Mill (machine)

“ Whenever possible, the job should be set up so that the end mill will cut on the lower side of the blank, as this brings the mill and table nearer together and makes the job more rigid. It also prevents chips from accumulating, and enables the operator to better see any lines that may be laid out on the face of the cam.
When the lead of the machine is over 2 inches the automatic feed can be used, but when the lead is less than 2 inches the job should be fed by hand, with the index crank, as shown on page 187. ”

“ It is a grewsome place. The machinery reminds one of the pictures that we have all seen of some of the contrivances they used to have in the days of the Inquisition with which to torture people, and it is hard to keep back a shudder as one looks at this work. Sometimes there is as much as a ton of powder at one time in the big hopper of this machine. In one of these mills at the Du Pont Works you will notice that the stone wall is eight feet thick on one side. This is on the side next to a press-mill. [Pg 778] One side of the place is entirely of wood. ”

“ The machine illustrated in Fig. 1 belongs to the lathe family and is known as a vertical boring and turning mill. This type, as the name implies, is used for boring and turning operations, and it is very efficient for work within its range. The part to be machined is held to the table B either by clamps or in chuck jaws attached to the table. When the machine is in operation, the table revolves and the turning or boring tools (which are held in tool-blocks T) remain stationary, except for the feeding movement. ”

“ All the machines for grinding corn and seeds are mills, whatever may be their particular application. One very common form is that of an iron machine, supported on four legs, having a winch handle on one side, a fly wheel on another, a hopper at the top, and a crushing apparatus in the centre. The grain or seed is put into the hopper, the winch handle is turned, the grain becomes crushed to powder, and falls out at the bottom of the apparatus. Sometimes the mill is made chiefly of wood, but with iron wheel and crushing apparatus. ”

“ The machine is massive in all its parts, and is intended for heavy milling of any description, but more particularly for shafting, railroad, or engineering shops, being specially adapted for key-seating long and heavy shafting, finishing guide bars, connecting rods, &c.
Its weight is 7,500 pounds. The work table is 7 feet long by 20 inches wide; length of longitudinal feed, 84 inches; distance between uprights, 24 inches. The cast-steel spindle is 4 inches in diameter, and the mill arbor 21⁄2 inches diameter. Arm for outer centre support 5 inches diameter at its smallest part. ”

“ To begin with, it is more convenient to clamp work to a horizontal table than to the vertical surface of a lathe faceplate, or, as someone has aptly said, “It is easier to lay a piece down than to hang it up.” This is especially true of the heavy parts for which the boring mill is principally used. Very deep roughing cuts can also be taken with a vertical mill. This type of machine mill is designed for turning and boring work which, generally speaking, is quite large in diameter in proportion to the width or height. ”

“ The entire mill, thus, is about as simple a machine as one could devise. The moving parts are few and could be called primitively clumsy in comparison to some of the sleek masterpieces of modern industrial design. The miller can make only three operating adjustments: in the sail area presented to the wind, in the rate of grain fed to the stones, and in the distance between the stones. He has no control over wind speed, cannot shift the gear ratio of the mill—or even shift the stones out of gear—and, finally, cannot determine his own hours of work and rest. ”

“ Milling Slot in Bushing, Using High Speed Milling Attachment
This operation furnishes a good illustration of the use of the high speed milling attachment. The end mill is only 3/8'' in diameter, and where such small mills are used, it is necessary to run them at much higher speeds than are ordinarily obtainable on the machine, otherwise the finest feeds, either by power or hand, present material to the cutter faster than the teeth can remove it, and as a result, there is constant danger of breaking the mill. ”

“ The machinery of an old grist mill is used to operate a small dynamo, which charges a storage battery and furnishes light for the fish industry there. Another wheel in the same mill works an ice making machine, the whole being under the charge of one man. ”

“ If the sliver breaks, the support falls, and this stops the machine. Again, if one of the threads of the warp breaks when it is being wound on the beam, a slender bent wire that has been hung on it falls. It drops between two rollers and stops them. Then the workman knows that something is wrong, and a glance will show where attention is needed. Success in a cotton mill demands constant attention to details. A mill manager who has been very successful has given to those of less experience some wise directions about running a mill. ”

“ The small and medium sizes will swing work varying from about 30 inches to 6 or 7 feet in diameter, whereas large machines, such as are used for turning very large flywheels, sheaves, etc., have a swing of 16 or 20 feet, and larger sizes are used in some shops. The size of a vertical mill, like any other machine tool, should be somewhat in proportion to the size of the work for which it is intended, as a very large machine is unwieldy, and, therefore, inefficient for machining comparatively small parts. ”

“ The sliding-rest, the dividing and the drilling engine are of this kind: and hence, in manufactories of sufficient extent, it is found to be good economy to keep one machine constantly employed in one kind of work: one lathe, for example, having a screw motion to its sliding-rest along the whole length of its bed, is kept constantly making cylinders; another, having a motion for equalizing the velocity of the work at the point at which it passes the tool, is kept for facing surfaces; whilst a third is constantly employed in cutting wheels. ”

“ Consequently, when a large cutter is being used, the spindle is usually driven at its slowest speed, and the fastest feed that is then available is not coarse enough. Likewise, a correct combination of speed and feed cannot be had for a small mill, as this should run at the fastest spindle speed, and, when it does, the finest feed obtainable is much too coarse. The majority of work, however, does not require such combinations, and when medium-sized mills are used and work of ordinary classes is done, the cone drive machine is very satisfactory. ”

