Dr. N.K. SINGH Associate Professor(Workshop) Department of ME&MME, ISM, DHANBAD.

Dr. N.K. SINGH Associate Professor(Workshop) Department of ME&MME, ISM, DHANBAD

Clamping Tools. Measuring and Marking Tools. Cutting Tools. Striking Tools. Drilling Tools. Threading Tools.

The vice is the most common tool used for clamping or holding work

It is firmly fixed to the bench with the help of nuts and bolts. It consists of a cast iron and cast iron jaws. Two jaw plates are fitted on both the jaws. The holding surface of the plates is knurled in order to increase the gripping. Jaw plates are made up of carbon steel are wear resistant. One jaw is fixed to the body and the second slides on a square threaded screw with the help of a handle. The jaws are opened up to required length, job is placed in the two jaws and is fully tightened with the help of handle. Handle is used to move the movable jaw.

Vices should be kept clean and free from dust and metal chips, using a brush. The vice should never be used as an anvil. If should be occasionally oiled. The serrated jaws should be covered with soft metal clamps when finished work is held. Don't use hammer to move the handle.

For gripping very small work (objects) a hand vice is gelidly employed. These are made in different shapes and ides depending upon the job. A commonly used consists of the two steel legs hinged together at the bottom. A spring provided between two legs helps in opening out by its pressure. The jaws are adjusted from a flange nut. The vice s held in a one hand and the other hand performs the required operation.

It is used to hold wire or small diameter rods. It consists Pivot of a self-centered three jaw chuck made up of a tool steel. The work is gripped between the jaw of the chuck by rotating the handle.

It is used to hold pipes, shafts or round jobs. It consists of a vertical screw with square treads. A handle is attached on the top of the screw to move the movable jaw, which is fixed, on the lower end of the screw. It grips the work at four points.

In V Block, V grooves are provided to hold the round objects longitudinally. The screw dl clamp applies the holding pressure. When the handle is rotated there is movement in the screw.

It is used for checking squareness of two surfaces. It consists of a blade made up of steel, which is attached to a base at 90 degree. The base is made up of cast iron or steel. It is also used to mark the right angles and measuring straightness of surfaces. Never use try square as a hammer.

It is used for testing the flatness, trueness of the surfaces. It is made up of cast iron graphite. Its upper face is planed to form a very smooth surface. It is also used in scribing While not in use, it should be covered with a wooden cover.

It is made up of cast iron in different sizes. It has two planed surfaces at right angles to each other and has various slots in each surface to hold the work by means of bolts and clamps. Never do hammering on the angle plate to fasten (tighten) the nuts and bolts.

It consists of a steel dial divided into 360 divisions. The dial can be rotated around the centre. The value of any angle can be marked or measured by the straight edge. Straight edge can be slided along the length.

It is a multipurpose instrument that can be used as protector, a level, a centre square and a try square.

It is used to find the centre of the round jobs. It consists of a straight edge and two arms. For finding out the centre, the round job is placed between two arms.

It consists of a cast iron base on the centre of which a steel rod is fixed vertically. Scriber is made up of high carbon steel and is hardened from the front edge. It is used for locating the centres round bars or for marking of the lines.

It consists of a cast iron base, a spindle and a scriber. The spindle can be set at any angle. Scriber can also be set at any angle and at any height from the base maximum upto the length of spindle. It is used for marking purposes.

Punches are used for marking purposes. Dot punches are used for marking dotted line and centre punch is used to mark the centre of hole before drilling. Punches are made up of high carbon steel or high speed steels. One end is sharpened. Hammering is done on the second end while working. For dot punch, angle of the punching end is 60 degree while in centre punch, angle d punching end is 90 0 degree.

These are made up of stainless steel and are available in many sizes ranging from ft to 2 ft. These are marked in inches or millimetres. All the faces are machined true. The edges of rule should be protected from rough handling.

It is a precision instrument used for measuring heights, diameters and depths. It cat used for measuring external and internal dimensions. It consist of a beam, carrying the main scale, inside and outside measuring jaws, a depth gauge bar and an adjustable Vernier head which can be moved along the beam. Fine adjustment done with the help of a screw. Both the heads are provided with locking screw to lock at any desired position. The dimension is measured by the main scale reading and by the vernier scale division. Dimension = Main scale reading + Least count x Vernier scale reading Least count. It is the minimum reading that an instrument can measure.

