Copy Section

in the copy. Such rollers will enable "roughing out" to be done be means of a fairly large cutter, and then the roller can be changed for a smaller one, or for the style itself, and a correspondingly smaller cutter used to pass through the smaller spaces.

The cutter itself may be parallel, or it may have a slight taper on it, and in some cases, while a parallel

The standard line copies illustrated on page 9 have been developed with the assistance of leading authorities in type design and have been adopted as Standards for instrument work by H.M. Government and by many private firms. For general use we recommend the "A" copy characters. These are simple block capitals having a ratio of height to width of about 3 - 2.

The "C" copy characters are narrower,

the proportions being about 2 - 1, and are intended to be used where space is too limited for bolder "A" style. The "L" copy is lower case intended for use with "A" style.

The schedule below gives particulars of the various copies which can be supplied from stock. They are engraved on hard brass strip beveled to fit one or other of the copyholders listed on page 15.

When ordering other than complete "sets," please state exact number of characters required.

page 11

Wood

Cutters for wood should have the cutting edge angles made acute, and this can be done by grinding the flats past the cutter axis. A high speed is desirable for wood.

Glass

Diamond cutters are available for this purpose and are sometimes useful for other work on account or their resistance to wear. But they are liable to fracture on hard and tough materials such as steel. (See table on page 28.) They are only suitable for "scratching."

Using care and the exercise of taste, the ultimate engraving can be made to look very pleasing by the right and most fitting arrangement of the respective characters.

Spacing in order to be right must look right. As with printers type, the blanks upon which standard copy characters are cut are designed to give the best spacing with average combinations of characters. But there will always be

certain combinations which appear too crowded.

With uniform spacing, characters with straight vertical sides which come together appear cramped. In HILT for example, the appearance of the engraving can be improved if the H, I and L are spaced out the better to match the irreducible space between the L and the T. To adjust the spacing as above indicated we supply spacers of various widths with all standard copy.

It is obvious that, by varying the reduction, the same size of engraving may be done from copy of various sizes. For example characters 1/4-inch high may be engraved either from 3/4-inch copy with the 1:3 reduction, from 1-1/2 inch copy with the 1:6 reduction or from 3-inch copy with the 1:12 reduction.

Small copy permits of many characters, perhaps the complete inscription , being set up in the copyholder at once. This is generally an advantage. With large copy the leverage of the pantograph is greater and the operator, having more control over the cutter, moves it more steadily. The copy is less subject to wear, and slight defects due to wear are proportionally reduced in the engraving.

The height of copy is measured from centre to centre of line. The overall height of the characters

engraved is, therefore, the height of the copy divided by the reduction used and plus the width of cut. Thus, using the standard 2A copy (0.75 inch high) and engraving on the 1:10 reduction with a cut 1/100-inch wide we get (0.75 inch / 10) + 0.1 inch = 0.085 inch.

When using single "Line" copies the engraved characters will somewhat different from the copies on account of the thickening of the lines due to the width of cut. If too wide a cut is made, the lettering will be spoilt. For example, the little lands in the "a" and "e" will be left too small or even cut away altogether.

Block capitals should in no case have a width of cut exceeding 1/5 of their overall height. Generally a width of only 1/8 this height is desirable.

In order that the engraving shall conform to the copy the following precautions must be observed :-

If the cutter is cylindrical, the ratio of its diameter to the diameter of the style roller must equal the reduction in use. Thus - the 1:10 reduction and a 0.5 inch diameter roller call for a cutter 0.05 inch diameter.

If the cutter is conical, the same remarks apply, the diameter of the cutter being measured at the surface of the work, when the cut is the correct depth. If the engraving is in a moulding die, it is the diameter of the cutter at the bottom of the cut which would be proportionate to the style diameter, seeing that this would be the surface of the lettering on the finished product.

A trial cut is taken, which of course, will leave a raised character of too wide a face or a sunk character of too narrow a face. The end of the cutter is then truncated as required to bring the face width of the engraving correct.

With a parallel cutter the diameter must be determined precisely before any cut is taken. This diameter cannot be measured on the sharpened cutter itself since the cutting edge is more prominent than the parts relieved.

