Methodology Wood Work (Carpentry Tools)
It is a basic tool of the carpenter and is used as a striking tool, to drive nails and work various tools like chisel, nail punch, fix dowels etc.
The various parts of a hammer are shown below:
There are different types of hammers used by carpenters for different works. Commonly the hammers used by carpenters are:
i) Wooden Mallet
ii) Claw Hammer
iii) Warrington Hammer
iv) Pin hammer
Wooden Mallets: It is mainly used to strike the chisel working.
Claw Hammer: It is the main hammer of the carpenter and it weighs about 500 gm. It has poll on one side and claw on the other. The claw is used to pull out nails from the wood work, either which get bent during driving or required for some other reason.
Warrington Hammer: It is the next heavier hammer, weighing about 250 gm and is used for medium heavy work of driving nails.
Pin Hammer: The weight of the Pin hammer is about 110 gm and is used to drive small nails or pins. The poll of the hammer is the main striking face and the Pin is to start the nail driving holding the nail between fingers.
The cutting ability of a saw blade depends upon three measurements,
Rake: This is the angle at which the teeth are ground.
Pitch: This is the number of teeth per inch on the blade.
Set: The teeth are offset(bent) on each side of the blade on a straight set blade, on fine toothed blades they may have a wavy set in which several teeth in a row will be offset to the same side. The distance across the points of the teeth is known as the width of the cut.
Back (Tenon) Saw: A handsaw has a rectangular blade with a reinforcing rib along the back. This is used for more precise cutting, such as dovetails, miters or Tenon joints etc. Because of stiffened edge they can cut to limited depth. These have relatively more pitch and little or no set.
Handsaws: Handsaws are available in many sizes and configurations; a good general purpose saw is 26″ long and has 8 teeth per inch. Crosscut saws (to cut across the grain) have teeth with a negative rake; ripping saws (to cut in the direction of the grain) have a zero rake. The saws shown above are used if the job piece is held in the vice on a work bench; however, in India carpenters also work holding the job piece between their toes, and cut in the sitting posture. The cutting stroke is towards one’s body as against away from body in case the piece is held in vice and the rake of the saws is reverse i.e. sloping tooth is towards the handle.
Keyhole or Compass Saw: These saws have narrow blades to cut along curves or short distances. To start inside cuts one or more holes are drilled, depending on the shape of the cut-out. For longer inside straight cuts, the keyhole saw is used to make a cut long enough so that a regular handsaw can be inserted to finish the cut.
Coping Saw: These saws use very narrow blades so intricate designs can be cut. The blade can be rotated a full 360° to negotiate tight corners. Inside cuts are started by drilling a small hole to allow the blade t
o pass through it, and then the blade is inserted into the saw frame. Deep throated saws called scroll saws with frames having 18″ clearance are available.
Traditional Frame/Bow Saws: Frame saws are useful tools for a great many jobs—often called bow saws, the traditional shape has two hardwood handles separated by a wood bar, with the blade below the bar and a twisted wire or cable above. The result is a, H shape that makes handling very easy. The wire is turned and tightened to add tension to the blade, which then cuts straight and true.
The size of the drill is determined by the maximum drill bit shank that its chuck can accommodate. Used primarily for boring holes in nearly all materials, the electric drill can also be used for a variety of other tasks, facilitated by a number of accessories and attachments. These include sanding, screw driving, grinding, and mixing paint to name but a few.
The Different types of drills
Hand Drill: Uses a hand operated crank handle to turn an interlocking gear, which in turn rotates the drill bit. With a quicker set-up time than the electric drill, the hand drill is most useful when one requires only a small number of holes. Effective for drilling into wood, soft metal, and plastics, hand drills will generally accommodate most drill bits up to 6mm (1/4″) in diameter in either keyed or keyless chucks, and can also be used for screw driving.
Miniature Hand Drill: Particularly useful for fine work, such as model making, the miniature hand drill bores holes with very small, high-speed steel bits. Useful for making pilot holes for small screws, some models have collets at both ends allowing the user to have different size drills available without having to change the bit.
Brace: Similar to the hand drill, with the drill bit being rotated by manually cranking the handle whilst applying pressure. Effective for drilling into wood, the brace will generally accept larger drill shanks than the hand drill, and can also be used for screw driving. Some models have a ratchet fitted to the chuck, allowing the user to drill/drive in places where a full rotation of the handle is not possible.
Electric Rotary Drill: The most basic of the electric drills, the rotary drill is used mainly for boring holes in a variety of materials. These can be either mains-operated (i.e. corded), or battery-operated (i.e. cordless). Different functions incorporated into some models include variable speed and reversing, and attachments can be used to enable different functions, such as sanding and grinding.
Auger: An auger is a device for boring by removing material by means of a rotating in helical pattern. The shaved material is moved along the axis of rotation.
