Carpentry introduction

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CARPENTRY

Introduction

Carpentry may be designed as the process of making wooden articles and components such as roots, floors, partitions, doors and windows. Carpentry involves cutting, shaping and fastening wood and other materials together to produce a finished product. Preparation of joints is one of the important operations in wood work. Joinery denotes connecting the wooden parts using different points such as lap joints, mortise and tenon joints, bridle joints, etc.

Carpentry Tools

Carpentry tools are used to produce components to an exact size.
The types of carpentry tools are as follows.
1. Marking tools

2.Measuring tools

3. Holding tools
4. Cutting tools

5.Planning tools

6.Boring tools
7. Striking tools

8.Miscellaneous tools

Marking tools

It is used to marking lines parallel to the edges of a wooden piece. It consists of a square wooden stem with a sliding wooden stock on it. On the stem, a marking pin is attached which is made up of steel. This stem is provided with a steel nail to scratch the surface of the work. It consists of two pins; the distance between the pins is adjustable. It is used to draw parallel lines on the stock.

Measuring tools

The carpentry measuring tools are classified as follows Steel tapes and steel rules are mainly used for measuring short and lengths in millimeters.

A try square is used for testing squareness and marking of joints.

A mitre square is used for marking and measuring an angle of 45 degree.

A bevel square is used for marking and listing angles between 0 degree to 180 degree.

Calipers are used for the precision measurement of cylindrical surface. Inside calipers are used for measuring outside diameter and outside calipers are used to measure inner diameter of a pipe

Holding tools

The carpentry holding tools are shown in fig.

Carpentry vice

A carpentry vice is the common work holding device. It consists of one fixed jaw and one movable jaw. Its one jaw is fixed to the side of the table while the other is movable by means of a screw and a handle.

Bar clamp

The bar clamp (or) sash cramps are generally used in pairs in glueing up operations at the final assembly of joinery work. It is made up of a steel bar of T-section, wine malleable iron fittings and a steel screw.

G-cramp

G-cramp is made up of malleable iron with acme threads of high quality steel .It can be used for clamping small work when glueing up.

Cutting Tools

Saws

A saw is used to cut wood into pieces. There is different type of saws, designed to suit different purpose. A saw is specified by the length of its tooled edge. The following saws are

used in the carpentry section.

Rip Saw

The blade of rip saw is either straight or skew-backed. The teeth are so set that the cutting edge of this saw makes a steeper angle about 600

Cross Cut saw

This is similar in shape of a rip saw. It is used to cut across the grain of the stock. The correct angle for cross cutting is 450.The teeth are so set that the saw kerf is wider than the blade thickness. This allows the blade to move freely in the cut without sticking.

Tenon or back saw

A tenon saw is used for fine and accurate work. It consists of a very fine blade, which is reinforced with a rigid steel back. The teeth are shaped like those of cross cut saw.

Chisels

Chisels are used for cutting and shaping wood accurately. Wood chisels are made in various blade widths, ranging from 3 to 50mm .Most of the wood chisels are made into tang type, having a steel shank which fits inside the handle.

Firmer chisels

These are general purpose chisels and are used either by hand pressure or by a mallet. The blade of a firmer chisel is flat and their sloping face is at an angle 150 to 520 .

Mortise Chisels

These are general purpose chisels and are used for cutting mortises above 9 mm wide. The blade of a firmer type in which they have a thicker section and a stronger neck. By means of this chisel we can apply more Leverage to remove waste wood from the mortise.

Bevel chisels

A bevel chisel is similar in construction to the firmer chisel. Its edges are beveled to allow access to difficult corners. It has a blade with a beveled back due to which it can enter sharp corners for finishing in dovetail joints.

Planning Tools

In general, planes are used to produce flat surfaces on wood. The cutting blade used in a place is very similar to a chisel. The blade of a plane is fitted in a wood or metallic block at an angle.

Jack plane which is about 35 cm long is used for general planning. A smooth plane that is about 20 to 25cm long is used for smoothening the stock .Being short; it can follow even the slight depressions in the stock better than the jack plane. Smooth plane is used after using the jack plane.

                  A rebate plane is used for making a rebate .A rebate is a recess along the edge of a piece of wood which to generally used for positioning glass in frames and doors. A plough plane is used to cut grooves, which are used to fix handle in a door.

Boring Tools

Boring tools are used to make holes in wood .Common types of boring tools are as follows.

