Bolt the machine to the floor before putting on the belt. Do not adjust the position of the machine to the running of the belt. Set the machine true with the countershaft or main line by dropping down a plumb bob from each end of the shaft. Since plumb bobs are not in the kit of every machinist, an inch nut or any weight on the end of a string thrown over the shaft will answer. The countershaft should line up perfectly with the shaft from which the power is received and it should be perfectly level. It should be well oiled before starting and examined after it has run fifteen minutes to see if any of the bearings are warm.
After the machine has been set parallel with the counter, the lag screws should be put through the legs into the floor, but should not be screwed down until after the machine is leveled. As the bed rests on three points and is flexibly connected to one pair of legs, the leveling of the machine is not done in the usual way. When the level is placed across the V's of the lathe bed and is found to be a little high on one side, drive the wedges under the edge of the leg at head end. Do not try to change it by wedging up under the back leg, for it is not connected to the bed by the usual means, but only serves as a pivotal support. Wedging under this leg will only raise or lower this end of the machine. Care should, however, be taken to have this leg stand on a fairly level spot. Now place the level on one of the V's lengthwise and wedge up carefully until both ends of the machine are equal in height.
Locate the stock supports as indicated in the drawings and adjust them for height by placing a bar of stock in the machine and slowing revolving it.
If the countershaft clutches slip, screw up the two small nuts at the rim of friction and slightly turn each the same amount. The speed should be exactly 450 revolutions per minute. If this speed is not as prescribed, the table of sizes of work for which the various speeds are intended will be of no value. This table is furnished for ready reference in a suitable frame with each machine.
Do not put your belts on too tight at first. It is much easier to lace the belt two or three times while it is stretching than it is to get a new bearing running smoothly after it has been roughened up by the belts being too tight.
To Start the Machine on Bar Work, begin on some very simple work. Suppose the diameter of the head is 1 13/16 and the body 1 1/4 inches, that the total length is 6 inches and that the piece must be finished all over. Get a bar of 1 7/8-inch stock; see that it is fairly straight and free from short kinks and that there is no burr of any size on either end. If the bar has been cut off in the shear, the burr should be hammered down. The large adjusting collar under the sleeve should be screwed back to open the chuck and forward to close it. Now remove the bushing from the spindle, for this is only used for smaller bars than 1 inch, and would not admit the 1 7/8-inch bar. It is necessary to let back the rolls in the roller feed in order to remove this bushing. After this is done, push the bar through the stock supports into the spindle and through the chuck until the end projects about 3/4 of an inch beyond the face of the chuck. Adjust the jaws at the back of the roller feed till they are about 1/32 of an inch loose on the stock. Adjust the chuck till it requires much force to thrust the chuck lever to the left. The rolls of the roller feed should be set down against the bar till each spring is raised a trifle.
Now, the next thing is to determine the speed to be run. This can be done by the use of the table, or by experience. Turn the turret around until the cross slide comes in working position, set the cut-off tool and trim off the rough end of the bar. Before turning to the next place, set the stop. See directions for adjusting the stops on page 222. No. 1 is the stop for the cross slide. Next move the "back stop" up close and clamp it. Run the turret back against it till it turns to the next position; next loosen the back stop again and push it back till the end of the swinging "stock stop" measures a distance equal to the length of the work, which is 6 inches, plus the width of the cut-off tool, which we will call 3/16. That is, the stock stop should be swung up into place, and the turret should push the back stop until the length between the end of the bar in the chuck and the end of the stock stop is equal to 6 3/16 inches; then clamp the back stop firmly.
Now open the chuck and hold the lever to the right until the roller feed pushes the bar out against the stop, then forcibly close the chuck. Turn the turret to turner. Now use the turner carefully and without the back rest, till the cutter is adjusted to size. This must be done on the first piece by use of calipers or any other gauge; take off about 1/8-inch chip each time while roughing, and allow it to run on about 3/4 of an inch. After the end has been reduced to 1 1/4, adjust the back rest, have it follow the tool and bear on the 1 1/4 size, then throw in the feed by the lever on front of the apron near the pilot wheel. Let this cut run up the required distance and adjust the feed stop for this tool.
Before running back, withdraw the tool by pulling the small cam lever towards you. Run back the turret until it brings the next tool into position, and adjust this tool for turning the head of the piece; the head may be turned without the use of the back rest.