Bradawl: It is used to bore small holes. This is operated with pressure from top by hand and drives it as screw driver. This is mostly used to make pilot holes or clearance holes of small diameter, in thin members.
It is used to level and plane the wood surface. There are three distinct planes, namely, the jack plane, the beading plane and rebate plane, to work at all the surfaces required to be planed.
The Jack Plane: This plane has the cutting edge of its blade ground so it is slightly curved because, as the bit must be driven out so it will take a deep bite into the rough surface of the wood, the curved cutting edge prevents the corner edges of the bit from digging into the planed surface On the other hand, the bits of the smoothing and finishing planes are ground straight across their cutting edges. The bit is ground at 25° and at the edge hooved at 30°.
Beading Plane: This plane has an adjustable blade. It is used for smoothing or shaping the wood for the fine work. It cuts less material as compared to Jack Plane.
Rebate Plane: This plane is used to cut wood along the grains. It is normally used to cut recess, shoulders and rebates. This plane is small in width. The blade of the plane slightly comes out of the body.
Plough Plane: It is used to produce groves of different size.
Try Square or Carpenter’ Square: Try squares are L-shaped, with a thin metal blade that is marked in graduations like a ruler and a “STOCK” called the body, which is thicker than the blade. For woodworking, the body is typically made of wood, while machinists use a variation that has a metal body. Try squares are used primarily to mark a straight line across a piece of wood for cutting. The thicker body of the square is placed against the edge of a piece of wood and the blade is placed on top of the wood, which ensures that the blade is then exactly perpendicular to the edge of the board. The thicker body of the try square also allows it to be placed flat on a table or tool with the blade sticking up in the air, making this a useful tool for measuring things, such as the height of table saw blade or router bit etc.
Marking Gauge: This is simply a straight bar, with a sharpened point projecting out on one side near its end, and having an adjustable sliding head or cheek piece. This tool is used for marking straight lines parallel to one edge of piece and is very important in making mortises or Tenon’s, because the sharpened steel point which projects from the side of the bar, serves to outline and define the edges of the mortises or Tenon’s.
Screwdrivers: Screwdriver is used to drive the screws. Only proper screw driver should be used i.e. full consideration should be given to the type of head, drive and size of the screw. Improper screw driver not only will damage the screw head but also may cause injury to the workman. The screws should not be hammered to fit into the wood. The screwdriver is to be operated with both the hands so that it should not be slipped from screw. Carpenter’s screwdriver has a broader handle compared to others to apply adequate pressure to the screwdriver.
Pincer – This is used to remove small nails from wood.
Plier – The plier is used to hold or remove the nails.
Working of Important Tools
Jack Plane – The correct posture and the stance is given in the fig. below:
a) For longer edges or surfaces to be planed, longer planes are required.
b) To keep the plane straight, press down on the knob of the beginning of stroke and down on the handle at the end of stroke.
c) The jack plane is handled with both hands, and the smoothing plane with one hand, but only when used for dressing the ends of boards. For other uses both hands are required.
d) Before commencing to plane a board, observe the direction in which the grain of the wood runs. This precaution will save many a piece of material, because if the jack plane is set deep it will dig into the wood and cause a rough surface.
e) Never move the jack plane or the smoothing plane over the work so that the body of the tool is in a direct line with the movement of the plane. It should be held at an angle of about 20-25 degrees (see Fig).
f) Never draw back the plane with the bit resting on the board. This wears out the tool, and if there should be any grit on the board it will be sure to ruin the bit. This applies particularly to the jack plane, but is bad practice with the others as well.
Plough Plane: Stance is same as for jack plane.
a) Work should be started from the far end of the job.
b) Take succession of cuts working towards the other end.
a) The saw should be held perpendicular to cutting edge. The saw should not be held on the line. The work should be so laid out that the saw cut is on the discarded side of the material. Little material must be left for trimming and finishing.
b) The saw should be firmly held by the hand during the initial cut or two, duly guided by the thumb, afterwards always hold the handle loosely.
c) The first stroke should be upwardly, not downwardly. While in the act of drawing up the saw we can judge whether the saw blade is held by the thumb gauge in the proper position to cut along the mark, and when the saw moves downwardly for the first cut, you may be assured that the cut is accurate, or at the right place, and the thumb should be kept in its position until two or three cuts are made.
d) For ordinary cross-cutting the angle of the saw should be at 45- 60 degrees. For ripping, the best results are found at less than 45 degrees, but avoid flattening down the angle. An incorrect as well as a correct angle are shown in Figs below.
To make a cross cut: Cross cuts go against the grain, mark the cut with a square, guide the side of the blade with the knuckle of your thumb. Start the cut by pulling up on the handsaw two or three times, then push the saw forward at about a 45° angle, continue with full even strokes. In case of Indian saw the pushing is required in place of pulling and vice-versa.
