3. In making an S-wrench, which is preferable: to forge the jaws separately and then weld on the handle, or to cut the jaws from a solid piece of metal and draw down the material between them to the proper size for the handle?
6. What is meant by scarfing?
7. Why should the ends of pieces to be welded be upset?
8. What is a flux, and why is it used in welding?
9. Why are scarfs used in welding?
10. Make a sketch and show all dimensions of a hexagonal head bolt 3/4 in. X 8 in.
11. How much would the connecting rod shown in Fig. 89 weigh before any machine work was done on it?
12. What are the characteristics of a good forge coal?
13. (a) What do you understand to be meant by an oxidizing fire? (b) What do you understand to be meant by a reducing fire?
14. How are tongs fitted to work?
1. What is meant by clearance on lathe tools?
3. What is meant by annealing?
4. What is meant by "the hardening heat"?
5. Is annealing necessary for steel that is to be made into tools? If so, for what reason?
6. What is the difference in the heat treatment of carbon and high-speed steels? Explain.
7. What determines the size of the grain in hardened steel?
8. Why has mild steel replaced wrought iron?
9. If high-speed steel retains its cutting quality at a higher degree of heat than carbon steel, what is the cause?
11. Should the annealing heat be higher or lower than the hardening heat? Explain why.
12. What is the effect of uneven heating of tool steel for hardening? Why?
13. How is the final hardness of steel affected by the rate of cooling?
14. Why is it necessary to reheat large pieces after they have been hardened?
15. Explain why brine is sometimes used for hardening, and sometimes oil.