Part 4 (1/2)
[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.