(b) Mention some of the others.
8. (a) When is it advisable to grind, or “V” out, the ends of the pieces to be welded?
(b) When is it not advisable?
9. (a) Does the application of heat cause contraction or expansion in metals?
(b) Are there any excepts to this rule? Name one.
10. (a) Were two cast-iron bars measuring 2 × 12 inches and ¹⁄₂-inch thick, to be welded, end to end, what precaution should be observed in laying out, if the finished job is to measure just 24 inches long?
(b) In what respect would this problem differ were the bars only 6 inches originally and the finished job to measure 12 inches overall?
(c) Is the action of the metal in the weld a constant, or a variable quantity depending upon the length of the bar in this problem?
LECTURE NUMBER FOUR
Subject—Welding of Cast Iron
(Part Two)
11. (a) How could a spoke, broken midway between the hub and rim, of a 24-inch, 4-spoke wheel (otherwise intact) be welded without preheating? (Use a sketch if necessary to make method clear.)