“ The important requisite in this class of mills is such design and proportion of parts as will insure durability and continued movement at the highest speed, safely increasing the quantity and improving the quality of work done at a lesser feed, and admitting the use of thinner saws than is practical in the slower moving sash. These are among the advantages gained in the iron frame machine, overcoming the necessity of an expensive mill frame, saving time and expense in setting up, and avoiding the liability of decay or change of position. ”

“ The common paper mill being limited by its number of vats, no advantage can be taken of the frequent accessions of power which generally happen in the course of the year, but, on the contrary, as scarcely any mills are capable of preparing stuff for twelve vats, every accession of power to the mill, where a machine is employed, will increase its produce without any additional expense. ”

“ Uncanny machines are everywhere in this mill. Machines carve shingles and battens or billets with an almost human accuracy. A conveyor removes all sawdust from the danger of lights with mechanical intelligence. ”

“ It will also be necessary occasionally to adjust or repair the machine; and this can be done much better by a workman accustomed to machine-making, than by the person who uses it. Now, since the good performance and the duration of machines depend, to a very great extent, upon correcting every shake or imperfection in their parts as soon as they appear, the prompt attention of a workman resident on the spot will considerably reduce the expenditure arising from the wear and tear of the machinery. ”

“ Edge-moulding machine. A machine for dressing the edges of wood-work to shape, and usually for forming a moulding thereon.
Emery grinder, or emery-grinding machine. A machine in which emery wheels are used to grind the work.
Emery wheel. A wheel composed of emery cemented together under pressure.
Endless screw. A short length of screw formed to drive the teeth of a worm wheel.
End-mill. A milling-machine cutter, having teeth on its end face.
Engine-lathe. A lathe having a feed motor for the cutting tool. ”

“ The shorter distance the mill has to travel, the time saved in shifting feeds, and the fact that the operator does not have to give his undivided attention to the job, are all important advantages.
The metal is 1/2" thick. By the usual method, it is difficult to secure the flat, oil-tight surface that is easily obtained in the way described above.
Milling Grooves in Rim of Pulley on the No. 3 Vertical Spindle Milling Machine
Here a vertical spindle machine equipped with a circular milling attachment is shown milling belt grooves in the rim of a three step pulley. ”

“ In a milling machine the cut is carried continuously from its commencement to its end, whereas in a shaping or planing machine the tool does not usually cut during the back or return stroke. In either of these machines, therefore, the operator’s skill is required as much in measuring the work, setting the tools feeds, &c., as in shaping the tools, whereas in the milling machine all the skill required lies in the chucking and adjustment of the work to the cutter, rather than in operating the machine, which may therefore be operated by comparatively unskilled labor. ”

“ The interchangeable system of manufactures and the general use of accurate working gauges, which were hardly known in England, developed rapidly in America. These, with the introduction of the turret, the protean cam, and precision grinding machinery, and the great extension of the process of milling, served in the next fifty years to transfer the leadership in machine-tool design from England to America. A visit to any one of the great machine shops in England, Germany or France will convince one that the leadership now rests with the American tool builders. ”

“ The work stands without a rival. It is a complete practical treatise on the art of American Tool Making and system of interchangeable manufacturing as carried on to-day in the United States. In it are described and illustrated all of the different types and classes of small tools, fixtures, devices, and special appliances which are in general use in all machine manufacturing and metal working establishments where economy, capacity, and interchangeability in the production of machined metal parts are imperative. ”

“ The head stock could be arranged to hold work-pieces, milling cutters or drills. Hardened tools for the necessary cutting operations could be fabricated by the machine from carbon steel in the annealed condition, then tempered, drawn, and sharpened by a separate simpler machine including a small furnace and a tool grinding wheel equipped with tool-holder and feeds. By careful standardization of parts, tools, and fixtures, it is conceivable that such a "one-machine shop" could succeed in reproducing itself. ”

“ It is only a matter of short time when our milling inventors will design machinery especially for small mills; in fact they are now doing it, and every day brings it more within the power of the small miller to improve his manner of milling. To show what can be done in this direction I will briefly describe a mill of about ninety barrels maximum capacity per twenty-four hours, which is as small as can be profitably worked. ”

“ It is essential that the table of all milling machines used for manufacturing purposes, with the exception of the very smallest of the plain type, be fitted with both hand and automatic feeds. In the case of this exception, the work done is of such a small character that the machine can be operated more rapidly by hand than it could be if an automatic feed were applied. By the use of automatic feeds, one operator is enabled to run several machines on the majority of commercial work. ”

“ But the position which they occupy, and the abstract excellence of which they are in arms to vindicate, is that which the united voice of mankind habitually selects as the type of all hateful qualities. I will not bandy chicanery about the more or less of stripes or other torments which are daily requisite to keep the machine in working order, nor discuss whether the Legrees or the St. Clairs are more numerous among the slave-owners of the Southern States. ”

“ Essentials of a Modern Milling Machine It has been previously stated that the foremost advantages attending the employment of the milling machine are, the production of a great variety of work, and the exact duplication of pieces at an economical cost. In order that these advantages may fully materialize, it is necessary that many requirements be fulfilled in the design and construction of the machine. ”