filing. Techniques and methods of filing metal. Manual filing of surfaces
Filing is an operation for processing metals and other materials by removing a small layer with files manually or on filing machines.
With the help of a file, a mechanic gives the parts the required shape and dimensions, fits the parts to each other, prepares the edges of the parts for welding, and performs other work.
With the help of files, planes, curved surfaces, grooves, grooves, holes of any shape, surfaces located at different angles, etc. etc. Sawing allowances are left small - from 0.5 to 0.025 mm. The accuracy of filing processing is from 0.2 to 0.05 mm, in some cases up to 0.001 mm.
Manual filing has now been largely replaced by filing special machines, but these machines cannot replace completely manual filing, since fitting work during assembly and installation of equipment often has to be done manually.
A file (Fig. 134) is a steel bar of a certain profile and length, on the surface of which there are notches (cuts) that form depressions and sharpened teeth (teeth) that have a wedge shape in cross section. Files are made of steel U13 or U13A (alloyed chromium steel ШХ15 or 13Х is allowed), after notching they are subjected to heat treatment.
Files are subdivided: by the size of the notch, by the shape of the notch, by the length and shape of the bar, by purpose.
Types and main elements of notches. The notches on the surface of the file form teeth that remove chips from the material being processed. File teeth are obtained on sawing machines using a special chisel, on milling machines- milling cutters grinding machines- special grinding wheels, as well as by rolling, pulling on broaching machines - broaches and gear-cutting machines. Each of these methods incised its own tooth profile. However, regardless of the method of obtaining a notch, each tooth has a back angle a, a sharpening angle p, rake angle y and cutting angle 5 (Fig. 135).
Files with knurled teeth (Fig. 135, a) with a negative rake angle (γ from -12 to -15 °) and a relatively large back angle (α from 35 to 40 °) provide sufficient space for chip placement. The resulting taper angle β = 62 (up to 67°) ensures the strength of the tooth.
Files with milled or ground teeth (Fig. 135, b) have a positive rake angle γ = 2 (up to 10 °). They have a cutting angle less than 90° and, therefore, less cutting force. The high cost of milling and grinding limits the use of these files.
For files with teeth obtained by pulling (Fig. 135, c), γ \u003d - 5 °, β \u003d 55 °, α \u003d 40 °, δ \u003d 95 °.
The outstretched tooth has a cavity with a flat bottom. These teeth cut into the metal being processed better, which significantly increases labor productivity. In addition, files with such teeth are more resistant, since the teeth do not become clogged with chips.
The fewer notches per 1 cm of file length, the larger the tooth. There are files with a single, i.e., a simple notch (Fig. 136, a), with a double, or cross (Fig. 136, b), point, i.e. with a rasp (Fig. 136, c), and arc (Fig. 136, d).
Single cut files can cut wide chips equal to the length of the entire cut. They are used when filing soft metals (brass, zinc, babbitt, lead, aluminum, bronze, copper, etc.) with low cutting resistance, as well as non-metallic materials. In addition, these files are used for sharpening saw blades, as well as for processing wood and cork. A single notch is applied at an angle λ = 25° to the file axis.
Files with a double (i.e., cross) notch are used for filing steel, cast iron and others. hard materials with high cutting resistance. In files with a double notch, the lower one is first cut - a deep notch, called the main one, and on top of it - the upper, shallow notch, called the auxiliary one; it cuts the main notch into a large number of individual teeth.
The cross cut cuts the chips more, making the job easier. The main notch is made at an angle λ = 25°, and the auxiliary one is made at an angle ω = 45°.
The distance between adjacent notch teeth is called step S. The step of the main notch is greater than the step of the auxiliary one. As a result, the teeth are located one after another in a straight line, making an angle of 5 ° with the axis of the file, and when it moves, the tooth marks partially overlap each other, therefore, the roughness on the treated surface decreases, the surface is cleaner and smoother.
A rasp (point) notch is obtained by pressing the metal with special trihedral chisels, leaving roomy recesses arranged in a checkerboard pattern, contributing to best accommodation shavings. Rasps work very soft metals and non-metallic materials(leather, rubber, etc.).
The arc notch is obtained by milling. The cut has large tooth gaps and an arc shape for high performance and higher quality processed surfaces. These files are used in the processing of soft metals (copper, duralumin, etc.).
