Project Report Circular Saw [PDF]

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SANT LONGOWAL INSTITUTE OF ENGINEERING AND TECHNOLOGY



CIRCULAR SAW SUBMITTED BY: SUBMITTED TO: Prince Kumar



MR. VIVEK KUMAR



DWT-132812 UNDER GUIDENCE OF: MR. MOHD. MAJID



Project report submitted in partial fulfillment of the Requirements for the Award of the diploma in welding technology. 1



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ACKNOWLEDGEMENT We express our deep sense of gratitude to Dr. V.K Jain, Director, SLIET and Mr. Shankar Singh, HOD central workshop, SLIET for their constant support.



We are thankful to our project guide Mr. Mohd. Majid, SLIET, for his aspiring guidance, invaluably constructive criticism and friendly advice during the project work. I am sincerely grateful to him for sharing his truthful and illuminating views on a number of issues related to the project. We are grateful for the guidance he have rendered throughout the project.



We are thankful to our lab technicians and assistants, who has shown keen interest in our project and encouraged us all along its course.



We are thankful to our Project Review Committee members, who have supported us during the entire project.



We express our thanks to all those who contributed for the successful completion of our project work.



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ABSTRACT



The mechanical field is improving day by day. Lots of innovative ideas are entering into the field. In the industries, the cutting of the objects plays an important role. In our project, the mechanical arrangements are fixed such that the cutter which is fixed with the shaft of the motor. Ac motor is used for fixed cutter .The cutting tool can be changed at any time. The base is used to hold the full machine. A circular saw is a power-saw using a toothed or abrasive disc or blade to cut different materials using a rotary motion spinning around an arbor. It is a tool for cutting many materials such as wood, masonry, plastic, or metal and may be handheld or mounted to a machine. In woodworking the term "circular saw" refers specifically to the hand-held type and the table saw and chop saw are other common forms of circular saws. Circular saw blades are specially designed for each particular material they are intended to cut and in cutting wood are specifically designed for making rip-cuts, cross-cuts, or a combination of both. Circular saws are commonly powered by electricity. They can be replaced when the work is completed. Thus the circular cutting machine works.



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CONTENTS CHAPTER 1 INTRODUCTION---------------------------------------------------------------------------------------05 1.1 TYPES OF CUTTING TOOLS-------------------------------------------------------------------06 1.2 SAW---------------------------------------------------------------------------------------------------06 1.3 TYPES OF SAW------------------------------------------------------------------------------------07 1.31 HAND SAW------------------------------------------------------------------------------------08 1.32 MECHANICALLY POWERED SAW-----------------------------------------------------09 1.4 MATERIAL USED FOR SAW--------------------------------------------------------------------11 CHAPTER 2 CIRCULAR SAW---------------------------------------------------------------------------------------13 2.1 HISTORY---------------------------------------------------------------------------------------------13 2.2 PROCESS---------------------------------------------------------------------------------------------15 2.3 TYPES OF CIRCULAR SAW---------------------------------------------------------------------16



CHAPTER 3 DESIGN----------------------------------------------------------------------------------------------------21 3.1 SHAFT-------------------------------------------------------------------------------------------------21 3.2 CIRCULAR BLADE--------------------------------------------------------------------------------22 3.3 BEARING---------------------------------------------------------------------------------------------23 3.4 NUT----------------------------------------------------------------------------------------------------24 3.5 WASHER---------------------------------------------------------------------------------------------25 3.6 PLY WOOD------------------------------------------------------------------------------------------26



CHAPTER 4 FABRICATION------------------------------------------------------------------------------------------27



REFERRENCE--------------------------------------------------------------------------28 5



CHAPTER: 1



INTRODUCTION



A cutting tool (or cutter) is any tool that is used to remove material from the work piece by means of shear deformation. Cutting may be accomplished by single-point or multipoint tools. Single-point tools are used in turning, shaping, planning and similar operations, and remove material by means of one cutting edge. Milling and drilling tools are often multipoint tools. Grinding tools are also multipoint tools. Each grain of abrasive functions as a microscopic single-point cutting edge (although of high negative rake angle), and shears a tiny chip. Cutting tools must be made of a material harder than the material which is to be cut, and the tool must be able to withstand the heat generated in the metal-cutting process. Also, the tool must have a specific geometry, with clearance angles designed so that the cutting edge can contact the work piece without the rest of the tool dragging on the work piece surface. The angle of the cutting face is also important, as is the flute width, number of flutes or teeth, and margin size. In order to have a long working life, all of the above must be optimized, plus the speeds and feeds at which the tool is run.



