Mechanical tools

NEEDLE FILES AND SPECIAL FILES . the different shapes of need files . designate needle files as per BIS . the different types of special files . uses of esch type of special files Needle files are usually available in sets with assorted shapes. These types of files arw used for delicate, light kinds of work. These files are available in bastardization and smooth grade. Shapes The common shapes of needle files. The shape are round edge, flat edge, flat taper, half round, triangular, squre, round, kinfe, feather edge, crossing, barret and marking. Nomenclature of needle files These files are available in a nominal length of 120mm to 180mm. Grades The grades of cut may be identified by the cut number as follows- Bastard-cut 0 Smooth-cut 2 Designation of needle files The needle files are designated by their names grade of cut Nominal length BIS number Example A flat edge needle file with grade  of cut bastard, having a nominal length L=160mm shall be designated as flat edge needle file...

  Drilliing machine(portable type) . the different types of portable drilling machines .distinctive features and uses Necessity Portable hand drills of different types are used for certain jobs which cannot be handled on stationary drilling machines. Types There are  two types of portable drilling machines, power operated and hand operated. Power operated drilling machines Electric hand drill(light duty) These are available in different forms. The electric hand drills has a small electrical motor for driving the drill. On the end of the spindle, a drill chuck is mounted. Electric hand drills used for light duty will have, usually, a single speed. Electric hand drill (heavy duty) This drill  has an additional features,the drill speed can be varied through a system of gears. This is particularly used for  drilling larger diameter holes. Pneumatic hand drill This type of drill is operated by compressed air. An air driven motor is housed in the casing, and a handle is fi...

  DIAL TEST INDICATORS .principal of  a dial test indicator . parts of a dial indicator . the important features of a dial test indicator . the functions of a dial test indicator Dial test indicators and instruments of high precision, used for comparing and determining the variation in the sizes of a component. These instruments cannot give the direct reading of the sizes like micrometers and  vernier calipers. A dial test indicato magnifies and vernier calipers. A dial test indicators magnifies small variations in sizes by means of a pointer on a graduated dial. This direct reading of the deviations gives an accurate picture of the conditions of the parts being tested. Principle of working The magnification of the small movement of the plunger or stylus is converted into a rotary motion of the pointer on a circular scale. Types Two types of dial test indicators are in use according to the method of magnification. They are Plunger type Lever type The plunger type dial tes...

  DEPTH MICROMETERS . name the parts of a depth micrometers . the constructional features of a depth micrometer Constructional features The depth micrometers consists of a stock on which a graduated sleeves is fitted. The other end of the sleeve is treaded with a 0.5mm pitch 'V' thread. A thimble which is internally threaded to the same pitch and form, mates with the threaded sleeve and slides over it. The other end of the thimble had an external step machined and threaded to accommodate a thimble cap. A set of extension rods is generally supplied. On each of them the range of sizes that can be measured with that rod, is engraved as 0-25,25-50,50-75,75-100,100-125 and 125-150. The extension rods can be inserted inside the thimble and the sleeve. The extension rods have a  collar-head which helps the rod to be held firmly. The measuring faces of the stock and the rods are hardened, tempered and ground. The measuring face of the stock is perfectly machined flat. The extension ro...

  WASHERS-TYPES AND USES . purpose of washers . the type of washers . uses of each type of washers Purpose It is a common practice to provide washers under the nuts in bolted joints. Washers help to Increse the frictional grip Prevent loosening of nuts due to vibrations Prevent damage to  the workpiece and distribute force over a larger area. Types of washers There are different types  of washers available. They are Plain of flat washers Taper washers Spring washers Tab washers Toothed lock washers Plain or flat washers These washers are used for bolting assemblies with flat surfaces. The diameter, thickness and the bore diameter are proportional to the diameter of the bolt. Plain washers are available as machined or punched washers. Machined washers These washers are used for assemblies using machined components. These washers are available with chamfer on one side or on both sides. They are heat treated and ground. Punched washers These do not have chamfers and are comm...

. purpose of using clamps . requirements of the clamping devices .Features and uses of 'C' clamps .features of toolmaker's clamps Purpose of using clamps Clamps are different types are used for  preventing the movement of work Requirements of clamping devices Should be able to manipulate for easy loading. Should provide the required clamping force. Should be capable of locking with minimum movement. Should accommodate a range of sizes of jobs. A typical clamping device, employing a screw and nut to provide the clamping force. 'C' clamps These clamps are in the shape of a 'C'. The 'C' clamp has its body forged or cast. One end of the clamp is machined flat. The other end is drilled and threaded to accommodate a screw rod which is operated by a handle. The screw rod carries a swivel pad which is free to revolve. The clamp is hardened and the face is serrated. These clamps  are used to hold work, an angle plate or a drill press table,and also, for holdi...

  V blocks . the constructional features of 'v' blocks . the types of 'v' blocks and state their uses Constructional features 'V' Blocks are devices used for marking and setting up work on machines.The features of the common 'v' blocks. The included angle of the VEE is 90° in all cases.'V' blocks are finished to a  high accuracy in respect of dimension flatness and squareness. Types Different types of 'V' blocks are available. As per BIS there are four type. Single level single groove 'V' Block This type has only one 'V' groove, and has single groove (slots) on their side. These grooves are for accommodating the holding clamps. Single level double groove 'V' Block This type will have one 'V' groove l, and two grooves (slot) on either side for clamping in two positions. Double level single groove 'V' Block In this case, the 'V' block will have two 'V' grooves on the top and bottom, an...

  Parallel blocks .the types of parallels .the constructional features of parallel blockd . uses of parallel blocks The parallel blocks of different types are used for setting workpieces for machining. The commonly used are of two types. Solid parallels Adjustable parallel Solid parallels This is the type of parallel which is very much used in machine shop work. They are made of steel  pieces of rectangular cross secction and are available in different lengths and cross sectional sizes. They are hardened and ground and, sometimes, finished by lapping. Paralles are machined to close limits, and are perfectly flat squre, and parallel throughout the length. These are made in  pairs of indentical diemensions. Grades Parallels are made in two grades-Grade A and Grade B. Grade A is meant for fine toolroom type of work, and Grade B for general machine shop work. Adjustable parallels These consist of two tapered blocks sliding one over the other in a tongue and groove assembly. T...