Bench filing
To category:
filing metal
Bench filing
Filing is a method of dimensional processing of workpieces with a file. Sawing is intended to obtain the required shape, size, roughness and surface location. Sawing such surfaces of workpieces, the processing of which on machines is technically impossible or economically impractical (working cavities of dies, molds, etc.). Filing is also used to fit the mating surfaces of parts at the assembly site of the product.
Types of sawing. Sawing can be done by hand or by machine. Sawing to improve surface finish is sometimes referred to as deburring.
Filing is based on the destruction of the surface layer of the workpiece material by the cutting elements of the tool (file), made in the form of a wedge. Each cutting wedge cuts a layer of material from the workpiece and turns it into chips, which are placed in the chip space.
Rice. 1. Cutting elements various types files: a - the process of filing, b, c; g - double, single and dotted (rasp) notches, respectively; 1 - file, 2 - workpiece, 3 - auxiliary notch, 4 - main notch, 5 - cutting edge; y - rake angle, a - back angle, fi - taper angle, 6 - cutting angle
When filing, the file is moved manually forward (away from you) at the speed Tsr.x. working stroke and back (toward yourself) with a speed of v0.x. reverse motion (Fig. 1, a). Horizontal force is applied both during working and idle strokes, and vertical (with two hands) - only during working strokes. To ensure that the file is always parallel to the surface being processed, at the beginning of the working stroke, the file is pressed harder with the left hand, and as it moves, the pressure with the left hand is reduced, and with the right hand it is increased.
Cutting tool for filing. A file is a multi-blade cutting tool whose teeth are located on the surfaces of hardened steel bars with different cross-sectional profiles and lengths. The file has a working part and a shank. The drawn part is called the toe. On the working part, a narrow side, a wide side and a rib are distinguished.
File teeth are obtained by notching, milling; grinding and other technological methods. The most widespread is the notching of teeth on notching machines with special chisels. The cut teeth are more durable.
Files are made with different lengths and shapes. cutting edges. A short edge in the form of an irregular triangle is obtained with a double notch, a long (straight or radius) edge with a single notch. A short edge is also obtained with a rasp (point) notch.
Locksmith's files general purpose usually have a double notch - the main one (at an angle of 65 °) and the auxiliary one (at an angle of 45 °). The latter divides the main notch into numerous teeth, which allows, with the same expenditure of forces, to increase the amount of chips removed.
Rice. 2. Rod file (a) and burr (b): 1 - toe, 2 - working part, 3 - shank, 4 - shoulder
The step of the main and auxiliary notches is made different. As a result, each subsequent tooth is displaced relative to the previous one in a direction perpendicular to the axis of the file. Without such a displacement, each subsequent tooth would follow strictly the previous one and grooves would form on the machined surface. Overlapping of the teeth ensures low surface roughness.
The size of the chip space has big influence on the quality and productivity of filing. The volume of the chip space is determined by the notch pitch, i.e. the number of main notches over a length of 10 mm. This number is determined by the notch number. General purpose locksmith's files have six cut numbers ranging from zero (largest pitch) to 5 (smallest pitch).
According to the cross-sectional shape, general-purpose files are: flat, flat pointed, square, trihedral, round, semicircular, rhombic and hacksaw. General purpose files are made in length 100; 125; 150; 200; 250; 300; 350 and 400 mm.
Files of small sizes are called needle files. The produced needle files have ten notch numbers: 00; 0; one; 2; 3; 4; 5; 6; 7 and 8. The cross-sectional shapes of the needle files are the same as for general purpose files. In addition, trihedral unilateral, oval and grooved needle files are produced. Each type of needle file is produced in three sizes. The total length is respectively 100; 120 and 160 mm; the length of the working part, respectively, 50; 60 and 80 mm.
General purpose locksmith files and needle files are made from steels U12, U12A, U13 and U13A. It is allowed to manufacture files from steels 13X and SHKH15. The files are hardened to a hardness of 54 HRQ.
Files for difficult-to-cut materials are made from 14HF and 13X steels, as well as from high-speed steel. They differ from general purpose files in the number and angle of cuts. Their wide surfaces have a radius shape, due to which fewer teeth are involved in the work at the same time.
