Carpentry Workshop Practice PDF

Work Instruction Meghnad Saha Institute of Technology 1.0 JOB/EXPERIMENT NO.: ES-ME192/01/Carpentry 2.0 NAME OF EXPERIMENT: Making a single piece wooden pattern 3.0 OBJECTIVE: To make a wooden pattern of specified dimension for mold making in foundries. 4.0 INTRODUCTION TO...

Work Instruction Meghnad Saha Institute of Technology 1.0 JOB/EXPERIMENT NO.: ES-ME192/01/Carpentry 2.0 NAME OF EXPERIMENT: Making a single piece wooden pattern 3.0 OBJECTIVE: To make a wooden pattern of specified dimension for mold making in foundries. 4.0 INTRODUCTION TO CARPENTRY SHOP: Carpentry is the process of shaping Timber, using hand tools. The products produced are used in building construction, such as doors and windows, furniture manufacturing, patterns for molding in foundries, etc. Carpentry work mainly involves the joining together of wooden pieces and finishing the surfaces after shaping them. Hence, the term joining is also used commonly for carpentry. A student studying the fundamentals of woodworking has to know about timber and other carpentry materials, woodworking tools, carpentry operations and the method of making common types of joints. Materials Used in Carpentry: Basic materials used in carpentry shops are timber and plywood. Auxiliary materials used are nails, screws, adhesives, paints, varnishes, etc. Timber: Timber is the name given to wood obtained from exogenous (outward growing) trees. In these trees, the growth is outward from the centre, by adding almost concentric layers of fresh wood every year known as annual rings. After the full growth, these trees are cut and sawed to convert into rectangular sections of various sizes for engineering purposes. Timber is available in the market in various shapes and sizes. The common shapes and sizes an: given below: 1. Log: This is the trunk of a die tree which is a tree from branches. 2. Balk: This is the log after sawing roughly to square cross section. 3. Deal: This is the log after sawing into a rectangular cross section of width about 225 mm and thickness up to 100 mm. 4. Plank: This is the timber piece having width more than 275 mm and thickness 50 to 150 mm. Department of Mechanical Engineering Page 1  Work Instruction Meghnad Saha Institute of Technology 5. Board: This is the timber piece below 50 mm in thickness and above 125 mm in width, 6. Batten: This is the timber piece below 175 mm in width and thickness between 30 mm to 50 mm in thickness. 7. Scantlings: These are timber pieces of various assorted and nonstandard sizes other than the types given above. Classification of Wood The timber used for commercial purposes can be divided into two classes as softwood and hardwood. A soft wood is light in weight and light colored. They may have distinct annual rings but the medullary rays (radial lines) are not visible and the color of the sapwood (outer layers) is not distinctive from the heart wood (inner layers). These woods cannot resist stresses developed across their fibers; hence, not suitable for woodworking. Classification of timber According to the manner of growth of trees, timber can be classified as i) Exogenous or outward growing ii) Endogenous or inward growing i) Exogenous or outward growing In exogenous trees the growth takes place from the centre by the addition of concentric layers of fresh wood every year, known as annual rings. These varieties of trees are suitable for building and other engineering uses the exogenous trees are again classified as Department of Mechanical Engineering Page 2  Work Instruction Meghnad Saha Institute of Technology a) Conifers or evergreen trees b) Deciduous or broadleaf trees The conifer give softwoods and the deciduous gives hard wood common example of hardwood are Sal, teak, rose wood, sandal, shisham, oak beach, ash ebony, mango, neem, babool, etc., softwood include kail pine, deodar chair, walnut etc. ii) Endogenous or inward growing timber These trees grow in wards i.e..every fresh layer of sap wood is added inside instead of outside cane, bamboo, coconut Seasoning Seasoning of wood carried out for removing the sap and reducing the moisture content the presence of sap and moisture will render the wood unsuitable for engineering works due to uneven shrinkage, crack, wrapping and decay. Different methods of seasoning 1. Air seasoning or Natural seasoning 2. Water seasoning 3. Electrical seasoning 4. Kiln seasoning Plywood Thick sheet formed by pasting veneers of wood is called ply. Three or more plys joined by glues is called plywood. The grains of adjacent layers are kept at right angle to each other in order to get better strengthening both directions the outer layer are called facing plys and good hard wood veneers are used for this inner ones are called core plys and low quality wood is used for this the ply wood is made by either cold pressing or hot pressing. Tools for