Special Note.

Your attention is directed to Cutters and Cutter Grinding, page 17, and to separate information obtainable upon request.

For exact measurements a microscope is available.

When any revolving cutter is fed into its work at the beginning of a line as at "A" in Fig.9, it has no lateral displacement but as soon as it is traversed it tends to move to one side of its proper course. In the case of the engraving cutter, rotating clockwise, this tendency is to the left of its line of advance. Whether the displacement is perceptible or not depends upon the heaviness of cut and the degree of freedom in the machine joints.

In cutting the outlines of raised characters it is generally desirable to

Where any inscription is to be engraved repeatedly, for example a firm's name or trade mark, the copy should be engraved on one plate, as "Set" copy.

We have special facilities for making set copies to customers requirements.

Well-designed set copies save time and give a finish and uniformity to work which is not obtainable be means of loose characters.

Set copies are sometimes used in conjunction with loose characters. For example, inscription plates for electro-motors, machine tools, etc., may have to be engraved with progressive serial numbers, in addition to a repeated inscription. In such cases a set copy carries the repeated matter and is provided with slots in which the serial numbers can be built up with standard copy figures.

In case of inscriptions too large to be engraved at one setting, the set copy

may be in two or more parts ; and to ensure engraving these in correct relation the copies and the work holders may be provided with registers such that at each re-setting the copy and work will be located in the correct relative positions.

Where the expense of such provision is not justified, the set copies may be made to overlap so that after a change of copy the work may be placed correctly by setting the style in the overlapping part of the copy and setting the engraved portion of the work correspondingly under the cutter.

Set copies too large for standard copyholders may be adapted by mounting them on standard beveled strip. Alternatively they may be held on the No.0 copyholder (Fig.11, page 15), which measures 16 inches x 9 inches and is provided with a fence for locating copy squarely.

For circular set copy see page 16.

Temporary copies are very conveniently made from transparent celluloid about 1/32-inch thick. They are cheap to make and with care can be used about thirty to one hundred times.

The copy is made direct from the drawing by placing the celluloid over it and tracing the diagram with a steel scriber ; a straight edge and French curves may be used as guides.

A cut 2-hundredths of an inch deep is quite sufficient to guide the style.

Line copy may be cut with a standard graver which we supply on request.

Copy for sunk or relief engraving may be made as above by scribing the lines deeply and breaking the celluloid along the lines. The point of a knife may be used instead of a scriber. Celluloid copies

should be tacked down to wood or stout card in order to protect them and hold them out flat. Shoe tacks should be used and should be placed close to the cut or the edge, as the case may be, so that there will be no tendency for the copy to lift and become distorted.

It is advisable to hammer the tacks in about two-thirds of their length only, then to cut off the heads with a pair of pliers. This avoids any tendency to split the celluloid. The tack stumps are hammered flush with the surface to avoid injuring the operator.

Where dies or moulds are required to be engraved with reverse characters and reversed copy is not available, an ordinary copy and copyholder may be packed upside down above the style to effect the necessary reversal.

The Copyholder

All copyholders have two bosses which bear against stops on the head (see Fig.2, page 4). The stops are so set that when the copyholder is turned against one of them it is either at right angles to (Fig.2) or in line with the work-table.

The copyholder may be used in either of these positions or any intermediate position, but that shown (Fig.2) is the most favourable.

Dovetailed slots in the copyholders receive the standard beveled edge copies, which are secured by the end clamps provided.

Copyholders for standard copy are supplied in the following sizes:-

The Circular Copyholder

Fitted on the Engraving Machine head and moveable through 90 degrees. Used with rotatable disc copies which are notched to engage the spring catch for engraving in circular fashion (see page 16). A notch is positioned relative to the width of the character and ensures correct balance about the radial line. In use the notch is located by the spring pin in the Circular Copyholder. The catch is released by depressing the central knob.

For "C", "CB", "CX", and "CXL" machines we can supply a disc engraved with one size of character (3/4-inch) in either of two styles, "A" and "C" or both on one disc. Discs can also be engraved with any special characters, graduations lines, etc., which may be required.

