The American machinist shop note book

Many of the kinks shown in this book are from your own pen or from the pens of men you have known and worked with. They are the solutions of problems similar to those that you and I and all other mechanical men bump into. Few of us have access to a file of the American Machinist, but even when such a file is within reach it is often difficult to find what is wanted. The object of this kink-book is to preserve in permanent and accessible form selected articles covering work performed on various machine tools.

A book like this is of twofold value:

First It shows exactly how a certain specific job was successfully accomplished. Unfortunately it is seldom that the other man's device or method can be used by others exactly as it was used by him. Either the work itself is somewhat different or the shop equipment is not the same. Only where all the conditions are similar can we use the other man's device in its entirety for our work.

Second To a far greater degree is such a book valuable because of what it suggests. This function of suggestion is limited only by the ability and resourcefulness of those who find their suggestions here. A kink here elaborated in connection with a milling machine may with slight alterations be applicable to the lathe, drill press or planer.

The field of machine-shop work is so wide that no book can cover it, but the experiences gathered in this compilation can be of great assistance to the ingenious mechanic in suggesting a way out of his troubles.

FIG. 93 shows a device which I find very helpful in laying out work on the milling machine where a series of holes is to be located at different points. The body of the tool has a hole to fit the arbor of the milling machine, and at a right angle thereto is a smaller hole to which is fitted a small prick punch held in position by a collar and spring as clearly shown in the sketch.

To use the tool it is clamped tightly on the arbor in the same manner as a cutter, care being taken to have the body set square with the table. Fasten the die blank to the milling-machine table and spot the center. Then by means of the indexes on the traverse and cross-screws any number of holes can be laid out in quick time and to good advantage.

In a shop the line of manufacture of which included large quantities of cast-iron pulleys, the turning of the crown face got to be a considerable item of labor expense, as it was a slow operation and required closer attention because of the crown.

A fixture, or machine, like that shown in Fig. 94 was made, and its success was immediate.

Except for changing the pulleys and starting the cut the machine takes care of itself, and having finished a pulley (which it does in one revolution) it will run merrily along without damage until somebody gets ready to put on another casting.

It was made the duty of everyone, from the floor sweeper up, whenever he passed one of the machines that was running idle to take off the finished pulley and start a new one. Thus the labor cost was brought to a very low figure as the changing would almost always be done by someone who was waiting for a cut to run out on the milling or planing machine or by someone who for one reason or another could spare a moment without interfering with his regular work.

The drawing is self-explanatory. The diameter of the inserted-tooth cutter and the relation between the center lines of the two shafts is so computed that the path of the cutters will leave the requisite amount of crown.

Whenever a man sees a machine idle and he has a moment to spare he simply turns back the handle A turn or two, loosens the nut B, takes off the finished pulley, puts on a casting and runs up the cutter again to a fixed stop, at which time it is cutting the full depth required to size the pulley.

Several castings were to be machined, as shown in the upper right hand corner in Fig. 96. The work was ordinary shop practice up to the point of cutting the slots across the face of the rim. A formed cutter was plainly the only tool to use that would insure interchangeability of the pairs of slots two adjacent slots constituting a working pair in the special machine of which the wheels were to be a part. A limit of 0.008 in. was allowable in the spacing of the pairs of slots. The only machine available for the slotting was a No. 2 plain milling machine which was in good condition, but too small for such a job.

After the, lathe work was finished, the rim was carefully laid out into 20 divisions, using a glass to secure accuracy and a line to indicate working depth marked before removing from the lathe. For each pair of slots milled, the wheel was set by the division marks from a fixed point on the face of the milling machine, again using the glass to insure close work. The finished parts showed this method to be quite accurate enough.

The castings were laid in a horizontal plane on the table of the milling machine and the vertical (hand) feed used for cutting. A casting that served as a center stud and baseplate was made and the work was placed upon it. A parallel under the front and a clamping bolt completed the arrangement.

Owing to the size of the wheels the table had to be run out to its limit, causing it to overhang to such an extent that would have rendered feeding not only difficult but would have imposed serious strains upon the machine itself. The castings weighed 600 lb. each, nearly half the weight of the machine. To avoid trouble, the simple counterbalancing scheme shown in the drawing was adopted. An eye-bolt was screwed into the center stud, to which was fastened a rope that passed over two grooved pulleys and down in the rear of the machine to a counter weight. The weight was made 80 Ib. heavier than the wheel casting and attachments. With the aid of this counterbalance the loaded table could be run up and down as easily as when empty and the possibility of distortion was removed.

In most cases in repetition work a man can work much faster by using a quick-acting vise which is operated by lever and eccentric instead of a screw. I much prefer to have two vertical Vs, one near each end of the jaw; this results in increased speed of operations, and puts a more equal strain on the vise. I have aways made the horizontal V as shown at A in Fig. 97.

This clearance at the upper part of the jaw renders it much easier to load and unload the vise because when the vise is open the work can be dropped into position where it will be definitely located by the lower part of the V. If the jaw is of uniform thickness it too often happens that the work, especially if a short piece, falls between the jaws, resulting in loss of time and in annoyance.

Many times in milling flat surfaces, oil grooves, keyways, etc., in shafts or bolts, it is not possible to locate these parts with a shoulder against the jaws as the pieces to be machined may then project too far, resulting in chattering, or else may be too close to the jaws for the cutter to pass.

For all these cases, and they probably form the majority, I have used the tool shown at B with very satisfactory results.

The base of this tool is provided with a slot so that it can be clamped to the milling-machine table in any position. The stud is threaded at one end so that it may be turned to any desired position and then secured by means of the locknut. The stud is about as high as the top of the vise ; it has two flat surfaces which form a knife edge, slightly rounded.

Whenever a milling operation has to be located accurately in relation to a shoulder the knife edge is used as at (7, and no matter what variations there may be in the length of the pieces the relation of the milling operation and the shoulder used for locating will be absolutely uniform.

A very handy shop kink is shown in Fig. 98 for the angular setting of milling-machine centers to insure even width of the land when fluting taper reamers.