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1.1 TYPES OF CUTTING TOOLS Linear cutting tools include tool bits (single-point cutting tools) and



broaches.



Rotary cutting tools include drill bits, countersinks and counter bores, taps and dies, milling cutters, reamers, and cold saw blades. Other cutting tools, such as band saw blades, hacksaw blades, and fly cutters, combine aspects of linear and rotary motion.



1.2 SAW Once sawing was considered a secondary machining process and saws were used mostly for cutting bar stock in preparation for other machining operations. In recent years, the development of new types of saws and better blade materials have made metal sawing a much more effective, versatile and economical process. In many cases band saws are now being used as the primary means of shaping certain types of metal parts. When the proper sawing machines and blades are used, sawing is one of the most economical means of cutting metal. The saw cut (kerf) is narrow, and relatively few chips are produced in making a cut. When a band saw is used for cutting the contours of complex shapes, only a small portion of the metal is removed in the form of chips. Therefore, the power used in removing large amounts of waste metal is at a minimum. A saw is a tool consisting of a hard blade, wire, or chain with a toothed edge. It is used to cut through relatively hard material, most often wood. The cut is made by placing the toothed edge against the material and moving it forcefully back and forth. This force may be applied by hand, or powered by steam, water, electricity or other power source. An abrasive saw has a powered circular blade designed to cut through metal.



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HAND SAW



BACK SAW CIRCULAR-BLADE SAW



TYPES OF SAW



MECHANICAL POWERED SAW



RECIPROCATING BLADE SAW CONTINUOUS BAND SAW CHAINSAW



1.3 TYPES OF SAW 1.31 HAND SAW Hand saw typically have a relatively thick blade to make them stiff enough to cut through material. (The pull stroke also reduces the amount of stiffness required.) Thin-bladed handsaws are made stiff enough either by holding them in tension in a frame, or by backing them with steel or brass (on account of which the latter are called "back saws.") Some examples of hand saws are:



Bow saw or Buck saw: a crosscut saw with the thin blade held in tension in a frame; Coping saw: for cutting wood patterns; Crosscut saw: for cutting wood perpendicular to the grain; 8



Dovetail Saw: for cutting intricate joints, mainly found in drawers; Frame saw or "sash saw": In general any saw with a thin blade held in tension by a frame, this term often specifically means the ripsaw also called a whipsaw. Fret saw: for cutting intricate wood patterns; Hacksaw: a fine-toothed tempered blade under tension, for cutting metal, [citation needed], and other hard materials;



bone



Japanese saw: a thin-bladed saw that cuts on the pull stroke; Pad saw or "keyhole saw" or "jab saw": a narrow-bladed saw; Plywood saw: a fine-toothed saw (to reduce tearing), for cutting plywood; Rip saw: for cutting wood along the grain; Turning saw: a frame saw with a narrow blade used for cutting curves, larger than a coping saw. Two-man saw: a general term for a large crosscut saw or rip saw for cutting large logs or trees; Veneer saw: a two-edged saw with fine teeth for cutting veneer; Whipsaw or pit saw: a kind of rip saw for cutting logs into lumber; Wire saw: a toothed or coarse cable or wire wrapped around the material and pulled back and forth.



Back Saw "Back saws," so called because they have a thinner blade backed with steel or brass to maintain rigidity, are a subset of hand saws. Back saws have different names depending on the length of the blade. Some examples are:  



Miter saw: for making accurate crosscuts and miters in a work piece Tenon saw or "dovetail saw" or "sash saw": for doing precision cutting in woodworking.