Engraving falls into three classes :-

(1). In straight lines on flat surfaces or along cylinders. This is done from standard or set copies held in standard copyholders and requires no special equipment.

(2). In curved lines from curved set copy. Set copy must be used for engraving on curves which are not circular, and should be used for for circular curves where the amount of work to be done justifies the outlay. Curved copies for temporary use may be made by mounting separate copy characters with wax on pieces of ply-wood or cardboard. See paragraph below on the "balancing" of unsymmetrical characters.

(3). In circular curves or around circular

surfaces from copy moved with the work, step by step. This may be done on the dividing head, described below, used in conjunction with the circular copyholder or with loose or set copy mounted in a standard copyholder.

Balancing the Characters

In engraving curved lines of characters on the flat or on shallow cones, the "balance" of the characters requires attention. Thus, if unbalanced characters like L and J are set with their centres radial to the centre of the curve, they will appear to be falling over as compared with symmetrical characters such as A and O. To correct this it is necessary to displace the unbalanced characters ; in the case of the L, for example, its vertical line should be nearly radial

The dividing head, Fig.14, is used to hold and rotate circular work to present successive portions to the action of the engraving cutter.

It comprises a rotatable face plate, 6 inches in diameter, having T slots and a central 3/4 inch hole by which work or special fixtures may be attached. The hole is accurately formed to carry plugs for centering the work. The edge of the face plate is graduated in degrees and the plate can be locked in any position of rotation. A graduated swivel enables the axis of the face plate to be set at any angle from vertical to horizontal.

The attachment is fastened to the Engraving Machine table by means of two dogs and may be set squarely thereon by the machined edges of its base.

When using this attachment for

engraving around circular or conical work, it is necessary to rotate the work step by step and to bring the copy characters in turn to one position on the copyholder. This position should generally be above the central hole or zero of the copyholder.

Fig.14. The dividing head.

Code No. 110/79

Dividers

Accurate steel division plates (dividers, see A) engaging a hardened steel pawl may be used for dividing the circle quickly. These dividers are interchangeable and are supplied plain or with any of the following number divisions: 12, 72, 90, 120, 180 and 360, or with irregular spacing's if ordered specially. Dividers are accurate within 1-1/2 minutes of arc.

The Direct Copying Attachment

A device for making engravings exactly the same size as the copy. It is illustrated in Fig.17 and consists of the part C, which replaces the head of the machine and carries the copyholder, and the curved arm A, which is connected to the cutter frame and communicates the motion of the style direct to the cutter. This attachment will not operate conveniently with No.0, No.2X, No.5X copyholders.

It covers an area approximating to a 3-1/2 inch circle.

Extension Table for large Plates

For work outside the scope of the ordinary machine tables, we supply an extension table measuring 14 inches x 18 inches x 1 inch and carrying four T slots length-wise which take the standard work clamps. This table fits all machines.

As an added convenience for exceptionally large plates, we can supply extending bars and screws for this table. The bars extend in either direction and form convenient surfaces for accommodating extra clamps. Fig.18 shows the table in use with the bars.

Knife Dividing Attachment for Marking Fine Graduations.

The knife Dividing Attachment is for ruling such fine lines as cannot be well made with a revolving cutter.

It should be bolted to the Engraving Machine in place of the head, which together with the pantograph, must be removed. The cutter frame is swung out of the way. The attachment is provided with adjustable changeable stops to vary the lengths of line, and the tool, a sample of which is provided with the attachment, should be pressed into the work and drawn along to cut the line or graduation.

For circular dividing, the work should be mounted on the dividing head (see page 16).

The Presser Foot

Attaches to the machine spindle in place of the ordinary feed yoke (Fig.20). Its function is to maintain an even depth of cut over slightly undulating surfaces or thin materials which are apt to buckle. It is liable to scratch the surface of the work and cannot therefore be used where there is no finishing operation after engraving.

Fig.20 The Presser Foot. CodeNo.110/230.

