequence:

1. Marking is done in the usual way.
2. The hacksaw is prepared for work, and the quality of the blade and its suitability for work are checked.
3. The blade in the side slots of the heads must be installed perpendicular to the plane of the hacksaw (the teeth are directed away from the handle); then you should lay the pins in the hole and stretch the canvas.
4. Install the workpiece and clamp it in a vice from the side, extending the cut cut so that during vertical cutting the head of the hacksaw does not touch the side surface of the vice and does not interfere with the movement of the hands. In addition, the workpiece must be slightly elevated above the level of the vise jaws, otherwise the workpiece will vibrate during cutting. When cutting, it is necessary to follow the direction of the blade, keeping the plane of the hacksaw in a horizontal “position.

The movement of the hacksaw should be performed smoothly, without jerking, avoiding warping of the blade, as this can lead to its removal or breakage.

As the metal is cut, the workpiece must be moved higher to continue cutting (Fig. 78), reducing the rate of movement and the pressure on the hacksaw at the end of the cut.

The size of the cut workpiece is checked according to the marked risks.

1. Before starting work, it is necessary to check the correct installation and tension of the blade.

2. The marking of the cutting line must be made along the entire perimeter of the bar (strips, parts) with an allowance for subsequent processing of 1 ... 2 mm.

3. The workpiece should be firmly fixed in a vise.

4. Strip and corner material should be cut at the wide end.

5. In the event that the length of the cut on the part exceeds the size from the blade to the frame of the hacksaw, cutting must be done with a blade fixed perpendicular to the plane of the hacksaw (hacksaw with a turned blade).

6. Sheet material should be cut directly with a hacksaw if its thickness is greater than the distance between the three teeth of the hacksaw blade. More thin material for cutting it is necessary to clamp in a vise between wooden blocks and cut with them.

7. Gas or water pipe must be cut, fixing it in the pipe clamp. When cutting thin-walled pipes, fix them in a vice using profiled wooden spacers.

8. When cutting, the following requirements must be observed:

At the beginning of cutting, tilt the hacksaw away from you by 10 ... 15 °;

While cutting, hold the hacksaw blade in horizontal position;

In work, use at least three quarters of the length of the hacksaw blade;

Perform working movements smoothly, without jerks, approximately 40 ... 50 double strokes per minute;

At the end of cutting, loosen the pressure on the hacksaw and support the cut part with your hand.

9. When checking the size of the cut off part according to the drawing, the deviation of the cut from the marking line should not exceed 1 mm to the greater side.

Labor safety rules

1. Do not cut with the blade too loose or too tight, as this may break the blade and injure your hands.

2. To avoid breaking the blade and injuring your hands when cutting, do not press the hacksaw hard down.

4. When assembling the hacksaw, use pins that fit tightly, without pitching, into the holes of the heads.

5. If the teeth of the hacksaw blade are chipped, stop work and replace the blade with a new one.

6. To prevent the handle from jumping off and injuring the hands during the working movement of the hacksaw, do not hit the front end of the handle on the part being cut.

Basic rules for cutting sheet metal up to 0.7 mm thick with hand shears

1. When marking the cut out part, it is necessary to provide for an allowance of up to 0.5 mm for subsequent processing.

2. Cutting should be done with sharpened scissors in gloves.

3. Place the sheet to be cut strictly perpendicular to the blades of the scissors.

4. At the end of the cut, the scissors should not be completely brought together to avoid tearing the metal.

5. It is necessary to monitor the condition of the axis-screw of the scissors. If the scissors begin to "crumple" the metal, you need to slightly tighten the screw.

6. When cutting material with a thickness of more than 0.5 mm (or when pressing the handles of the scissors is difficult), one of the handles must be firmly fixed in a vise.

7. When cutting a curved part, such as a circle, the following sequence of actions must be observed:

Mark the contour of the part and cut the workpiece with a straight cut with an allowance of 5 ... 6 mm;

Cut out the part according to the markup by turning the workpiece clockwise.

8. Cutting should be done exactly along the marking line (deviations are allowed no more than 0.5 mm). The maximum value of "gouge" in the corners should not be more than 0.5 mm.

Basic rules for cutting sheet and

strip material with lever shears

1. Cutting must be done with gloves to avoid cuts to the hands.

2. Cutting a significant size sheet material(more than 0.5 × 0.5 m) should be done by two people (one should support the sheet and move it in the direction “away from you” along the lower knife, the other should press the scissors lever).