In machine filing, core files and burrs are used. The core file, unlike the bench file, has a shank with which it is attached to the machine. When filing stamps and molds, end and extension burrs (diameter 3 - 32 mm) of cylindrical, angular, disk and other shapes are widely used. Burr cutters are made of high speed steel or U12A tool steel and hardened to a hardness of 66 HRC s. Burrs are made with extra large, large, medium, small and extra small teeth.
Equipment and devices for sawing. Filing by hand is usually done at a locksmith's workbench. The workpiece is placed in a bench vise equipped with aluminum or copper tips and wooden spacers protecting treated surfaces from damage.
Processing the workpiece with burrs is performed using electrical machine with flexible shaft. Filing with core files is carried out on stationary filing machines. The use of devices such as copiers makes it possible to increase the productivity of filing, since in the process of work it is not necessary to control the deviation of the shape and location of the surfaces to be processed.
The sequence and methods of performing work when filing. The surface of the workpiece is cleaned of dirt, oil and scale. The hard surface crust of castings and forgings is previously removed with an old file or chisel. Then the workpiece is marked.
When choosing a file, consider physical and mechanical properties material being machined, dimensions, shape of the machined surface and its location relative to other surfaces of the workpiece, the amount of machining allowance, the required accuracy and surface roughness.
Flat and flat pointed files are used for processing flat and convex surfaces, grooves. Square and rectangular slots and the holes are filed with square files. Triangular files are useful for processing sharp corners in grooves, as well as triangular and polygonal holes. Round and oval holes, concave surfaces are filed with round files; concave and flat - semicircular; narrow shaped surfaces, slots and grooves - rhombic.
The length of the file is recommended to be chosen 150-200 mm longer than the length of the surface to be filed. Needle files are used for very precise processing of small surfaces and hard materials. Rough filing soft materials, plastics and wood it is rational to carry out rasps.
Filing is carried out sequentially with each type of file (starting with the coarsest and ending with the most accurate). The workpiece is placed in a vice so that the marking risk is clearly visible, and the sawn surface is horizontal.
To increase the productivity and quality of processing, cross filing is used: first, the entire surface is filed with an oblique stroke from left to right; then - with a direct stroke; then - with an oblique stroke from right to left.
As a result of improper use, files lose their cutting properties. If oil gets on the working part of the file or chips clog its cavities, then it becomes unsuitable for work. Greasy files are cleaned with a hard piece charcoal. The file is cleaned of chips with a pointed spatula made of soft iron (or brass) and a steel stiff brush. Cleaning is carried out in the direction of the upper notch. Before filing aluminum alloys the file should be rubbed with stearin to reduce clogging.
When filing, control the roughness, shape, size and location of the surface. Roughness, as a rule, is controlled by reference samples. Deviation from flatness (the most common type of marriage when filing) is controlled by a straightedge (through the light). Mutual arrangement surfaces are controlled by squares, templates and goniometers; linear dimensions are checked with calipers.
filing- this is metalworking, during which material is removed from the surface of the part using a file.
File- this is a tool that is used for metalworking, consists of multi-blade cutting elements, it provides high accuracy of the work being done, as well as a slight roughness of the workpiece surface. The metal cutting itself is carried out qualitatively and with a small error.
With the help of filing, details are attached right size and shape, adjust the part to each other and carry out many other works. Metals of various shapes are processed with files: curved surfaces, planes, grooves, holes various forms, grooves, various kinds surfaces, etc. Leave allowances during filing small size- from 0.55 to 0.015 mm. And the error after the work done can range from 0.1 to 0.05, and in certain cases even less - up to 0.005 mm., Which ensures high-quality metalworking /
A file tool is a steel bar of a certain length and profile, which has a cut on the surface. The cut (notch) forms small and sharp teeth, which determine the shape of the wedge in the section. The cross-sectional angle of a file with a split tooth is usually 65-70 degrees, the back angle is from 35 to 50 degrees, the front angle is 16 degrees.
Single cut tools remove wide chips from the metal, along the entire notch. They are used in the metalworking of soft metals.
Double cut files are used when filing cast iron, steel and other solid metals, due to the fact that cross-cutting grinds the chips, and therefore facilitates the work.
A notch with a rasp is obtained by pressing the metal with special teeth consisting of a trihedron. Rasping of metals is performed only on soft metals and non-metallic materials.