woodworking The principle hand tools used in a carpentry workshop can be classified into i) Marking and measuring tool ii) Cutting tool iii) Planning tool iv) Boring tool v) Striking tool vi) Holding tool Department of Mechanical Engineering Page 3  Work Instruction Meghnad Saha Institute of Technology Marking and measuring tool a) Rules Rules are used for measuring dimensions. For measuring and setting out dimensions various types of rules are used in carpentry shop. Steel rule - Stainless Steel Rule of length 30cm and 60cm. Flexible Measuring Rule- for measuring large dimensions as well as curved or angular surface dimensions. b) Straight Edge and Squares This is a machined flat piece of wood or metal having perfectly straight and parallel edges. c) Steel Tape: It is used for large dimensions, such as marking on boards and checking the overall dimensions of the work. d) Gauges Gauges are used to mark lines parallel to the edges of a wooden piece. It mainly consists of a wooden stem sliding inside a wooden stock. The stem carries a steel point for marking lines. The stock position on the stem can be varied and fixed rigidly by tightening the thumb screw. To mark a line parallel to an edge the gauge stock is held freely against the edge and pushed along it, pressing the steel points to the surface e) Try square Try square consists of a rectangular steel blade fixed rigidly to cast iron stock. The length of blade varies from 150mm to 300mm. Marking Knife or Scriber Marking Knives are used to convert the pencil lines drawn on the wooden surface into deep scratch lines on the surface. They are made of steel with a sharp point at one end and flat blade at the other end. Department of Mechanical Engineering Page 4  Work Instruction Meghnad Saha Institute of Technology Holding tools a) Work Bench This is a table of size and raised construction made of hardwood. The size ranges from 50- 80 cm in length and about 90cm in width. Two or four carpenters can work at a time on the workbench. Carpenters Bench Vice It consists of a jaw fixed on the table side and a movable jaw kept in position by means of screw and handle. The body of the vice is made of cast iron or steel. The jaws are lined with hard wood which can be removed when it is damaged. The screw moves inside the fixed half nut which can be engaged or disengaged by operating the lever. This is made up of a bar of steel. The work is clamped between jaws by rotating the screw using the handle. It is used for clamping glued pieces or holding the workpiece of larger size together for various operations. Department of Mechanical Engineering Page 5  Work Instruction Meghnad Saha Institute of Technology Cutting tools a) Saws Saw is a cutting tool which has teeth on one edge and cutting is affected by reciprocating motion of the edge relative to the work piece. Cutting occurs during the forward motion; such a saw is called push type saw, the cutting occurs during the backward motion. i. Hand Saw- This saw is used for short straight cuts. It has a blade of 25-40cm length 6- 10cm width. The number of teeth per cm length ranges from 3-5. Department of Mechanical Engineering Page 6  Work Instruction Meghnad Saha Institute of Technology ii. Tenon Saw (Back Saw)- It has a parallel blade of 25-40 cm length and 6-10cm width. The number of teeth per cm length ranges from 5-8. b) Chisels The common type of chisels used is briefly explained below. i. Firmer Chisels- they are the most common and general purpose chisel used by a carpenter. They have a flat blade of 15-50mm width and 125mm length. ii. DoveTail Chisel (beveled edge firmer chisel) - These chisels are used for fine and delicate works as well as for cutting corners. iii. Mortise chisel – These chisels are used for heavy and deep cuts to remove large quantities of wood. These chisels have a width of about 15 mm but the blade thickness may range from 6- 15mm. Department of Mechanical Engineering Page 7  Work Instruction Meghnad Saha Institute of Technology Planing Tools Planing tool is used to smoothen the wooden surfaces. a) Wooden jack plane This is the most commonly used plane in the carpentry shop. The main part of a wooden jack plane is a wooden block called a sole, in which a steel blade having a knife edge is fixed at an angle with the help of a wooden edge. The angle of the blade is kept about 45 ° to the bottom surface of the blade. b) Metal Jack Plane Department of Mechanical Engineering Page 8  Work Instruction Meghnad Saha Institute of Technology It serves the same purpose as the wooden jack plane but facilitates smoother operations and better finish. The body of a metal jack plane is made from a grey iron casting with the side and sole machined and ground to better finish. Drilling and boring tools: a) Bradawl: It is a hand operated tool, used to bore small holes for starting a screw or large nail. b) Carpenters