3. During operation, the cut material (sheet, strip) must be placed strictly perpendicular to the plane of the movable knife.

4. At the end of each cut, do not bring the knives to full compression in order to avoid "tearing" the material being cut.

5. After finishing work, it is necessary to fix the scissors lever with the fixing pin in the lower position.

Basic rules for cutting pipes with a pipe cutter

1. The cut line should be marked with chalk around the entire perimeter of the pipe.

2. The pipe must be firmly secured in a pipe clamp or vise. Fixing the pipe in a vice must be done using profile wooden spacers. The cutting point should be located no further than 80 ... 100 mm from the clamping jaws or vise.

3. During the cutting process, the following requirements must be observed:

Lubricate the cut;

Make sure that the handle of the pipe cutter is perpendicular to the axis of the pipe;

Pay close attention to cutting discs located exactly, without skew, along the cut line;

Do not apply great effort when turning the screw of the pipe cutter handle to feed the cutting discs;

At the end of the cut, support the pipe cutter with both hands; make sure that the cut piece of pipe does not fall on your feet.

Power tools and cutting equipment

metals

Mechanization of work when cutting materials is carried out in two ways: using a mechanized hand tool and through the use of stationary equipment.

Hand power tool

Hacksaw(Fig. 2.62) is effective when cutting materials at the locksmith's workplace. It consists of a housing 2, which houses an electric motor. A drum 7 is installed on the motor shaft, in the spiral groove of which a pin 3 enters, connected to the slider 4. A hacksaw blade 6 is fixed on the slider. When the drum rotates, the hacksaw blade receives a reciprocating motion and cuts the metal. During operation, the hacksaw rests on the bracket 5 and is supported by the handle.

Manual electrovibrating scissors(Fig. 2.63) provide cutting of sheet steel up to 2.7 mm thick. They consist of a housing 3, in which an electric motor is mounted, and a cutter head housing 2. The motor drives the eccentric roller 1 through a worm pair. The lower knife 5 is attached to the bracket 4. During operation, the connecting rod 9, reciprocating, causes the knife lever 7 with the upper knife 6 to swing, providing cutting of the metal. The gap between the knives is adjusted by moving the bracket 4 in the crankcase of the cutter head. The size of this gap depends on the thickness of the material being cut.

Cutting metal with a hacksaw

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metal cutting

Cutting metal with a hacksaw

A hand saw (saw) is a tool designed for cutting thick sheets of strip, round and shaped metal, as well as for cutting slots, grooves, trimming and cutting blanks along the contour and other works. A manual locksmith's saw consists of a machine (frame) and a hacksaw blade. At one end of the frame there is a fixed head with a shank and a handle, and at the other end there is a movable head with a tension screw and a nut (lamb) for tensioning the web. The heads have slots into which the hacksaw blade is inserted and fastened with pins.

Frames for hacksaws are made either solid (for a hacksaw blade of one specific length) (rarely), or sliding, allowing the fastening of a hacksaw blade of various lengths.

To expand the hacksaw, the knees are bent until the rivet comes out of the cutout, and displaced. The rivet is inserted into another cutout, and the knees are straightened.

The machine with a mobile holder consists of a square with a handle, along which the holder can be moved and fixed in the desired position.

Rice. 1. Crank sheet shears with inclined blades

The hacksaw blade is a thin and narrow steel plate with two holes and teeth on one of the ribs. Cloths are made of steel grades: U10A, R9, X6VF, their hardness is HRC 61 -64. Depending on the purpose, hacksaw blades are divided into manual and machine. The canvas is inserted into the frame with the teeth forward.

The size (length) of a manual hacksaw blade is determined by the distance between the centers of the pin holes. Most often, hacksaw blades are used for hand saws with a length L - 250 - 300 mm, a height b - 13 and 16 mm, a thickness h - 0.65 and 0.8 mm.

Each tooth of the hacksaw blade has the shape of a wedge (cutter). On the tooth, as well as on the incisor, there is a rear angle, a, a sharpening angle (3, a front angle y and a cutting angle of 5. a + p + y \u003d 90 °; a + p \u003d 5.

