MAKING A CENTER PUNCH AND DESCRIPTION OF LATHE MACHINE (Part 2)

Different Parts of Lathe Machine

1.     BED:

                     It is the backbone of the lathe. A lathe is built around a bed made machine & rigid to resist different vibration. It is usually made of well normalized or aged gray or regular iron & provides a heavy rigid frame on which all the other basic component are mounted.

2.     Head Stock:

                     It is mounted on the top of left side of be bed. It carries a revolving spindle. A lathe spindle is hollow to take long barstock & the diameter of the hole determines the largest size handstock that can be passed through the spindle for chucking. The spindle hole has a define taper at the front end to receive tapered center & tool shanks. The nose or end of the spindle has true locating surfaces for positioning & means for fastening a chuck, a face plate or a dog plate.

3.     Tail Stock:

                      It is on the top of the bed & opposite of the headstock. Tailstock can be adjusted along the bed of the lathe to accommodate different lengths of stock. Its spindle does not removable but can be moved a few inches otherwise & clamped as desired, drills, rimming, taps & other end coding tools are held & feed to the work piece by the tail stock spindle, which is hollow with a taper to take the shanks of centers drill rimmers etc. The whole tail stock can be moved to end calmed in any position along the bed where it can bested serve its purpose.

4.     Carriage Assembly:

                     Between the head stock & tail stock as the carriage that has severed points that serve to support, move & control the cutting two of these parts, the saddle slides on ways on top of the bed. On top of the saddle is a cross slide that is adjusted & fed at right angles to the length of the bed by a chuck.

5.     Feed Rod:

                     The fed mechanism of a lathe is employed for imparting various feeds to the cutting tool. The feed, i.e. , the movement of the tool relative to the work may be longitudinal, Cross & angular. The feed mechanism changes gears, feed gear box quick change gear box, lead screw, feed rod, apron mechanism & half mechanism.

Use of Lathe Machine:

    Turning:

            For this purpose center holes on end faces of work piece are drilled using a combination drill & countersink tool. The angle of tool is identical with the center

         Facing:

            It is the lathe operation of finishing the ends of the work to make the ends flat & smooth & to make the piece of the required length for this work the job is held in a chuck.

         Chucking Work:

             Work that cannot be readily mounted between the lathes centers it usually held in a chick. Many machine operations can be performed on work held in a chuck such as threading, baring, turning etc. Independent (4 jaws) chuck is used move that other types because if can hold practically any shape of work & can be adjusted to any degree of accuracy desired.

          Knurling:

             It is the process of embowering a diamond shaped regular patterns on the surface of a work piece using a special knurling.

         Taper Turning:

             A job which decreases in diameter gradually so that it assumes a conical shape is said to be tapered. Taper angle is the angle, included between the tapering sides of the job when extended to meet at a point.

         Thread Cutting:

             On lathe internal & external threads are cut either with the help of a threading tool or with the help of top & dia respectively.

Operations:

Our supplied mild steel rod was longer than out required size of the center punch. So firstly we cut the rod to its desired size & wake a hole at one side of the hole.

            We then placed our job into the lathe machine. We put the job into the hole of the support body & other side of the job was attached with tail stock. The tailstock can be mound from left to right & right to left longitudinally.

             After that we will execute turning of the material as required. Our required diameter is 0.5”. The turning was completed by the help of the carriage. We then set the relieving. Slide on the job material & also set apron accurately. Apron can be moved longitudinally & the other can be moved transversely, with the help of relieving & apron we finished our turning must be executed carefully because a little bit of carelessness may damage the job. It takes a lot time.

             After turning we set our calculated angle of the machine swivel vice. Different angle are set for different side of the job was not accurately by the machine as angles are set in the machine swivel vice.

             Outside of the job was a little taper while the outer side of the job was taper enough. We made to taper job smooth with the help of a file. Then our enquired center punch was fully completed by us with help of different tools & lathe machine.

 

Calculation:

Taper angle, tanφ = (D-δ)/2L_t

        Here, D= Large Diameter= 0.5”

                   δ= Small Diameter= 0.25”

               & L_t= Length of taper=1.25”

         So, tanφ= (0.5-.25)/ (2×1.25) = 0.1

ð     Φ= tan^-1(0.1)=   5ᵒ42’

        Again for,

                   D= 0.5”

                   δ= 0.375”

                & L_t= 0.375”

       

 Now, tanφ= (0.5-0.375)/0.75= 0.167

             ∴ φ= tan^-1(0.167) = 9.66ᵒ

Precaution:

1.      Sliding parts of the lathe should be cleaned & lubricated.

2.      Speed selector control should not be changed when the spindle is rotating.

3.      The carriage clamping screw should be unlocked before moving the carriage.

4.      If the chuck is moving forward reverse switch should not be operated.

5.      Chips should be changed using a brush.

6.      We should use correct size of lathe centers.

7.      We should set up correct angle in the lathe machine to get the taper angle.

Over all, we use lathe machine very carefully

Discussion:

              By the help of our respected teachers we managed well to make a center punch very carefully. We did have to face some minor problems. But we were capable to overcoming it. Our measurements may not come out accurately.

              The setting of the taper angle may be at a little difference then the required angle. In spite of thus problems, we performed all necessary steps to make a center punch.

Questions & Answers:

How are lathe sizes determined?

Ans:

        The lathe sizes are determined by the following:

1.      The height of the center above the top of the bed.

2.      The sawing or the maximum diameter of the work that can be related over the ways of the bed. This is equal to twice the height of the center.

3.      The maximum length of the work that can be accommodated between the lathe centers.