Preparing saw teeth for work. Preparing circular flat saws for work Preparing drills for work
Preparing for use of circular saws with hard alloy blades.
The preparation of saws during operation includes notching the teeth, measuring the ring gear, sharpening and jointing the teeth.
Notching of teeth is carried out using manual (PSh) or mechanical (PShP-2) saw blades when it is necessary to change the tooth profile if 3 (total) or 2 teeth in a row are broken on the saw. The final shape of the teeth is achieved on grinding machines.
Widening of the ring gear(on the side) depends on the species and condition of the wood being cut and ranges from 0.3 mm for hard wood to 1.0...1.3 mm for soft wood at high humidity. Planer saws do not require widening of the cut due to the shape of the disc, which tapers from the periphery to the center. In carbide saws, the widening of the cut is achieved by the overhang of the carbide plate. All other saws require periodic widening of the toothed rim by spreading or flattening.
Tooth set– the most universal method used for rip saws and cross cutting with straight and oblique sharpening. The setting consists of alternately bending the teeth to the left and right side by 1/3…1/2 of the tooth height from its size. You can spread saw teeth both before and after sharpening.
For setting teeth, RPK8, RP8 machines (for Æ saws up to 800 mm), manual setting PI-39, a vice for clamping saws during setting, indicator setting meters and templates for monitoring the accuracy of setting are used. The advantages of setting saw teeth are their relative simplicity and versatility. The disadvantages are that each cut cell is formed by only half of the teeth and that an unbalanced force acts on each tooth, which reduces the stability of the saw in the cut.
Tooth flattening used to widen the toothed rim of saws for longitudinal sawing with straight sharpening. A flattening roller 3 is pressed against the tip of tooth 1 from the front edge, and an anvil stop from the rear edge.
2. When the flattening roller is rotated, it penetrates into the material of the saw tooth due to a smooth increase in the radius of its working area. The tip of the tooth rests on both sides (I). Then it is given the correct shape by molding, pressing it with dies (II) and tightening (III). The two-sided widening of the tooth ensures a symmetrical action of forces during saw operation, and the cutting surfaces are formed by each tooth. The quality of the cut is higher, the stability of the saw is greater. The flattened teeth retain sufficient widening for 3…4 regrinds. Due to greater stability, saws with flattened teeth can be 0.2...0.4 mm thinner, allow a 15...20% higher feed per tooth and 0.1 mm less widening of the gear rim than saws with set teeth. For flattening the teeth, a semi-automatic machine for cold flattening and forming of teeth PHFK8 (PHFD) for saw diameters up to 800 mm, a manual conditioner PKTs, a manual molding FKTs, and a device for installing the saw during flattening and forming are used. Subject to availability large quantity saws for longitudinal sawing, it is rational to use machines for flattening and shaping teeth in cold and hot (heating up to 800...600 o C in a high-frequency field) state.
Sharpening teeth sawing with an abrasive wheel consists of grinding off a layer of metal from the edges of the teeth, the thickness of which is sufficient to restore their sharpness and correct form. In one pass, a layer 0.02...0.05 mm thick is sanded off, so saws are sharpened in several passes. In this case:
1. All teeth after sharpening must have the same profile, pitch, height, angles, etc.
2. The tops of all teeth must be located on the same straight line (frame and band saws) or circle (circular saws).
3. To avoid the formation of a crack in the plane and breakage of the teeth, the bottom of the depressions must have a smooth rounding.
4. Saw teeth should not have curls, blue tips or other defects.
5. The sharpened teeth should not shine at the corners formed by the intersection of the edges. Shine indicates that the tooth is not sharp enough.
Distinguish sharpening methods along the front, along the back edge, along the front and back edges. Sharpening along the front edge allows for the maximum number of resharpenings, but requires more time. Sharpening along the back edge is uneconomical in terms of saw blade consumption. Therefore, steel saws are sharpened along the front and back edges. There are sharpening machines for frame, round, band and disk saws with hard alloy plates: TchPR, TchPK (TchPD), TchL and TchPT and others.
Tooth jointing Peeling is the process of grinding off metal from the tips of the most protruding teeth to align the height and width of the ring gear. This makes it possible to reduce the depth of kinematic irregularities and ensure the participation of all teeth in the formation of the cut. Jointing can be lateral or radial and is carried out using jointing bars manually and on a sharpening machine (static) or on the shaft of a circular saw (dynamic). As a result, jointing pads are formed at the tips of the teeth. Within their limits, the rear angle is 0, therefore, their size should not be more than 0.3 mm to eliminate large friction forces. Diamond sharpening and finishing increases the tool life by 2..3 times and reduces the consumption of hard alloys by 1.5...2 times.
Basic operations for preparing circular saws with hard alloy inserts: milling sockets for carbide plates, soldering carbide plates, sharpening and finishing of teeth. Use silver or copper-zinc solders in the form of thin wire and calcined dehydrated borax flux in the form of fine powder. Heating during soldering is electrical contact; in the HDTV field; gas burner; oxy-acetylene flame. Sharpening and finishing are performed with abrasive (carborundum) or diamond wheels; as well as combined rough sharpening - with abrasive wheels, and fine sharpening and finishing - with diamond wheels.
The main sharpening is carried out along the rear edge 4, auxiliary - along the front 3. Sharpening on the back edge includes sharpening on the steel part of 1 tooth at an angle of a+6 o, finishing sharpening on plate 2 at an angle of a+2 o and finishing of the plate (part) at an angle a. Sharpening on the front edge(if necessary) consists of preliminary sharpening along the entire edge at an angle g. Sharpening is carried out only along the plate (a + 2 o) with an allowance<= 0,2 мм, доводку по фаске (a) припуск <=0,05 мм.
TECHNOLOGY
PRODUCTION
FURNITURE
Admitted
Ministry of Education of the Russian Federation as a teaching aid for educational institutions of primary vocational education
Klyuev G. I. Furniture production technology:
Textbook guide for beginners prof. education / Gennady Ivanovich Klyuev. - M.: Publishing center "Academy", 2005. - 176 p.
The technology of carpentry work in the manufacture of furniture is considered: manual and mechanized wood processing, carpentry joints, gluing and bending wood, veneering furniture blanks, as well as the technology of finishing, repair and restoration of furniture.
For students of primary vocational education institutions, as well as for young workers of furniture enterprises.