The working conditions of the hacksaw blade are different from the working conditions of the cutter, so the angle values ​​​​are different here. When cutting metal of large width, cuts of considerable length are obtained, in which each tooth of the blade removes chips that look like a comma. This chip must be placed in the chip space until the point of the tooth exits the kerf. The size of the chip space depends on the size of the back angle a, the front angle y and the pitch S of the tooth.

Rice. 2. Manual locksmith's saw (machine): a - one-piece, b - sliding, c - with a movable holder, d - hacksaw blade; 1 - wing nut, 2 - frame (machine), 3 - movable head, 4 - hacksaw blade, 5 - fixed head, 6 - shank with handle, 7 - pins, 8 - slots, 9 - tension screw, 10 - movable brace

Depending on the hardness of the metal being cut, the front angle of the teeth of the hacksaw blade can be zero, positive or negative.

The cutting performance of a hacksaw blade with a zero rake angle is lower than blades with a rake angle greater than 0°.

For cutting more hard materials blades are used, in which the angle of sharpening of the teeth is greater, for cutting soft materials taper angle is smaller. Cloths with a large angle of sharpening are more wear-resistant.

For cutting metals, they mainly use hacksaw blades with a pitch of 1.3 -1.6 mm, in which there are 17 - 20 teeth on a length of 25 mm. The thicker the cut workpiece, the larger the teeth should be, and vice versa, the thinner the workpiece, the finer the teeth of the hacksaw blade should be. For metals of different hardness, blades with a number of teeth are used: soft metals - 16, medium hardness hardened steel - 19, cast iron, tool steel - 22, hard, strip and angle steel - 22.

When cutting hand saw at least two or three teeth should participate in the work (simultaneously cut metal). To avoid jamming (pinching) of the hacksaw blade in metal, the teeth are bred.

The setting of the teeth of the hacksaw blade is done so that the width of the cut made by the hacksaw is slightly more thickness canvases. This prevents the blade from jamming in the section and greatly facilitates the work.

Rice. 3. Elements of a hacksaw blade tooth: a - hacksaw blade teeth; front angle of the teeth: b - positive, c - zero, r - negative; d- step

Rice. 4. Installation of the hacksaw blade: a - correct, b - incorrect, c - blade tension

Depending on the size of the step S, the wiring is done along the canvas and along the tooth.

Hacksaw blades with a tooth pitch of 0.8 mm (also allowed for a pitch of 1 mm) must have a set of teeth along the blade (wavy), i.e., every two adjacent teeth are bent in opposite directions by 0.25 - 0.6 mm. The setting is performed at a height of no more than twice the height of the tooth. The wiring step is taken equal to 8S.

A blade with a tooth pitch of more than 0.8 mm is bred along the tooth (corrugated divorce). With this divorce, with a small tooth pitch, two or three teeth are retracted to the right and two or three to the left. With an average step, one tooth is taken to the left, the second - to the right, the third - is not taken away. With a large step, one tooth is taken to the left, and the second to the right. Tooth setting is used for blades with a pitch of 1.25 and 1.6 mm.

The wiring of the hacksaw blade should end at a distance of no more than 30 mm from the end.

Preparing to work with a hacksaw. Before working with a hacksaw (hacksaw), the material to be cut is firmly fixed in a vise. The level of fastening of the metal in the vise must correspond to the growth of the worker. Then a hacksaw blade is selected, in accordance with the hardness, shape and size of the metal being cut.

For long cuts, hacksaw blades with a large tooth pitch are taken, and for short cuts, with a fine tooth pitch.

The hacksaw blade is installed in the slot of the head so that the teeth are directed away from the handle, and not towards the handle. In this case, the end of the web is first inserted into the fixed head and the position is fixed by laying the pin, then the second end of the web is inserted into the slot of the movable pin and fixed with a pin. The web is tensioned manually without much effort (it is forbidden to use pliers, a vice, etc.) by turning the wing nut. At the same time, because of the fear of breaking the blade, the hacksaw is kept away from the face.

A tightly stretched blade with a slight skew and a loosely stretched blade with increased pressure create a kink in the blade and can cause a break. The degree of web tension is checked by lightly pressing the finger on the web from the side: if the web does not bend, the tension is sufficient.

The position of the worker's body. When cutting metal with a hand saw, they stand in front of the vise straight, freely and steadily, half-turned in relation to the jaws of the vise or the axis of the workpiece. The left leg is somewhat put forward, approximately along the line of the cut object, and the body is supported on it. The feet are placed so that they form an angle of 60 - 70 ° with a certain distance between the heels.

