BERNARD LEVINE'S KNIFE LORE NUMBER 64 NOVEMBER 1993 (c)1993 Bernard Levine, exclusive to the NKCA PERRET ON SHARPENING In alternate months beginning in January of this year I have been translating excerpts from the finest cutlery "how-to" book ever written. It is the three-volume L'Art du Coutelier (The Art of the Cutler) written in French by master cutler Jean Jacques Perret, and published in Paris in 1771. As I noted earlier, there is no particular order to the chapters in Perret's book. For example, Chapter 1 deals with the selection of polishing materials, while Chapter 2 covers the selection and cutting of handle materials. Therefore I have chosen excerpts that I believe would have the widest interest to a modern audience, without regard to their order in the original work. Topics covered thus far have included: forging damascus steel, making and using specialized hand tools, employing pocketknife patterns, organizing the cutler's shop, and making veterinary instruments for use on military and draft animals. Recently NKCA member Gary Nichols of Alabama wrote, "Please continue the publication of Jean Jacques Perret's work in your 'Knife Lore.' All of his work looks interesting. I would be particularly interested in anything he wrote on sharpening techniques, sharpening stones, and other sharpening devices." Sharpening is of course a fundamental part of the art of the cutler. There are three basic elements to sharpening a blade. First is grinding or filing it to establish its profile. Second is polishing it, to make its surface smooth, durable, and attractive. Third is whetting or honing it, to shape the actual cutting edge. Each of these three elements can consist of many distinct operations, and this is especially true of polishing (for a description of the many steps employed for fine polishing in 1840 Sheffield, see this column in the December 1992 National Knife Magazine). Of course in terms of cutting function, polishing can be omitted entirely. However, without grinding of the bevels and honing of the cutting edge, a blade will not function at all. Perret devotes a great deal of attention to all aspects of sharpening. He deals with the selection of abrasives, including wheels, hones, and polishing compounds; with the construction, adjustment, and powering of grinding and polishing wheels; and with the application of this equipment to the various classes of blades, including knives, pen knives, ink erasers, scissors, razors, and surgical instruments. Perret's chapter on grinding and polishing wheels (Chapter 5) is long and detailed. Of course some of it has been rendered obsolete by such modern inventions as the uniform synthetic grinding wheel, the belt sander, the ball bearing, and the electric motor. Many aspects of it are still interesting, however, so I include a severely abridged translation of it here. Portions of text enclosed in [square brackets] are my summaries of much longer passages. Perret's treatment of hones and final sharpening (Chapters 6 and 17) is fairly brief, by contrast, since honing does not involve any complex and potentially dangerous mechanical apparatus. Much of this 1771 material is still of value at the present time. Indeed in most of today's most modern knife factories, final sharpening is still a handcraft operation. I will translate these two chapters in an upcoming column. THE ART OF THE CUTLER by JEAN JACQUES PERRET - 1771 FIFTH CHAPTER Choice of Grindstones; Manner of Mounting them on Arbors, also Polishing Wheels, and of adjusting both the one and the other to be well-rounded and evenly turning. There are many sandstone quarries in France, but not all of their products are suitable for making grinding wheels for sharpening. Passably good ones are located in Languedoc, in Auvergne, and in Champagne. However the best stone for the cutler is found in the Sel [rock salt] quarry near Langres [an ancient cutlery center, where Perret had worked for a time]. These grindstones are whitish gray in color, of a grain both even and soft, and with a tendency to harden slightly when soaked in water. To determine if a grindstone is good or bad, examine its grain. If it is close and tight, the grindstone is hard. If it is open, and yet despite that is still fine and uniform, the grindstone is soft. Having examined those qualities which the eyes can observe, it is next necessary to probe beneath the surface. To do this one scrapes a little bit with the cutting edge of a knife, and one judges from this just how soft the grindstone is. It is necessary, above all else, to make sure that there are no cracks in the stone, no matter how small, because if there are any flaws, then do not risk using that grindstone. I suspect that any vein denotes a flaw, although the eye might not be able to perceive it. To be certain, take some clear water and pour a little of it on to the place in question. If there is a flaw at that spot, it will absorb water more quickly than the rest of the grindstone. * Polishing wheels are made of walnut wood, using only the hardest, the least porous, and the most uniform in color. Black or brown walnut is preferable to white, because white walnut is softer, and wheels made from it will not stay round very long. In black walnut one sometimes find knots that impair its quality, being substantially harder than the parts without knots. It is the same with polishing wheels as with grindstones, in regard to flaws and cracks. It is important not to use a polisher that is even a little bit split. No matter how tiny the crack, a damaged polisher will not be able to endure rapid turning without breaking. This sometimes is the cause of serious accidents, and workers are sometimes