Without the lathe, our great industrial progress of the last century would have been impossible. A hinged cover encloses the head cone pulley when the lathe is in operation. See page 19. The lathe must be large enough to accommodate the various classes of work to be handled.
The head is the most important unit of the lathe and must be moved back as shown in fig.
A set-up plan showing how to set up and level the lathe is included with the shipment of the lathe. Level across the lathe bed at both the head end and the tailstock, as shown in Fig. If the lathe is set on a concrete floor or foundation, mark the location of the bolt holes and drill holes in the concrete with a star drill.
The bench must be securely bolted to the floor so that there is no danger of the bench moving and throwing the lathe out of level.
SPINDLE SPEEDS OF LATHES
The tool angle or the included angle of the cutting edge of this tool must be approx. 61° for regular machine. This tool is used to face the left side of the work, as shown in fig. 77, and the tip of the tool must be ground to an included angle of 60°, as shown in.
This type of tool can be sharpened by sharpening the end of the cutting blade to an angle of 5° as shown in Fig.
APPLICATION OF LATHE TOOLS
Tungsten Carbide Cutting Tools Cutting tools with tungsten carbide tips are used for production operations where maximum cutting speeds are desired and are very efficient. Tantalum Carbide Cutting Tools Tantalum carbide is a term applied to a combination of tungsten carbide and tantalum carbide. Cutting tools with tantalum carbide tips are similar to tungsten carbide tools, but are most commonly used for machining steel.
The machinability of non-ferrous materials such as copper, bronze, aluminum and plastics varies widely, and such materials often require specially sharpened cutting tools.
CUTTING SPEEDS AND TOOL ANGLES FOR NON-FERROUS MATERIALS
To increase the amount of back rake, the cutting edge of the tool is sometimes placed high above the center. The proper application of the outer caliper in measuring the diameter of a cylinder or a shaft, as shown in Figure 101, is set exactly the same from the end of the scale as the outer caliper.
The micrometer reading is the sum of the scale readings on the barrel and finger. The locations of the holes to be made are first carefully laid out on the work in the usual way, using scale measurements. There are several good methods for accurately locating the center holes, which should be drilled at each end of the work before it.
Turn the work with the left hand and mark the high points at each end of the cylinder with a piece of chalk in the right hand. Once the centers have been accurately located, center holes should be drilled and countersunk into each end of the axle. When this method is used, the end of the shaft must be smooth before the center hole is drilled.
To remove the tailstock center, turn the tailstock handwheel counterclockwise until the end of the tailstock screw contacts the end of the center. The tail of the lathe should fit freely in the slot of the faceplate so that the workpiece rests firmly on both the center of the headstock and the center of the tailstock, as shown.
CUTTING SPEEDS IN SURFACE FEET PER MINUTE
The most efficient turning speed varies with the type of metal being machined, the depth of cut, the feed and the type of cutting tip used. After taking the first rough cut across a shaft, check the diameter on each side of the cut with calipers or micrometers to make sure the lathe is turning straight. Sometimes when the position of the tail head is changed for a different length of work, it will require adjustment.
This is especially true for old lathes, which may have scuff marks and burrs on the bed. If collar A is not the same diameter as collar B, then the center adjustment is incorrect and the top of the tailstock will need to be adjusted in the desired direction. The top of the tailstock is adjusted by loosening one of the adjusting screws from the top of the tailstock and tightening the opposite screw a similar distance.
Then make another test cut on the collars, measure and continue this operation until the desired accuracy is achieved. There is a mark on the end of the tailstock where the bottom and top meet to indicate the relative position of the top and bottom of the tailstock. After chalking the axle, set the hermaphroditic calipers to the desired size and draw a line around the rotating axle with the sharp point on the caliper.
Locating shoulders with a parting tool In a production job where a quantity of pieces is required, shoulders are usually located with a parting tool as shown in the figure. When a square corner is required, as in a bearing, the neck or undercut of the shoulder is usually slight, as shown in fig.
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Concentric rings inscribed on the face of the chuck allow the round to be centered approximately, as it is. For accurate work, the long end of the pointer must remain stationary when turning. Lathe chucks should be selected carefully for the size of the lathe and the work for which they will be used.