Hand position (grip). The posture of the worker is considered correct if the right hand with a hacksaw mounted on the vise jaws (in its original position), bent at the elbow, forms a right angle (90 °) between the shoulder and elbow parts of the arm (Fig. 121, a).

The handle (handle) is grasped with the right hand so that the handle rests against the palm (Fig. 5, b). The handle is clasped with four fingers, the thumb is placed on top along the handle. The fingers of the left hand wrap around the nut and the movable head of the hacksaw.

When cutting with a hacksaw, as well as when filing, strict coordination of efforts (balancing) must be observed, which consists in the correct increase in hand pressure. The movement of the hacksaw must be strictly horizontal. They press the machine with both hands, but the greatest effort is made with the left hand, and with the right hand they mainly carry out the reciprocating movement of the hacksaw.

The cutting process consists of two steps:
- working, when the hacksaw moves forward from the worker, and idle, when the hacksaw moves back towards the worker. When idling, the hacksaw is not pressed, as a result of which the teeth only slide, and during the working stroke, light pressure is applied with both hands so that the hacksaw moves in a straight line. When working with a hacksaw, the following rules must be followed: short workpieces are cut along the widest side. When cutting rolled corner, tee and channel profiles, it is better to change the position of the workpiece than to cut along the narrow side;
- the entire hacksaw blade should be involved in the work;
- work with a hacksaw slowly, smoothly, without jerking, making no more than 30-60 double strokes per minute (hard steel - 30-40, medium hard steel - 40 - 50, mild steel - 50-60).

Rice. 5. Position at work: b - right hand, c - left hand, a - body and hacksaw d - legs

At faster rates, fatigue sets in more quickly and, in addition, the canvas heats up and dulls faster:
- before the end of the cut, the pressure on the hacksaw is weakened, since with strong pressure the hacksaw blade abruptly jumps out of the cut, hitting the vise or the part, as a result of which it can cause injury;
– when cutting, do not allow the blade to heat up. To reduce the friction of the blade against the walls in the cut, the parts are periodically lubricated with mineral oil or graphite grease, especially when cutting viscous metals;
- brass and bronze are cut only with new blades, since even slightly worn teeth do not cut, but slide;
- in the event of a breakage or chipping of at least one tooth, work is immediately stopped, the remains of a broken tooth are removed from the cut, the blade is replaced with a new one or two or three adjacent teeth are grinded on the machine and then work continues.

Rice. 6. Cutting with a hacksaw for deep cuts: a - without turning the blade, b - with turning the blade by 90 °, c - work in closed loop, d - the position of the fingers of the left hand

>>Technology:Cutting metal with a hacksaw

Billets from long products are cut with a hacksaw (Fig. 67). The main parts of the hacksaw are a one-piece frame 2 (it can also be detachable, as in Fig. 68), a hacksaw blade 4 and a shank with a handle 6.
The hacksaw blade is a thin strip of tool steel with two holes at the ends. On one or two edges of the blade, teeth are cut, having an inclination in one direction. The hacksaw blade is attached to the frame with pins 7 and tensioned with a tension nut 1. In this case, the teeth should be directed in the direction opposite to the handle. The tension of the hacksaw blade should not be too strong or too weak, as this may cause it to break.

♦ Hacksaw, frame, hacksaw blade, shank, hacksaw.

1. What is the difference between sawing with a carpenter's saw and cutting with a bench saw? What is their similarity?

2. List the safety rules when working with a hacksaw.

3. What are the main parts of a hacksaw?

4. For what purpose is a triangular file cut on the workpiece at the cutting point?

5. Why is it necessary to release the pressure on the hacksaw at the end of cutting the workpiece?

6. How is a long workpiece cut?

Simonenko V.D., Samorodsky P.S., Tishchenko A.T., Technology Grade 6

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metal cutting

Techniques for cutting metal with a hand saw

Before proceeding with cutting metal, it is necessary to choose a hacksaw blade, according to the hardness, shape and size of the material being cut.

