To anneal "Novo" or "Blue Chip" highspeed steel or any of the air-hardening steels, pack the steel in a piece of gas pipe with powdered charcoal, and seal the ends with clay or caps screwed on. Heat to a cherry red, giving time for the contents of the pipe to reach this temperature, and then set in a dry, sheltered place to cool. The steel will be found annealed so that it can be readily drilled, turned, planed or worked as required.
A. A. Stevenson.
An excellent bath for hardening highspeed steel consists of a mixture of table salt and paraffine oil, in the proportion of one pound of table salt to each gallon of pure oil. The steel is heated to a lemon color, and plunged into the bath, being kept in motion until it has thoroughly cooled. The steel should come out of this bath gray in color, and nearly free from black spots. The bath referred to can be used for almost all brands of high-speed steel, with good results. It has been used to great advantage for the Midvale steel, and also on a large number of tools made of Novo, Sime-teora, Rex, Jessop high-speed, and Blue Chip steel. On all these, good results have been obtained, but it may be added that this bath seems to give the best results with the Midvale steel. H. S. Steel.
The hardening paste made according to the following receipt has been used on highspeed steel with success, enabling it to be hardened by heating in an ordinary gas oven, and thus making unnecessary the very high heat usually called for in hardening such steels. Mix 2 pounds rye meal; 1 pound common salt; ¼ pound pulverized borax; ¼ pound pulverized charcoal; 1-3 pint (or ½ pound) liquid cyanide of potassium; ½ gill or 2 ounces of water glass (silicate of soda); and 3 pints of water. The liquid cyanide is made by dissolving 3 ounces of pulverized potassium cyanide in one pint of boiling water. Mix thoroughly to form a paste.
When using this paste I have found it best to apply it in the following manner: Provide a small cast-iron vessel or a crucible of the shape of a drip-pan, and spread a thin layer of the paste on the bottom; put the work in the pan and cover that with paste also. Place work and pan In the gas oven and heat until it reaches a nice full red. Dip in sperm, fish or kerosene oil. Jos. M. Stabel.
Rochester, N. Y.