Making of the Cast Iron Carpenters’ Plane at the Stanley Rule & Level Company
Reprint from THE IRON AGE THURSDAY, NOVEMBER 3, 1898
Few in the trade, and perhaps none out of it, appreciate fully the time, care, skill and peculiar refinement displayed in the manufacture of the highest grade iron carpenters’ plane, A mere statement of the steps essential to the production of this tool would be a revelations to per cent of those who handled it A book would be required to describe fully all the processes through which the raw materials pass. A lump of cast iron and a plate of steel are united in a product which is absolutely reliable and absolutely accurate in every way. The blade is designed for cutting, and it may be relied upon implicitly to perform its duty. The body of the plane is true; even that most crucial test, the straight edge, will fail to permit the faintest ray of light to pass between it and the surface. There are others, but these two examples suffice to make our meaning clear. The accomplishment of these ends is due to extended experience, the long exercise of wonderful me chanical ingenuity and the adaptation of those methods which will assure the best results from their combination. Through the courtesy of the Stanley Rule & Level Company of New Britain , Conn. , a representative of The Iron Age was recently permitted to examine many of the most important steps connected with the making of their planes and to obtain data necessary for a general description of the processes. In the following no attempt will be made to follow either the body of the plane or the plane iron through the works as they pass from one operation to another. The aim has been to take up the work piece by piece and complete the work of one machine, even though the piece may in its progress leave that machine for another and then return.
The Cast Iron Body.
The body of the plane has been pickled and perfectly cleaned before coming to the works, its appearance being as indicated in Fig. 2. It is made of high grade cast iron poured early in the heat and cast in molds which must be of the highest accuracy, this being rendered necessary by the thin and comparatively large surfaces of both the bottom and sides. An extra portion of the metal is provided at the mouth in order to prevent chill which might otherwise occur if this part were made extremely thin. It is first snagged on the ends on a grinding machine, the true curve being obtained by this means. The top and interior of the sides are then japanned.
Two reasons are given for this: If the plane were machined before being Japanned the high heat of the japanning oven might warp it out of true, and would certainly tend to discolor the finished surfaces.
Planing the Bottom and Sides.
The bottoms of two planes are operated upon simultaneously in the planing machine in Fig. 3. Each body is held bottom up in a jig. One rests upon a stud projecting from the jig, an adjusting screw being provided under the other end in order that the surface may be maintained in accurate parallelism with the cutting movement of the tool. The inner edge or facing sides of the two planes rest against the straight portion of the jig, while against the opposite or outside surfaces bear two swivel clamps, each of which is provided with two bearing points which rest against the plane. The clamps are brought forcibly against the plane, which is held in a rigid grip by a tightening bolt near the center of each clamp. The plane is thus held against one straight edge, is supported vertically upon two studs, one of which is movable, and is clamped upon the outer side by the four bearing points of the swiveled clips. The sides are planed two at a time in a similar ma chine, indicated in Fig. 4. Each jig in this case consists of a vertically placed straight surface against which the plane is held by a set screw. Two cuts are taken. The first or roughing cut is with a diamond pointed tool, while the second or finishing cut is made with a flat tool. The mouth of the plane is cut with a small cold saw of the exact width of the opening and of such size as to produce the length of opening required. The plane is held as shown in Fig. 5, in a sliding jig, which is moved toward the saw. This produces, of course, a hole the sides of which are perpendicular to the bottom of the plane, and it therefore becomes necessary to take away the inner portion of the rear side of the hole in order to provide the bevel against which the cutting blade is supported. This bevel is sawed or milled upon another machine, after which the corners of the mouth are hand filed to make them truly rectangular. Drilling and tapping the holes for the attachments, knob, handle, &c. , are done upon the usual vertical drill presses. The top edges of the sides are ground upon the machine, as shown in Fig. 6. This is practically a double machine, the two sides being similar and work being carried forward at the same time upon each, so that a description of one will suffice for the other. An emery belt passes first over a large pulley, then is guided upon a curved plate, after which it passes around a small pulley at the right. The several curves thus imparted to the belt admit of the plane being so held that the edges may be ground in the straight and also in the curved portions. At the left end, placed just over the large pulley, is a hood connected with a large pipe, through which air is drawn. These several hoods and pipes collect all the dust arising from the grinding and deposit it in a suitable receptacle in another room.
Grinding the Bottom.
These planes have always been guaranteed, both in regard to material and accuracy. We therefore find that one of the most interesting operations connected with their manufacture is the grinding of the bottom. It might be supposed that for all intents and purposes the plane would be accurate enough as it came from the finishing cut on the planer, but the method pursued and the inspection to which the plane is finally subjected make necessary a grinding operation in order to produce the results.