It is necessary to fix the blade in the hacksaw so that the tip of the teeth is directed forward along the hacksaw; blade tension in the hacksaw must be adjusted. When starting to work with knives, you should firmly fix the material being cut in a vice. The height of the metal in the vise must correspond to the height of the worker. Then you need to stand in front of the vise half-turn, i.e. at an angle of 45 to center line vise (the distance between the vise with the body of the worker should be 120-150mm). left leg, set slightly forward, the right one must be placed in relation to the left at an angle of 60-70 °. When working, the body must be straight. The hacksaw should be taken with the right hand as shown in Fig. 1, a, pos. /, and with the left hand - for the front end of the hacksaw to balance it and get a stable movement during cutting. During cutting, the hacksaw should be kept in a horizontal position. You need to move it smoothly, without jerking, slightly pressing down with both hands when moving forward. It is generally accepted that the pressing force should be approximately 1 kg per 0.1 mm of web thickness. At the end of the cut, the pressure should be loosened.

Rice. 1. How to work with a hacksaw

The speed of movement of the hacksaw depends on the hardness of the material being cut and averages from 30 to 60 double strokes per minute. To reduce friction on the walls of the workpiece being cut, the hacksaw should be periodically lubricated with mineral oil or other lubricant.

In the process of work, the hacksaw blade sometimes “leads” away from the markup; it should not be straightened, as breakage or chipping of the teeth of the blade is possible. In this case, it is better to start cutting the workpiece from the opposite side.

The chipping of the teeth of the hacksaw blade also occurs due to the excessive hardness of the metal being cut, from strong pressure on the blade in the process of cutting narrow workpieces, the presence of gas bubbles (voids), non-metallic inclusions, etc. in the metal. to ensure a smooth transition from broken teeth to whole teeth. It is possible to continue working with a hacksaw with a restored blade only after removing the remnants of broken teeth from the slot.

For more economical use of hacksaw blades, new blades should first be used to cut soft metals - copper, aluminum alloys and then use them to cut steel or cast iron. It is recommended to cut brass and bronze only with new blades, as even slightly worn blades slide more than they cut.

It is easier to cut strip metal along the narrow side (thickness). In this case, the cutting force is distributed over a smaller area and cutting is faster. To avoid blade breakage, it is necessary that the thickness of the strip overlap with at least three teeth. If this cannot be done, then a thin strip is cut along its wide side. Clamping the strip in a vise with the wide side, make a cut on the edge with a file, and only after that they start cutting, slightly tilting the hacksaw away from you. During the cutting process, the inclination of the hacksaw is reduced, capturing the entire width of the strip and holding the hacksaw in a horizontal position.

In some cases, when cutting long (high) workpieces, it is not possible to complete the cut due to the fact that the hacksaw rests against their end. To eliminate this obstacle, you can re-clamp the workpiece and, crashing into it with a hacksaw from the other end, finish the job. More appropriate, however, is another way: to cut with a hacksaw with the blade rotated by 90 ° (Fig. 1, b). In this way, strips of any length can be cut.

Thin sheets or strips are placed between wooden bars, clamped in a vice, and then cut together with the bars (Fig. 1, c).

Cutting in thin places of curved or angular slots is carried out with special hacksaws, called jigsaws (Fig. 1, d), in which a narrow thin saw with fine teeth is fixed instead of a hacksaw blade. They work with a jigsaw "for themselves." When cutting curly cuts with a jigsaw, in places where the direction of the cut contour changes, holes are drilled with a diameter equal to the width of the jigsaw saw. Having passed the saw through such an opening, it is fixed in the frame and cutting is carried out in a given direction.

Cutting round metal small sections are made with a hand saw. Workpieces with a diameter of more than 50 mm are cut, as a rule, on a hacksaw, circular saws, cutting and other machines.

The cutting process boils down to the fact that a marking risk is preliminarily applied on a piece of steel of a circular cross section. Then the workpiece is clamped in a vice in a horizontal position and a small cut is made with a trihedral file at risk in order to cut the hacksaw blade into the metal at a given length along the length. Sometimes, to guide the hacksaw at the beginning of the cut, proceed as follows. At the risk, the thumb of the left hand is placed on the workpiece, resting the nail against the risk, and the hacksaw blade is moved close to the nail. Then the hacksaw, supported by the right hand with outstretched index finger, create a stable direction when cutting it into the metal. And only after making sure that the hacksaw blade is cut correctly, they stand in a working position and continue cutting to the end, preventing the workpiece from breaking off. Breaking off the workpiece is allowed in the case when its ends must be sawn off. In this case, cuts are made in the bars (pieces) from two to four sides, and then in a vice or with a hammer, resting the workpiece on metal bars, they break it.