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1.32 MECHNICALLY POWERED SAW Circular-blade saws Circular saw: a saw with a circular blade which spins. Circular saws can be large for use in a mill or hand held up to 24" blades and different designs cut almost any kind of material including wood, stone, brick, plastic, etc. Table saw: a saw with a circular blade rising through a slot in a table. If it has a direct-drive blade small enough to set on a workbench, it is called a "workbench saw." If set on steel legs, it is called a "contractor's saw." A heavier, more precise and powerful version, driven by several belts, with an enclosed base stand, is called a "cabinet saw." A newer version, combining the lighter-weight mechanism of a contractor's saw with the enclosed base stand of a cabinet saw, is called a "hybrid saw." Radial arm saw: a versatile machine, mainly for cross-cutting. The blade is pulled on a guide arm through a piece of wood that is held stationary on the saw's table. Rotary saw or "spiral-cut saw" or "RotoZip": for making accurate cuts, without using a pilot hole, in wallboard, plywood, and other thin materials. Electric miter saw or "chop saw," or "cut-off saw" or "power miter box": for making accurate cross cuts and miter cuts. The basic version has a circular blade fixed at a 90° angle to the vertical. A "compound miter saw" has a blade that can be adjusted to other angles. A "sliding compound miter saw" has a blade that can be pulled through the work, in an action similar to that of a radial-arm saw, which provides more capacity for cutting wider work pieces. Concrete saw: (usually powered by an internal combustion engine and fitted with a Diamond Blade) for cutting concrete or asphalt pavement. Pendulum saw or "swing saw": a saw hung on a swinging arm, for the rough cross cutting of wood in a sawmill and for cutting ice out of a frozen river. Abrasive saw: a circular or reciprocating saw-like tool with an abrasive disc rather than a toothed blade, commonly used for cutting very hard materials. As it does not have regularly shaped edges the abrasive saw is not a saw in technical terms. 10



Reciprocating blade saws Jigsaw or "saber saw" (US): narrow-bladed saw, for cutting irregular shapes. (Also an old term for what is now more commonly called a "scroll saw.") Reciprocating saw or "sabre saw" (UK and Australia): a saw with an "in-and-out" or "up-and-down" action similar to a jigsaw, but larger and more powerful, and using a longer stroke with the blade parallel to the barrel. Hand-held versions, sometimes powered by compressed air, are for demolition work or for cutting pipe. Scroll saw: for making intricate curved cuts ("scrolls"). Drag saw: for bucking logs (used before the invention of the chainsaw). Frame saw or sash saw: A thin bladed rip-saw held in tension by a frame used both manually and in sawmills. Some whipsaws are frame saws and some have a heavy blade which does not need a frame called a mulay or muley saw. Sternal saw: for cutting through a patient's sternum during surgery. Ice saw: for ice cutting. Looks like a mulay saw but sharpened as a cross-cut saw.



Continuous band Band saw: a ripsaw on a motor-driven continuous band. Portable sawmills are typically band saw mills.



Chainsaw Chainsaw: an engine-driven saw with teeth on a chain normally used as a cross-cut saw. Chainsaw mill: a chainsaw with a special saw chain and guide system for use as a rip-saw.



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1.4 MATERIAL USED FOR SAW There are several materials used in saws, with each of its own specifications. Brass Mostly used in back saws because of its low price and its flow characteristics, which make it relatively easy to cast. Brass contributes to the rigidity that is needed in back saws, which require less force to operate than other kinds of saws because of the pulling motion involved. Steel Used in almost every existing kind of saw. Because steel is cheap, easy to shape, and very strong, it has the right properties for most kind of saws. Diamond Fixed onto the saw blade's base to form diamond saw blades. As diamond is a super hard material, diamond saw blades can be used to cut hard brittle or abrasive materials, for example, stone, concrete, asphalt, bricks, ceramics, glass, semiconductor and gem stone. There are many methods used to fix the diamonds onto the blades' base and there are various kinds of diamond saw blades for different purposes. High speed steel (HSS) The whole saw blade is made of High Speed Steel (HSS). HSS saw blades are mainly used to cut steel, copper, aluminum and other metal materials. If high-strength steels (e.g., stainless steel) are to be cut, the blades made of cobalt HSS (e.g. M35, M42) should be used.