PREFACE.. 7
SECTION 1 JOINERY... 8
Chapter 1 MANUAL WOOD PROCESSING... 8
1.1 Organization of the workplace and ensuring the safety of the carpenter. 8
1.2 Marking wood... 9
Marking tools. 9
Marking techniques. 11
1.3 Sawing wood... 12
Tools for sawing wood... 12
Preparing hand saws for work. 13
Sawing techniques with hand saws. 15
Requirements for sawing quality. 16
Occupational safety when working with hand saws. 16
Useful tips for a carpenter. 17
1.4 Planing wood... 17
Tools for planing wood.. 17
Tools for profile planing. 19
Preparing the planing tool for work. 21
Planing with hand planes. 22
Labor safety during planing. 24
Useful tips for a carpenter. 24
1.5 Chiseling wood and cutting with a chisel. 25
Chiseling tools. 25
Preparing chisels and chisels for work. 25
Techniques for chiseling wood.. 25
Chisel cutting techniques. 26
Occupational safety. 27
Useful advice for a carpenter. 27
1.6 Drilling wood... 27
Drilling tools. 28
Preparing drills for work. 28
Techniques for drilling holes. 28
Occupational safety when drilling. 29
Useful tips for a carpenter. 29
1.7 Sanding wood... 29
Test questions.. 30
Chapter 2 MECHANIZED WOOD PROCESSING... 31
2.1 Manual electrified machines.. 31
Electric circular saws.. 31
Jigsaws. 31
Electric planers. 32
Electric drilling machines.. 32
Electric screwdrivers.. 33
Electric grinders.. 33
Occupational safety when working with electrified hand-held machines. 33
2.2 Woodworking machines. 34
Characteristics of machines. 34
Circular saws. 35
Band saw machines. 37
Longitudinal milling machines. 37
Milling machines. 40
Tenoning machines. 42
Drilling and grooving machines. 42
Slotting machines. 43
Grinding machines. 43
Combined machines. 44
2.3 General safety rules when working on woodworking machines. 45
Test questions.. 46
Chapter 3 JOINERY... 46
3.1 Corner tenon joints. 46
3.2 Length and edge connections. 49
3.3 Adhesive joints. 49
3.4 Connections with screws, metal pins and staples. 50
Useful tips for a carpenter. 51
Test questions... 51
Chapter 4 TECHNOLOGY OF GLUEING WOOD... 51
4.1 Preparation of materials to be glued. 51
4.2 Types of adhesives for gluing wood... 52
4.3 Methods of applying glue. 52
4.4 Methods of gluing. 53
4.5 Gluing blanks and parts made of solid wood... 54
4.6 Wood gluing mode... 55
Useful tips for a carpenter. 56
Test questions... 56
Chapter 5 TECHNOLOGY OF BENDING WOOD... 57
Chapter 6 TECHNOLOGY FOR FURNITURE BLANKET COVERING.. 58
6.1 Preparing the base for cladding. 58
6.2 Preparation of natural veneer. 59
6.3 Gluing the cladding to the base. 62
Test questions.. 65
SECTION 2 TECHNOLOGY OF MANUFACTURING AND ASSEMBLY OF JOINERY AND FURNITURE PRODUCTS. REPAIR AND RESTORATION OF FURNITURE.. 66
Chapter 7 STRUCTURES AND MANUFACTURE OF JOINERY AND FURNITURE PRODUCTS 66
7.1 Manufacturing of modern windows. 66
Useful advice for a carpenter. 71
7.2 Production of modern doors. 71
7.3 Modern materials for making furniture. 77
7.4 Classification of furniture. 78
7.5 Main structural elements of furniture products. 79
7.6 Designs and manufacture of cabinets. 83
7.7 Designs and production of dining tables, desks and stools. 88
7.8 Office furniture designs. 93
Test questions.. 94
Chapter 8 ASSEMBLY OF JOINERY AND FURNITURE PRODUCTS... 94
8.1 Types and organizational forms of assembly. 94
8.2 Unit assembly. 95
8.3 General assembly. 97
8.4 Assembly accuracy. 98
Test questions.. 99
Chapter 9 FINISHING FURNITURE PRODUCTS.. 99
9.1 Preparing the wood surface for finishing. 99
9.2 Technology for applying finishing materials for transparent wood finishing... 102
9.3 Technology for applying finishing materials for opaque wood finishing 106
9.4 Technology for applying finishing materials for imitation wood finishing 106
9.5 Elimination of finishing defects. 107
Useful tips for a furniture maker. 108
Test questions.. 109
Chapter 10 REPAIR AND RESTORATION OF FURNITURE... 109
10.1 Elimination of damage to structural elements from the array. 109
10.2 Elimination of damage to the facing coating. 110
10.3 Elimination of damage to finishing coatings. 111
10.4 Fighting the furniture grinder bug.. 112
Test questions.. 112
REFERENCES... 113
PREFACE
This textbook was written for students based on the training programs “Master of Carpentry and Furniture Production” in the subject “Technology of Furniture Production” for the training of workers in primary vocational education institutions in the specialty “Carpenter of Furniture Production”.
The content of the manual corresponds to the main topics of the program material. The main attention in the manual is given to the technology of carpentry and furniture work, the structure and rules of operation of hand and mechanized tools, basic woodworking machines and equipment for performing furniture manufacturing operations. The sequence of presentation of the material allows us to trace the manufacturing technology of joinery and furniture products, taking into account modern achievements of technology and technology in woodworking and furniture production.
Much attention is paid to various types of devices and templates used in furniture production, as well as labor safety issues. The topics of the subject are covered in detail on gluing and veneering, assembly and finishing of joinery and furniture products, repair and restoration. A furniture production carpenter must not only be able to manufacture products, but also develop the designs of these products himself, studying the basics of designing joinery and furniture products.
In addition to this manual, the future master of joinery and furniture production must also use additional literature on automation of furniture production, standardization and quality control, design of joinery and furniture products and labor protection at woodworking enterprises. Each topic of the manual ends with control questions to consolidate and repeat the material being studied.
The main purpose of this textbook is to assist students in primary vocational education institutions and young workers at furniture factories in obtaining theoretical and practical knowledge of furniture production technology.
SECTION 1 JOINERY WORK
Chapter 1 MANUAL WOOD PROCESSING
Wood marking
To obtain a part of the desired shape and size, you must first make markings on the appropriate material from which this workpiece will be made. Marking is usually divided into rough (preliminary) and finishing (final).
During preliminary marking, the boards are cut into rough blanks, i.e. blanks with allowances for processing, and after processing, finishing markings are made, finishing parts are obtained in accordance with the drawings and sketches for this type of joinery product. Markings are made with a pencil in the form of lines (scores) or dots using a ruler or special templates to facilitate marking work.
