US225457A - Process of engraving printing-surfaces - Google Patents

Description

r M. BRADLEY.

Process of Engraving Printing Surfaces; v

'No. 225,457. Patentedv Mar. 16, 1880. I

UNITED STATES PATENT Orrrc.

MILTON BRADLEY, OF SPRINGFIELD, MASSACHUSETTS.

PROCESS OF ENGRAVING PRINTING-SURFACES.

SPECIFICATION forming part of Letters Patent No. 225,457, dated March 16, 1880. Application filed February 2, 1878.

T0 allwhom it may concern: I

Be it known that I, MILToN'BRADLEY, of Springfield, county of Hampden and Commonwealth of Massachusetts, have invented a new and useful Process for Engraving on Wood, Metal, or other Surfaces for printing therefrom; and I do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the accompanying drawings, making a part of this specification, in which- Figure l is a front view, and Fig. 2 a side View, of the cutting mechanism of an ordinary engravers ruling-machine as used for making relief-printing plates, such as engravings on wood. Fig. 3 represents the printing-surface of a block or plate, B, engraved with the mechanism shown in Figs. 1 and 2, after having been prepared in the ordinary manner. Fig. trepresents the printingsurface of a block or plate, B, which was prepared according to my process and afterward engraved with the above named mechanism. Fig. 5 is an enlarged cross-section of a portion of block or plate B on line as y, showing portions of the cutting mechanism in operative positions at different portions of the artificial surface superimposed upon the face of the block or plate B by my process. Fig. 6 is a similar cross-section after having been engraved by my process.

In all the figures the same letters of reference designate identical parts. I

In order to more clearly describe my process, I will first briefly explain the ordinary method of engraving.

Original engraved plates of wood or metal for printing, known as relief-plates,'are made by first preparing a plane surface and then removing such portions as are not to print-i. a, not to receive inkleaving all the printinglines and portions at the original height of the surface. When prepared mechanically, as distinguished from etched and photo-relief plates,

--the parts which are to appear white when printed on white paper are cut away with graving-tools, either in the hands of engravers or in suitable machines. I

In engravings of mechanical and architectural subjects the fiat and cylindrical surfaces are much better and more rapidly engraved has a V or diamond point andhencethe deeper I it cuts into the material or block B the Wider the line removed at the surface.

The depth of the cut in the block is regulated and controlled by the foot 0, which bears on the surface of the block 13, and is adjusted vertically relatively to the cutting-tool A by the screw D passing through and working in the support E, to which the tool A is positively attached by the set-screw F,

The operation of engraving with a rulingmachine is as follows: The desired depth of out having been decided upon and secured by the adjustment of the foot 0 to the tool A, the foot is held firmly down onto the surface of the block to be engraved by the hand of the engraver while it is being moved across the block by means of some suitable mechanism, such as a rack and pinion. One line having been engraved, the block is moved a suitable distance and another line parallel to the firstis engraved, as before, and so on over the surface to be engraved. If a uniform tint is desired, the block must be advanced exactly the same distance each time, and the relative adjustment of the foot 0 to the tool A must remain constant; but if a cylindrical surface is to'be represented the movement of the block and the adjustment of the foot to the tool must be varied and regulated by the skill of the operator; and when the parts are adjusted for a given line they must remain undisturbed throughout the whole length of that line, in order to produce a uniform thickness or width of line, for the reason that the amount of skill and labor required to adjust the tool by hand during its cutting action would be so great as to rendersuch adjustment impracticable and unprofitable.

In Figs. 3 and 4 the black-lines represent the raised or printing surface of the block.

By my process the clouded appearance in I when the V-shaped toolA is raised relatively to the surface of the block the white line cut away is more shallow and narrower, and when the tool is depressed the cut is deeper and wider, so that when the tool is raised the printed tint is darker, and when depressed lighter. To accomplish this raising and depressing of the tool with regularity and method, I apply to the surface to be ruled some foreign substance, makingthe body of the substance, when applied, thickest where the shades are to be darkest, and leaving the block bare, or nearly bare, at those parts which are to print the lightest tints. In Fig. 5 the black portionsH H H represent some suitable substance, as above described, which may be a gum or resin, or other substance which can be dissolved and applied with a brush, the thicker portions being produced by repeated coats. For some purposes sheetgelatine or a like form of material may be applied to form the necessary raised surface, and I do not limit my invention to the use of any specified material, as the .kind of substance to be applied in any particular case will, of necessity, vary with the requirements of the particular work in hand and the varying effects to be produced.

Two positions of the cutting-tool A and foot 0 are shown in Fig.5. In one position, at t', the foot 0 rests on a portion of the block nearly or quite uncovered by the gum or varnish, and consequently the tool A cuts deep into the block, while in the other position, at k, the foot is on a thick portion of the gum,

and thereby the tool is nearly or quite removed from the block.

In Fig. 6 portions H H H of the gum are shown as remaining on the block; but in practice the gum nearly all crumbles off during the process of ruling, as the lines are usually ruled much nearer together than represented in the enlarged sectional views, Figs. 5 and 6.

If any of the gum remains on the block after engraving, it may be removed by carefully scraping and rubbing either' dry or slightly moistened.

To still further facilitate the work of the artist, the coating may be slightly colored, so that the thicker it is applied the darker it will appear, thereby enabling him to see just what effect he is producing; but this is not necessary to the perfect operation of the process.

The desired shades having been modeled on the surface of the block, as above described, the engraving is done with the ruling-machine without more necessary care than is requisite in ruling a plain tint by ordinary process.

The machine may be so arranged as to rule straight lines, as shown in Fig. 4, or, by a wellknown mechanism common to rulin g-machines, the lines may be somewhat waved or serpentine. My process is equally applicable to both styles of ruling.

It will be seen that, as the bearing portion m of the foot 0 must be of some appreciable size and somewhat removed from the point of the tool A, the location of the shades produced on the ruled block will be removed from the location of the corresponding raised portions of the model by the distance of the portion m of the foot from the point of the tool, and also all the shaded portions will be enlarged from the corresponding raised portions of the model by the diameter of the portion m; but as in any one machine these proportions are constant the effect can be easily foreseen and provided for by the artist. A plate, after being engraved by my process, may be more completely finished by handengraving, and in some cases must necessarily be, as is the case with any ruled work.

By a proper adaptation of the machine to the effect required and the expenditure of a comparatively small amount of hand-labor, a very close imitation of a hand-engraved surface can be produced by this process at a very great saving in time and by a much less skillful workman.

Now, having fully described my invention, what I desire to secure by Letters Patent is 1. The method of producing clouded or irregular engraved surfaces by an engravingmachine, consisting in the application to the surface to be engraved of a foreign substance varying in thickness at different points to correspond with the depth of cut required.

2. As an improvement in the art of engraving clouded or irregular surfaces by machinery, the employment of an irregular or uneven surface of wax or like material to govern the depth of cut of the graving-tool, substantially as described and shown. I

3. A prepared block or plate to be cutin an engraving-machine, having its face provided with a foreign substance varying in thickness at different points according to the different depths of cut required.

MILTON BRADLEY.

Witnesses:

JAS. M. BRYAN, E. H. DARLING.

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