You can also get another notch by milling. It has an arcuate shape and large recesses between the teeth - this ensures good quality surfaces and high productivity in metalworking
Files are made from steel U13A and U13, and also from chromium steel ShKh 15. When the notching of the teeth ends, the files are thermally processed. File handles are made of wood (maple, birch and others).
According to their purpose of cutting metal, files are divided into the following groups:
- General purpose.
- Files.
- Special Purpose.
- Machine files.
- Rasps.
By the number of notches per 1 cm, the files are divided into 6 different numbers:
- Files with cuts from number 0 to 1 (bastard) are used for coarser filing, as they consist of large teeth. When processing metals, the error is from 0.6-0.3 mm.
- Files with cutting No. 2-3 are used for clean filing of parts. The error in metalworking is 0.2-0.005 mm.
- Files with cut number 4-5 serve as the final processed process. The error in this process is 0.1-0.004 mm.
For the processing of metals of small shapes, small-sized files are used - needle files. Processing of hard and hardened steels is carried out with special needle files, and diamond grains are fixed on steel rods.
Improving productivity and working conditions in metalworking by filing is achieved by using mechanized (pneumatic and electric) files. Interchangeable angle and straight heads with round shaped tools facilitate filing at different angles and in hard-to-reach places.
The quality of work is controlled by various kinds of tools. The quality of the sawn plane is checked with a ruler. If the plane must be filed accurately enough, it is subjected to a check on the test plate. If you need to file a plane at a certain angle, it is checked with a goniometer or square. To control the parallelism of two planes, a caliper is used, where the distance between the planes should be the same.
If the control needs to be carried out on curved surfaces, it is carried out using marking lines and special templates.
Filing is used for cutting and surface treatment and differs significantly from the process of plasma cutting of metal, which in turn is used to completely cut the product, as well as to process it.
General techniques and rules for filing
The product to be filed is clamped in a vice so that the surface to be processed protrudes above the vise jaws to a height of 5 to 10 mm. The clamp is made between the muffs. The vise should be set to the height of the worker, and well secured. When filing, you need to stand in front of the vise half-turned to them (left or right, depending on the need), i.e. turning 45° to the axis of the vise. Left leg, push forward in the direction of movement of the file, right leg set aside from the left by 200-300 mm so that the middle of her foot is against the heel of the left foot.
The file is taken in the right hand by the handle, resting its head on the palm; thumb put on the handle along with the rest of the fingers support the handle from below. Putting the file on the workpiece, apply left hand palm across the file at a distance of 20-30 mm from its end. In this case, the fingers should be half-bent, and not tucked in, since otherwise they can be easily injured on the sharp edges of the workpiece. Raise the elbow of the left hand. The right hand - from the elbow to the hand - should form a straight line with the file.
Actions of hands during sawing.
The file is moved with both hands forward (away from you) and back (towards yourself) smoothly, moreover, with its entire length. When moving the file forward, they press it with their hands, but not equally and not evenly. As it moves forward, increase the pressure of the right hand and weaken the pressure. When moving the file back, do not press on it. It is recommended to make 40 to 60 double file strokes per minute. When filing planes, the file must be moved not only forward, but at the same time move it sideways to the right or left in order to cut a uniform layer of metal from the entire plane. The quality of filing depends on the ability to regulate the force of pressure on the file. If you press the file with a constant force, then at the beginning of the working stroke it will deviate with the handle down, and at the end of the working stroke - with the front end down. With such work, the edges of the treated surface will “fill up”.
Sawing methods.
The most difficult thing about filing is whether it really removes that layer of metal at the moment and in the exact place where it is needed.
It is possible to correctly file a plane only if a file with a straight or convex, but not concave surface is selected and if filing is performed by moving the file with an oblique stroke, i.e., alternately from corner to corner. To do this, filing is first carried out, for example, from left to right at an angle of 30-40 ° to the sides of the vise. After the entire plane has been traversed in this direction, it is necessary, without interrupting work (so as not to lose pace), go to filing with a straight stroke and then continue filing again with an oblique stroke, but from right to left. The angle is kept the same. As a result, a network of cross strokes is obtained on the plane.
