Measuring tools by machinerys reference series pdf download

Milling machine — Principles of working — specifications — classifications of milling machines — Principal features of horizontal, vertical and universal milling machines — machining operations Types geometry of milling cutters — milling cutters — methods of indexing — Accessories to milling machines, kinematic scheme of milling cutters — milling cutters — methods of indexing. Grinding machine — Fundamentals — Theory of grinding — classification of grinding machine — cylindrical and surface grinding machine — Tool and cutter grinding machine — special types of grinding machines — Different types of abrasives — bonds specification of a grinding wheel and selection of a grinding wheel Kinematic scheme of grinding machines.

Lapping, honing and broaching machines — comparison to grinding — lapping and honing. Kinematics scheme of Lapping, Honing and Broaching machines.

Constructional features of speed and feed Units, machining time calculations. Principles of design of Jigs and fixtures and uses. Typical examples of jigs and fixtures. Machine Tools — C. Elanchezhian and M. Workshop Technology — B. Raghu Vamshi — Vol II. Production Technology by R. Steel Rule. This measuring instrument enables work to be laid out accurately, holes located correctly, and distances and sizes measured with precision, and is therefore one of the most important tools in the engine room.

It is made from spring steel with a high degree of accuracy in both over-all length and graduations, a 6-inch rule being the most common size, although the inch rule is also used, and there are other standard lengths, up to 48 inches. One side of a steel rule is ordinarily graduated in 8ths and 16ths and the other side graduated in 32nds and 64ths, as shown in Fig. When measuring with the steel rule, the methods shown in Fig.

It is often helpful to measure from the 1-inch graduation, as demonstrated in the illustration, instead of FIG.

Wear and tear are hard on the ends of the rule and it is difficult to measure accurately when starting at that point. Always remember to subtract the correct amount, however. The width of the rectangular piece in Fig. A steel rule must always be handled carefully. Guard against rough usage that may cause nicks or scratches, as these reduce accuracy. The rule should be stored in a leather sheath when not in use and the leather oiled slightly to prevent rusting and discoloration which would make the graduations difficult to read.

Some other rules that may be found aboard ship are shown in Fig. These are used for making measurements beyond the capacity of the machinist's rule, or for measuring curved objects, as can be done conveniently with the steel tape or the flexible steel rule. A depth rule , Fig. It is used to measure the depth of holes, slots, keyways, and other recesses. Some of these rules can FIG. The hook rule , Fig. Short steel rules, sometimes called "tempered steel rules," are used where other rules cannot reach.

A number of small rule sections are provided as a set, with a long-handled holder. Adjustment is made by a knurled nut at the end of the holder so that the rule can be held at different angles to suit the work. Outside caliper rules are used to measure the outside diameters of rods, shafts, bolts, etc. Inside caliper rules are used to take measurements of slots, grooves and openings. A special type of rule used by some mechanics is known as the circumference rule. The purpose of the rule is to enable the circumference of a piece of work to be obtained without calculation, when the diameter is known.

The rule has two sets of graduations on the same face, as shown in Fig. One set is graduated in FIG. To use the circumference rule, read straight across from the diameter measurement to the number on the opposite edge. This is the circumference of the tube, in inches, and is very close to the result that would be obtained by calculation, as 3. It the tube is to be constructed with a lap joint, the material will naturally have to be cut wide enough to allow for the lap. It is important to remember that graduated measuring instruments must be handled carefully so that they will retain their accuracy.

In addition they must be kept clean and dry, as dirt and moisture tend to wear and rust away the graduations. Even the touch of the fingers will tend to corrode steel rules.

It is therefore essential that they be wiped off with a clean cloth and machine oil after each use, and then stored carefully so as to be protected against damage and deterioration. It is used to enable a perfectly straight line of considerable length to be marked across a flat surface.

Where comparatively short distances are involved, a steel scale in good condition can be used as a straightedge. When using a scriber and straightedge, care must be taken to make sure that the point of the scriber is drawn along the guiding edge of the face in contact with the work, as otherwise inaccuracies will result. A straightedge must be handled and stored very carefully.

If dents, bends, or rusty spots are permitted to occur, the value of the tool will be seriously affected. The instrument is long enough so that FIG. Before using a scriber it is advisable to examine the point, as it must be sharp and evenly ground.

An oilstone is used to keep the point in good condition. When using the scriber, hold it firmly, and in much the same manner as a pencil. In Fig. Note that it is tilted slightly in the direction of the line being drawn. Also note how the scriber touches the guiding edge of the lower face of the straightedge.