The machine shown upon the first page consists of a traveling bed which carries the plane, bottom up, in a suitable jig. This bed is carried to and fro under the emery wheel, which is inclosed, as shown, and is fed transversely across the face of the wheel. The planes are all ground wet, and while some are finished at the first operation and pass the scrutiny of the inspector, others have to be returned to the machine for regrinding, the inflexible rule being that no deviation from ab solute accuracy is permitted.
Testing the Surface with the Straight Edge.
The diagram, Fig. 10, illustrates the usual way of testing a bottom. A steel straight edge is placed in three positions, a a a, parallel with the sides, one at each edge and one at the center. It is then placed diagonally, ccc, across the corners, and then transversely, bob, at each end and at the mouth. If the finest ray of light can be seen between the surface and the straight edge the plane is sent back for regrinding. It must stand all of the eight tests and show not the slightest irregularity. The half – tone engraving, Fig. 11, is reproduced from an actual photograph taken at the works and shows the testing straight edge resting upon the plane. The left hand ends of the straight edge and plane were separated by a hair which caused the beam of light shown in the engraving, which is made direct from the photograph without any manipulation whatever. This plane is one which was picked up at random and that was one of the tools passing through that department in the usual way. It was not in any sense a particularly accurate specimen. Removing the hair and placing the straight edge upon the plane in the same position entirely obliterated the passage of light between the two. This will convey. some idea of how the sides and other portions of the plane are tested.
The Corrugated Plane.
The corrugated plane is shown in Fig. 7. While a plane of this general character was introduced many years ago it met with but little success. Recently it has been once more placed upon the market and there now seems to be a steady demand for it. The common supposition is that these corrugations lighten the plane a trifle, and since they present less surface in contact with the wood are thought by some to reduce the friction of working. Since the user is willing to accept this theory the manufacturers provide the corrugations. The ma chine for doing this work is shown in Fig. 8, which is an ordinary milling mac in which the plane is held in a jig upon the table and in which the grooves are made with a gang mill.
The “ Buzzer
The “ buzzer,” shown in Fig. 9, is designed for truing the fork in the lever which clamps the plane iron in position. Its nickname is derived from the fact that when it is running it can be heard all over the room. It consists of a heavy arbor, on the right hand end of which is mounted a plain soft steel disk, 10 inches in diameter and about 5-16 inch width of face. This wheel is driven at 6000 turns per minute. The lever is held in a clamp upon a table in front of the wheel, which is moved toward the wheel by a suitable elbow lever connected with and operated by a treadle. The lever is cast iron and the fork in its small end comes from the foundry in some cases with slight imperfections in the shape of burred edges. The wheel removes these edges and perfects the contour of the fork. It does this work perfectly and rapidly, a peculiarity being that the wear upon the wheel is almost infinitesimal.
The plane iron or cutting blade, which is really the vital part of the tool, is made from the best English sheet steel of the same brand which has been used by the company since 1869. It is first pickled and then cut into the desired lengths. It is blanked out, as shown at the left in Fig. 12, then pierced or punched for the slot, and then straightened under a drop and also between hot blocks. These blocks, which are similar to those also used for tempering, consist of cast iron pieces placed one upon the other, the meeting surfaces of which are true and maintained parallel with each other. The piece of steel is placed between these and pressure applied.
The mutilated thread in the under face of the cutter is cut in the usual milling machine. To harden the plate it is heated to a white heat in the furnace, gripped by the tongs and dipped in a hardening solution. In performing this operation the workman uses great care in entering the blade edge first, the supposition being that this method will tend to obviate warping and also to produce a uniform degree of hardness. After having been hardened the temper is drawn by placing the plate between hot blocks similar to those described and is straightened by band on an anvil, and the surface ground and polished, after which it is whet upon an oil stone and is ready for the assembling room.
Testing and Inspection for Making of the Cast Iron Carpenters’
Every part of every plane is tested and inspected at every step in its manufacture. No deviation whatever is permitted from this rule. Any imperfection discovered is corrected or the piece is discarded then and there. The final inspection of the assembled plane is made under actual working conditions. While the plane has been tested with the straight edge in the grinding room, it is again tested with the straight edge after having been placed in condition for actual service. The working test consists in the cutting of hardwood. The edge must be perfect its entire length and it must be able to take a perfect chip the entire length and width of the block of wood used. After passing this department the planes go to the packing and shipping room. As an interesting feature, it may be stated that if the owner of one of these planes stamps his name upon the side, a more or less common practice, it is apt to distort the body and throw it completely out of true, and often cracks the plane near the mouth.