It is used for measuring diameter or thickness of any job. It is more precise than Vernier Caliper. It consists of a hook type frame. A hard anvil is screwed on one end. On the second arid, a spindle moves to and fro carrying another small anvil on its end. The sleeve on the spindle graduated and is called main scale. The Vernier scale is provided on the thimble that is around the spindle. The gap between the two anvils is adjusted by moving (rotating) the thimble. Ratchet is provided on the side of the spindle to apply fine pressure. Lock nut is provided to lock any desired position.

In one complete turn of the thimble distance covered on main scale = 0.5 mm = pitch Divisions on Vernier scale (i.e. on thimble) = 50 Pitch = 0.5 mm Least count = Pitch/Division on Vernier scale = 0.5/50 = 0.01 mm Final reading = Main divisions x 1 mm + sub division on main scale x 0.5 mm + least Count x division on Vernier scale. Example : If there are 8 mm division crossed, one 0.5 mm sub division on main scale also crossed and the 15th division of the thimble coincides with the datum line then 8 main divisions = 8.00 mm 1 sub division on sleeve = 0.50 mm 15 divisions on thimble = 0.15 mm (15 x 0.01) The final reading = 8.65 mm (Provided zero of the thimble coincides with the datum line i.e. no zero error)

It is a round gauge in which a pointer moves over a graduated scale. The movemerd magnified through links. When there is movement in plunger pin, this movement is magnified various mechanical links and shown by the rotatory motion of the pointer. A nut is also prove on the head for zero adjustment. End of the plunger touches with the job while measuring. Complete revolution of the main pointer corresponds to 1 mm that is divided into 100 parts. Total no. of revolution of main pointer is indicated by small pointer. It is used to check the run out modality of jobs.

These are made up of steel. Dividers have two legs having sharp feet. These are hinged at the top. It is used for marking arcs, dividing a line or transferring a dimension.

These are generally used to measure the inside or outside diameters. Different types are : Outside Caliper. It is used to measure the outside dimensions. Inside Caliper, it is used to measure the inside dimensions. Spring Caliper. Spring is provided to apply the pressure and lock nut is provided to lock any desired position. Hermaphrodite, Jenny or Oddleg Caliper. One leg is bent at the tip inwardly and the other has a straight pointed end. It is used to scribe lines parallel to the straight edges.

Depth Gauge. It consists of a stainless steel head and a beam. The head slides the beam and can be tightened with the help of a screw. The beam is graduated in' or millimetres. Feeler Gauge. It is used to check the gap between two mating parts. It consists number of metal leaves. These have different thickness (marked on each leave fastened together in a small holder. The material of the leaves is stainless steel. Radius Gauge. It is just like a feeler gauge. Every leaf has different radius. It is of two typesinternal or external. It is used to check the radius of outer and inner surfaces. The radius is marked on each leave and is fastened together in a small holder. Thread Gauge. It is used to check the pitch of threads. It consists of a number of leaves. On every leaf cuts art provided to check the threads on the job. The thread on the leave should be properly fit on the thread to be measured. The material of the leaf is stainless steel and is assembled in a holder. Wire Gauge. This gauge is used to check the diameter of wires. It is made up of a steel sheet disc. Vernier Height Gauge. It is used for measuring the height of the parts or scribing lines at height or for marking purposes. It consists of a vertical bar mounted on a base. A sliding head with pointer is carried on the vertical rectangular part (bar). The bar and head are graduated. The scale on the bar is called main scale and on the called vernier scale. It is always used by placing it on the surface plate. The base of height gauge is made up of cast iron and the beam is made up of stainless steel.

Marking means setting out dimensions with the help of a working drawing or the transferring them from a similar part. The procedure of marking is as follows The surface to be marked is coated with the paste of chalk or red lead and allowed dry. Then the work is held in a holding device depending upon shape and size. if it is use surface plate, if it is round use V block and clamp, else use angle plate etc. Lines in horizontal direction are scribed by means of a surface gauge. Lines at n angles can be drawn by turning the work through 90 degree and then using the sat% If true surface is available, try square can also be used. The centre on the end of a round bar can be located by using an odd leg caliper, swim gauge etc. The circles and arcs on a flat surface are marked by means of a divider. After the scribing work is over, indentations on the surface are made using dot punch arid hammer.

