[Ill.u.s.tration: Figure 80.--(1) Coulter Clamp. Plow-beam clamps should be made in the farm shop to fit each plow. (2) Garden Weeder. The quickest hand killer of young weeds in the garden is a flat steel blade that works horizontally half an inch below the surface of the ground.]
[Ill.u.s.tration: Figure 81.--Stock and Dies. Taps and dies and stocks are best kept in compartments in a case made for the purpose.]
[Ill.u.s.tration: Figure 82.--Stock for Round Dies. The opening is turned true and sized accurately to fit. The screw applies pressure to hold the die by friction.]
[Ill.u.s.tration: Figure 83.--Taps and Dies. Standard threads are tapped into blank nuts and corresponding threads are cut onto bolts with accuracy and rapidity by using this style taps and dies. They may be had in all sizes. The range for farm work should cut from 1/4" to 5/8", inclusive.]
[Ill.u.s.tration: Figure 84.--Taper Tap for Blacksmith"s Use.]
[Ill.u.s.tration: Figure 85.--Machine Bolt and Carriage Bolt. The first is used against iron and the second against wood, but this rule is not arbitrary. The rounded side of the nuts are turned in against wood; the flat side against washers or heavier iron. Use square head bolts if you expect to take them out after the nuts have rusted on.]
[Ill.u.s.tration: Figure 86.--Plow bolts and sickle bar bolts should be kept in stock. Standard sizes and shapes are made for several different makes of plows and machines.]
Taps and dies are made to fit each size of rod. If the thread on the bolt is cut with a solid, or round, plate die, the corresponding tap is run clear through the nut. In that case the nut will screw on the bolt easily, possibly a little loose for some purposes. It is so intended by the manufacturers to give the workman a little leeway. If it is desirable to have the nut screw on the bolt very tight, then the tap is stopped before the last thread enters the nut. A little practice soon qualifies a workman to fit a nut according to the place the bolt is to occupy.
[Ill.u.s.tration: Figure 87.--Lag Screw. To set a lag screw in hardwood, bore a hole the size of the screw shank as calipered between the threads.]
[Ill.u.s.tration: Figure 88.--(1) Wagon-Box Irons, showing how to attach the box and the rave to the cross-piece and to brace the side of the box to hold it upright. There may be several of these braces on each side of the wagon box. (2) U Bolt in Cement. A solid staple to be embedded in concrete for a horse ring, door hinge, cow stanchion, etc.]
Generally it is desirable to have nuts fit very snug on parts of machines that shake a good deal, and this applies to almost all farm machinery and implements.
[Ill.u.s.tration: Figure 89.--Wagon-Box Brace. It is offset to hold the rave and to brace the sideboard at the rear and the front ends and sometimes in the middle of light wagon beds.]
[Ill.u.s.tration: Figure 90.--Two Plow Clevises and a Plow Link.]
Ordinarily a horse rake is supposed to travel steadily along like a cart, but the ground is rough and in practical use the nuts loosen almost as soon as haying commences.
Some farmers make a practice of riveting bolt ends to prevent nuts from working loose. When the bolts have square heads, this practice is not objectionable, because with two wrenches a nut can be twisted off over the riveting, but a great many bolts have round heads and very short, square shanks. Theoretically, the shanks are driven into the wood firm enough to prevent the bolts from turning. Practically this theory is a delusion and a snare, as every farm boy can testify.
Bolts are not manufactured in quant.i.ties in the farm blacksmith shop.
They can be made by machinery cheaper, but so many times a bolt is needed on short notice that the farm shop should have the necessary tools and materials to supply the need quickly.
_Forging Iron and Steel._--Iron and steel are composed of the same properties, but differ chemically. Steel also is finer grained than iron and it requires different treatment. Iron should be forged at a light-red or white heat. If forged at a dark-red heat the iron generally will granulate or crack open and weaken the metal. For a smooth finish the last forging may be done at a dark-red heat, but the hammer must be used lightly. The weight of the hammer as well as the blows also must differ with the different size of iron under heat. Small sizes should be treated with hammer blows that are rather light, while for large sizes the blows should be correspondingly heavy. If light blows be given with a light hammer in forging heavy iron the outside alone will be affected, thus causing uneven tension and contrarywise strain in the iron.