The electric sanding attachment is mounted on the lathe instead of the tool stand and joint rest. When drilling into steel, use plenty of grease on the tip of the drill bit. The top of the thread cutting tool must be positioned exactly in the center, as shown in Figure 217 right, to cut the external threads of the screws.
If desired, the micrometer collar on the lathe's cross feed screw can be used in place of the threading stop. Count the spaces between the end of the scale and the first inch mark, and. The angle of the sides of the wire will be incorrect if the tool is not set as shown.
The spindle and half nuts of the lathe are usually used to achieve a uniform pitch so that the. However, for fine and precise work, most mechanics prefer to mount the left end of the workpiece on the center of the trestle, as shown in Fig.
The spindle of the lathe tail can be graduated in centimeters, as shown in Fig.
When equipped with a good electric grinding attachment, the lathe can be used to sharpen reamers and cutters, grind hardened bushings and shafts, and much more.
GRINDING WHEELS FOR VARIOUS KINDS OF WORK
Before mounting a part on the mandrel, always oil both the inside of the part and the door. The dial indicator mounted in the tool post of the lathe reads in thousandths of an inch and will show exactly how much. The equipment will vary with the purpose of the shop and the amount to be invested.
The lathe is the most important of all the tools in the portable machine shop because it can be used for any classes of work. Diameter of drive pulley—Multiply the diameter of the driven pulley by its number of revolutions, and divide by the number of revolutions of the driver. Diameter of driven pulley—Multiply the diameter of the driven pulley by its number of revolutions, and divide the product by the number of revolutions of the driven pulley.
Speed of the driven pulley—Multiply the diameter of the driven pulley by its number of revolutions and divide by the diameter of the driven pulley. Speedof Driving Pulley – Multiply the diameter of the driven pulley by its number of revolutions and divide by the diameter of the driven pulley. Before a drill chuck can be used on a lathe, it must be fitted with a collet that is threaded to fit the spindle nose of the lathe.
Before screwing the chuck onto the top of the lathe spindle, thoroughly clean the chuck threads and spindle nose. Oil the threads of the headstock spindle and the clamping plate and screw the clamping plate onto the nose of the spindle.
METRIC AND ENGLISH LINEAR MEASURE
SHOP KINKS
Do not leave too much stock on a piece of work to take off with the final cut. Do not put a piece of work on centers unless you know the internal centers are clean. Do not put a piece of work on the lathe centers unless you know that all your centers are at the same angles.
Do not remove a lathe tool from its socket without having a witness mark on it, and reinsert it according to the mark. Do not start polishing a shaft on lathe centers without enough slack to allow for expansion by heat from the polishing process. Don't forget that a good center punch can be made from a piece of round file.
Don't start looking for work on lathe centers unless you know the centers are up to the rules. Do not attempt to dry cut even steel or wrought iron; use lard oil or cutting mix. Do not suddenly run up to the shoulder with the chuck or faceplate; stresses the spindle and threads and makes removal difficult.
To drive the center out of the main spindle, use a rod and drive through the hole in the spindle. When the center is removed from the main spindle of the lathe, always put a piece of ragin spindle hole to prevent dirt from collecting.
INDUSTRIAL APPRENTICE TRAINING
When the work is to be completed by filing in the lathe, the stock left for filing should be as small as possible. Very little stock should be left if the cutting tool is properly sharpened and set to produce a smooth result. The amount of material removed by polishing with emery cloth is so small that it is usually not taken into account.
MOTORS FOR OPERATING LATHES
DIMENSIONS FOR TOOLING SOUTH BEND LATHES
Finishing Allowance 119 Aluminum, Machining _ 36 US National Thread...70, 71 Mild Steel and Brass 113 Lathe Tool Application 34. Center and Dial 54, 55 Industrial Apprenticeship Training 118 International Thread Form 70 Keyways, US Standard Sizes 96 Knurling theLathe _ 87 Fastening Straps .
INDEX
Keep your eyes on the man in front of you; Perhaps one day you will be called upon to take his place. Before working on a lathe, roll up your sleeves and remove your tie: safety pays off.