brace: it is used for rotating auger bits, twist drills, etc., to produce holes in wood. In some designs, braces are made with ratchet devices. c) Auger bit: it is the most common tool used for making holes in wood. During drilling, the lead screw of the bit guides into the wood, necessitating only moderate pressure on the brace. The helical flutes on the surface carry the chips to the outer surface. d) Hand drill: carpenter’s brace is used to make relatively large size holes; whereas hand drill is used for drilling small holes. A straight shank drill is used with this tool. It is small, light in weight and may be more convenient than the brace. The drill bit is clamped in the chuck at its end and is rotated by a handle attached to gear and pinion arrangement. e) Gimlet: it has cutting edges like a twist drill. It is used for drilling large diameter holes with the hand pressure. Department of Mechanical Engineering Page 9  Work Instruction Meghnad Saha Institute of Technology Striking Tools a) Mallet This is a wooden headed hammer of round or rectangular cross section. The striking face is made flat. Mallet is used for striking the cutting tools and has a wooden handle. b) Claw Hammer This is a hammer with a steelhead and wooden handle. The flat face of the head is used to drive nails and claw portion for extracting nails out of the wood. c) Pincer: it is made of two forged steel arms with a hinged joint and is used for pulling-out small nails from wood. The inner faces of the pincer jaws are bevelled and the outer faces are plain. The end of one arm has a ball and the other has a claw. The bevelled jaws and the claw are used for pulling out small nails, pins and screws from the wood. d) Screw Driver: it is used for driving wood screws into wood or unscrewing them. The length of a screwdriver is determined by the length of the blade. As the length of the blade increases, the width and thickness of the tip also increase. Department of Mechanical Engineering Page 10  Work Instruction Meghnad Saha Institute of Technology Finishing tool Wood rasp files: it is a finishing tool used to make the wood surface smooth, remove sharp edges, and finish fillets and other interior surfaces. Sharp cutting teeth are provided on its surface for the purpose. This file is exclusively used in wood work. 5.0 JOB DESCRIPTION: Material: Wood Drawing: Department of Mechanical Engineering Page 11  Work Instruction Meghnad Saha Institute of Technology Real photograph: 6.0 TOOLS AND EQUIPMENTS USED: 6.1 Steel rule 6.2 Try square 6.3 pencil 6.4 Rip saw 6.5 firmer chisel 6.6 hammer 6.7 Jack plane 6.8 Wood rasp file 7.0 OPERATIONS TO BE CARRIED OUT: Department of Mechanical Engineering Page 12  Work Instruction Meghnad Saha Institute of Technology 7.1 Planning 7.2 Measuring & Marking 7.3 Sawing 7.4 Chiseling 7.5 Finishing 8.0 PROCEDURE: 8.1 The wooden piece of 120mm×45mm×45mm is cut from a long wooden beam. 8.2 One side of the pieces is planned with a jack plane and considered as a reference plane. 8.3 An adjacent side is planned and checked for squareness with a try square. 8.4 Steel rule is set and lines are marked according to the given front view of the job. 8.5 The excess material is planned to correct the size of the outer dimension. 8.6 Using a rip saw, the portions to be removed are cut. 8.7 The excess material is chiseled with firmer chisel. 8.8 The end of both the pieces is filed properly to give final surface finish. 8.9 All readings, calculation, drawing etc. should be done on a loose sheet. On completion of the Job/Experiment present it to the sessional in – charge for his signature and performance gradation. Grading shall be as per University rules. 9.0 PRECAUTION: 9.1 Wood should be free from moisture 9.2 Marking is done without parallax error 9.3 Care should be taken while chiseling. 10.0 DISPOSAL: N.A. 11.0 REPORT WRITING: 11.1 Attach the rough note with your final report. 11.2 The front page of report shall be as per the format given. Department of Mechanical Engineering Page 13  Work Instruction Meghnad Saha Institute of Technology 11.3 Report sheet must contain the following article in order. Experiment No Name of Experiment Objective of the Experiment Principle Apparatus used Procedure Results & Discussion Calculation (Calculation must be given at least for one reading.) 11.4 ASSIGNMENT QUESTIONS: 1. What is seasoning of wood? Name different types of seasoning. 2. What is the pattern? 3. What are the common materials used for pattern-making? Discuss their relative merits and demerits. 4. What are different carpentry operations? 5. Name different types of files and their specification and application. 6. Name different types of saws and their specification and application. 7. Name different types of chisel and their use. 8. What is the mechanism of vice? 9. What is a mallet? Department of Mechanical Engineering Page 14