Markup Tools
To mark and check the accuracy of processed workpieces and parts, use a scale ruler, tape measure, folding meter, square, ruler, gauge, thicknesser, compass, bracket, caliper, templates and level (Fig. 1.3).
Roulette is a metal or plastic case containing a measuring tape of various lengths (1... 100 m) with divisions marked on it in meters, centimeters and millimeters. The tape measure is used for rough marking of long lumber.
Folding meter is a set of metal or wooden rulers with divisions applied to them. The rulers are connected to each other on hinges and can be easily folded or moved apart. The meter is used for linear measurements of objects of small length.
Square(see Fig. 1.3, A) designed for applying marks at an angle of 90° and checking the right angle (squareness) of joinery elements. The square consists of a base and a ruler on which divisions can be applied. Squares come in wood and metal.
Yarunok(Fig. 1.3, 6) used for marking and measuring 45° angles. It consists of a base (block) into which a wooden or metal ruler is inserted at an angle of 45°.
Malka(Fig. 1.3, V) designed for measuring angles based on a sample and transferring them to workpieces. It consists of a base (block) and a ruler, hingedly connected to each other.
Reismus(Fig. 1.3, G) used to apply marks parallel to the edge or face of the workpiece being processed. It consists of a body and two movable blocks, at the ends of which there are sharpened pins. The blocks are secured in the required position with a wedge or screws if the thicknesser body is made of plastic.
Compass(Fig. 1.3, d) used for marking circles and arcs with a diameter of no more than 0.5 m. For marking large diameters, a rod sliding compass is used.
Bracket used for marking tenon joints.
Calipers(Fig. 1.3, e) are used to measure the external and internal dimensions of parts and products. There are four types of calipers. The most commonly used caliper ShTs-1 with a double-sided arrangement of jaws for external and internal measurements and a ruler for measuring the depth of holes.
When marking spikes and lugs, various types are widely used templates(Fig. 1.4). Overlay templates for marking dovetail and box tenons are made from metal, hard fiberboard and support bars. The template is set in place, and then the contours of the spikes are outlined with a pencil.
Level used to check the horizontal and vertical arrangement of surfaces of shelves, cabinets, mezzanines, as well as when installing furniture structures.
Auxiliary tools for marking and control are a protractor, a measuring ruler, an awl, a pencil, bars for checking the accuracy of machined surfaces of workpieces, and rulers for measuring diagonal angles when gluing frames and boxes for joinery.
Marking techniques
In order to correctly mark lumber, you must first familiarize yourself with the drawing and prepare the necessary marking tools. Markings are done on a workbench or table. Marking lines (marks) are applied to the surface of the material with a sharply sharpened hard pencil or awl.
In Fig. 1.5, a, b, c Markings are shown using a ruler, a square (at an angle of 90°), and a ruler (at an angle of 45°). When marking workpieces, first apply transverse, then lobar and inclined marks, and then circles and arcs.
Transverse marks are applied with a pencil along a square. To do this, the ruler of the square is placed on one of the front sides of the workpiece, and the base of the square is pressed against the other front side of the workpiece and marked with a pencil.
Share parallel marks are applied with a thicknesser (Fig. 1.5, G). Thickness gauge pins are installed using a scale ruler. The thicknesser block is pressed tightly against the front side of the workpiece. Risks are caused by moving the thicknesser using a “pull” or “pull” technique.
Sloping marks are carried out along a guide, a mark, a ruler or a template. The techniques for performing operations are the same as for performing transverse scratches.
Marking with a bracket (Fig. 1.5, d) used for manual cutting of tenons and lugs. The marks are applied using the sharp ends of nails, which are driven into the quarter of the staple at a certain distance equal to the width of the eye.
In Fig. 1.5, e shows the marking of a circle with a compass. First, use a ruler to mark the center of the circle or arc on the face of the part or the end. Then the leg of the compass is placed in the center and the required line is drawn. The markings must be made with sufficient accuracy and in accordance with the drawings or sketches.
To mark the profiles of curved parts, templates (patterns) are used. They are made from plywood or solid fiberboard. The contour of the pattern is cut out with a jigsaw. The template is placed on the workpiece and the pattern is outlined with a pencil.
Sawing wood
Sawing is one of the main and initial methods of wood processing using multi-cutting tools of various designs.
Preparing hand saws for work
The preparation of saws for work includes the following operations: checking the quality of the tool, sharpening, planing and setting saw teeth.
Saw quality check includes an assessment of their technical condition - the strength and integrity of the handles, the reliability of the blades and their fastening, the sharpness of the teeth and the quality of the setting. The effort spent on sawing largely depends on the quality of sharpening and the correct alignment of the saw teeth.
During the sawing process, the saw teeth become dull, and in order to restore their cutting ability, sharpening. Hand saws are usually sharpened with triangular or diamond files.
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The teeth of saws for cross-cutting wood have an oblique sharpening; they are sharpened at an angle of 60...70° to the saw blade (Fig. 1.9, A). These saws have teeth that are sharpened one at a time and, when sharpening, the metal is removed from the beveled surface of the tooth. Having sharpened the teeth on one side, turn the saw towards you with the other side and, having secured it in a vice, sharpen the remaining teeth at the same angle.
The teeth of saws for longitudinal sawing are straight sharpened, so they are sharpened on one side at an angle of 90° to the saw blade (Fig. 1.9, b).
The teeth of rip saws, in which the angle between the front and rear edges of adjacent teeth is less than 60°, are sharpened with a diamond file.
The teeth of saws for universal sawing are sharpened with a triangular file using direct sharpening, removing metal simultaneously from the front and rear surfaces of the teeth (Fig. 1.9, V).
When sharpening teeth, for each working pass of the file, you need to remove a layer of metal of the same thickness. To do this, the file pressure must be uniform and only when moving forward. You need to move the file in the opposite direction freely, without pressure, tearing it off or without tearing it off the surface to be sharpened. The final finishing is done with a finely cut (velvet) file. After filing, the burrs from the side edges of the teeth are removed with a wet whetstone. For ease of sharpening, the saw blade is clamped in a wooden vice of various designs.
To prevent the protrusion of individual saw teeth and straighten their position along one line, they resort to jointing a whetstone or a triangular file. If the deviations of the tops of the saw teeth from a straight line are significant, then all the teeth are planed with a file inserted into a wooden block (Fig. 1.10). The saw blade must be secured in a wooden vice. The saw teeth are planed with a file before sharpening or, as a rule, after setting.
During the sawing process, the saw blade rubs against the walls of the material being cut and is clamped in the cut. To avoid this, the teeth must be set apart.