Steel should never be heated above a yellow heat. If heated to a white heat the steel will be burned. Steel should never be forged at a dark-red heat. If this is done it will cause considerable strain between the inner and outer portions, which may cause it to crack while forging.
The weight of the hammer and the hammer blows in forging of steel is vastly of more importance than in forging iron. If the blow or the hammer is not heavy enough to exert its force throughout the thickness of the steel it will probably crack in the process of hardening or tempering. If steel be properly forged it will harden easily and naturally, but if improperly forged the tempering will be very difficult--probably a failure. The quality of a finished tool depends greatly upon the correct heat and proper method used in forging and hardening it.
_Making Steel Tools._--Steel for tools should first be annealed to even the density and prevent warping. This is done by heating it to a dull cherry red in a slow fire. A charcoal fire for this purpose is best because it contains no sulphur or other injurious impurities. After heating the piece of new steel all over as evenly as possible it should be buried several inches deep in powdered charcoal and left to cool.
This completes the annealing process. While working steel into proper shape for tools, great care is required to prevent burning. It should be worked quickly and the process repeated as often as necessary. Practice is the only recipe for speed.
When the tool is shaped as well as possible on the anvil it is then finished with a file by clamping the new tool in the vise, using single cut files. b.a.s.t.a.r.d files are too rough for tool steel. After the tool is shaped by cross-filing and draw-filing to make it smooth it is sometimes polished by wrapping fine emery cloth around the file. Oil is used with emery cloth to give the steel a l.u.s.ter finish. Tempering is the last process in the making of such tools as cold chisels, drills, dies, punches, scratchawls, etc.
_Tempering Steel Tools._--Good judgment is required to get the right temper. Good eyesight is needed to catch the color at the exact instant, and quick action to plunge it into the water before it cools too much.
Dies are made very hard. The color of the steel at dipping time should be a bright straw color. Cold chisels will break when being used if tempered too hard. If cold chisels are to be used for cutting iron, the color should be violet; if the chisels are for cutting stone, purple is the color. Drills for boring iron are tempered a dark straw color at the cutting edge merging back into blue. The water in the dipping tub should be warm, as steel is likely to check or crack when it is tempered in cold water.
[Ill.u.s.tration: Figure 91.--Blacksmith Hammers. Some smiths use a heavy machinist"s hammer. But the flat peen is more useful when working around the anvil and the leg vise.]
Tool steel should be held in a perpendicular position when it enters the water to cool all sides alike. Otherwise the new tool might warp. It is better to dip slowly, sometimes holding the point, or cutting edge, in the water while permitting the shank to cool slowly enough to remain soft. Some sizes of steel may be tempered too hard at first and the temper immediately drawn by permitting the heat of the shank to follow down almost to the edge, then dip. This is done quickly while watching the colors as they move towards the point or edge.
_Draw-filing._--Making six-sided and eight-sided punches and scratchawls out of hexagon and octagon tool steel is interesting work. The steel is cut to length by filing a crease all around with a three-cornered file.
When it is sufficiently notched, the steel will break straight across.
To shape the tool and to draw out the point the steel is heated in the forge to a dull cherry red and hammered carefully to preserve the shape along the taper. Special attention must be given to the numerous corners. A scratchawl or small punch, must be heated many times and hammered quickly before cooling. An old English shop adage reads: "Only one blacksmith ever went to the devil and that was for pounding cold iron."
After the punch or scratchawl is roughed out on the anvil, it is fastened in the vise and finished by cross-filing and draw-filing.
Copper caps on the vise jaws will prevent indentations.
[Ill.u.s.tration: Figure 92.--Vise Jaw Guards. Soft auxiliary vise jaws are made of sheet copper or galvanized iron.]
[Ill.u.s.tration: Figure 93.--Roll Filing. To file a piece of steel round it is rolled by one hand while the file is used by the other hand.]