Now the end of the piece may be shaped by the pointing tool held in one of the tool holders. The screw cutting comes next. Directions for using the automatic die will be found on pages 234 to 239. The next operation is rounding the head, which may be done by an offset tool in the back tool post of cross slide, or it may be done by putting a crowning tool in place of the cut-off tool and then having the cut-off tool work from the back post of cross slide. By using the former instead of the latter, an additional tool may be set in the back post for shaving the under side of the head. This, however, is not often necessary. Then cut the piece from the bar and proceed to run off the required number.
If but one piece is desired, it is not necessary to set any of the stops. These stops were set only for the benefit of more rapid production of the other pieces wanted. In starting the turner on a piece of this proportion, do not throw in the feed until the edge of the back rest is started on the work; it should be fed thus far by hand. The fine feed should be used with a chip of this kind, but if the tool is beveled slightly, the medium feed can be used.
If the Bar is crooked and the end runs out too much to true up, the piece may be partly severed from the bar, enough to weaken it so that it can be bent to run true.
The Jaws may be used on work a trifle larger, but never on smaller diameters than is marked on the jaws. For instance, the 1 7/8-inch jaws will hold 1 15/16, but will not hold 1 13/16. The latter size must be held by the 1 3/4-inch jaws.
Hexagon Stock is held by the same jaws that hold round and square by removing one of the jaws and inserting spacers that will hold the jaws in place for taking bearing on three sides of the stock. Round stock may be held in the jaws as arranged for holding hexagon or square, but if it is a trifle oval in section arrangement of jaws for hexagon is better.
The Chuck should be wiped clean every time the jaws are changed, and should be kept well oiled. To remove the chuck from the spindle of the 3-inch machine it should be gripped on a short piece of 2-inch stock to which a lathe dog is fastened. By the use of a lever placed between the tail of the dog and the bar of stock, the chuck may be readily loosened. This also serves as a good means of screwing the chuck firmly against the collar when putting it on again.
The chuck body of the 2-inch machine is part of the spindle and cannot be removed.
The Roller Feed should be kept as clean as possible and well oiled. The bar of stock should be wiped free from grit and dirt before the bar is placed in the machine.
The Turret Stops and how to adjust them. There are 12 feed stops for the turret, two for each position of the turret. These stops are numbered A1 and B1 for No. 1 turret position, and A2 and B2 for No. 2 turret position, and so on up to 6. The lever marked stop controller is arranged to lift out of position all of the A stops or all of the B stops, or both the A and B stops. When only one stop is required for each position of the turret, the stop controller is set to keep either the A or the B stops out of position, allowing the others to . do the work.
If more than two stops are required for any one position, then the extra stop pin at the back of the turret slide may be dropped into any one of the other five holes, thus borrowing one or more of the B stops not required by the other tools. This extra stop scheme makes it possible to give one of the tools seven stops, if desired, and still leave one stop for each of the other five tools.
Each of the 12 stop bars is held in place while setting by the set screw directly over it, but these set screws should not be set down hard or depended upon for holding against the carriage feed. The stop binder at the side clamps all of the stops together and should be set hard.
The notched edge of the stops should be up when the stop is to arrest the forward motion of the carriage, and down when stop is to arrest motion of carriage traveling away from the chuck.
The back stop serves two purposes: first, it forms an abutment for the rack that turns the turret; and second, it determines the backward travel of the turret, and thus locates the stock stop which is attached to the turret carriage. The back stop should be set with reference to the desired position of the stock stop, against which the bar of work strikes when a new length of work is being pushed out of the chuck. Care in setting the back stop will leave very little to be done in adjusting the screw at the end of the stock stop.
The Turners. The adjustments for the turning tools and for the back rests are provided with binder screws to prevent their moving after being once set. These screws are setup with a screw driver from the back of the turner. The cutters may be made of self-hardening, or ordinary tool steel.
For all kinds of work, set the tool so that the part of it that does the finishing is just a trifle ahead of the back rest. The tool should be so adjusted that the part that does the finishing will come exactly to the center of the bar when the tool holder is swung in.
The double adjustment of the turner is effected by the employment of a double-throw cam, instead of the single cam formerly used, and a double-end latch back of the back rest.