Saw tooth alignment consists in the fact that they are alternately bent in one direction (even teeth), then in the other (odd) direction. When setting, the tooth is bent not entirely in height, but halfway. When sawing hardwood, the teeth are set apart by 0.25...0.5 mm per side, and softwood - by 0.5...0.7 mm. The total tooth set should not be greater than the thickness of the blade.
When setting teeth, it is important to ensure that the teeth bend equally on each side. If this condition is not met, the cutting quality will decrease. The teeth are set manually using settings of various designs - from simple to universal (Fig. 1.11). The saw blade is tightly clamped in a vice, and then the teeth are bent alternately, in one direction or the other. You need to spread the saw teeth evenly with a simple set, without much effort, otherwise the tooth can be broken. In addition to the simple setting, a universal setting is used, which makes it possible to obtain the correct amount of saw tooth set. The amount of tooth set is checked with a template. You can set the teeth before and after sharpening, depending on their wear. If the saw is significantly distorted, it is better to first loosen and then sharpen the saw.
Requirements for sawing quality
The quality of sawing is characterized by the roughness of the resulting surfaces and accuracy
processing the workpiece. A rougher surface is obtained when working with a dull and poorly set saw, so before work the saw should be sharpened and set well. Inaccurate cutting of wood occurs when the saw presses hard and when it deviates from the marking line. Sawing tenons and lugs should only begin after you have gained sufficient experience in working with hand saws and have practiced cutting techniques. When sawing, the marking line is preserved. The cutting line should pass next to the mark, and the cutting accuracy is determined along this line. During further processing by planing, the processing allowance is removed.
To avoid flakes and broken edges when cross-sawing parts, their ends should be supported with your left hand when finishing sawing. Sawing of tenons and eyes must be done with sufficient precision.
Useful tips for a carpenter
The thinner the part, the smaller the saw teeth should be. Therefore, to file small glazing beads or strips, you can use a slotted metal file, but you should work with it in a miter box.
When cutting across the jacket layer, the edges of plywood will not chip if the cut area is pre-moistened with water.
To prevent a saw with a narrow tooth spread from getting stuck in wood (especially damp wood), just rub it with soap and the work will go faster.
Wood planing
Planing is cutting wood with a cutter (knife) in different directions in relation to its fibers. By planing sawn blanks, blanks of the correct shape, specified dimensions and a certain roughness of the wood surface are obtained.
For planing, a hand-held planing tool is used (Fig. 1.15), which is used to process straight, curved, flat and shaped surfaces.
Planing tools are made from hardwood (hornbeam, ash, maple, beech, pear and apple), which must be straight-grained without defects and with a moisture content of no more than 10%.
In addition to wooden planes, metal sherhebels and planes with single or double knives are used for planing wood.
Preparing the planing tool for work
Before planing the workpieces, first select the required plane, check the sharpness of the knife and adjust the tool for the specified cutting mode.
Planer knives are sharpened on an abrasive wheel, which is periodically moistened with water.
To sharpen knives, tabletop sharpeners ET-1, BET-1, TN-100, etc. are used. Knives can also be sharpened on a sharpening block using straight-line or circular movements, tightly pressing their chamfers to the surface of the block (Fig. 1.28). The knives are edited using a whetstone until the burrs are completely removed. The sharpening stones are moistened with water, and the whetstones are moistened with kerosene. The sharpening angle of the knives is within 25 ... 30°. The edge of the knife blade must be strictly straight or have a different profile (concave, convex, stepped). The correct sharpening of knives is checked using a ruler, a square, visually and a template.
Techniques for setting up a plane are shown in Fig. 1.29. Setting up a plane consists of correctly installing and securely securing its knife. The adjustment of the plane is checked by trial planing of the workpieces.
The tsikli knife is sharpened on a whetstone and trimmed on a whetstone. After editing, the knife should not have burrs. Then a sting (burr) is applied to the knife using a polished steel rod with rounded corners (Fig. 1.30). The aiming point is made from a file. After aiming the sting, the knives form a very thin blade, which is used to clean the planed surface.
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Planing with hand planes
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The workpiece prepared for planing is fixed on the workbench with the front (base) side up so that the direction of the wood fibers coincides with the direction of planing. Planing is necessary by moving your arms to full swing in a straight line with even pressure on the plane. In this case, the main role should be played by the movements of the worker’s hands, and not the body of his body. Planing and jointer techniques are shown in Fig. 1.31. As a rule, the workpiece is first planed with a sherhebel and a single-knife plane, and then with a double-knife plane or jointer.
After touching one base surface of the workpiece, it is turned over and the remaining sides are planed, controlling the planing process with a square. The surface of the wood must be clean and smooth, without scoring or tearing out fibers. The quality of planing is checked visually (by eye), with a ruler and a square (Fig. 1.32). The quality of the planed profile surface can be checked with the simplest templates (standards).
When processing the ends of a workpiece, first plan one edge away from you to the middle of the workpiece, and then the other towards you (Fig. 1.33). This reduces flakes and spalls. To avoid these defects, at the end of the part along its perimeter, you can first remove chamfers with a width equal to the planing amount, and then trim.
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Techniques for working with humpback, zenzubel, fillet and folded ridge are shown in Fig. 1.34. With a humpback, in the same way as with a regular plane, wood surfaces of various curvatures are processed.
Zenzubel selects quarters according to pre-made markings. Planing is carried out at a short distance from the marking line, and the chips are successively removed to the depth of a quarter (approximately 3...4 mm). After selecting parts of the quarter along the entire length of the workpiece, they are planed with a zenzubel to the full span of the arms, without going beyond the markings. Then the quarter is cleaned with a zenzubel.
The techniques for working with a fillet are almost the same as with a zenzubel. The radius of curvature of the knife is selected depending on the purpose and size of the recess (groove).
The quarters are selected with a folding gebel in the same way as with a zenzubel, but without preliminary marking, since the stepped sole of the folding ridge determines the size of the quarter. When planing wood, the workpiece must be correctly placed on the workbench and secured between its stops.
A special type of wood planing is scraping with a special scraping knife. When working, the scraper is placed at an angle to the surface being scraped, held with the fingers of both hands and moved in the direction of the wood fibers. The cycle planes only when moving in one direction. For scraping, you can also use a manual plane-type scraper.
Work safety when planing
Planing should be done with a serviceable tool with a well-sharpened knife and its secure installation in the block of a plane or jointer. When sharpening knives on a metal sharpener, you must wear safety glasses. The sharpener must have a protective screen with a locking device. Planing tools on a workbench should be laid on their sides with the blade facing away from you, and after work they should be cleaned of chips and put away in a tool cabinet.