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Tungsten carbide Normally, there are two ways to use tungsten carbide to make saw blades: 1. Carbide-tipped saw blades: The saw blade's teeth are tipped (via welding) with small pieces of sharp tungsten carbide block. This type of blade is also called TCT (Tungsten Carbide-Tipped) saw blade. Carbide-tipped saw blades are widely used to cut wood, plywood, laminated board, plastic, grass, aluminum and some other metals. 2. Solid-carbide saw blades: The whole saw blade is made of tungsten carbide. Comparing with HSS saw blades, solid-carbide saw blades have higher hardness under high temperatures, and are more durable, but they also have a lower toughness.



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CHAPTER 2 CIRCULAR SAW A circular saw is a power-saw using a toothed or abrasive disc or blade to cut different materials using a rotary motion spinning around an arbor. A hole saw and ring saw also uses a rotary motion but are different from a circular saw. Circular saws may also be loosely used for the blade itself. Circular saws were invented in the late 18th century and were in common use in sawmills in the United States by the middle of the 19th century.



2.1 History A circular saw is a tool for cutting many materials such as wood, masonry, plastic, or metal and may be hand-held or mounted to a machine. In woodworking the term "circular saw" refers specifically to the hand-held type and the table saw and chop saw are other common forms of circular saws. "Skill saw" has become a generic trademark for conventional hand-held circular saws. Circular saw blades are specially designed for each particular material they are intended to cut and in cutting wood are specifically designed for making rip-cuts, cross-cuts, or a combination of both. Circular saws are commonly powered by electricity, but may be powered by a gasoline engine or a hydraulic motor which allows it to be fastened to heavy equipment, eliminating the need for a separate energy source. The circular saw was invented around the end of the 18th century as a rip-saw to convert logs into lumber (timber) in sawmills and various claims have been made as to who invented the circular saw. Before the design was invented logs were sawn by hand using a pit saw or using 14



powered saws in a sawmill using an up-and-down saw with a reciprocating motion. The rotary nature of the circular saw requires more power to operate but cuts faster because the teeth are in constant motion. The sound of the circular saw is different from the sound of an up-anddown saw and earned it the nickname buzz-saw. Sawmills first used smaller diameter circular saws to ripsaw dimension lumber such as lath and wall studs and for edging boards. As the technology advanced large diameter saw blades began to be used for the head saws and to cut clapboards. Claims to the invention of the circular saw include: • A common claim is for a little-known sail maker named Samuel Miller of Southampton, England who obtained a patent in 1777 for a saw windmill. However the specification for this only mentions the form of the saw incidentally, probably indicating that it was not his invention. • Gervinus of Germany is often credited with inventing the circular saw in 1780. • Walter Taylor of Southampton had the block making contract for Portsmouth Dockyard. In about 1762 he built a saw mill where he roughed out the blocks. This was replaced by another mill in 1781. Descriptions of his machinery there in the 1790s show that he had circular saws. Taylor patented two other improvements to block making but not the circular saw. This suggests either that he did not invent it or that he published his invention without patenting it (which would mean it was no longer patentable). • Another claim is that it originated in Holland in the sixteenth or seventeenth century. This may be correct, but nothing more precise is known. • The use of a large circular saw in a saw mill is said to have been invented in 1813 by Tabitha Babbitt, a Shaker inventor, after she noted 15



the inefficiency of the traditional saw pits used by the sawyers in her community and sought an improvement.



2.2 Process



Typically, the material to be cut is securely clamped or held in a vise, and the saw is advanced slowly across it. In variants such as the table saw, the saw is fixed and the material to be cut is slowly moved into the saw blade. As each tooth in the blade strikes the material, it makes a small chip. The teeth guide the chip out of the work piece, preventing it from binding the blade.



Characteristics • Cutting is by teeth on the edge of a metal blade or by an abrasive wheel •



The cut has narrow kerf and relatively smooth surface finish



•



Cuts are straight and relatively accurate



• The saw usually leaves burrs on the cut edge of metal and plastic (which should then be addressed with sand paper) •



Saw setting should be done geometrically.



