To Restore Burnt Steel
The best thing to do with steel which has been overheated is to throw it in the scraps. However, if a piece which cannot be replaced without loss has been burnt, it may be improved by the following method: Heat to a low red heat, and cool off in water with a light solution of salt in it. Repeat this a half dozen times, and, if it can be hammered lightly, so much the better.
Cast Iron Bob Shoes
In fitting cast-iron bob shoes to the runners, it is the custom to whittle down the runner to fit the shoe, while the shoe should be fitted to the runner. For years, I imagined that it was impossible to heat and bend the shoe without breaking it, but, after some experiments, I finally succeeded in bending the shoe so as to fit the runner. Here, as in many other instances, the trick lies in the heat. Heat the shoe to a low red heat, and in heating go slowly, and keep turning the shoe in the fire for the corners of the shoe may melt before the center is hot. When red, put in the vise or in a bending device made for such a purpose. Bend or straighten the shoe to fit the runner. The heat should be a low red heat.
Mending Circular Saws
I circular saw will often crack because the bottom of the teeth are filed with a sharp cornered file. The file should be round edged, or the saw gummed over a saw gummer. Where there is a crack in the saw, find the end of the crack, the drill a small hole, and put in a rivet; this will prevent the crack from going any further. It will also be well to drill another hole close to the edge of the saw, and then put in another rivet. The rivet will hold the edges together, and prevent the working apart of the edges, which will further break the saw. Of course, the holes should be countersunk on both sides, to give room for a head on the rivet.
When a band saw breaks, first file the joints together, so that one end will lap over the other, one or two teeth, according to the length or size of them. Then place the band saw in a vise, so that it will be held straight. Now place silver and copper over the joint, and on top of same a little fine borax. Then heat a pair of tongs, with the jaws one inch square iron, red hot, and take hold over the joint. When melted, let go with these heavy tongs, and the same moment take hold with a pair of small tongs, which are not hot, over the joint, to close them together in cooling. If the ends of the saw are held rigid, one end should be loosened the same moment one takes hold with the small tongs, for else the saw will shrink in cooling, and pull loose in the joins.
There are many methods practiced in hardening springs, but no man will succeed with any method until he has experimented some, for there are things we must learn through failures, and work which at first seems difficult will often become easy after some practice. In tempering springs, remember that it will not do to use any kind of steel, and above all don’t be guilty of such a blunder as to make springs out of old files, for the cuts in the file will be hammered down into the springs and render it worthless. One method: Heat to a low red heat in the dark, and cool in water. When one has found the right heat, this method is all right. Another: Heat to a low red heat, and bury the spring in dry sand. Another: Heat to a low red heat in daylight, and cool off in oil; then hold the spring over the fire until the oil is burnt off; then apply oil with a small brush, and burn off again. If this makes the springs too hard, burn off the oil three times. When you have made a few springs, you will find the right temper.
For iron case hardening, animal carbon should be put into the iron. This is done as follows: Place the article you wish case hardened in an iron box, together with pieces of horns, hoofs, bone, and leather. Then close the box tight with clay, and place in a fire, where it should be kept in accordance to the depth of case hardening desired. Then empty the contents of the box into water. Another method: Grind cyanide of potassium into a fine powder and sprinkle on the article to be case hardened while hot; then plunge into water. This is the most powerful compound for case hardening. For plow work, prussiate of potash is used, but it has not the power to penetrate that is found in cyanide of potassium. This is a powerful poison, and should be handled with care.
How to Tip Boiler Tubes
First scarf the old tube, and when it is scarfed down, turn the flue on the horn of the anvil; that is, place the flue with the horn inside of the flue. Now press up against the horn, and turn at the same time; this is done to true the flue. Next scarf the tip, and hammer it out enough to slip over the tube about one-fourth inch. Next heat the tip, and drive it over the flue. Now have a half inch rod the length of the flue, with a large washer under the head on one end, and a tail nut to tighten on the other end. When the rod is tight, hammer down the scarf with a light hammer, so that there will be no chance for cinders to get in between. Now have a big, clean fire ready, and use borax freely first, and then sand; this will make a splendid welding fluid. For a hammer, take a 3/8-inch round rod, and bend one end and use as a hammer, but strike very lightly over the scarf while the flue is in the fire, turning round all the while. Now, if you have fitted the tip and had the right size on the scarf, the flue will be right without any other trouble. Some have a piece of a shaft go inside, and smooth it off with a swage outside; but this is not the best, for you will break the weld of one-fourth by this method. All that is needed is a shaft the size of the inside of the flue; taper it a little, and, when the weld has been taken, push the flue over this shaft, and that will smooth it on the inside. When cool, drive a wooden plug into one end, and put some water into the flue. If it don’t sweat or leak, it is welded.
To Whiten Iron
Dissolve ashes of ash bark in soft water, heat the iron, and dip it in this solution, and the iron will turn silvery white.