It is often advisable to coat the surface of a piece of metal with chalk before drawing lines on it, as this causes the lines to stand out more clearly. The use of chalk is also helpful when using dividers. They can also be used to check and compare dimensions, or to scribe arcs and circles.

The correct way to set dividers to the desired dimensions is shown in view a of Fig. Note that one leg is on the 1-inch FIG. Handle the dividers carefully while in use, as otherwise they may work loose and creep open, thus altering the measurement. Points should be kept sharp by means of an oilstone. One way to check the setting of dividers is to draw a circle on a piece of scrap paper or metal.

Then measure the diameter of the circle with a rule. If the diameter measures exactly twice the desired setting, the dividers are set properly. When using dividers to scribe a circle or an arc, be sure to tilt the dividers in the direction of the arc, as shown in view b of Fig. Keep the dividers at the same inclination throughout the complete circle or arc.

In this instance the trammel points are attached to an extension bar by means of lock screws. When using the trammel, make sure that there is no sag or bend in the extension bar and that the screws are tight. Incline the trammel in the direction of the arc, and keep the same angle of inclination constant through the entire length of the curve.

A non-adjustable trammel may be used aboard ship when placing the crank of an engine on dead center, as explained in another lesson.

Surface Plate. Its top surface is precision ground to form a true fiat surface, and this surface is used as a base for making layouts with precision tools, such as the surface gage.

The surface plate can also be used for testing machine and engine parts that are required to have fiat surfaces. To do this, a thin film of Prussian blue or some other color pigment is spread evenly over the surface plate. The surface of the part to be tested is then rubbed on the surface plate. The color pigment will adhere to the high spots of the part and indicate the areas to be scraped off. After scraping the high spots, the part is tested again on the surface plate, and the procedure continued until the color distributes evenly over the tested surface, indicating that the job is completed.

On large work it may be necessary to lift the surface plate and rub it against the part being tested, but otherwise the procedure is the same. It is not recommended that a surface plate be used as a means of grinding in flat valves, as this practice would affect the true surface of the plate.

It is usually made of a transparent substance, such as celluloid, so that lines can be seen through it, but it can be made of metal or other materials. A protractor is made semicircular in shape so as to FIG.

By placing the base of the protractor on a line, with the midpoint of the protractor where a second line intersects the first line, the angle between the two lines can be read directly from the instrument. With the aid of a straightedge, or when used in a combination bevel protractor, lines can be drawn on sheet metal, for example, at any desired angle. The protractor can also be used in the construction of triangles used in mathematical problems, or can be used in the graphical solution of such problems, if the work is done with great care.

Squares and Combination Set. A steel square, 16 X 24 inches, is shown in Fig. This set can be used for various purposes, some of which are shown in Fig. Note that a scriber, a spirit level and a protractor are included. Several types of calipers are shown in Fig. Outside calipers are used for measuring outside dimensions, for example, the diameter of a piece of round stock. The calipers should first be set approximately to the diameter of the material to be measured. Then, while held at right angles to the center line of the stock, as shown in Fig.

The points FIG. Inside calipers have curved legs for measuring inside diameters, such as the diameters of holes, the distance between two surfaces, the width of slots, etc. To measure the diameter of a hole with inside calipers, first set them approximately to the size of the hole; then, holding one leg against the wall of the hole, adjust the other leg until it just touches the point exactly opposite , as shown in Fig. The dimension can then be determined with a rule, or FIG. With practice, such a measurement can be taken with a high degree of accuracy.

Hermaphrodite calipers are generally used to scribe arcs, or as a marking gage in layout work, as shown in Fig. To adjust them to a rule, set the scriber leg slightly shorter than the curved leg; then, with the curved leg against the end of the rule, adjust the scriber leg to the desired graduation on the rule. Hermaphrodite calipers should not be used for precision measurements. Fixed Gages. They are made both adjustable and nonadjustable, or fixed.

A fixed gage is made with extreme accuracy to some fixed standard of measurement or shape, so that when it is applied to a piece of work, the standard is transferred to the work.

For example, if a mechanic wants to fix two surfaces so that they are 0. Such a piece of metal would be a fixed gage. They must be stored in a case or box so as not to come in contact with other tools or metal objects, and should be protected with oil or petrolatum to prevent corrosion.

Plug gages and ring gages , examples of which are shown in Fig. Tolerance in this case means the allowable variation in a dimension that is permissible without rejection of the finished part when inspected. Such gages are usually made in pairs, either in one piece or two units. For instance, a plug gage generally has a "go" end and a "no go" end.