Useful tips for a carpenter
The blades of the knives of planes and jointers should be slightly (no more than 0.5 mm) rounded at the edges. This eliminates the operation of the side front edges of the knives, which leave streaks when planing the workpieces being processed.
If the “sole” of a wooden plane has become unusable, it is replaced with a new one by gluing a 15...20 mm thick plate made of hornbeam, maple, ash, or beech wood. For better gliding, it is recommended to lightly lubricate the new “sole” with a thin layer of linseed oil and dry it for 8... 10 days.
To adjust a metal plane to the required chip thickness (0.2...0.3 mm), it is enough to place a sheet of ordinary paper folded in several layers under its front and back parts. The paper and plane should be placed on a flat surface (table, glass). When the clamping screw is lowered, the knife will lower to the plane on which the plane rests.
Chiseling tools
For chiselling, chisels and chisels (flat and semicircular) are used.
Carpenter's chisel consists of a steel blade, handle, ring and cap (Fig. 1.35, A). The chisel handle is made of hardwood or impact-resistant plastic. Chisels are manufactured in lengths of 315, 335 and 350 mm with blade widths of 6...20 mm. The sharpening angle of the chisel chamfer is 25...30°, and the sharpening angle of the side edges is 10°.
For selecting small nests, stripping quarters, grooves, tenons, eyes, chamfering and adjusting joints of wooden parts, use flat chisels(Fig. 1.35, b).
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When processing rounded surfaces of workpieces and sockets, use semicircular chisels.
The length of the chisels is 240, 250 and 265 mm; width of flat chisels - 4...50 mm, semicircular - 4...40 mm; sharpening angle - 25...30°.
Preparing chisels and chisels for work
Chisels are sharpened on a mechanical sharpener and trimmed on a whetstone and whetstone, just like planer knives. The sharpening of the chisel should be one-sided with a chamfer and a rectangular blade. Flat chisels are sharpened in the same way as chisels, with a sharpening angle of the cutter of 25...30°. The blades of semicircular chisels are sharpened with a sharpening stone and a personal file.
Wood chiselling techniques
To obtain a through socket, first mark it on two opposite sides of the workpiece, and a non-through socket on one side. When performing through chiselling, place a board under the workpiece so as not to damage the workbench cover. Chiseling techniques are shown in Fig. 1.36. The chisel is selected according to the width of the marked socket, placed vertically near the nearest marking line (with a chamfer inward), retreating from the line at a distance of 1 ... 2 mm, after which the first blow is applied to the chisel with a mallet, and then the second blow is applied to the chisel tilted inside the socket. and cut off the first chip. Next, repeat the same thing and hollow out approximately 2/3 of the length of the nest. Then the chiseling process is continued at the opposite marking line. Then the workpiece is turned over and chiseling is performed on the opposite side in the same sequence. It is undesirable to cut off thick chips when chiselling, since as a result
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This deteriorates the quality of the workpiece.
Chisel cutting techniques
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When trimming and cleaning surfaces, the chisel is held with the palm of the right hand around the end of the handle, and the palm of the left hand is grasped around the blade of the chisel. With your right hand you press the end of the handle, causing the chisel to cut into the wood and move forward. Use your left hand to adjust the thickness of the chips removed and the direction of cutting. At the same time, to make cutting easier, the cutting edge of the chisel is placed at an acute angle to the wood fibers. Cutting techniques with a chisel are shown in Fig. 1.37.
Occupational safety
Careless handling of chisels and chisels and failure to follow safety regulations can cause serious injuries. When working with a chisel and chisel, it is forbidden to cut towards yourself, in the air, with the part resting on your chest, or with the part on your knees. When cutting with a chisel, the fingers of your left hand should always be behind the blade. Before starting work, you need to make sure that the chisels and chisels are well and correctly sharpened. A chisel or chisel can be passed next to someone working only with the handle, and not with the blade forward. The wooden handles of chisels and chisels should not have chips, cracks, sharp corners and other defects that could lead to injury to the skin of the worker’s hands.
Useful advice for a carpenter
To make it easier to hollow out a nest in the workpiece, you need to moisten the selected area by placing a rag moistened with hot water on it. After the top layer gets wet, it can be easily removed with a chisel. Then repeat soaking and hollowing out until the nest reaches the desired size.
Drilling wood
Drilling is a carpentry operation performed to produce round holes for dowels, screws, bolts and other rod fastenings of wooden parts. Drilling also removes wood defects - knots, followed by sealing them with wooden plugs and glue. For drilling wood, drills are used: spiral, center, auger and countersink (Fig. 1.38).
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Drilling tools
Various types of drills are used for drilling.
Twist drills with conical sharpening (see Fig. 1.38, A) used for drilling wood along and across the grain, as well as at an angle to the surface of the part. Twist drills with a guide center and scorers (see Fig. 1.38, b) used for drilling wood across the grain. Twist drills have helical grooves on the surface of the shaft to remove chips from the hole. They choose deep and precise holes.
Center drills with a flat one (see Fig. 1.38, V) and a cylindrical head (see Fig. 1.38, G) used for drilling through and shallow holes across the grain in wood. Center drills with a cylindrical head are also used for drilling holes for hinges. Using center drills, shallow holes with a diameter of 12...50 mm are drilled. Such a drill consists of a rod with downward-facing undercutters, a cutting edge (blade) and a guide center (point).
During operation, the drill must be frequently removed from the hole to remove chips.
Auger drills(see Fig. 1.38, d) used for drilling wood across the grain. The diameter of auger drills is 10...30 mm.
Countersink drills, or countersinks(see Fig. 1.38, e), used for countersinking holes for screws and bolts.
Preparing drills for work
Drills are sharpened with fine-grained grinding wheels on a sharpener or manually with files. When sharpening with a file, the hardness of the drill should be less than the hardness of the file. The cutting blade of drills with a guide center is sharpened from the back side, the scoring blade is sharpened from the inside, and the guide center is sharpened along the edges of the pyramid. For spiral drills with conical sharpening, the back edge is ground along the generatrix of the cone. Sharpening
done manually or using sharpening devices.
Hole drilling techniques
When drilling a hole, the drill must make two movements: rotational (clockwise) and translational (deep into the hole). To rotate the drill, it is better to use a brace with a ratchet (Fig. 1.39), which is an articulated rod in the middle of which there is a handle for its rotation. At the upper end of the rod there is a pressure head, and at the lower end there is a chuck for fastening the drill. The rotator should rotate left and right. The direction of its rotation is set by a ring - switch. The hammer can be used to tighten screws, bolts and nuts by inserting a screwdriver or socket wrench into the chuck. The drill can drill holes with a diameter of up to 10 mm. Drilling techniques using a brace are shown in Fig. 1.40. In addition to the brace, a mechanical drill is used for manual drilling (Fig. 1.41).