The two cams are diametrically opposite and side by side. The lever for turning the cams is like a machinist's vise handle. When one end is up, one of the cams engages one of the adjusting screws, and when the other end of the handle is up, the other cam is brought against the other adjusting screw.
The Cutting Tool used in the Turner is usually ground so as to leave a square shoulder. This form of tool, with plenty of rake, is preferable for several reasons, although it is not the form of tool that has been found to take the largest cuts under other conditions. It is not recommended for chucking operations or turning without the back rests.
Since the use of high-speed cutters the limit of turning speed has been determined by the endurance of the back rests, and since the pressure on the back rests is increased by the use of cutters having beveled or rounded corners, this is one of the reasons for using the cutter which leaves a square shoulder.
Of course it is assumed that the rake or top angle of the tool is always to be as sharp as experience with this machine would determine.
Another reason for the tool that takes this square or face cut is that it leaves the kind of a shoulder that is usually required.
Still another reason for its use is that the cutting pressure to hold it into its chip is mostly end pressure on the work and not radial - that is, no very great pressure is required to hold it into the proper depth to produce the desired diameter, hence a slight variation in depth of chip due to eccentricity of stock has little or no tendency to change the position of the tool. For this reason this tool may be depended upon for true work in taking long cuts, even if the stock runs a trifle crooked.
The Cutting Tools for Chucking operations, whether turning or boring, should have their rake or top angle sharp to the heaviest part of the chip. For instance, if a tool is to be used for facing a hub of a gear, the part that begins to cut first should be a sharp angle, so that the heaviest part of the chip should flow easily away, while that part of the tool that leaves its mark on the finished face should take a shearing cut or angular shaping cut, which leaves the smooth surface.
Perhaps there is no more important point to be borne in mind by any one wishing to know how to make the machine do its best work than the cutting angles of the tools. In a general way every one knows that a tool should have the least amount of clearance and the greatest amount of rake consistent with the wear of the tool, but the man who makes the greatest record is the one who puts it into practice.
The next point is that no tool should be allowed to project beyond its holder or support more than is absolutely necessary. After having ground and set the tool properly, see that it has a chip or feed coarse enough to keep it from losing its edge in the vain employment of making thin chips - for if the chips are very fine it means that you have made the tool not only remove the Facing Tool metal, but cut it into fine chips having no special value. Even weak lathes generally do better work with a medium feed than a fine feed. It is not uncommon to see a very fine feed being used in trying to turn an extra true piece of work, with the only result that the tool does not leave an even surface. It alternately rides and "digs in" with a fine feed, when an even, steady cut would have been obtained by a medium feed.
Chattering frequently occurs because there is not chip or cut large enough to hold all the slack of springing parts. The cure for chattering is frequently more, not less, feed. Of course chattering may be caused by a cut that is just heavy enough to balance the weight of the work and spindle, and then the slight necessary looseness of spindle bearings gives the chance for chattering. An old-fashioned remedy for this is to turn the tool upside down to get the pressure down on the work.
Chattering is destructive of the sharp edge of the tool and should be stopped as soon as noticed; but don't think a lighter cut is necessary, for frequently a heavier cut stops the chattering.
Facing cuts should be taken by the tools with round shanks, for these can be turned so as to give the desired rake for free cutting.
In facing a piece in which the diameter of the cut in one place is two or three times its smallest diameter, make sure to take advantage of the convenient means of changing the speed, for a very important reduction in time of operation as well as the durability of the tool may be effected by using the speed controller.
The Cross Slide is arranged with stops for the front and back tools. The upright which supports the pinion shaft is bored out to receive bushings for supporting the work against the forming tool when it is necessary to use a broad tool near the end of a slender piece of work.
Never use a longer drill than is absolutely necessary. If the depth of the hole is to be great in proportion to its diameter, a short, stiff starting drill should be used to start a true hole. Never drill beyond the piece that is to be cut off, for after the piece has been cut off and the bar run out to make another, it will be found that the end does not run exactly as it did when it was drilled into, and consequently the hole runs out. In some cases, where the mouth of the hole is to be larger, it does not make any difference, because the larger drill will true the hole, but generally it makes trouble that is difficult to overcome without the waste of stock.
The stock-stop screw must be lengthened out when drills are used, and the length of the extension should be equal to the length of the longest drill used.