killed by shattered grindstones, or badly injured by broken polishers. PLATE VII goes near here >>>Caption: Plate VII: Emplacement d L'Auge (Set-up of the grinding Trough) I. On Grindstone Arbors and their fixtures; method of proper mounting. The axle-tree or arbor for a grindstone is made of an iron bar a little over a half inch square, for medium sized grindstones, or a little over three quarters of an inch square, for larger grindstones. One takes a piece of this iron bar about 10 inches long and forges a chaudre-grasse [?] at each end. In order to make the two points even and flawless, after having rounded them with light hammer blows, one should dress the whole arbor while hot as perfectly as one can. Then one files the two points very round and very smooth. One should not bring them to a sharp point; it is necessary that their tips be blunt. Figure 16 [bottom, to right of center] shows this arbor. Note that having been made from a bar of iron that started out 10 inches long, after the points have been drawn out it is now about 12 inches long. This is the length that is required in order to leave enough room for one's hand between the grindstone and the drive pulley, when mounting the grindstone on the trough. Next one lays the grindstone down flat, and with a compass one locates the center (see Figure 17 - bottom, second from right). One marks the center with a point of the compass. Then one takes a large drill bit (Plate VIII, figure 1), and by hand only one carefully enlarges the hole. PLATE VIII goes near here >>>>Caption: Plate VIII: Monter les Meules (Mounting Grindstones) Figure 2 in Plate VIII shows a tool called a perce-meule (grindstone piercer). It is made of steel without being hardened. This tool is about 7 or 8 inches long, and about an inch thick. The tip terminates in two teeth similar to saw teeth. The two sides over its entire length are filed to bevels to form cutting edges. The hole at the end (M) serves to hang it from a nail in the shop. In use one pinches this tool firmly upright in the vise (b in figure 3). One places the hole in the grindstone upon the two points of the tool. Then one rotates the grindstone, always horizontally, as if it were on a pivot. The two teeth cut continuously, and will pierce the hole in less than fifteen minutes. One should take care to put a small rag atop the vise. This will keep sandstone grit from getting into the box of the vise, and wearing down the threads of its screw. When the hole is pierced through, it is then necessary to turn over the grindstone. Remount the piercing tool in the vise, and pass it through the hole in the opposite direction. This is to assure that the hole will be even on both sides. When the grindstone has been well pierced, it is necessary to make wedges for mounting it to its axle. One takes a piece of dry straight-grained oak wood about 2-1/2 inches long by 1/2 inch thick, and one pinches it in the vise to saw it into wedges. Figure 4 shows this wood marked for cutting [into 18 wedges]. After sawing the wedges, it is necessary to round them on one side, while leaving the other side flat, and above all to make them all of equal thickness. All these pieces being ready, one now can mount the grindstone. For this one holds it upright, either on the ground or on the workbench. One then inserts the arbor in the hole [and secures it using wedges, pairwise in groups of four - ABcd in Figure 3. Drive the wedges with light blows of a very small hammer with a 3 to 4 ounce head - Figure 6. The wedges should overlap, as in Figure 8, not abut, as in Figure 9]. [Figure 7 shows how to check the wheel for true. A hole in the side of the workbench holds one end of the arbor, while a hole in the wooden palette F that rests on one's chest holds the other end. Hold a file on the bench with one hand, and rotate the wheel with the other. If the end of the file rubs unevenly on the turning wheel, then the wedges need to be adjusted.] [Next the drive pulley with its square hole is driven on to the arbor - Figure 10. If the hole is too large, wrap the arbor with a strip of cloth, or else use wood or iron wedges. The point of the arbor should protrude about an inch and a half. [When the pulley is also true] then take the grindstone over to the trough and smear some fresh wet wheel swarf on to the wedges. The grit will fill the small voids, and the moisture will cause the wood to swell, affixing the grindstone and pulley very firmly to the arbor. It is essential that the diameter of the pulley be in proportion to that of the grindstone, to regulate its speed and its cutting power...] At least a dozen grindstones are needed by a cutler. One should be 18 to 20 inches in diameter. The others should range from 4 to 12 or 13 inches in diameter. II. Manner of mounting Polishers on their arbors [Mounting polishers is similar to mounting grindstones, except in regard to adjustment. Like pulleys, polishers are made of wood have square holes. They are secured with iron wedges, not wooden ones. The easy way to make these wedges is to roughen the surface of an old knife blade, and then chop it into pieces - Figure 12. Polishers turn faster than grindstones, so their pulleys are smaller... Either type of wheel can be fitted with a variable speed drive pulley - Figures 11, 13... Large polishers should be mounted with reinforcing plates and be keyed to the arbor - Figures 13, 15-19...] A cutler needs to have at least 15 polishers mounted for use. They should be sized in one inch increments, from 4 inches in diameter for the smallest, on up to 18 inches. III. Manner of mounting Grindstones and Polishers on the Trough [Grindstones and polishers are mounted exactly the