To perform drilling, the workpiece is fixed on a workbench, then the center of the hole is marked and pricked with an awl. Once the center of the hole is determined, drilling begins. Through holes in thick parts are usually drilled from both sides. In thin workpieces, one-sided through drilling is done with a backing board on the reverse side. When drilling at an angle to the surface of the workpiece, first drill a vertical hole to a small depth, and then, without stopping rotation, turn the drill at the desired angle to the surface of the workpiece. When drilling at an angle, you can first
cut out the top of the socket with a chisel, and then drill.
Often, for drilling several holes, overhead templates are used, which have holes of the required diameter and eliminate marking. Templates (conductors), made of hardwood, are bars in which 2...3 holes are drilled, equal to the diameter of the drill. The conductors are secured to the workpiece with a clamp and holes are drilled to the required depth. The resulting holes must have an exact size, and their axes must be strictly perpendicular to the top surface of the workpiece. When drilling wood, you must use properly sharpened drills without cracks or defects. The drill should be fed into the hole easily and smoothly.
Useful tips for a carpenter
A piece of foam placed on a drill can serve not only as an indicator of the depth of the drilled hole, but also act as a fan that blows away chips.
The main operations for preparing circular saws for work are cutting and notching teeth, straightening, rolling or forging, sharpening teeth, setting them or flattening them, and installing the saw on the machine.
Trimming and notching teeth. These operations are performed in cases where the dimensions of the tool do not correspond to the conditions of its operation, the breakage of several adjacent saw teeth, or the appearance of cracks in the blade.
Rice. 102. Detection and elimination of defects in the shape of a circular flat saw blade: a-diagrams for detecting a defect in the disk by checking on both sides; b-location of blows when correcting defects; C-weak points; T-tight spots; B-bulges; I-bends
When cutting teeth, the gap between the punch and the matrix should not exceed 0.5 mm. The stamped contour of the teeth must provide an allowance of 1 -1.5 mm relative to the required profile. The final shape of the teeth is achieved by sharpening them on machines.
Editing saws. By editing, local and general defects in the shape of the canvas are eliminated. A device for straightening circular saws is shown in Fig. 101.
To detect defects in the shape of the blade, set the saw in a horizontal position on three supports and check it with a short straight edge on both sides. The established boundaries of the defects are outlined with chalk (Fig. 102).
The correction method depends on the type of defect. Weak spots “C” are corrected by striking a forging hammer with a round striker around the defect, gradually weakening as one moves away from it.
The blows are applied on both sides of the saw (Fig. 102 I). Tight spots “T” are corrected by blows of a forging hammer inside the defect zone, starting from the borders and ending in the middle. The blows are applied on both sides of the saw (Fig. 102 II).
Bulge “B” is corrected by blows of a forging hammer from the side of the bulge (Fig. 102 III). In order not to change the overall tension of the blade, a cardboard or leather spacer is placed between the saw, placed with the bulge upward, and the anvil.
The bend of the saw “I” (folds at the jagged edge, bent areas, humpbackedness and one-sided wingedness of the disk) is corrected by blows with the correct bend of a hammer (with an elongated striker) either along the ridge itself at the bend, or, if the size of the defect is significant, from the edges of the bend to the ridge with sides of the convexity. The axis of the striker must coincide with the direction of the bending axis (Fig. 102III).
It is recommended to check the quality of saw cutting using a special device (Fig. 101). In this case, the test takes place under conditions close to operational ones. The criterion for assessing the quality of straightening is the magnitude of the greatest deviation of the side surface of the saw (in the peripheral part) from the plane of the end surface of the saw.
The saw is considered straightened if deviations (in mm) from flatness (warping, bulging, etc.) on each side of the saw blade do not exceed for saws with a diameter (mm) of up to 450-0.1; from 450 to 800 - 0.2; from 800 to 1000-0.3. Deviations from the flatness of the central part of the saw in the flange area should not exceed 0.05 mm.
To straighten circular flat saws, use a PI-38 sawing anvil, PI-40, PI-41 forging hammers; straight hammers PI - 42, PI - 43; device for checking the quality of editing; calibration rulers PI - 44, PI - 45, PI - 46, PI - 47 and G1I - 48.
The length of the handles of straightening hammers should be 30 cm; weight of hammers with cross strikers - 1 kg, with oblique strikers - 1.5 kg; convex radius - 75 mm.
Rolling of saws is carried out in order to create the initial stresses necessary to compensate for the temperature stresses that arise when the saw blade is unevenly heated during the sawing process, and to reduce the risk of the occurrence of resonant states of the tool.
The essence of rolling is to weaken the middle part of the saw, due to its elongation when rolled between two working rollers under pressure.
A rolled saw acquires lateral stability of the gear ring during operation, i.e., the ability to withstand unbalanced lateral forces acting on the disk during sawing, and thereby ensure the straightness of the cut
It is enough to roll the saw along one circle with a radius of 0.8 R (where R is the radius of the saw without teeth) for 3-4 revolutions of the saw under the influence of the rollers.. Average roller pressure values for new unforged saws when rolling along one circle with a radius of 6 ,8 R must be set in accordance with the data in Table 25.
Table 25. Roller clamping force when rolling flat circular saws
Depending on the initial stress state of the saw, the pressure of the rollers may fluctuate.
A correctly rolled saw, when positioned in a horizontal plane on three evenly spaced supports located inside the circle of the tooth cavities at a distance of 3-5 mm from it, with free sagging of the middle part, should acquire a uniform concavity (taper shape). The convexity values of rolled saws operating at cutting speeds of 40 - 60 m/s, measured on both sides at a distance of 10 - 15 mm from the edge of the central hole of the saw, must correspond to the values specified in Table 26.
If the required weakening of the middle part of the saw is not achieved, the saw is turned over and re-rolled with the same roller pressing force. Turning the saw over helps to slightly reduce the bending of the blade by the rollers. If the middle part of the saw has not received the necessary weakening, the rolling process is continued along the same circle with increased pressing force of the rollers.
Excessive weakening of the middle part of the saw during its re-rolling is corrected by rolling along a circle spaced 3 - 5 mm from the circumference of the tooth cavities. In this case, the pressing force of the rollers is taken from 10 to 30 kg, depending
from the initial stress state of the tool.
