Outline of manufacture & inspection of the service bayonet.
The sword bayonet, pattern 1907, Mark I/C/ for rifles, short, M.L.E. is just under 22" long, and weighs, complete, between 16 & 18 ounces.
The blade and tang are manufactured in one solid piece from the best cast steel. The steel employed must be from Swedish or other high class
approved ores only, and the following analysis is recommended, though the only actual requirements are that the phosphorus, sulphur, copper and other impurities are within the stated limits.
Carbon .. .. .. .. 0.90 per cent, to 1.20 per cent.
Silicon .. .. .. .. Not above 0.20 per cent.
Manganese .. .. .. 0.15 per cent to 0.45 per cent.
Phosphorus .. .. .. Not above 0.20 per cent.
Sulphur .. .. .. Not above 0.20 per cent.
Copper and other impurities .. Only traces.
The principal manufacturing processes in the making of the blade and tang are milling, grinding and polishing. In milling a hardened steel wheel, with appropriate cutting edges on its rim, or on one or both its sides, is revolved and the work is automatically fed forward or rotated as the cutting progresses. Milling machines, in some cases, have the wheels arranged in batteries of two or more so that the work on several blades is performed in one operation. In grinding and polishing the work is held against a revolving wheel supplied with a suitable abrasive.
The flat bars of cast steel are first sawn to length. Then the sides of the tang are milled and the rough bars brought to the correct overall length. The backs and points of the blades are next roughed to shape. A pair of gang mills of six wheels each is used to mill the backs and mill the blades to width. A straddle mill working on both sides reduces the roughed-out bar to approximately the correct wedge shape, and it is then flat milled on both sides.
The next step is milling the tang back and front. The back is milled flat and the front to the curved figure necessary to give a comfortable hand grip. Other milling machines, flat and rotary, put on the correct figure to take the cross-piece where blade and tang join. The blade is then reduced to thickness and hand ground on an emery disc. Considerable skill is necessary in this operation, which is one of the few actual hand processes in the whole course of manufacture.
The fullers, or recesses in the sides of the blades, are next milled and ground. The whole blade is then polished. One or two small processes, such as drilling the tang for the grip screws, are completed and the whole blade and tang is finished so far as actual machining is concerned. The blades are now hardened by being heated and plunged into oil or water, or through oil into water, according to the steel used, and are subsequently tempered to stand the severe test which they have to go through before they are passed into service.
The cross-piece and pommel are made of the best wrought iron or mild steel. The cross-piece is worked to shape in several milling machines. The pommel is milled and slotted, the bolt hole drilled and drifted to size front, back and end profiled to shape. The profiling machines are particularly interesting. The cutting tool is guided by a wheel which presses on a dummy of the correct shape which is caused to revolve at the same rate as the work.
The grips are made of walnut wood and are shaped in ordinary woodworking machines. The bolt and nut and the necessary screws for holding the grips in place are of mild steel. The bolt spring is of best No. 20 gauge steel wire.
Assembling is all hand work. The pommel is brazed to the tang and the cross-piece to the shoulder of the blade. The brazing has to be done to stand the tests of the ½Inspection Department. The grips are oiled on the undersides before being fitted into place, and are fixed with two screws and nuts.
Before being assembled the pommel and cross-piece are browned and the bolt is blackened or browned. Browning is a chemical process in which the component is dipped in an acid mixture which gives the steel a dark, dull appearance. Oil blackening is effected by heating the component, then dipping it in oil and burning off the oil that adheres to the surface. This leaves the surface a black carbonaceous deposit. Subsequent to these operations the components are “bobbed” or polished.
The blade and mountings are viewed in the shops in all stages of manufacture, gauges conforming to the dimensions laid down being used. In most cases the manufacturer submits the bayonet to the same tests as those used by the Inspection Department.
