. Forging of iron and steel, a text book for the use of students in colleges, secondary schools and the shop . with an equalmixture, by measurement, of granulated wood charcoaland raw bone. The packing is done as described underpack-annealing. Test wires should be used to tell whenthe pieces are raised to the proper heat (a good red) toabsorb the carbon, and the time should be counted fromthat point. The time the box should be left in thefurnace depends upon the material and the size of thework. Pieces \ thick should stay about 2 work requiring a hard but not very deepcoating
. Forging of iron and steel, a text book for the use of students in colleges, secondary schools and the shop . with an equalmixture, by measurement, of granulated wood charcoaland raw bone. The packing is done as described underpack-annealing. Test wires should be used to tell whenthe pieces are raised to the proper heat (a good red) toabsorb the carbon, and the time should be counted fromthat point. The time the box should be left in thefurnace depends upon the material and the size of thework. Pieces \ thick should stay about 2 work requiring a hard but not very deepcoating can be left 5 hours. As a rule a coating about\ deep can be obtained in from 15 to 18 hours. Whenthe pieces have been heated the set length of time, thebox is withdrawn from the fire and the pieces plungedinto water as quickly as possible. The pieces can becolored by being allowed to fall from the box into thewater, a distance of 12 to 16 inches. Straightening Bent Tools. — Sometimes tools will warpin hardening. They can be straightened by placing thepieces between the centers of a lathe with the bowed. CARBON TOOL STEEL 153 side towards the tool-post. A piece of iron should be placed in the post so that it will bear on the tool when the transverse feed is moved forward (Fig. 192). The tool is covered with oil and heated with a flame from a Bunsen burner with a wing top, till the oil begins to smoke; then pressure is applied to the tool with the transverse feed until the lg tool is bent slightly in the other direction, then removed and cooled. QUESTIONS FOR REVIEW How does machinery and tool steel differ from wrought iron?What are the two principal classes of steel? How do they differwhen dipped into water at a high heat? What is meant by temper?What is the principal hardening element in tool steel? What ismeant by point? Why is heating one of the most important partsof the hardeners duties? What must be looked out for in heatingtool steel? Why does charcoal make a good fuel?
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Keywords: ., bookcentury1900, bookdecade1910, bookpublishernewyo, bookyear1915
