How A Linotype Machine Works, The Book of Wonders
This article appears on pages 569-573 of The Book Of Wonders, 1915. It provides an overview of the mechanical process used by the Linotype machines to produce 'slugs' of typeset text ready for the press.
This picture shows the wonderful Linotype machine by which the type of this book was "set," as the printers say. The men who operate the machine are compositors. Originally the type matter of books was set by hand and the compositor composed in type what the author of the book had written. By pressing down on the keys which you see in the picture, the compositor sets the words in lines of metal. This machine is almost human. By touching the proper keys, the operator assembles a line of matrices the details of which are explained in another picture, and after this is done the machine automatically casts a slug from them, turns and delivers a slug into a galley ready for use and finally distributes the matrices back into their respective channels in the magazine, where they are ready to be called down again by the touch of the key button. The latest model linotype has four magazines and can be equipment with matrices which when assembled will cast lines from six to twelve different sizes and styles of type.
The assembling mechanism is the only part of the linotype where the human mind is applied to the working of the machine. It is necessary for the eye to read what is to be printed, and the mind, through the medium of the fingers, to translate this into assembled lines of matrices; after that the machine acts automatically.
The keyboard is made up of 90 keys, which act directly on the patrices in their channels in the magazine. The slightest touch on the keybuttons releases the matrix, which drops to the assembler belt and is carried swiftly to the assembler. When a word is assembled, the spaceband key is touched and a spaceband drops into the assembler. When the necessary matrices and spacebands fill the line and have been assembled, the operator raises the assembler by pressing a lever on the side of the keyboard. When the assembler reaches its highest point it automatically starts the machine and the patrices are transferred to the casting position.
This illustration shows the manner in which matrices are constantly circulated in the Linotype. From the magazine they are carried to the assembler, then passed to the mold, where the line is cast, and from the mold after casting they are raised to the top of the machine and redistributed to their proper channels in the magazine.
The Linotype is sometimes called a typesetting machine, but this is not correct: it does not set type. It is a substitute for typesetting. It is strictly speaking a composing machine, as it does composition but its product is not set type, but solid slugs in the form of lines of type with the printing face cast on the edge.
It is in reality four machines so arranged that they work together in harmony — the magazine, the assembling mechanism, the casting mechanism, and the distributing mechanism. The magazine is at the top of the machine sloping to the front at an angle of about 31 degrees, and consists of two brass plates placed together with a space of about five-eighths of an inch between. The two inner surfaces are cut with 92 grooves or channels running up and down way of the magazine, for carrying the matrices. The matrices slide down these channels on edge, with the face or punched edge down, and the V-end extending toward the upper part of the magazine. Each of these channels will hold twenty matrices.
Linotype matrices are made of brass. In the edge of each matrix is either one or two letters or characters in intaglio. The thickness of the individual matrices is dependent on the width of the character. By an ingenious arrangement either one-letter or two-letter matrices can be used in the same machine, and either character on a two-letter matrix can be used at will.
The two-letter matrix bears two characters, one above the other, one of which may be a Roman face and the other an italic, small capital, or black face. If a line is to be composed partly of the Roman face, which is in the upper portion on the matrix, and partly of the other face, which is in the lower position, this is accomplished by means of a slide on the assembler operated by a small lever.
When the lower characters on the matrices are required, the slide is shifted and the matrices are arrested at a higher level, so that the lower characters align with the upper characters of the other matrices in the assembler. When the slide is withdrawn the matrices are assembled at the lower level. By means of this simple contrivance, a line may be composed partly of one face, partly of the other face, or entirely of either face.
Linotypes are guaranteed to be capable of setting above 5000 ems of 6 point per hour, and this output is widely obtained in commercial printing offices with first class operators. When a compositor speaks of the amount of type he sets per hour or day he speaks of "ems." A column of type matter is so many "ems" wide. The term "em" means the square of the particular size of type that is being set. Thus if a column is said to be 13 ems wide it means that an em quad or square could be set 13 times in the width of the column. Type is graded according to size by points. Machine type for book works runs from 4 points to 12 points. A point is one seventy-second of an inch, that is, there are 72 points to an inch. This guarantee, however, by no means indicates the limit of speed at which the machine can be operated, as evidenced by records of 10,000 to 11,000 ems per hour maintained for an entire day. The rapidity of the Linotype is limited only by the ability of the operator to manipulate the keys, and the extreme capacity of the machine has never yet been attained.
This picture shows the machine with part of the magazine top and the side removed. We can thus see how the matrices are arranged in their respective grooves in the magazine. When one of the keys of the keyboard is pressed down the first matrix in the corresponding grove (sic) in the magazine escapes and drops upon a conveyor belt and is carried in its proper order to an assembler, which answers much the same purpose as a printer's stick. The correct spacing or justification of the line of matrices is accompanied by means of spacebands, which are assembled automatically between the words in the line by the touch of a lever at the left of the keyboard.
Instead of producing single type characters, the Linotype machine casts metal bars, or slugs, of any length desired up to 36 ems, each complete in one piece and having on the upper edge, properly justified, the characters to print a line. These slugs are automatically assembled in proper order as they are delivered from the machine, when they are immediately available either for printing from direct or for making electrotype or stereotype plates. They answer the same purpose and are used in the same manner as composed type matter.
After the slug has been cast, the matrices are carried up to the second transfer position, where they are pushed to the right, and the teeth in the V at the top of the matrices engage the grooves in the distributor bar of the second elevator, which descends from the distributor box at the same time that the matrices rise to the second transfer position. The second elevator then rises toward the distributor box, taking the matrices with it, but leaving the spacebands; these are then pushed to the right and slide into the spaceband box, to be used again.
As the second elevator rises toward the distributor box with its load of matrices, the distributor shifter lever moves to the left until the elevator head has reached its place by the distributor box. It then moves back to the right and pushes the matrices off the second elevator distributor bar into the distributor box, where they meet the "matrix lift" and are lifted, one at a time, to the distributor screws and distributor bar proper. The teeth in the matrix and the grooves in the bar are so arranged that when a matrix arrives at a point directly over the channel in which it belongs, it "lets go" and drops into its channel.
If, however, there is a matrix in the line which is not designed to drop into one of the channels operated by the keyboard, it will be carried clear across the distributor bar and dropped into the last channel, and from there it will find its way to the sorts box.
The casting mechanism consists of the metal pot, the mold disk, mold, ejector, and trimming knives. The illustration shows a cross-section of the metal pot, mold disk, and mold, with a line of matrices in the casting position. When the line of matrices leaves the assembler, they pass to a position in front of the mold disk. The disk then makes a one-quarter turn to the left, which brings the mold from the ejecting position, where it stands while the machine is at rest, to the casting position. It then advances until the face of the mold comes in contact with the matrices. The metal pot advances until the pot mouthpiece comes in contact with the back of the mold; at this point the pump plunger descends and forces the metal into the mold and against the matrices. The pot then recedes, and the mold disk withdraws from the matrices and makes three-fourths of a refolution to the left, stopping in the ejecting position, from which it started. The slug is ejected and assembled in the galley.
During the last revolution of the disk the bottom of the slug is trimmed off, and in the process of ejection the sides of the slug are trimmed, so that when it drops in the galley the slug is a perfect line of type, ready for the form.