 Hello, I am Mr. D. J. Doshi working as assistant professor, Department of Mechanical Engineering, Valchen Institute of Technology, Solapur. At the end of this session, students will be able to discuss the construction of the lathe machine. Answer this question. Enlist different types of metal cutting machine tools and surface finishing machine tools. I hope you might have written the answers of this question. The answer is machine tools are broadly classified under metal cutting machine tools and surface finishing machine tools. Metal cutting machine tools are lathe machine, drilling machine, milling machine and shaping machine, whereas surface finishing machine tools are grinding machine, honing machine, lapping machine and polishing machines. If you observe the sketch, the construction of lathe machine is divided into three parts, three main elements that is headstock, tailstock and in between these two headstock and tailstock there is a carriage which are mounted on the bed. So, this is called bed of the lathe machine and this is a tray. So, this tray is to collect the chips removed during machining and the coolant if applied for cooling the component will be collected in this tray. So, main components as I told you this is headstock, tailstock, carriage and bed ways. Now, what is headstock? Headstock is a fixed mounted on the bed ways which contains the drive mechanism. So, what is drive mechanism? If it is a geared head lathe this part will be containing the gear train which will having so many gears which can be mesh with each other by changing this lever. These are the change lever or spindle speed levers. We have different positions depending upon the lathe manufacturer we can position it at different positions and we can change or we can give the speed to the spindle So, this is drive mechanism which is driven with the help of electrical motor. So, electric motor will give drive to the drive mechanism through gear train that a drive will be transferred to the spindle. So, what is spindle? The spindle is a hollow shaft of threaded portion at the one end and this hollow shaft will be mounted with gear gears to get different speeds if it is gear drive lathe or it will be mounted with the step down pulley if it is a belt driven lathe. So, there are two types you can say one is gear driven lathe where the headstock will be containing the gear trains whereas, if it is a belt driven lathe then here there will be cone pulley or step down pulley which will give you different speeds to the spindle. So, that cone pulley will be mounted on the spindle. Spindle is hold between two bearings usually called as thrust bearing. So, these bearings will support or will make the shaft or spindle to rotate at the centre of the axis. Now, this threaded portion is used to mount the holding mechanism for work piece or job holding device. So, it may be a chuck, it may be a fixture, it may be a face plate depending upon the type of job to be hold we can mount the holding device on the spindle. Now, when the motor starts that will give drive to the gear train or gear head which will make the spindle to rotate at different speeds. Now, this will be connected or joined through gear train to the feeder drive shaft. So, that we will discuss later on. Now, this is about headstock, there is a greasing or lubricating arrangement here at both the ends for the bearings and for the gears also. Second part is tailstock, this contains the body of tailstock, the wheel to rotate the spindle. Here there is a threaded shaft on which the spindle is mounted and at the end of the spindle there will be more stepper m t 4 or depending upon the manufacture in which dead sentries hold. So, now here if you see the headstock is for holding the device sorry holding the device whereas, the tailstock is to support the component or support the job from front side usually long components or long jobs will be supported from front side. So, that there will not be any other movement to the shaft. So, it can be used for holding dead center, hold holding drill bits, for holding remers, for holding tabs. So, that if you want to apply drill or aperture at the center of the shaft along this axis we can hold the drill in it and make the spindle to move in the axial direction. So, that it will generate the required hole or aperture. Here if we want to carry out reaming which is carried out after drilling. So, we can hold the drill in it and accordingly we will make it to travel along this axis to remove small component or small material which will give the finished surface and the reamed size. In case of tapping also we can hold the tap in it. Now, this spindle will move when we rotate this tailstock wheel. So, this tailstock is mounted on the screw when we rotate this wheel the tailstock spindle will move forward or backward. Now, this total tailstock assembly can be moved towards headstock that is towards left hand side or it can be taken back to its original position. So, depending upon the job length or work piece length we can move the tailstock forward or backward and by rotating this spindle we will clamp this and by rotating this wheel we can make the dead center to support the compound. In between headstock and tailstock there is a carriage. So, this is total carriage assembly which is containing first apron gearbox or apron then saddle, this is cross slide, this is compound slide and this is tool post which is hold with the tool post holder. Now, on the bed ways the saddle is mounted which has the guide ways as the bed and this saddle can move towards headstock or away from the headstock. Now, the saddle has a ground bed ways on which the cross slide is mounted. Again there are guide ways on this saddle which will make the saddle to slide along the perpendicular of the axis. So, when we rotate this saddle wheel it will the cross slide wheel it will travel perpendicular to the axis. On this cross slide there is a compound slide. So, this compound slide is fixed on the cross slide and it can be swelled along its own axis at any angle. So, if you want to generate the taper surface or taper cylindrical surface we can rotate the swell or swell the compound slide to the required angle and when we rotate this cross slide wheel compound slide wheel it will make the taper surface or it will generate the taper surface on the compound. On the compound slide we have a tool post which has 8 bolts. So, we can hold 4 tools in this by clamping these bolts and we can use the required tool by rotating this. So, this is the tool post bolt or tool post holder which will clamp the tool post firmly on the compound slide. Compound slide is firmly hold on the cross slide and cross slide may slide perpendicular to the axis of the lathe on the guideways which are mounted on the saddle. Saddle is holding the apron gearbox which has the automation or mechanized gear train in it. So, if we want to mechanize the operations or automatically turn or face the job we can engage this apron to the lead screw. So, this is called lead screw. So, when we engage the bolt or the half nut which is provided on the apron it will give you the parallel movement automatically or perpendicular movement automatically to the tool. So, the apron is below the saddle. So, this total assembly is called as carriage. Now, this is called carriage wheel, this is called cross slide wheel, this is called compound slide wheel. This is the screw cutting handle or screw cutting engaging lever which engages the half nut with this lead screw. So, if we want the manual movement of the carriage we will not engage any of the mechanism here only we will rotate this carriage wheel which is in turn rotates the gear behind it and that gear is meshing with this rack pinion mounted on the bed width below the bed width and it will move parallel to the axis of the lead. Now, this total assembly that is headstock, carriage and tailstock are mounted on the bed width. So, this is called bed. Now, if you observe this total weight of the headstock, tailstock and carriage is supported by the bed. So, bed is the heaviest structure or heaviest element of the lead which is made up of cast iron and these bed weights are ground so that there will not be any friction between the surfaces which are sliding on it. So, these are ground and case hardened. So, usually what is case hardening? The surface of these bed weights on which the saddle is sliding or tailstock is sliding are harder and smoother. So, grinding makes you harder and smoother and this can slide and this is hardened to avoid the friction as well as to avoid the wear and tear of the this component. So, this is made up of cast iron, bed weights are case hardened so that those will not have more wear and tear and this is made up of rigid material or rigid ribbing so that the shocks during machining will be absorbed by this part and there will not be any further wear and tear of this. The lead screw will be given the drive through headstock by certain gear train and that can be changed by replacing different gears or different gears here which will make the relative speeds of spindle and lead screw depending upon the finish. So, if it is faster and if you want good finish you can make it slower. If we want to remove more material it will be slower and it will be comparatively slower, but depending upon the requirement of the surface it the speed or the travel of the carriage or compound slide can be increased. So, all these things are mounted on the bed weights. The references used for this particular video are BL single a textbook of basic mechanical engineering, Tecmax publication thank you.