Putting Chasers into the Die. One set of chasers may be removed and another put into place by simply withdrawing the two knurled thumb screws which are located in approximately opposite positions on the cam holder. After these screws have been withdrawn about one-quarter of an inch the cam holder may be removed. In changing the chasers always see that the chaser grooves in the die are wiped out clean; also that the interior of the cam holder and cam are free from chips and dirt. Place the chasers in the respective grooves in the die body by making the numbers on the chasers correspond to those on the body; then slide them towards the center till they meet. Now put on the cam holder, and after having pushed it as far back as possible with the chasers in this position, push each of the chasers out against the cam surface; this will allow the cam holder to go back the full extent. Now see that the screws in the cam holder enter the holes in the spring collar.
To Close and Adjust Size. To close the die pull the handle with the thumb pressing gently on the latch pin. Before adjusting the die for size see that the latch pin is in its notch, and that the O. K. is uppermost; then turn the adjusting screw till the lines on the cam and chaser come together. This gives only an approximate adjustment; the micrometer or thread gauge should be tried on the work. A binder screw will be found to prevent accidental turning of the adjusting screw.
Adjusting Cutting Length. Now the die is ready to cut its thread, but it is yet necessary to adjust the stop which will determine the length of the thread. The stop which arrests the motion of the carriage is the one which determines the length of the thread, for when the die is cutting it is only necessary to retard the travel of its holder to cause it to fly open. If the thread is to be cut close to the shoulder the stop must be so adjusted as to avoid all possibility of the chasers screwing against the shoulder. It is not safe to allow the chasers to get closer to the shoulder than 1/32 of an inch. The die head travels forward 3/16 of an inch before opening after the carriage has been arrested.
Roughing and Finishing Cuts. One cut is sufficient for all U. S. S. threads under 1 inch in diameter, under ordinary conditions, but to obtain best results on larger dimensions, extra coarse pitch or very rough material, two cuts are necessary. The latch pin is made reversible for this purpose. It may be readily turned from one position to the other after it has been pulled out. The letters O. K. should be uppermost when the finishing cut is taken. The work should never be allowed to run backwards in the die.
Cutting Speeds for Screw Cutting. Do not run your work too fast. If the pitch is extra coarse or the work warm from previous operations, the speed of threading should be proportionately slower. Better half speed than a trifle too fast. Do not turn the part to be threaded under size, for the line of travel of the die is governed at the top of the thread, without which the die is inclined to travel crooked or to wabble.
Use Lard Oil Only, Always use a heavy stream, from at least a 1/4-inch pipe, of lard oil in cutting tenacious irons and steels. The so-called cutting oils and compounds of soda and oil give good results on brittle material only. Nothing less than lard oil that is lard oil should be used in cutting the general run of Bessemer and openhearth steels, as well as tenacious irons, as they are found on the market, for these metals will average tough and hard. If the same purse pays for the labor and tools that pays for the oil, there is no saving in buying a cheap oil, whether it is called lard oil or some more truthful name.
To Resharpen the dies grinding must be done very sparingly. Grind the least possible amount off the face; do the principal grinding in the throat of the die. This, of course, carries back the cutting edge into the die so far that it is impossible to cut close to a large shoulder. If the work requires cutting close to a small shoulder, the chasers may be ground back enough to admit that shoulder. Some grinding must be done on the face of the die, as it wears back to the last threads, but it should be done with great care. In grinding the throat, do not follow the curved lines of the teeth in order to obtain the correct clearance, for the teeth were produced by a mill 2 1/2 inches in diameter; following this shape would give too much clearance. Don't change the angle of chamfer; it is better to be guided by the wearing of the die. See that each chaser is ground an equal amount, either by gauge or by bringing the teeth only to a cutting edge.
Ordering Parts. The chaser and all other parts of the dies are made by special machinery and are perfectly interchangeable; any one of the standard chasers may be duplicated from stock, and special chasers on short notice, providing you give in your order all the letters and numbers appearing on the chaser. Chasers may be sent by mail. When ordering other repair parts please use list number of piece given on pages 240 and 241, and always state size of die head. The head which has capacity for threads up to 2 inches diameter is called No. 6, the 1 1/4-inch capacity No. 3 (cut on page 241 illustrates parts of our later pattern 1 1/4-inch die, No. 4), and the 1/2-inch capacity No. 1.
Parts of Nos. 3 and 6 Dies.
Parts of No. 4 Die.