FOLDING MACHINES. The folding of printed sheets for books or newspapers was performed by hand up to 1856, when Cyrus Chambers, Jr., of Philadelphia, invented a prac tical folding machine, which was manufactured by him and his brother Edwin, who within a few years produced a considerable line of folders of various sizes and capacities. The folding machine of C. S. Forsaith, of Man chester, N. H., designed for folding newspapers only, came out some years later. A good many Stonemetz folders were sold between 1880 and 1890. The leading folders on the American market are the Dexter, Chambers, Brown, Cleveland and Eclipse. The vital prin ciple, on which nearly all paper folders are based, is the descent of a dull blade on the paper sheet at the point where the fold is to be made, the blade thrusting the paper between rotating rollers which draw it in folded. The making of a second fold is accomplished in the same way, the paper being passed along by traveling tapes from one stage to another, up to three or four folds. The earlier machines were not positive in their register, that is, the fold was apt to vary slightly in position, but the modern machines are very accurate, and large 64-page sheets are commonly folded on the machines with entire satisfaction. The heavy coated paper introduced about 1890 to 1895 developed a tendency to buckle or crease slightly on the last fold of a large sheet, and the most recent folding machines have intro duced devices to overcome this difficulty. The most conspicuous improvement of recent years has been the drop-roll, which has added mate rially to the speed of the machines. • This was introduced by Dexter, and enabled the sheet to be fed sideways—that is, the shortest way. Registering by means of points, that slip into holes or slits in the sheet, is another feature of modern machines. The equipping of machines with palters was accomplished early in the history of the folding machine, and this feature has been brought to a high degree of perfec tion. The paste is held in fountains and laid
on the paper in strips as it passes by.
Folders are now made in so many styles that the mere enumeration of them requires considerable space. They may be either drop roll or point-feed; there are quadruple 16s and double 32 folders some of which insert one sheet within another; there are marginal folders for books and 'pamphlets and for job bing work; also large single and combination periodical folders, rapid circular folders, plain circular folders, jobbing circular folders and various so-called newspaper folders. Then there are special newspaper and periodical folders, combinded folding and wire-stitching machines, combined folding and feeding machines and combined feeding, folding and wire-stitching machines.
The Dexter combined folding and wire stitching machine was introduced in 1897, and it is continuous and strictly automatic. It takes the sheets from the platforms of the feeders, and folds, gathers, collates, covers and wire-stitches, delivering completed copies with out intermediate handling.
There are variousother combinations and arrangements for special work, which, together with those above named, have greatly reduced the cost of binding books, pamphlets and periodicals.
On fast web newspaper printing presses there is used a rotary type of folder that was brought out by the Hoes, and controlled by them for many years, being probably their most valuable patent in connection with these presses. Three folding blades were mounted on a single cylin der, catching the paper three times in a single revolution, thus securing immense speed. The device is not accurate enough for book folders, but it made possible the enormous speeds ob tained by the so-called lightning newspaper presses.
The job folding machines for doing odd work of varying sizes have come into extensive use within a few years. They are small and comparatively simple machines capable of operating at high speed. See NEWSPAPERS.