Draw-filing means grasping each end of the file and moving it back and forth sidewise along the work. For this purpose single-cut files are used. The smoothing is done with a very fine single-cut file, or if very particular, a float file is used. Then the polish is rubbed on with fine emery cloth and oil. The emery cloth is wrapped around the file and the same motion is continued. With some little practice a very creditable piece of work may be turned out. Such work is valuable because of the instruction. A good test of skill at blacksmithing is making an octagon punch that tapers true to the eye when finished.
_Set-Screws._--It is customary to fasten a good many gear wheels, cranks and pulleys to machinery shafts by set-screws. There are two kinds of set-screws; one has a cone point, the other a cup end. Both screws are hardened to sink into the shaft. A cup is supposed to cut a ring and the point is supposed to sink into the shaft to make a small hole sufficient to keep the wheel from slipping. However, unless the cone-pointed screw is countersunk into the shaft, it will not hold much of a strain. The point is so small it will slip and cut a groove around the shaft. To prevent this, the set-screw may be countersunk by first marking the shaft with an indentation of the point of the screw. Then the wheel or crank or collar may be removed and a hole drilled into the shaft with a twist-drill the same size, or a sixty-fourth smaller, than the set-screw. Then by forcing the end of the set-screw into the drill hole, the wheel is held solid.
[Ill.u.s.tration: Figure 94.--Machine-Bolt and Set-Screw. The bolt to the left is used to clamp cylinder heads in place. The set-screw to the right is the cup variety. The end is countersunk to form a cup with a sharp rim.]
The princ.i.p.al objection to set-screws is that they are dangerous. The heads always project and are ready to catch a coat sleeve when the shaft is revolving. In all cases, set-screws should be as large as the hub will allow, and it is better to have them protected so it is impossible to catch anything to wind around the shaft. Cup set-screws are not satisfactory except for very light work. If necessary to use them, the ends may be firmly fixed by cutting a ring with a sharp, diamond-point cold chisel.
_Setting the Handsaw._--Nine teeth to the inch is the most satisfactory handsaw for all kinds of lumber. Setting the teeth of this kind of saw is best done with a hand lever set. The plunger pin should be carefully adjusted to bend the teeth just far enough to give the necessary set.
For general work a saw needs more set than is needed for kiln-dried stuff. The teeth should cut a kerf just wide enough to clear the blade.
Anything more is a waste of time and muscle. It is better to work from both sides of the saw by first setting one side the whole length of the blade. Then reverse the saw in the clamp and set the alternate teeth in the same manner. There should be a good solid stop between the handles of the set to insure equal pressure against each sawtooth. The pin should be carefully placed against each tooth at exactly the same spot every time and the pressure should be the same for each tooth.
The best saw-sets for fine tooth saws are automatic so far as it is possible to make them so, but the skill of the operator determines the quality of the work. The reason for setting a saw before jointing is to leave the flattened ends of the teeth square with the blade after the jointing and filing is completed.
_Jointing a Handsaw._--After the saw has been set it must be jointed to square the teeth and to even them to equal length, and to keep the saw straight on the cutting edge. Some woodworkers give their saws a slight camber, or belly, to correspond with the sway-back. The camber facilitates cutting to the bottom in mitre-box work without sawing into the bed piece of the box. It also throws the greatest weight of the thrust upon the middle teeth. A saw with even teeth cuts smoother, runs truer and works faster than a saw filed by guess. It is easy to file a saw when all of the teeth are the same length and all have the same set.
Anyone can do a good job of filing if the saw is made right to begin with, but no one can put a saw in good working order with a three-cornered file as his only tool.
[Ill.u.s.tration: Figure 95.--Saw Jointer. The wooden block is about two inches square by 12" or 14" in length. The block is made true and scribed carefully to have the ripsaw slot square, straight and true. The file is set into a mortise square with the block.]