The tools, which are used to remove the material from the work piece, are known as cutting tools. The cutting tools used in fitting are hacksaws, files and chisels. These are described below in detail.

Hacksaw is used for cutting of rods, bars, pipes, flats etc. it consists of a frame, which is made from mild steel. The blade is placed inside the frame and is tightened with the help of a flange nut. The blade is made up of high carbon steel or high speed steel. The points of the teeth are bent in a zig-zag fashion, to cut a wide groove and prevents the body of the blade from rubbing or jamming in the saw cut. The teeth of the blades are generally forward cut so in that case, pressure is applied in the forward direction only.

Depending upon the direction of cut, blades are classified as : Forward cut Backward cut. Depending upon the pitch of the teeth (Distance between the two consecutive teeth) blades are classified as : Coarse (8-14 teeth per inch) Medium (16-20 teeth per inch) Fine (24-32 teeth per inch)

Precautions while using Hacksaw : Always move the hacksaw in perfect straight and horizontal direction. Never tilt the frame while sawing. Work should be held firmly in the vice. Blade must be properly strained in the frame. Don't apply too much pressure. Don't use a new blade in the cut made by another blade. Entire length of the blade should be used in the sawing. Don't allow wing nut to strike the workpiece. For forward stroke blades, the teeth should be in forward direction. Don't use hacksaw as a hammer. While cutting thin sections wooden piece must be clamped along with the workpiece Sawing. It is the cutting operation and is performed as follow : The work is held tightly in the vice. Blade is fixed with its teeth facing forward so that cutting stroke is forward stroke. The blade is tensioned sufficiently by a wing nut. The desired cut is marked and a notch is made with a file. The frame is held by one hand just above the wing nut and hold the handle by the second hand. Cutting is started by keeping the blade slightly inclined. Pressure is applied during the forward stroke only and it should be relieved during the return stroke.

Files are multi points cutting tools. It is used to remove the material by rubbing it on the metals. Files are available in a number of sizes, shapes and degree of coarseness. Classification of files On the basis of grade : Rough (20 teeth per inch) Bastard (30 teeth per inch) Second cut (40 teeth per inch) Smooth file (50 teeth per inch) Dead smooth (100 teeth per inch) Rough and bastard files are the big cut files. When the material removal is more, these file are used. These files have bigger cut but the surface produced is rough. Dead smooth and smooth files have smaller teeth and used for finishing work. Second cut file has degree of finish in between bastard and smooth file.

The length of the files varies from 4" to 14". The various shapes of cross-section available are hand file, flat file, triangular, round, square, half round, knife-edge, pillar, needle and mill file.

Single cut files. Double cut files. Rasp files.

Files should be stored in wooden racks. Files should not be used without handle or with loose fitting handle. The file should not be allowed to rust. To prevent it, it should be coated with machine oil. The oil should be removed before using the file. File cleaner should be used for cleaning the files. Use file card or hard wire brush for cleaning. The new file should be used first on copper, brass and then on wrought iron or mild steel. Never use files as a hammer.

Filing is required after chipping, cutting or to finish the shape of the work piece. The operation consists of the following steps 1. The work should be held tightly in the vice. The amount of projection of the workspace from the vice should be minimum to reduce the noise. 2. The file handle is hold by the right hand. Left-hand palm is pressed against the end the file. 3. The file must remain horizontal throughout the stroke. The stroke should be long, and steady. Pressure should be applied only in the forward direction. 4. The pressure is relieved during the return stroke but file should remain in contact the workpiece. 5. When quantity of material removal is more, use rough files and for finishing cut smooth files. Surface smoothness is generated progressively,

These are used for chipping away the material from the work piece. These are made up high carbon steel. The top is flattened and a sharp cutting edge is ground to an angle suited the material being worked upon. The most commonly used cutting angle is 60 degrees, but varies according to the type of material cut.

Commonly used forms of chisels are flat, cross cut, half round and diamond point. Flat chisel is used for general work. Cross cut chisel and half round chisels are used for grooving and diamond point chisels are used for precision work.