By the arrangement of the strokes, you can check the correctness of the machined plane. Suppose that on a plane sawn from left to right, by applying a test ruler, a bulge was found in the middle, and a blockage along the edges. It is obvious that the plane is filed incorrectly. If now we continue filing by moving the file from right to left so that the strokes lie only on the bulge, then such filing will be correct. If the strokes are indicated both on the bulge and on the edges of the plane, then this will mean that the filing is again being done incorrectly.
Finishing of the processed surface.
The filing of the surface usually ends with its finishing, which is produced different ways. AT plumbing surfaces are finished with personal and velvet files, paper or linen abrasive skins, abrasive bars. Finishing with files is done with a transverse, longitudinal and circular stroke.
In order to obtain a smooth and clean surface as a result of finishing, it is very important not to allow deep scratches when pre-finishing sawing. Since scratches are caused by sawdust stuck in the notch of the file, it is necessary to clean the notch more often and rub it with chalk or mineral oil during work. Even more carefully it is necessary to clean and rub with chalk or oil (and when filing aluminum with stearin) the notch of the finishing files, especially when working on viscous metals.
After finishing with a file, the surface is treated with abrasive stones or abrasive sandpaper (small numbers) dry or with oil. In the first case, one gets shiny surface metal, in the second - semi-gloss. When finishing copper and aluminum, the skin should be rubbed with stearin. Sanding a flat surface requires skill; Improper work with sandpaper can lead to damage to the product.
Also used for surface finishing wooden blocks with abrasive paper glued on them. Sometimes the skin is wrapped on a flat file (in one layer) or a strip of skin is pulled over the file, holding it while working.
When finishing a curved surface, as well as in those cases of finishing a straight surface, when a possible small blockage of the edges will not be considered a marriage, the skin is wrapped on a file in several layers.
Measurement and control when filing.
To make sure that the plane is filed correctly, it is necessary from time to time to check it with a test ruler for clearance. If the ruler lies tightly on the plane, without a gap, this means that the plane has been filed cleanly and correctly. If a clearance is even along the entire length of the ruler, the plane is filed correctly, but roughly. Such a gap is formed because the notch of the file leaves imperceptible grooves on the metal surface and the ruler rests on their burrs.
On an incorrectly sawn plane, when applying a ruler, uneven gaps will be found, which will indicate the presence of hills (humps).
Checking for clearance is carried out in all directions of the controlled plane: along and across and from corner to corner, i.e. diagonally. The ruler must be held with three fingers of the right hand - thumb, index and middle. You can not move the ruler along the plane being checked: it wears out from this and loses its straightness. To move the ruler, it must be lifted and carefully placed in a new place.
When checking with a square, it is carefully and tightly applied long side to the wide plane of the part, the short side is brought to the side to be checked and looked at the light. If the part on this side is filed correctly, the short side of the square will lie snugly across the side of the part. In case of incorrect filing, the square will touch either only the middle of the side (if this side is convex), or some edge (if the side is oblique).
To check the parallelism of two planes, use a caliper. The distance between parallel planes in any place must be the same. Caliper hold right hand for the swivel washer. Setting the solution of the legs of the caliper to a certain size is done by lightly tapping one of the legs on any hard object.
The legs of the caliper must be installed on the parts so that their ends are opposite each other. Skewed legs, misalignments, and tilts will produce incorrect test results.
To check, set the solution of the legs of the caliper exactly according to the distance between the planes in any one place and move the caliper over the entire surface. If when moving the caliper between its legs, a rocking is felt, this means that in this place the distance between the planes is less, if the caliper moves tight (without pitching), this means that the distance between the planes in this place is greater than in another.
Two planes can be considered parallel to each other if the legs of the movable caliper slide evenly over them with slight friction .
Tinsmith work is carried out in various industries National economy: mechanical engineering, construction, Agriculture and many others. The book is dedicated to technological processes manufacture of tin products, such as filing and cutting metal. Here it is described in detail about the process of filing metal, types, sizes of files and caring for them, about filing by hand. In addition, the book presents detailed information about cutting metal and its methods.
- filing metal
* * *
by the LitRes company.
filing metal
Sawing is the operation of metal processing with a cutting tool - a file, as a result of which a certain layer of metal is removed from the workpiece and given to it. required dimensions, desired shape and required surface finish.