Cutting square metal is carried out in the same way as round metal, with the only difference that the hacksaw is slightly tilted away from itself at the beginning of the cutting process. As

plunge, the slope is gradually reduced until the cut reaches the opposite edge of the workpiece. Then they are already cutting with the hacksaw in a horizontal position.

Before proceeding with cutting the metal of a shaped section, for example, an angular profile, it is necessary to mark the cut points on both shelves using a square and a scriber (when cutting a channel, the risk should also be applied on the wall). After that, the metal to be cut is clamped in a vice so that the risks of both shelves are visible, and with a triangular file, make a small cut along the risk from the side of the base ~ profile corner. Having installed the hacksaw blade in the cut, start cutting along the profile, holding the hacksaw in an inclined position, and then align it and continue cutting, as in the previous case. When cutting profiles of shaped steel, it is necessary to constantly monitor the direction of the hacksaw, preventing it from deviating from the marking risk.

Rice. 2. Techniques for cutting metal: a - round; b - square section

In some cases, locksmiths have to make slots (slots) in the heads of locking and other screws. For cutting shallow and narrow slots, it is recommended to use a special hacksaw with a thin blade. Wider slots (slots) in the screw heads can be obtained with an ordinary hacksaw with one or two hacksaw blades inserted together in a hacksaw.

Necessary conditions correct execution works on cutting pipes with a manual hacksaw are: marking the places of the cut, right choice hacksaw blade and compliance with the basic rules for working with a hacksaw.

The marking of the cut site is performed using a simplified template and a scriber. The template is cut out of thin tin in the form of a plate. rectangular shape bent along a pipe. Then this template is brought to the place of the cut and a marking line is applied along its edge with a scriber along the circumference of the pipe.

The pitch of the teeth of the hacksaw blade should be chosen the smaller, the harder the material of the pipe and the thinner its wall.

For cutting, the pipe is clamped in a vise in a horizontal position. Thin-walled pipes with a clean surface should be clamped in a vise between special wooden muffs. They also use pipe clamps with wooden linings, in which recesses are cut along the diameter of the pipe. Convenient is the fastening of pipes in chain, screw, and when cutting thin pipes - in special clamps.

When cutting the pipe, hold the hacksaw horizontally and, as the hacksaw blade deepens into the pipe, tilt it slightly towards you. If the blade is pinched in the slot, the hacksaw should be removed, turn the pipe away from you by 45-60 ° and continue cutting, slightly pressing on the blade.

If, when cutting, the hacksaw leads away from the marking risk, then the pipe must be turned and the cut started again.

Cutting pipes with a hand saw is a laborious and difficult operation, especially when cutting pipes of large diameters. More productive is cutting with the help of special pipe cutters, fixtures, etc.

The pipe cutter is special device, which one cutting tool steel disk cutters (rollers) serve. The most common are roller, clamp and chain structures pipe cutters.

The roller pipe cutter consists of a bracket, a screw lever and three disc rollers, two of which are mounted on axles in the bracket, and the third is mounted on an axle fixed in a movable bracket. The pipe to be cut is fixed in the clamp with a screw, after which the pipe cutter is installed on the pipe 5. When the screw lever is rotated to the right, the bracket will move the cutting roller until it comes into contact with the pipe wall under some pressure. A pipe cutter with three rollers cuts simultaneously in three places, so during operation it is swayed with a lever (about 1/3 turn in both directions). To prevent heating cutting rollers in the process of work, the cut point is lubricated with machine oil, and cutting is carried out without much effort. Pipes large diameter cut with a clamp or chain pipe cutter.

Rice. 3. Cutting pipes with pipe cutters

The disadvantage of roller pipe cutters is that during the cutting process they press the end of the pipe into the hole and form external and internal burrs, which must be removed to remove them. extra work. This disadvantage is eliminated when working with a pipe cutter designed by the innovator A. S. Misyuta. Here, instead of a cutting roller, a prismatic cutter is installed, which, as it cuts into the pipe, is fed by rotating the screw, and the rollers are pressed by the screw. This pipe cutter has found application in cutting pipes of large diameters.

At large volumes pipe cutting work is usually performed with mechanical disc pipe cutters.