“Do the taps that shorten most in length increase the most in diameter?”
Answer.—“Not always; sometimes a tap that shortens by hardening becomes also smaller in diameter, while sometimes a tap will increase in length, and also in diameter from hardening.”
“Do taps that remain of true pitch after hardening remain true, or increase or diminish in diameter?”
Answer.—“They will generally be of larger diameter.”
“Do small taps alter more in diameter from hardening than large ones?”
Answer.—“No; the proportion is about the same, and is about .002 per inch of diameter.”
“What increase in diameter do you allow for shrinkage in hardening of hob taps for tapping solid dies?”
Answer.—“As follows:—
| Diameter of Hob Tap | Shrinkage about | ||
| 1⁄4 | inch | .003 | |
| 1⁄2 | „ | .003 | |
| 3⁄4 | „ | .005 | |
| 1 | „ | .008 | ” |
“Suppose a tap that had been hardened and tempered to a straw color contained an error 1⁄1000 inch both in diameter and in pitch, was softened again, would it when soft retain the errors, or in what way would softening affect the tap?”