If the "go" end of such a gage will enter a finished hole and the "no go" end will not, the size of the hole is within the tolerance for which the gage was designed.

Feeler Gage. All of the blades have the same shape, but each blade is accurately ground to a definite thickness, which is stamped on the blade. Feeler gages are used to measure the distance between two surfaces, for example, when determining bearing clearances, valve tappet clearances, etc.

The feeler gage blades usually range in thickness from 0. By selecting combinations of two or more blades it is possible to measure clearance up to the total thickness of all of the blades. The secret of checking clearances accurately is the ability to "feel" the tension on the blade when it is moved back and forth in the space that is being measured. The best way to develop this sense of feel is to practice measuring clearances of known dimensions.

Always take care not to force the feeler blades into an opening. The thinner blades must be handled with particular care to prevent kinks and creases. When using the thinner blades in combination with other blades, always protect the thin blades by placing them between heavy blades.

Wipe the blades with a clean cloth before using them, otherwise they will not measure accurately. After using the feelers, wipe each blade clean and then apply a protective coating of oil or petrolatum. Remember that feeler gages are easily corroded by perspiration applied during handling, and if carried around in the pocket or otherwise neglected after use, the blades may rust together.

A typical use of a feeler gage, in addition to those previously stated, would be in lining up or checking the alignment of a shaft coupling. When this is to be done, all coupling bolts and nuts are removed and a straightedge is placed across the outer surface of the two coupling halves, in line with the shaft.

The straightedge should rest evenly across the rims of both coupling halves. If it does not rest evenly across the coupling and clearance is noted, the coupling is out of line. Tests should be made with the straightedge at degree intervals around the circumference of the coupling. A feeler gage should next be used to measure the clearance between the faces of the coupling halves, the clearance also being measured at degree intervals around the circumference.

All four measurements should be equal. However, if there is any discrepancy in either test, the coupling is misaligned.

When a coupling is out of line, noisy operation is likely to occur, bearings will run hot, packing glands will wear and leak, etc. One or both of the connected units therefore must be moved until the coupling halves are aligned. In the case of motor-driven pumps, for example, it is usually more convenient to move the motor. The alignment of a coupling may also be determined by the use of a machinists', or dial, indicator.

This instrument is described later. Angle and Radius Gages. Each blade of an angle gage, for example, has a different end angle, as shown in Fig. The rounded corner of each blade of a radius gage is the arc of a circle, and the radius of the arc is stamped on the blade, as shown in Fig. The gage can be used to check outside radii as well as inside radii.

Wire and Sheet Gage. Standard wire and sheet gage. It can be used to measure FIG. Before using one of these gages be sure that all burrs are removed from the material being measured. Snap Gage. The gage shown in Fig. Adjustable snap gages have anvils that can be set to the desired dimensions by means of a micrometer or gage blocks.

The gage FIG. Center Gage. The center gage can also be used for setting thread-cutting tools square with the work. Center gages are usually marked on both faces and along both edges with scales that are convenient for measuring the number of threads per inch of bolts, studs, etc.

One face has 20 divisions to the inch on one edge and 14 divisions to the inch on the other edge. On the opposite face of the center gage there are 24 divisions per inch on one edge and 32 divisions per inch on the other edge.

The different sized divisions are used to check the pitch, or number of threads per inch, of screw threads. The different numbers of threads per inch for which each scale is suitable are those which divide into the scale number without a remainder. Optimization of product quality, 3. Protection of workplace and environment and 4.

Minimization of farm production flexibility. Other objectives include: 1. Improvement in timeliness of agricultural operation and its increased efficiency 2. Preservation and improvement of quality of agricultural production e. Achievement of a better utilization of natural resources and increased raw material supply for industrial use 4. Provision of off- farm employment and increased human labour availability in other sectors.

Enhancement and stabilization of high commodity price through improved inputs and food supply 6. Increase in foreign exchange earnings through massive agricultural products exportation and diversification of economic base 7.

Improvement in water supply and living standard of rural dwellers. Purpose of mechanization Farm mechanization has been known to help in the effective utilization of farm inputs in order to achieve the following purposes: 1.

Increase land productivity: The purpose of mechanization is here to produce more from the existing land. Machinery is a complementary input, required to achieve higher land productivity, for example, through the introduction of pump sets, or faster turn-around-times to achieve higher cropping intensity.

In labour surplus economies, net labour displacement or replacement should be avoided. Decrease cost of production: Introduction of a machine may lower production costs or offset increased costs of draft animals or labour. Benefits of mechanization Beside reduction in human drudgery and costs of farm operations, mechanization offers potential benefit of increased returns from agricultural inputs.