Before being accepted and passed into service the bayonets must be inspected and proved by the Chief Inspector of Small Arms or by an officer deputed by him for this duty. Inspection is carried out at various stages of manufacture. If one-fourth of any delivery is found inferior to the sealed pattern, or contrary to the terms of specification governing manufacture, the whole consignment is liable to rejection.
The blades are first submitted to view by the Inspection Department in the hardened and tempered stage, in batches of not more than 200, with tangs finished and ready for the assembling of cross-piece and pommel. One blade in each batch is submitted to an overtest, rendering it unserviceable, to ascertain that hardening and tempering are correct. This test consists of reducing the length of the blade 2½ inches by bending in a powerful machine. The blade must not break or take a permanent set of more than 7/16 of an inch.
If the trial blade stands this severe test the remainder are tested in an ingenious machine that strikes them with a severe blow. With the back and edge the blow is struck on an oak block; with the flats it is delivered on the iron table of the machine. The machine consists of an iron arm, to which the blade is fixed, which is held back in a vertical position, by means of a pawl, against a spring with a tension of from 17 to 19lbs. The iron arm is 14½ inches long, and weighs about 14½ lbs. The tension of the spring ceases when the arm has reached a position about 22½º from the horizontal, the arm and the blade completing the blow by the momentum they have acquired. When the flats are struck the blow is not so severe, the arm starting from a position 45º from the horizontal, and not from the vertical.
The blades are also tested in the bending machine used to test the first blade to destruction. In this case a weight of 110 lbs is used, and the blades must straighten out after having been bent ¾ inch in both directions. They are further sprung round a curved block on both flats, and must not take a permanent set. The greatest depth of curve in this test is 1.75 inches. The blades are trough gauged, and must not be more than 0.02 inch narrow in any part. They are then gauged and examined for grinding, and a percentage is weighed. The blades are marked with an X on the right flat to denote the convex side for subsequent bendings, and are further marked with the examiners mark on the left hand side of the X. The weight of the blade must be between 10¾ and 12 ounces.
All the small parts of the bayonet, the grips, bolt, spring, screws and nuts, are inspected before assembling. The grips are gauged for size and shape and position of screw-holes, and for depth of recess for nut and screw head. The springs are kept under compression for a period of not less than 14 hours, after which they are examined and gauged. They must not have taken any appreciable set. The screws and nuts are gauged for diameter, length and thread. The grips are marked with the examiner’s mark on the outside.
The bayonets are next inspected rough-mounted, assembled with bolt. The set of the pommel and cross-piece, which have been brazed on, ate gauged in a receiver. To test the soundness of the brazing, the blade is struck on the edge, by hand, on an oak block. Weak brazing can be instantly detected by this method, the weakly-brazed part shifting from position. After striking the bayonet is examined and gauged for position of grip screw holes in the tang, size and figure of the bolt, bolt recess, distance of bolt from the top end of the neck of the mortise in the pommel, size of sword bar mortise and thickness of the cross-piece. They are also gauged with a sword bar mandril. In some cases they are sprung round the curved block on the left flat, and may be trough gauged if considered necessary. They are marked with the examiner’s mark on the right flat, on the right side of the X.
The final inspection is in the browned and finished stage, with the blade polished and the edge ground to an angle of 36º, commencing about 2 inches from the cross-piece and extending to the point, the ground edge being left 0.01 inch in thickness. The blade is examined for flaws and for the finish of the polishing. It is sprung round the test block on the left flat, gauged in the trough, any blade 0.02 inch narrow in any part being rejected. The thickness of the fullering is gauged and must not be thicker at the point end than at the shoulder. All the details of the assembling and fixing of the small parts and furniture of the hilt are checked in this examination, note being taken that there are no sharp edges on the cross-piece or pommel. The completed bayonets are weighed and the examiner slightly rivets over the screwed end of the bolt. All bayonets that have passed the tests and examinations are then marked with the proof mark and with the examiner’s mark under the proof mark on the right flat. The left flat is marked with the “crown G.R.” over, and the date mark under, the pattern mark (1907).
The bayonets are then greased and packed and passed into store.