Sawing is a very labor intensive operation. This circumstance makes it necessary to find and use all available opportunities to increase labor productivity when filing (choosing the right files, using filing and cleaning and other machines, etc.).
In tinsmithing, sawing off:
external flat and curved surfaces;
outdoor and internal corners, as well as complex or shaped surfaces;
recesses and holes, as well as grooves and protrusions, fitting them together;
edges of parts to remove burrs.
Depending on the use of certain files, the accuracy of filing workpieces or parts ranges from 0.2 to 0.05 mm.
Types and sizes of files
Files are a cutting tool in the form of hardened steel bars of various profiles and lengths with teeth cut on their working surfaces.
Each such file tooth is a cutter that removes a layer of metal in the form of chips.
The file consists of a working part and a tail part - a shank. In addition, the elements of the file are: nose, edge, edge, heel. A handle is placed on the tail of the file.
File teeth are obtained in several ways:
Notching on notching machines with a special chisel, milling, grinding and broaching.
Each method corresponds to a certain file tooth geometry.
According to their purpose, files are divided into two groups: general-purpose locksmith files, designed to perform various metalworking work on metal; Special designed to perform various works for metal and non-metal materials.
Special files are divided into manual and machine.
Files are made with a notch of the following types: with a simple, or single; with cross; with arc.
Each type of notch has its own advantages and is used for files of a certain purpose.
A simple or single cut is used in the manufacture of certain types of special files (for example, for sharpening saws for wood).
It is advisable to use files with a simple notch in all cases when it is required to remove an insignificant layer of metal from a narrow work surface.
Cross, or double, notch is used in the manufacture of general-purpose files. In these files, the main cut is made at an angle (lambda)=25º, and the auxiliary cut is made at an angle (omega)=45º.
These notch angles provide high productivity.
Dot, or rasp, notch is used in the manufacture of rasp files. Rasps with a point notch have large teeth and capacious grooves, which contributes to better chip separation when filing soft metals, rubber, leather, plastics, etc.
Locksmith's files differ in two main ways: in the shape of the cross section and in the number of notches per centimeter of the length of the file.
Locksmith's files are made according to the cross-sectional shape of eight types: flat (type A), flat pointed (type B), square (type C), trihedral (type G), round (type D), semicircular (type E), rhombic (type G), hacksaw (type K).
According to the number of notches, bench files are divided into six numbers: 0, 1, 2, 3, 4, 5. The notch number is an indicator of the operational purpose of the size range of files according to the pitch of the main notch.
Files with a notch No. 0 and 1, the so-called bastard ones, have the largest teeth and are used for filing parts with an accuracy of 0.2-0.5 mm with a processing allowance of 0.5 to 1 mm.
Files with a notch No. 2, the so-called personal ones, are used for fine filing of parts with an accuracy of 0.02-0.15 mm, while the processing allowance is from 0.1 to 0.3 mm.
Notched files No. 3, 4, 5, the so-called velvet, are used for final finishing parts with an accuracy of 0.01 to 0.005 mm, while the machining allowance ranges from 0.025 to 0.05 mm.
Files are made from tool carbon steel U13 or U13A and hardened for hardness not lower than HRC 54-58.
Rasps differ from metalwork files in a notch. Their teeth are large and short in the form of pyramids. Thanks to large sizes teeth and ample grooves behind each tooth, the rasps are suitable for filing soft metals. The teeth of the rasp are arranged in rows perpendicular to its axis.
To avoid grooves when filing, the rows are offset relative to each other by half a step between the teeth.
In tinsmithing, general-purpose rasps are used for scalding parts made of soft metals (aluminum, duralumin, etc.).
General purpose rasps are made in four types: flat blunt, flat pointed, round, and half round. Rasps of all four types are made in lengths of 250 and 350 mm.
For the manufacture of rasps, tool carbon steel is used, mainly grades U7A, U10A, hardened to a hardness of HRC 35-40.
The smallest files, the so-called needle files, are designed to make very small and precise work. They differ in the shape of the cross section and in the number of notches per centimeter of the file length.
Needle files are made according to the cross-sectional shape of eleven types: flat blunt, flat sharp-nosed, square, trihedral one-sided, round, semicircular, oval, rhombic, hacksaw and slot.
According to the number of notches, the needle files are divided into six numbers: 1, 2, 3, 4, 5, 6.