Increased returns from agricultural input can be achieved in the following ways: a. Improvement in crop yield per hectare and quality b. Extension of cultivated area c. Possibility of raising new crops and livestock which were not initially possible d.

This is most advantageous in communities where labour is scarce or expensive. As labour is a constraint in many farming communities, the use of animal traction and tractors brings the opportunity to expand the acreage. Motorization is likely to have an even greater potential for area expansion as long as land is available. Labour productivity will increase considerably. A farmer owning a tractor would normally be able to increase his income through increased production and by doing contract work for other farmers.

Inadequate attention had been paid to mechanization in Nigeria over a long time which is obvious from the scanty and uncoordinated nature of data available. This trend is being reversed by the recent advances of the federal government in the agricultural revolution currently taking place in Africa in general and Nigeria in particular.

Despite these advances, the following problems still hinders agricultural mechanization 1. Huge cost of investment on equipment. Government policies on agricultural machinery import and implementation. Inadequate man power development and skill acquisition on technological advancement in agricultural mechanization. Poor infrastructure development regarding appropriate machinery requirement.

Poor price control common commodity price of products of agricultural mechanization during peak production and harvest gluts. Poor accessibility to credit facilities loans, grants etc from agricultural development banks. Loss of technical skills and service: The Agricultural engineers who made significant contributions to transforming society and solved most of the major problems in the agricultural industry have essentially became a victim of their success, as the demand for their specialized expertise dwindled and young people with technological interests veered away from the agriculture industry.

Socio-economic factors, 2. Availability of mechanization supporting infrastructure and 3. Land and agro-ecological conditions. Involvements of mechanization in agricultural production The involvements of mechanization in agricultural operations and production include: 1. The process of selection of agricultural systems and inputs, 2. Maintenance of mechanical devices and systems involved in agricultural operations and production Nigeria agricultural mechanization programme The fortunes from oil notwithstanding, successive governments experimented with different programmes and agencies to rejuvenate the agricultural sector.

Some of these programmes and agencies Table have agricultural mechanization as a cardinal mandate. Green Revolution GR Federal level Giles reviewed power availability in different countries, and demonstrated that productivity was positively correlated with potential unit farm power. The NCAER assessed the impact of tractorisation on the productivity of land yield and cropping intensity , and economic growth income and employment.

Status of agricultural mechanization: Binswanger defined the status of mechanisation by the growth of mechanical power-operated farm equipment over traditional human and animal power operated equipment. Rijk reviewed the growth of mechanisation in different Asian countries, and suggested the formulation of strategy for mechanisation policy based on economics of use of animate and mechanical power for different field operations. Such policies are in different stages of formation and implementation in various countries across Europe and some part of the developed and developing world today.

Indicators of agricultural mechanization Singh and De reviewed the methodologies adopted by several authors to express agricultural mechanisation indicator. Three indicators of agricultural mechanization identified include; levels of mechanization, mechanization index, and degree of mechanization. The level, appropriate choice and subsequent proper use of these inputs into agriculture has a direct and significant effect on achievable levels of land productivity, labour management, profitability of farming, sustainability, environmental and the quality of life of people engaged in agriculture.

For instance in Nigeria, M1 and M3 were generally applicable. The tools and implements used in each level of agricultural mechanization are as classified below. Level 1: hand-tool technology HTT This is the most basic level of agricultural mechanization, where human being is the power source, using simple tools and implements. A farmer using hand-tool technology can cultivate only about one hectare of land.

He cannot do more than that because of certain scientifically established facts Odigboh, It has been suggested that a power-use intensity of 0.

Some basic features of tools in use include: Hoes: A wide variety of hoes used in farm operations includes; forked hoes and pickaxes. The main use for the forked hoes and pickaxes is to dig compacted manure out of animal compounds.

Figure Traditional hand hoes Material handling tools: Material and earth handling tools such as rakes, shovels and spades are found within the agricultural hand tool list. The shovels and spades are mainly of the D-handled type, commonly used in moving materials from one place to another. Some very old ones have T-handles. Rakes are used mainly to prepare fine seedbeds in the vegetable plots.

Hoes were made by blacksmiths from high-quality material. Some hoes are also made from old discs from tractor-operated implements. Blacksmiths often use very basic production methods but turn out effective tools provided they can find the right type of scrap steel, such as vehicle leaf-springs. Figure Cutting tools Various types of sickle were seen: some were made locally but others were very old imported examples. The wooden handles on the latter usually had been broken and were replaced with a piece of rag wrapped around the tang.