CHAPTER XV. USEFUL RECIPES FOR MACHINERY USERS. Bearings for Machinery.-4 parts copper, 1 part tin. Brass Guns, &c.-8 parts copper, 1 part tin. Britannia Metal.-336 parts tin, 28 parts antimony, 8 parts copper, 8 parts brass. Bronze.-8 parts copper, 1 part tin. For Type Metal.-1 part antimony, 3 parts lead. Fusible Alloy (fusible at 212° Fah.).—8 parts bismuth, 5 parts lead, 3 parts tin. Gongs.-16 parts copper, 3 parts tin. Hard Silver Solder.-3 parts silver, 1 part brass. Ordinary Brass.-16 parts copper, 8 parts zinc. Pewterers' Soft Solder.—2 parts bismuth, 4 parts lead, 3 parts tin. Plumbers' Solder.-1 part tin, 3 parts lead. Soft Spelter.-61 parts copper, 1 part zinc. Speculum Metal.--16 parts copper, 7 to 8 to 9 parts tin. Anti-friction metal (Belgian) for work exposed to great heat, the proportions are 0·5 parts tin, 0·25 lead, 1 zinc, and 17 of copper, the first three of which should be mixed before adding the last ingredient. For parts liable to much concussion the constituents are 1 of tin, 6 of zinc, and 20 of copper; and for those exposed to much friction 0.5 antimony, 0.25 lead, 4 of tin, and 20 of copper. Babbet's Anti-friction metal for bearings is composed of copper, 1 part, antimony, 5 parts, tin, 50 parts. Muntz's metal is a brass composed of 3 parts copper to 2 parts zinc. Cement for Boiler Joints.-10 part of white lead ground in oil, 3 parts of black oxide of manganese, and one part of litharge. Cement for Steam and Gas Pipes.-When rings or washers of indiarubber are used for packing joints of steam, gas, or other pipes the following cement may be used. Resin, well pulverised and mixed with ten times its weight of strong ammonia. A viscous mass is obtained which liquifies by itself after three or four weeks. This mass adheres very well to india-rubber as well as iron. Steam Boiler Cement.-Mix two parts of finely powdered litharge with one part of very fine sand and one part of quicklime, which has been allowed to slake spontaneously by exposure to the air. This mixture may be kept for any length of time without injuring. In using it a portion is mixed into paste with linseed oil, or, still better, boiled linseed oil. In this state it must be quickly applied, as it soon becomes hard. Iron Cement for closing the Joints of Iron Pipes.-(1.) Take coarsely powdered iron borings 5 lbs., powdered sal-ammoniac 2 oz., sulphur 1 oz., and water sufficient to moisten it. This composition hardens rapidly; but if time can be allowed it sets more firmly without the sulphur. It must be used as soon as mixed and rammed tightly into the joint. (2.) Take sal-ammoniac, 2 oz., sublimed sulphur, 1 oz., cast-iron filings or fine turnings, 1 lb. Mix in a mortar and keep the powder dry. When it is to be used mix it with twenty times its weight of clean iron turnings or filings, and grind the whole in a mortar; then wet it with water until it becomes of convenient consistence, when it is to be applied to the joint. After a time it becomes as hard and strong as any part of the metal. Turner's Cement for securing work in the Lathe.—Burgundy pitch, 1 lb.; resin, 1 lb.; dry whiting, 1 lb.; yellow wax, 1 oz.; melt in an earthenware pipkin, and thoroughly mix. Or mix pitch and resin in the proportion of 1 to 4, and whilst these are boiling add a small quantity of brick-dust. Paint for preserving Machinery may be made by adding together 1 lb. shellac, 1 lb. india-rubber, 2 lbs. resin, and 2 gallons of benzoin. Welding Composition.—Mix borax with 1-10th of sal-ammoniac, fuse the mixture and pour it on an iron plate. When cold, pulverise it and mix it with an equal weight of quicklime, sprinkle it on the iron, which should be heated to redness, and replace it in the fire. With this mixture iron may be welded below the usual heat. NOTES ON RED LEAD JOINTS. 1. Flat-faced joints, as pipe flanges, cylinder covers, &c. Each face must have all the old lead removed, and then wiped over with a piece of oily waste (boiled linseed oil). The lead must be thoroughly worked, either by machine or by hand, to make it soft and pliable and also to remove all grit and lumps. It should then be rolled in the hands into thin ropes about inch in diameter and laid on once round inside the bolt holes. The two faces must now be brought together carefully and tightened up equally all round by screwing up opposite bolts, so as to avoid getting one side closer than another. Tar, twine, hemp, string, wire gauze, &c. should be studiously avoided wherever possible, as it prevents the faces from being brought into close contact. There are certain rough jobs where it may be permitted, but a joint so made is never so durable, and very clumsy. When joints are accurately faced by scraping or otherwise, as in locomotive practice, nothing but liquid red lead is used, made of red and white lead mixed with boiled oil to the consistency of paint: they are of exceptional durability. 2. Joints between male and female threads, such as screwed pipes and sockets, bolts, or studs screwed into boiler plates, &c. In these cases liquid red lead is used, and should be put on the female thread for inside pressure, on the male for outside pressure, as then the steam in each case forces any surplus lead into the thread, and forms a more reliable joint, or rather assists it, whereas, when it is applied in the reverse way as generally done, the threads are left quite bare and clear, leaving nothing to assist the joint. |