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2.3 Types of circular saw



In addition to hand-held circular saws (see below), different saws that use circular saw blades include:



 Abrasive saw  Biscuit joiner  Brush cutter  Carbide saws  Cold saw  Concrete saw  Flip over saws (the combination of a compound miter and table saw)  Miter saw (chop saw, cut-off saw)  Multi-tool (power tool)  Panel saw  Pendulum saw or swing saw  Radial arm saw  Sally saw  Table saw



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Sawmill blades Portable sawmill circular saw blade about 60 cm (2 ft.) diameter. Originally, circular saws in mills had smaller blades and were used to ripsaw lumber after it passed through an "up and down" (muley or sash) saw leaving both vertical and circular saw marks on different sides of the same piece. These saws made it more efficient to cut small pieces such as lath. After 1813 or 1822 saw mills use large circular saws, up to 3 meters (9 ft) in diameter. Large saws demand more power than upand-down saws and did not become practical for sawing timbers until they were powered by steam engines. They are either left or righthanded, depending on which side of the blade the plank falls away from. Benching determines which hand the saw is. Saws of this size typically have a shear pin hole, off axis, that breaks if the saw is overloaded and allows the saw to spin free. The most common version is the ITCO (insert tooth cut-off) which has replaceable teeth. Sawmill blades are also used as an alternative to a radial arm saw. Cordwood saws Allis-Chalmers B with a cordwood saw setup Cordwood saws, also called buzz saws in some locales, use blade of a similar size to sawmill. Where a sawmill rips (cuts with the grain) a cordwood saw crosscuts (cuts across the grain). Cordwood saws can have a blade from 20 inches (51 cm) to more than 36 inches (91 cm) diameter depending on the power source and intended purpose. Cordwood saws are used to cut logs and slabs (sawmill waste) into firewood. Most cordwood saws consist of a frame, blade, mandrel, cradle, and power source. The cradle is a tilting or sliding guide that holds logs during the cutting process. Some cordwood saws are run from a belt from a farm tractor power takeoff pulley. Others, mounted on a tractor's three-point hitch, connect to the rear power takeoff shaft. Self-powered 18



models are equipped with small gasoline engines or even large electric motors as power sources. The mandrel is a shaft and set of bearings that support and transfer power to the blade. The frame is a structure that supports the cradle and blade at a convenient working height. Cordwood saws were once very popular in rural America. They were used to cut smaller wood into firewood in an era when hand powered saws were the only other option. Logs too large for a cordwood saw were still cut by hand. Chainsaws have largely replaced cordwood saws for firewood preparation today. Still, some commercial firewood processors and others use cordwood saws to save wear and tear on their chainsaws. Most people consider cordwood saws unsafe and outdated technology.



Hand-held circular saws for wood



An unusually large hand-held circular saw for cutting timbers with a roughly 16 inches (41 cm) blade. In woodworking the term circular saw is most commonly used to refer to a hand-held, electric circular saw designed for cutting wood, but may be used for cutting other materials with different blades. Circular saws can be either left or right-handed, depending on the side of the blade where the motor sits. A left-handed saw is typically easier to use if held in the right hand, and contrariwise for the right-handed saw, because the user does not need to lean across the saw to see the cutting line. Blades for cutting wood are almost universally tungsten carbide tipped (TCT), but high speed steel (HSS) blades are also available. The saw base can be adjusted for depth of cut and can tilt up to 45° and sometimes 50° in relation to the blade. Adjusting the depth of cut helps minimize kickback. Different diameter blades are matched to each saw 19



And are available ranging from 14 centimeters (5.5 in) to 61 centimeters (24 in). The saw can be designed for the blade to mount directly to the motor's driveshaft known colloquially as a sidewinder, or be driven indirectly by a perpendicularly mounted motor via worm gears, garnering considerably higher torque called a worm-drive saw. The worm-drive portable circular saw was invented in 1923 by Edmond Michel. In 1924 Michel formed a partnership with Joseph Sullivan, and together they started the Michel Electric Handsaw Company, with the sole purpose of manufacturing and marketing the saw invented by Michel. The company later renamed itself Skilsaw Inc., which today is a subsidiary of Robert Bosch GmbH. Portable circular saws are often still called Skill saws or Skil saws. Its successor is still sold by Skil as the model 77. To get around the Skill patents, Art Emmons of Porter-Cable invented the direct-drive sidewinder saw in 1928. Recently smaller cordless circular saws with rechargeable batteries have become popular.