same way. The bearings for the arbors are simply wooden blocks drilled with many holes. One block is fixed in place, and the other is adjusted with wedges until the wheel runs true....] [After two or three hours work, the wheel will start to wobble. For safety the wheel must be completely stopped before adjusting it. It is adjusted by means of light hammer blows to the block and the wedge. Lazy cutlers adjust their wheels while they are turning, and many of them suffer serious injury as a result.] IV. Proper Tools for rounding Grindstones & Polishers Take a piece of iron from the scrap pile and forge it out to a length of 12 or 14 inches, and about 1/6 inch square - Figure 21. Then stick this into a strong file handle, and call the instrument a fer a regler [regulating iron, or wheel dresser] Figure 22. It serves to round the grindstone while cleaning and sharpening it. To round a new polisher, one uses a barleycorn tool (Figure 23) and a flat-bevel tool (Figure 24). [These are similar to wood turners' tools.] To round a polisher that has lost its shape from use, it is necessary to use a tool that has been hardened. Otherwise the emery on the polisher will destroy the point of the tool before it has any effect on the wooden wheel, and the tool will need to be resharpened frequently. To avoid this problem on can make a special tool out of an old file. Trim the narrow end of the tang, flatten this end a little bit, bend it slightly, and shape it with another file until it resembles a barleycorn... See Figure 25, which shows this file, whose tang is a turning tool... Figure 26 shows a piece of wood 14 to 16 inches long, 3 or 4 inches wide, and a little over 1-1/2 inches thick. It must be of oak or some other hard wood, because it is used to support the wheel dressing tools. V. Manner of rounding Grindstones... Have the grindstone turning, but not very fast. If space permits sit on stool, or else sit on the trough itself, or even kneel on the ground. Take the wheel dresser in one hand (R in Figure 27 - bottom right). Place it on the support, q. Hold two fingers of the other hand at the tip of wheel dresser, pressing down on the support to hold it firmly. The first hand, R, now moves slightly to make the first very small cut into the stone. If you try to cut too much, the grindstone and the drive wheel will stop short... One should start dressing at the right hand edge of the stone, and then work toward the center. This half being done, one should change the angle and direction of the dresser (see the dotted line S to the right of Figure 27). Now start at the left hand edge of the stone and work toward the center, continuing until the whole surface is even. [One works from the edges to the center in order to minimize the chances of breaking the edges of the stone.] For the wheel dresser to bite, it is necessary to present the flat at the tip of the tool to the wheel, and then make a slight movement of one's fist to engage the tip. After each pass with the tool, it should be rotated one quarter turn: counter- clockwise when in position R, clockwise when in position S... Otherwise the grindstone will chew up the wheel dresser without being affected itself... [When the grindstone is nearly round, stop its rotation and examine it. Note exactly how much more dressing is required, and then resume the operation.] [The final step is to "make the cheeks." This means to sharpen the corners of the grindstone by dressing the flats back 2 to 3 inches from the edge.] Then the grindstone is ready to work. VI. Manner of rounding Polishers... [Note: In later years wooden polishing wheels were covered with walrus hide, so they did not need to be dressed, only recoated with abrasive compound.] Polishing wheels are mounted to the trough in exactly the same manner as grindstones. Their surfaces are also dressed the same way, the tools being held on the rest in exactly the same fashion. The only difference is that the polisher dressing tools are presented to the wheel with a lighter touch... When the surface of the wheel is already impregnated with emery, dress it with the "barleycorn" file (Figure 25). However, if the black surface has been removed, and the bare wood is showing, then use the flat chisel (Figure 24)... The polisher needs to have very keen angles. To achieve this take the "barleycorn" tool (Figure 23) and use it like the wheel dresser in Figure 20. This way one can precisely form the flats, angles, and cheeks of the polisher. It is a good idea to shave down the flats of the polisher 3 or 4 inches in from the edge. This way if your fingers slip on to the wood while you are working, you will be less likely to pick up nasty little splinters. (Figure 28, bottom center) When the polisher is well rounded, apply a layer of emery to the edge. This is done with a wooden brush, V. Use it to take some emery that has been diluted with oil in the pot, y. Apply the emery to the wheel as shown in the figure, and then allow it to dry... A very essential point is the position of the tool rest, q, in Figure 27. If it is above the axis of the wheel, the dressing tool will not bite adequately. If it is below the axis, the tool will bite too deep. Therefore the rest should be affixed on the same level as the arbor of the wheel... and the dressing tools should be held in this exact plane... VII. Description of the Equipment for mounting the Grindstone and the Polishers; Placement of the Trough and its accessories. The apparatus which makes up the trough is very large and awkward. If one's cutlery shop does not have a back room, or a well lit cellar, then the trough and the wheels have to go near the door [for adequate illumination], and they are always in the way. The trough is made from a piece of oak about 4 feet long and 15 to 18 inches square (Plate VII, Figure 1). It is hollowed out in the middle, A, about 10 or 12 inches deep. It has another recess, B, about 7 or 8 inches deep and wide, which holds the water which one sprinkles by hand on the grindstone. A similar recess at the other end, C, allows the trough to be reversed if necessary... The support D is fixed in place and faces the wall. The block E is adjustable... [It is retained by an iron stirrup and wooden wedges - Figure 2.]