1. bradawl
2. Gimlet
3. Brace
4. Bit and drill

A brace bolds and turns the bit and boring of a hole is obtained. A brace having two jaws is used for holing the bit in one end. It has two types, namely ratchet brace and wheel brace. A bradawl and a gimlet are used for boring small holes. These tools are hand operated.

Striking Tools

Hammers

The cross peen hammer is mostly used for positioning small nails. The head is tightly held in the handle with the help of iron wedges. The claw hammer is effective in removing very large nails and also for driving the nails using the other end of the hammer.

Mallet

A mallet is used to drive the chisel, when considerable force is to be applied, which may be the case in making deep rough cuts. A steel hammer should not be used for this purpose, as it may damage the chisel.

Rasp file

A rasp file is shown in Fig. rasp is a file used for finishing the surface of wood. The rasp has sharp cutting teeth on its surface for this purpose. The file is used for removing rasp marks end finally the scratches left by the fix are removed with the scraper and glass paper.

Oil stone

This is an essential flat used for providing sharp edges on Cutting tools. The oil stones may be artificial or natural stones. The carborundum is the best artificial stones where as the Arkansas are the natural stones.

Miscellaneous Tools

Spirit level

The spirit level is used to check the level of the wooden surface. A narrow glass tube is fitted into a small rectangular wooden box. The glass tube contains spirit and a bubble. On placing the spirit level if bubble stays in the middle, then the surface is flat otherwise it is having a slope.

Pincers

They are made up of steel with a hinged joint and are used for pulling out small nails from wood.

Screwdrivers

Screwdriver is used for driving wood screws into wood or unscrewing them. The screwdriver used in carpentry is different form the other common types.

CAPPENTRY MACHINES

Carpentry machines are used for large production of components. The commonly used carpentry machines are described below.

Wood Turning Lathe

A wood turning lathe is the most important machines used in a carpentry shop. It is used A wood working lathe consists of a cost iron body, main motor, cone pulley system, spindle, tool post, head stock, liveanddead centers and speed control devices. In wood working lathes, the workpiece is held between the two centers. The tool is held in the tool post. The workpiece is rotated in between the two centers whereas the cutting tool passes towards the work and removes the material and produces the desired shape and size.

Circular Saw

A circular saw is used for ripping, cross cutting, leveling, grooving and rebating,. It consists of a cast iron table, a circular cutting blade, guide ways, saw guide, elevating hand wheel, tilting handwheel,and a main motor.

In circular saws, the workpiece is held on the table. Then the work is moved against the circular saw to perform the operations. The saw hand wheel is used to adjust the height of the saw above the surface of the table. The table can be tilted up to 45degrees for cutting with different angles. It is an ideal machine

Band Saw

A band saw is used for cross cutting, leveling, mitering, grooving and rebating. It consists of two wheels having an equal diameter, saw guider, frame table, wheel guard, saw tension, arrangement and steel blade having teeth on it. The saw blade travels over the rims of two wheels. The blade width varies from 6 to 25 mm and the thickness is about 1 to 2 mm.

CARPENTRY PROCESSES

In a carpentry shop, a number of operations are performed to get the finished workpiece.
The different types of process performed in a carpentry shop can be classified as follows.
Marking and Measuring
It is the process of setting of dimensions on wooden pieces to obtain the required shape.
This is the first step for further carpentry operations. The marking operation is done with use of
marking tools. Before marking, one end is planed for reference.
Sawing
Sawing is the process of cutting wood to the required shape and size such as straight,
inclined or curved. Sawing can be done along the grains or across the grains.
In sawing, wooden work is fixed in a vice and wood is moved up to prevent vibrations during
sawing.
Planing
Planing is an operation of obtaining, smooth, dimensionally true surface of wood by
using a planer. It is done along the grains.So; smooth surface is achieved. This process can be
also called facing or edging.
Chiseling
It is the process of cutting a small stock of wood to produce required shapes.
Mortising and Tenoning
Mortising is the process of producing a mortise, i.e. a rectangular or square holes and
recesses in wooden pieces. A tenon is a projected piece of wood that fits into the corresponding
mortise. This process is done by using mortise chisels and a mallet.
Boring
Boring is the process of producing through holes or blind holes in wooden piece. This
process can be done straight or inclined according to the type of work. The small holes are
produced by using bradawl and gimlet, whereas large holes are produced by using braces, drills.
Grooving
Grooving is the process of making grooves tonguing is the process of producing
corresponding projections of wood for fitting into grooves. Grooving and tonguing operation can
be seen in drawing boards, floor boards and partitions. Grooving is done with a plough plane
tool, and tonguing is done with a moulding plane tool.