Files flat blunt, flat pointed, square, trihedral, round, semicircular, rhombic, grooved are produced in two sizes: along the length of the working part 60 and 80 mm and the length of the shank, respectively, 60 and 80 mm.
Hacksaw files are made in three types: along the length of the working part 60, 80, 40 mm and the length of the shank, respectively, 60, 80, 40 mm.
Files are made from tool carbon steel U12 or U12A and hardened to a hardness of HRC 54-60.
The file has a wooden handle with a clamping ring, which prevents it from cracking when placed on the file shank.
The handle should fit snugly on the file shank, for which a hole is drilled in it with a diameter corresponding to the dimensions of the middle part of the shank and a depth, equal to the length shank. Then, with a red-hot shank of an old file of the same size, a hole is burned out exactly in the shape of the shank for 2/3-3/4 of its length.
When putting the handle on the shank, do not hit the file with a hammer, as its cutting part may break.
When put on correctly, the handle hits the locksmith workbench until it sits tightly on the shank.
When putting the handle on the file shank, make sure that it is planted without distortion.
Handles are made of wood (birch, beech) or pressed paper.
Wooden handles are used more often, as they are more practical. The length of the handle should be one and a half times longer than the file shank.
Handles for general-purpose files are available in lengths of 90, 100, 110, 120, 130, 140 mm, with a diameter of 12, 16, 20, 23, 25, 28 mm at the end, respectively.
The size of the handle is selected according to the size of the file.
File selection and care
Files are selected depending on the size of the allowance left for filing a given processing accuracy, the size and shape of the surface to be filed. Workpieces and parts can be processed with a file with different accuracy.
When filing the surfaces of workpieces and parts with bastard files, they achieve an accuracy of 0.2 to 0.5 mm, personal - from 0.02 to 0.15 mm, velvet - from 0.005 to 0.01 mm.
Allowances for filing the surfaces of workpieces and parts are also selected depending on the type of file. Allowances for surface treatment of workpieces are taken when filing with bastard files from 0.5 to 1 mm, personal - from 0.1 to 0.3 mm, velvet - from 0.025 to 0.05 mm.
The size of the metal layer removed with a file in one working stroke when filing with bastard files ranges from 0.08 to 0.15 mm, personal - from 0.02 to 0.08 mm, velvet - from 0.025 to 0.05 mm.
The length of the file is selected according to the length of the surface to be filed. When filing with a file that is too long, it is difficult to properly balance and hold it in horizontal position, as a result, it is difficult to correctly file the surface of the workpiece or part.
Files that are too short are inefficient, since they have a smaller working stroke and it is difficult to press them with your hands when filing.
Practice has developed the following relationships between the length of the file and the length of the surface to be treated:
For filing workpieces and parts made from various materials, use files with different notches. Workpieces and parts made of cast iron and mild steel are sawn with bastard flat and flat sharp-nosed files with a notch No. 0 and 1.
With a small thickness of workpieces and parts and when filing steel with increased hardness, personal files with a notch No. 2 are used.
For fine filing of steel and cast iron blanks and parts, personal files with a notch No. 2 are used, and with increased requirements for surface cleanliness, velvet files with a notch No. 3 and No. 4 are used.
Workpieces and parts made of copper, brass and bronze are filed with files with sharper teeth than when filing workpieces and parts made of steel and cast iron.
In cases where it is required to file brass and steel blanks or parts with the same file, brass blanks or parts are first filed, and then, when the file is sufficiently dull, steel blanks or parts.
For filing workpieces and parts made of aluminum and its alloys, special files with a large and deep notch are used, which ensure high productivity and good surface finish.
Blanks and parts made of lead, babbitt and other soft metals are filed with personal flat sharp-nosed files with a notch No. 2.
Lead and babbitt are much softer than copper and aluminum, so they are also filed with special files with very sharp teeth and deep depressions, providing high productivity and good frequency of sawn surfaces.
Files of each type are designed for filing surfaces of a certain type and size.
Flat and flat pointed files are used for filing flat and convex surfaces of various parts made of ferrous and non-ferrous metals and alloys, as well as for cutting slots and grooves.
End of introductory segment.
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The following excerpt from the book Tinsmith works. Sawing and cutting metal (Ilya Melnikov, 2013) provided by our book partner -