... [The trough should not sit directly on the ground, or its bottom will rot, and eventually it will leak. Ideally it should be anchored in place by a 5x5 oaken post 2 feet long driven into the ground - Figure 5 (bottom center).] It is with good reason that I insist upon the solid mounting of this apparatus. When it is holding a grindstone 20 to 24 inches in diameter that is turning rapidly, that stone is capable of shattering the entire machine, and of injuring not just the person working at it, but everyone in the vicinity. VIII. The Chevalet, the Platform, the Water-guards, the Drive-wheel, and their accessories The chevalet [horsing], so called because it supports the platform on which the Polisher (cutler) lies, is made of two parallel oak planks about 18 inches wide, cut and assembled as shown in Figure 6. They are joined together by another plank nailed from above, shown as a dotted line. The inside is reinforced by a wooden brace at y-y. Figure 7 (bottom right) shows a wooden plank about 5 feet long, more than a foot wide, and about an inch thick. A wooden cleat u-u is nailed at the bottom, on which the cutler rests his feet. This plank is relieved at V-V to provide free arm movement for the cutler, and it is relieved at the top, P, to provide a rest for his chin. It is a good idea to nail a cushion to this plank, making the pad thickest near the edges, and thinnest along the center. One then nails a piece of tapestry or other fabric on the ends of the plank... [The large drawing shows the trough with all its accessories in place. Atop the trough is the the chevalet, with the plank on top of it, inclined at about a 30 degree angle.] The cutler's grindstone, which soaks continually in water, is constantly picking up water while it is turning, and could spray it in the face of the cutler. However, a little three part device prevents this. It is shown in detail in Figure 9. The frame of this water-guard holds a piece of [felt] hat in light contact with the grindstone. The cloth strips excess water from the wheel, allowing it to fall back into the trough. (See b, directly beneath the cutler's right hand, in the large drawing). [Note: In areas of France where water power was available, it was used to turn wheels and operate trip hammers. However, in downtown Paris, where Perret worked, the only options in 1771 were man-power and dog-power.] The cutler's drive-wheel should be 6 feet in diameter, or at least 5 feet, and should be very solidly built. It is necessary that the groove which carries the drive cord be very smooth and even, and cut to at least an inch in depth. Its cross-section is shown in Figure 10 (top right). An angled chamfer is cut into the groove at r (about 10 o'clock on the wheel) to facilitate mounting the drive cord. The part of the arbor which passes through the hub of the drive-wheel is about 15 or 16 inches in diameter. The rest of the arbor is 12 inches in diameter (11 inches on a 5 foot wheel). The part of the crank which the turner holds in has hands is covered by a freely turning wooden handle. The drive-wheel is mounted on a solid base that is made of ten strong heavy pieces of wood... IX. Tasks of the Turner... The first concerns of the drive-wheel turner are to keep the water bucket filled, and to keep the grindstones and polishers neatly hung up and arranged in the proper order (Figures 12-13). The wheels should never be allowed to rest upon each other, because this can cause the wedges to work loose. The turner should know the correct tension of the drive cord. If the cord is too tight, the wheel becomes more difficult to turn because of increased friction. If the cord is too loose, it slips in the wheel and in the drive pulley, and the grinding wheel will stop turning under even slight pressure from the cutler. The turner should also understand that the larger a grindstone is, the tighter the drive cord should be... Every time that the grindstone or polisher is changed, it is necessary to remove the drive cord. This is the turner's job. To do this he takes the cord in one hand at a (top center) and pulls it toward him, so that it rides along the side of the groove. Then he turns the wheel slowly in reverse, and the cord will come off... When it is time to replace the cord, he must take care not to entangle it around the arbor, as is its tendency... He must look carefully before replacing the cord that it be seated in the throat of the drive pulley, and that it be crossed as it should be. Cutlers always use drive cords made of gut. The turner must know how to splice this material... The position of the turner must always be such that he is ready either to push forward or to pull back. For this he should place his front foot in line with the axis of the drive wheel, with the other foot about 12 or 13 inches behind... The turner should apply extra force at precisely the moment when the cutler applies his workpiece to the grindstone... [Polishing wheels must be turned at greater speed than grindstones, but this takes less work because the wooden polishers are much lighter. Ordinarily a turner can drive a polisher with just one hand... * * *