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Cold saw for metal



Cold sawing machines are circular saws that are used in many metal cutting operations. The saw blades used are quite large in diameter and operate at low rotational speeds, and linear feeds. There are three common types of blades used in circular saws; solid-tooth, segmental tooth, and the carbide inserted-tooth. The circular saw is typically fed into the work piece horizontally, and as the saw advances into the material, it severs the material by producing narrow slots. The material is usually held in place during the cutting operation by means of a vise. The chips produced by cutting are carried away from the material by both the teeth of the blade as well as the coolant or other cutting fluid used.



Abrasive saws Circular saw with a diamond blade for cutting asphalt and concrete. The rotary motion of a circular saw lends itself to cutting hard materials like concrete, asphalt, metal, tile, brick, and stone with an abrasive saws like a tile saw. Diamond blades and cut off wheels are commonly used in these applications.



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CHAPTER 3 DESIGN 3.1 SHAFT SPECIFICATIONS: Material: Mild Steel



Dimensions: Length: 220 mm (Before Facing) 200 mm (After Facing)



DIAMETER: 12 mm (Before turning) 9 mm (After Turning)



OPERATIONS PERFORMED: 1. Facing (length reduced by 2 mm) 2. Turning (finished till 40 mm: diameter reduced by 3 mm)



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3.2 CIRCULAR BLADE: SPECIFICATIONS: 105 mm Tungsten Carbide-Tipped (TCT) circular saw blade 40 Teeth 20 mm bore. Max. Speed: 13,500 RPM Recommended for Wood / Ply / Laminate.



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3.3 BEARING: SPECIFICATIONS: Inner Diameter:



10 mm



Outer Diameter:



40 mm



Width:



15 mm



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3.4 NUT: SPECIFICATIONS: Hexagonal Nut M14 Width across corners: 25 mm Width across flats:



20 mm



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3.5 WASHER: SPECIFICATIONS: Inner Diameter: 22 mm Outer Diameter: 35 mm Width:



4 mm



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3.6 PLY WOOD:



Thickness: 16 mm Use: Used for mounting blade assembly and framing the machine.



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CHAPTER 4 FABRICATION: The fabrication process starts with the machining of the shaft on Lathe Machine. The various machining processes performed are facing and turning which were done to optimize the length and diameter of the shaft to be able to fit effectively in the chuck of the motor for power transmission through shaft to the blade to be assembled at the other end of the shaft (as shown in the fig. below). Later on, some turning operation was also performed to fit the bearings on the shaft.



After finishing the required operation the shaft is inserted through the bearings (qty. 2) separated by a small distance (about 50 mm) from each other along the shaft. A hole of 40 mm is drilled from a 50 mm wooden which will hold the bearings. The bearings are placed at the ends of the hole drilled across the wooden block. The bearings should fit the drilled hole through the wooden block tightly and should be aligned parallel to each other to keep the shaft straight. Then the shaft is passed through these bearings. Shaft should be fastened with nuts to restrict its forward and backward motion of the shaft along the bearings. Before passing and aligning the 28



shaft through the bearings, the blade should be assembled rigidly at the end of the shaft with the help of fastenings such as nuts and washers (as shown in the fig. below).



Now the wooden frame is made with a ply board placed horizontally supported at its ends with two other ply board planks placed vertically. The wooden block with shaft, bearing and blade assembly is then attached under the horizontally placed plank. A clearance in provided on the horizontal plank for the cutting blade as it has to be projected above the horizontal plank for cutting the work piece passed against the cutting blade by sliding against it in horizontal direction (i.e. from right to left).



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FINAL ASSEMBLY



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REFERENCE



 www.google.com  www.wikipedia.org  http://mechanicalscet.blogspot.in  Production technology – PK Sharma



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