A hacksaw with large teeth cuts faster, but the cut is rough, with uneven edges. The degree of sharpness can be checked by running your thumb along the tips of the teeth. The setting is checked by eye: the teeth must be bent to the sides evenly, otherwise the saw will skid to the side. At the same time, check the evenness of the canvas. Even with a slight bend the saw will jam. The saw blade should bend and straighten quickly. A good saw has teeth that protrude slightly in the middle of the blade, forming a slight arc. In this case, fewer teeth are involved in engagement with the workpiece during the sawing process, while the pressure increases and the saw works better.
Figure 51 shows the sequence of preparing a hacksaw for work.
Rice. 51. Preparing a hacksaw for work: a – aligning the teeth; b – sharpening.
The handle is of great importance. It can be wooden or plastic, the main thing is that it is comfortable to hold in your hand. The stamped iron handle is very inconvenient to use - it makes your hand get tired faster and calluses form.
When storing the saw, it is better to put a piece of hose or PVC pipe cut lengthwise on its teeth.
To prevent the saw from getting stuck in the wood, its teeth must be set apart - bent one at a time to the left and to the right. Due to this, the width of the cut is slightly larger than the thickness of the saw blade, so that it does not get stuck in the cut.
There is a special tool for spreading the saw - wiring, with the help of which the saw teeth are bent to the sides by approximately 0.5 mm (Fig. 52).
Rice. 52. Wiring and template for checking the correctness of the saw: a – wiring; b – template: 1 – protrusion; 2 – setscrew nut; 3 – saw blade; 4 – plate; 5 – spring.
In this case, the teeth spread on each side should be the same. If, after setting, individual teeth turn out to be bent more than others, they are corrected - they are bent in line with the rest. If the teeth are different in height, then before sharpening they are aligned using a file (Fig. 52, b).
Setting and sharpening the teeth of a hacksaw can also be done using a vice, pliers and a triangular file with a fine notch (Fig. 53).
Rice. 53. Preparing a hacksaw for work: a – teeth set; b – sharpening.
First, using a wooden spacer, secure the blade in a vice and, using pliers, begin to carefully move the tops of the teeth alternately in one direction or the other (Fig. 53, a), but not more than half the thickness of the blade. A wider spread will only cause damage, as the cut will be too wide and uneven. It is also necessary to ensure that the spread of all teeth is the same, otherwise not all teeth will participate in the sawing process, but only the most bent ones, and it will be difficult to work with such a saw. The set teeth must be within the spacer, so the position of the blade is changed from time to time.
The saw is sharpened with a triangular file. The blade is clamped in a vice and moved as the teeth are sharpened. There are two types of sharpening - oblique and straight.
If the saw is intended for mixed longitudinal-transverse sawing and its teeth have the shape of a right triangle, a simpler straight sharpening is used, during which the file is held perpendicular to the blade (Fig. 53, b).
Inserting it one by one into each gap between the teeth, with light pressure they move along their edges in the direction away from you. In this case, the edges of the file should fit tightly to the edges. The reverse movement is performed by lifting the file so that it does not touch the saw. You shouldn’t run a file over the same place for a long time; it’s enough to go over each tooth 3 times, and when you sharpen again, just one is enough.
From the book: Korshever N. G. Works on wood and glass
Preparing saws for work consists of preparing blades, teeth, installing saws in the machine and repairing saws. The operations for preparing the toothed rims of saws of various designs are practically the same.
Preparing frame saws. Preparation of frame saws consists of the following operations: identifying and correcting defects in the shape of the blade; control of the tension state of the web; rolling; final control of the flatness and stress state of the saw blade.
Defects are detected by applying a control ruler to the surface of the saw laid on the surface plate. The gap between the ruler and the blade should not exceed 0.15 mm. Editing the saw consists of correcting local defects in the blade: bulges IN, tight spots T, weak points WITH, bending And (Fig.. 44, A). Defective areas are corrected by striking a forging hammer at certain points on a saw placed on an anvil.
The stressed state of the blade is assessed by the magnitude of the deflection of saw 2, curved with a radius R= 1.75 m (Fig. 44, b). The deflection arrow is measured with a test ruler and feelers or a special ruler 1 with indicators 3 and is estimated by the arithmetic mean of two measurements: with the saw positioned up, first with one side and then with the other. The optimal deflection value depends on the size of the saw and lies in the range from 0.8 to 0.35 mm.
Rolling frame saws is one of the measures to increase the rigidity and stability of saws in operation. During operation, the frame saw heats up, especially at the ring gear. The cutting edge lengthens and, under the action of cutting forces, loses its stable flat shape. The saw wanders in the cut, which leads to a wavy or curved cut. The rigidity of frame saws is ensured mainly by their longitudinal tension in the saw frame. However, only due to longitudinal tension it is not possible to provide the necessary rigidity of the saws due to the fact that the tension force is limited by the strength of the grips and the saw frame, which absorbs the tension forces of all saws in the set.
The essence of rolling is that the middle part of the saw blade 4 rolled under pressure between two rotating barrel-shaped rollers 5 and 7 (Fig. 44, V), based on the roller with the non-working edge. At the point where the roller passes, the saw lengthens and stretches the adjacent, non-rolled parts of the blade. As a result of the tension of the rolled saw in the saw frame, in the extreme parts of the saw there will be sufficient tensile stresses with relatively small tensile forces (Fig. 44, d, f). The number, location and order of applying rolling marks 1-5 are shown in Fig. 44, G.
At the end of rolling, the flatness and stress state of the saw is assessed as described above for non-rolled saws. If local defects are detected (deviation from flatness exceeds 0.15 mm), additional editing is performed.
Rice. 44. Preparing frame saws for work:
A- local defects of the canvas and the order of blows when editing; b - control of the tension state of the web; rolling of frame saws; V- schematic diagram: G - location of rolling marks; d - stress distribution in the saw after rolling and tensioning the saw; e - stress distribution in the saw after rolling
Preparing circular saws. Preparation of circular saw blades includes the following operations: assessing the flatness and stress state of the blade, straightening the blade, forging and rolling the saw blade. The flatness of the blade is assessed by two indicators: by the straightness of the disk in various sections and by the end (axial) runout.
The maximum permissible deviations (mm) from flatness depend on the diameter of the saw and range from 0.1 (for saws with a diameter of up to 200 mm) to 0.6 (for saws with a diameter of 1600 mm). To determine the end runout, the saw is mounted on the horizontal shaft of the device. Runout is measured with an indicator located perpendicular to the saw blade at a distance of 5 mm from the circumference of the tooth cavities during slow rotation of the saw with the shaft (Fig. 46).