The Forming Attachment

(For Models "C" and "CB")

Engraves on curved surfaces. The attachment (Fig.21) necessitates a special machine head in place of the standard one. (This special head can be fitted when new or at any time afterwards and does not interfere with the normal use of the machine.) An arm (A) bolts to this head and carries a master former (B) which should preferably be in hardened steel, forming a counterpart of the work surface. The feed mechanism is removed and the attachment (C) is fixed to the cutter spindle in place of the usual feed and yoke. A spring in this attachment keeps the style in part (C) in contact with the former so that as the cutter is traversed, it follows the contour of the work. To keep the style rigidly upright the steady (S) is attached to tapped holes in the long graduated pantograph bar. In setting this steady, it must be adjusted so that the spring can move the style and the spindle freely without bias.

The depth of the cut is adjusted by the vertical slide screw beneath the worktable. To withdraw the cutter for each character when the depth has been set, the feed screw (F) is slacked back. It is important to work always with this screw (F) up against its shoulder and the thickness of the former (B) must be such as to allow of this. The surface of the former needs lubricating.

Fig.21. Forming Attachment for Model "CB" Code No. 110/88

The Forming Attachment

(For Models "CX" and "CXL"

Comprises a bracket (A) Fig.22, which bolts to the machine frame and carries former (B), which should preferably be of hardened steel and have a 1/2 inch diameter shank machined on it to fit the bracket. The contour on the former face (a counterpart of the work surface) must be machined central with the shank. This facilitates setting up which ten can proceed as follows :-

Remove cutter spindle, yoke and feed mechanism. Set pantograph at reduction required. Fix copy loosely on copyholder and set style on a true centre spot on the copy. Fit setting bar (S) in cutter spindle frame and adjust head (H) on machine frame until 1/2 inch spigot on bar (S) will enter 1/2 inch hole in bracket (A). Tighten head (H) and clamp copy firmly, keeping style in centre spot. Remove grease cap from back end of cutter spindle and assemble feed screw (F). Replace spindle in cutter frame and assemble yoke, spring and spring box, as illustrated. Tighten yoke to prevent spindle revolving and lock feed screw (F) tightly on to spindle with tommy bar passing through hole in feed wheel (W) into hole in screw (F), The angular position of the spindle should be adjusted so that zero line on screw (F) is facing

Engraving to be wax filled is preferably executed with a parallel-sided cutter. From such cuts the filler is least liable to come away in rough usage. But if the material is such that a parallel-sided cut cannot be made without objectionable burr, it may be necessary to use a conical or truncated conical cutter. For security of the filler, the angle should not, however, exceed 60 degrees.

To obtain the best results when filling, a substance is required which does not shrink as it sets, otherwise it will not remain flush with the surface and may fall out. It should also wear well and stand exposure without discolouration. The "Taylor-Hobson" fillers possess all these qualities to a marked degree. They are of two kinds, Kwikfyl and Durafilla.

A wax filler for light engraving in metal, vulcanite, bakelite, ivorine, etc. Kwikfyl is stocked in black, white, red, blue, green, yellow, silver and gold, other colours made specially if ordered in bulk.

Kwikfyl is applied as follows :-

Entirely remove any lubricant used in engraving, Kwikfyl is applied warm ; the article to be filled, if of metal or a good heat conductor, should be warmed also. If using a large amount of filler, heat it in a water-jacketed vessel such as a glue or porridge pot (it becomes plastic at about the temperature of boiling water) and work it into the engraving with a smooth spatula.

On small jobs, rub Kwikfyl into the

engraving with a heavy spatula heated in a smokeless flame (a smoky flame discolours the filler). When quite cold, rub the work down flush with a single thickness of lint free cloth, such as twill sheeting, stretched tightly over a cork or wooden block and lightly moistened with paraffin. The paraffin sold as "turpentine substitute" is more effective than that sold for burning. Finally clean the engraving with a swab moistened with clean water.

Kwikfyl can also be melted and mixed with sufficient boiled linseed oil to leave the mixture just plastic when cooled. It can then be applied to very light work, such as press-formed graduations, but is suitable only for very fine cuts.

part which should then be heated up to the melting temperature of the filler which, as it settles into the engraving, will eject the air and ensure a firm, solid filling. The work should be filled over flush and finished by rubbing down with emery paper or pumice, and finally polished.