The same cutting angle of the chisel must be maintained during the chipping operation. Use proper cutting angle for proper metal. When removing large amount of metal, it is necessary to lubricate the cutting edge frequently. This increases the life of the chisel and the chipping operation becomes easy and smooth. Wear glasses on the eyes while doing chipping. While doing hammering on the chisel heads, keep your fingers away. Never use chisel as a hammer. If the surface to be chipped is very large, it is advisable to cut grooves along the whole surface by means of a cross cut chisel and then chip off the remaining metal.

The removal of thick layers of metal by chisel is known as chipping. This is carried out as follows. The work is properly held in a vice. The chisel is properly gripped in the left hand. The fingers are kept below the head of the chisel. The hammer is grasped in the right hand near the end of the hammer handle. Then apply the blow on the chisel. Lubricate the surface if needed.

Hammers are the only toots used for striking in fitting shop. A hammer consists of a heavy iron body with a wooden handle. The weight of the hammer ranges from 0.25 to 2 kg. The parts of a hammer are pean, eye neck, face and a handle as shown in Fig. 31 below :

1. The handle of the hammer should have proper strength. It should be tightly fitted, 2. Use proper size hammer for proper work. 3. Wipe off any oil, if there, from handle or face of the hammer. 4. Replace the worn out handles. Don't take risk. 5. While doing hammering, keep mind in job.

The tool used for making round holes is called drill. It is a multipoint cutting tool. It is made up of high speed steel. The parts of a twist drill are shown as below :

Reamer is used to finish the drilled hole and the operation is called reaming. So the reaming is a process of imparting necessary smoothness, parallelism, roundness and accuracy in size, to the previously drilled hole by using a reamer. The commonly used reamer is shown below:

Counter sunk are taper cutters used to make the hole cone-shaped from the upper end. It is made for fitting screws and nails.

Taps are used for making internal threads. The tap is provided with cutting edges hardened, so that when it is screwed into a hole, it cuts an internal thread to fit an external of the same size. The taps are made of high carbon or high speed steel These are made insets of three. First use taper tap then use medium tap and then use bottoming or plug tap.

Die and die stock are used for cutting internal threads. Dies are made from tool steel have internal treads. By holding the die into die stock, the handle is rotated by hand.

The drilling operation is carried out as below : The work is marked with a centre punch at the centre of the hole to be drilled. 1. Hold the job properly in a vice or in other suitable holding device. 2. The drill is fitted in the chuck. 3. The hand lever lowers the spindle with the chuck and it is ensured that the point of the drill is in exact alignment with the previously marked centre of the hole. 4. The motor is now started and the rotating drill is gradually pressed into the work to produce desired hole. 5. The pressure should be frequently relieved during the drilling operation, otherwise the cutting edges of the drill will be damaged. A coolant should be used constantly during the drilling operation. Coolant is not used for drilling in brass and cast iron. For drilling large size hole, first produce the small sized holes then produce large holes.

The process of cutting internal threads into a drilled hole by using a tap is known as Tapping. The procedure is described below : First of all, a hole is drilled to a diameter smaller than the outside diameter of the thread on the tap. The diameter of the hole to be drilled is called tapping size. 1. Tapping size = outside diameter 2 x depth of thread. 2. Where depth of thread = 0.64 x pitch of thread. 3. After drilling, the taper tap is fixed in the tap wrench and screwed in the hole. The tap is held with its axis vertical. 4. For all materials except cast iron, a little lubricate oil is applied to improve the action. 5. The tap is not turned continuously, but after every half turn, it should be reversed slightly to clear the threads. 6. When a blind hole is being tapped, the tap should be withdrawn from time to time the metal is cleared from the bottom of the hole. 7. When the hole is through, the reduction of resistance on the tap indicates the cutting of a full thread by taper tap. 8. Then use intermediate tap and follow the same procedure and after intermediate tap bottom or plug tap to finish the threads. 9. When large no. of holes are to be tapped, in that case tapping is done by drilling machine with slow speed. 10. If the tap is broken during the operation. it creates the problem.. 11. If the piece is project out of the hole, use pliers to unscrew it. For removing the piece, which does not pr out of the hole, two pins or four pins tool is used. The tool used is called tap extractor.

Dr. N.K. SINGH Associate Professor(Workshop) Department of ME&MME, ISM, DHANBAD.

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Transcript of Dr. N.K. SINGH Associate Professor(Workshop) Department of ME&MME, ISM, DHANBAD.