To make a rip cut: Rip cuts go in the direction of the grain of the wood, mark a line to follow, start the same way as cross cutting, then continue with full strokes at about a 60° angle. If it is a long cut use a wedge to spread the wood apart.
Working with Marking Gauge: The gauge should run straight. The gauge should hold properly to run it straight. It should be observed in figure that the hand grasps the stem of the gauge behind the cheek-piece, so that the thumb is free to press against the side of the stem to the front of the cheek-piece.
The hand serves to keep the cheek piece against the board, while the thumb pushes the gauge forward. The hand must not, under any circumstances, be used to move the gauge along. In fact, it is not necessary for the fingers to be clasped around the gauge stem, if the forefinger presses tightly against the cheek piece, since the thumb performs all the operation of moving it along. The hand grasps the tool in order to hold it down against the material, and to bring it back for a new cut.
Grinding and Sharpening of Tools
There is a principle involved in the sharpening of every tool. There is a particular way to grind the bits of each tool. A chisel cannot be made to do good work unless its cutting edge is square and at the right working angle. The saw will not work unless set properly. The saw not only requires sharpening but also setting and requires good skill. The procedure is explained here under.
How to set: Setting a saw means to set the teeth of the saw bent out of its plane by equal extent outwardly, in alternate manner. To set a saw accurately, that is, to drive out each tooth the same distance, is the first requirement, and the second is to bend out the whole tooth, and not the point only. The point is merely bent out, this is wrong (Fig). The right way is shown in Fig. The whole tooth is bent, showing the correct way of setting. If whole tooth is not bent and only point is bent, following problems will arise,
i) If the point projects to one side, each point or tooth will dig into the wood, and produce tooth prints in the wood, which make a rough surface.
ii) If there are inequalities in setting the teeth, the most exposed points will first wear out, and thereby cause saw deterioration.
iii) A saw with the points sticking out causes a heavy, dragging cut, and means additional labour.
Fig. A shows a very simple setting block. The teeth cannot go wrong in setting.
In Fig. of block shown above B, should be a pair of wooden pegs, driven into the wooden block on each side of the metal piece. The teeth of the saw rest against the pegs so that they serve as a guide or a gage, and the teeth of the saw, therefore, project over the inclined part (B) of the metal block. Now, with an ordinary punch and a hammer, each alternate tooth may be driven down until it rests flat on the inclined face (A), so that it is impossible to set the teeth wrongly.
a) In case of a Rip Saw the angle is 90 degree and Fig. shows an approximation to the right angle. The angle for Cross cut saw is about 12 degrees as shown in fig. marked A.
b) Two things must be observed: the pitch and the angle. By pitch is meant the inclination of the teeth. Fig. which shows the teeth of a rip saw. We will see at A that the pitch of the tooth is at right angles to the edge of the saw. In Fig. which shows the teeth of a cross-cut saw, the pitch (B) is about 12 degrees off. The teeth of the rip saw are also larger than those of the cross-cut.
The Grind Stone: As most of the tools require a grindstone for sharpening purposes, an illustration is given as a guide, with a diagram to show the proper grinding angle. In Fig., the upright of the frame serves as a line for the eye, so that if the point of the tool is brought to the sight line, and the tool held level, you will always be able to maintain the correct angle. There is no objection to providing a rest, for instance, like the cross bars, but many artisans do not prefer providing rest.
i) Never use one spot on the stone, however narrow the tool may be. Always move the tool from side to side.
ii) Never grind a set of narrow tools successively. If you have chisels to grind intersperse their grinding with plane bits, hatchet or other broad cutting tools, so as to prevent the stone from having grooves therein.
iii) Never use a tool on a stone unless you have water in the tray.
Correct Way to Hold Tool for Grinding: There is a correct way to hold each tool (see Fig.). The left hand should grasp the tool firmly, near the sharp edge, as shown, and the right hand should loosely hold the tool behind the left hand. There is a reason for this which will be apparent after you grind a few tools. The firm grasp of the left hand gives you absolute control of the blade, so it cannot turn, and when inequalities appear in the grindstone, the rigid hold will prevent the blade from turning, and thus enable to correct the inequalities of the stone.
Incorrect Way to Hold Tool for Grinding.—The incorrect way of holding a tool is shown in Fig. It is wrong for the reason that the thumbs of both hands are on top of the blade, and they serve as pivots on which the tool may turn. The result is that the corners of the tool will dig into the stone to a greater or less degree, particularly if it has a narrow blade, like a chisel.
The left hand serves both as a vise and as a fulcrum, whereas the right hand controls the angle of the tool. Do not try to force the grinding. The stone should always move toward the tool, so as to prevent forming a feather edge. These apply to all chisels, plane bits and tools of that character.