Before starting measurements, the indicator 2 oriented relative to the plane passing through the end surface
main washer 7. To do this, place a straight edge on the surface of the main washer and the indicator leg. The zero mark of the dial is brought to the large indicator hand. When determining the non-flatness of the saw 3 installed on the shaft 4, clamped with a washer 5 and slowly rotate the handle 6. The permissible end runout (mm) ranges from 0.15 (for saws with a diameter of up to 200 mm) to 0.6 (for saws with a diameter of 1600 mm).
Exceeding the standard values of non-flatness indicates the presence of fabric defects, which are divided into general (dish-like, winged, circumferential bending) and local (weak spot, tight spot, bulge, bend). All defects are corrected by straightening the canvas (Fig. 47).
The correction method depends on the type of defect. Weak spots C (/) are corrected by striking a forging hammer with a round striker around the defective area, gradually weakening the blows as they move away from it. The blows are applied from both sides of the saw. Tight places T(SH corrected by blowing a forging hammer inside the defect zone from the borders to the middle. The blows are applied from both sides of the saw. Bulging B (III) corrected by blowing a forging hammer from the side of the bulge. In order not to change the overall tension of the blade, a cardboard or leather spacer is placed between the saw, placed bulging upward, and the anvil. The bend of the saw (folds at the jagged edge, bent sections of the edge, humpbackedness and one-sided wingedness of the disk) is corrected by blows with a straight hammer (with an oblong striker) either along the ridge of the bend itself, or, if the size of the defect is significant, from the edges of the bend to the ridge on the side of the convexity. The axis of the striker must coincide with the direction of the bending axis.
Rice. 46. Detection of defects in the shape of a circular saw blade
Rice. 47. Editing the saw blade:
A - scheme for detecting a defect by checking on both sides;
b – placement of hammer blows when correcting defects
The stress state of the saw blade is assessed by the amount of deflection of the saw under the influence of its own weight. The saw is installed first with one side up, and then the other in a horizontal position on three supports, spaced at equal distances from each other and at a distance of 5 mm from the circumference of the tooth cavities. The deflection of the saw is measured with a dial indicator (or a straight edge and a set of feeler gauges) at three points on a circle with a radius of 50 mm and the average deflection is calculated. If this value does not correspond to the standard, the saw blade is forged or rolled.
Rolling consists of weakening the middle part of the saw due to its elongation when rolling between two working rollers under pressure (see Fig. 44, V). The rolled saw acquires lateral stability of the ring gear during operation.
It is enough to roll the saw along one circle with a radius of 0.8/? (Where TO - radius of the saw without teeth) for three to four revolutions of the saw under the action of the rollers. The pressing force of the rollers for new unforged saws when rolling along one circle with a radius of 0.87? is set depending on the diameter and thickness of the saw blade and is 15.5...24 kN (for saws with a diameter of 315...710 mm and a thickness of 1.8...3.2 mm).
Correctly The rolled saw should acquire a uniform concavity (disc shape). The concavity values of rolled saws operating at cutting speeds of 40...60 m/s, | measured on both sides at a distance of 10... 15 mm from the edge of the price- | of the saw blade must correspond to the values specified in the standard for saws (0.2...0.6 mm for saws with a diameter of 315...710 mm). After rolling, check the flatness and straighten the saw blade.
Equipment, devices and tools for rolling saws: machine PV-35 or PV-20 with an attachment that provides rolling saws with a diameter of up to 800 mm; a device for monitoring the degree of forging for rolling a circular saw with a hour indicator (saw diameter up to 710 mm); straight edges for sawing work, a set of feeler gauges. Forging saws is not mechanized and requires high qualifications. It consists of striking the central pre-marked part of the saw lying on the anvil with a forging hammer.
Rice. 48. Installing saws on the machine:
A - design of self-centering flanges; b - installation of a riving knife; V - disk guide installation diagram
The degree of weakening of the middle part of the saw is checked in the same way as during rolling (the standards are the same). If the middle part is not weakened enough, the forging is repeated, striking between the places where the first forging was struck.
Installation of circular saws. When installing circular saws, the following conditions must be met:
1. Saw plane 2 must be strictly perpendicular to the shaft axis, and the end runout of the main flange 3 should not exceed 0.03 mm at a radius of 50 mm (Fig. 48, A).
2. The axis of rotation of the saw must coincide with the axis of the shaft. To do this, the diameter of the saw mounting hole should not exceed the shaft diameter by more than 0.1... 0.2 mm. If the gap is larger, you need to bore the hole and insert a bushing into it. It is more rational to use flanges with a centering pin or with a centering cone 7 (see Fig. 48, A).
3. To ensure reliable clamping of the saw, the flanges contact the saw only with outer rims 20...25 mm wide. The diameter of the clamping flanges is selected depending on the diameter of the saw: d?f = 5U7), where IN - saw diameter, mm.
To prevent spontaneous loosening of the nut during operation, it must have a thread opposite to the direction of rotation of the shaft.
4. When sawing along the grain, a riving knife is installed behind the saw in the plane of the saw. 4 at a distance of 10...15 mm from the tops of the teeth (Fig. 48, b). For flat saws, the thickness of the knife is equal to the width of the cut or 0.2 mm greater than it. For conical saws, the knife has a wedge shape and its maximum thickness is 3...4 mm greater than the thickness of the central part of the saw.
5. For saws with a diameter of more than 400...500 mm, install side guides 5 and 6 (Fig. 48, V), limiting saw deflections in the axial direction. Guide pins are made of textolite, fluoroplastic or other anti-friction materials.
The gap between the saw and the guides depends on the diameter of the saw:
Saw diameter, mm.... 125...200 250...300 400...503 560...800 More than 800
Gap, mm............. 0.22 0.30 0.35 0.42 0.55
6. The protrusion of the teeth above the material being cut should not exceed 10... 20 mm, if the design of the machine allows for its adjustment.
Preparing saw teeth for work. Preparing saw teeth for work includes notching the teeth, widening the ring gear, sharpening and jointing the teeth.
Notching the teeth is performed if it is necessary to change the tooth profile or if three (total) or two teeth in a row are broken on the saw. For notching, manual (PSh type) or mechanical (PShP-2 type) saw dies are used. Dies and knives are made of steel 9ХС with a hardness after sharpening and tempering NKSd 55... 60. In the stamped contour of the teeth, an allowance of 1... 1.5 mm should be provided relative to the required profile. The final shape of the teeth is achieved by sharpening them on pilot machines. In this case, a layer of metal with defects formed during stamping is ground off.
Widening of the ring gear. The optimal values for the widening of the gear rim depend on the species and condition of the wood being cut and range from 0.3 (hardwood) to 1.0... 1.3 mm(softwood and high humidity) for circular saws.