_Filing the Handsaw._--First comes the three-cornered file. It should be just large enough to do the work. There is no economy in buying larger files thinking that each of the three corners will answer the same purpose as a whole file of smaller size. In the first place the small file is better controlled and will do better work. In the second place the three corners are needed to gum the bottoms of the divisions between the teeth. There is much more wear on the corners than on the sides of a saw-file. Also the corners of a small file are more acute, which means a good deal in the shape of the finished teeth.
After the saw is carefully set and jointed, clamp it in the saw vise and file one side of the saw from heel to point. Then reverse the saw in the saw clamp and file the other side, being careful to keep the bevel of each tooth the same. It is better to stop filing just before the tooth comes to a point. A triangular or diamond shaped point will cut faster and leave a smoother saw kerf and last longer than a needle point.
As the tooth of a crosscut saw is filed away from both edges, it is necessary to make allowances when filing the first side, otherwise some of the teeth will come to a sharp point before the gumming is deep enough.
_Using a Handsaw._--Anyone can saw a board square both up and down and crossways by following a few simple rules. Have the board supported on the level by two well made saw-benches 24" high. Stand up straight as possible and look down on both sides of the saw blade. Use long even strokes and let the saw play lightly and evenly through the saw cut.
Do not cut the mark out; cut to it on the waste end, or further end, if there are more pieces to be cut from the board. The saw kerf is about 3/32" wide for a nine-tooth saw set for unkilned lumber or dimension stuff. If both saw kerfs are taken from one piece and none from the next then one length will be 3/16" shorter than the other.
For practice it is a good plan to make two marks 3/32" apart and cut between them. Use a sharp-pointed scratchawl to make the marks. A penknife blade is next best, but it must be held flat against the blade of the square, otherwise it will crowd in or run off at a tangent.
_Setting a Circular Saw._--A good saw-set for a circular saw may be made out of an old worn-out flat file. Heat the file in the forge fire to draw the temper and anneal it by covering it with ashes. Smooth it on the grindstone. Put it in the vise and file a notch in one edge. The notch should be just wide enough to fit loosely over the point of a sawtooth. The notch should be just deep enough to reach down one-quarter of the length of the tooth.
Make a saw-set gauge out of a piece of flat iron or steel one inch wide and about four inches long. File a notch into and parallel to one edge at one corner, about one-sixteenth of an inch deep from the edge and about half an inch long measuring from the end. With the home-made saw-set bend the saw teeth outward until the points just miss the iron gauge in the corner notch. The edges of the gauge should be straight and parallel and the notch should be parallel with the edge. In use the edge of the gauge is laid against the side of the saw so the projecting tooth reaches into the notch. One-sixteenth of an inch may be too much set for a small saw but it won"t be too much for a 24-inch wood saw working in green cord wood.
_Jointing a Circular Saw._--Run the saw at full speed. Lay a 14-inch file flat on the top of the saw table at right angles to the saw. Move the file slowly and carefully towards the saw until it ticks against the teeth. Hold the file firmly by both ends until each sawtooth ticks lightly against the file. A saw in good working order needs very little jointing, but it should have attention every time the saw is set and it should be done after setting and before filing.
_Filing a Circular Saw._--The teeth of a crosscut circular saw point a little ahead. Sometimes they point so nearly straight out from the center that you have to look twice to determine which way the saw should run. There are plenty of rules for the pitch of sawteeth, but they are subject to many qualifications. What interests a farmer is a saw that will cut green poles and crooked limbs into stove lengths with the least possible delay. A saw 20 inches in diameter will cut a stick eight inches through without turning it to finish the cut. The front or cutting edges of the teeth of a 24-inch crosscut circular saw for wood sawing should line to a point a little back from the center. This may not sound definite enough for best results, so the more particular farmers may use a straight edge. Select a straight stick about half an inch square. Rest it on top of or against the back of the saw mandrel and shape the forward edges of the teeth on a line with the upper side or rear side of the straight edge. The teeth will stand at the proper pitch when the saw is new, if it was designed for sawing green wood. If it works right before being filed, then the width of the straight edge may be made to conform to the original pitch and kept for future use.