Saginaw Thermal Calculator May 2026

Mira Kostic eventually left Saginaw to teach at Lawrence Tech. But the calculator lived on. Well into the 1980s, old-timers would pull yellowed Saginaw Thermal Calculators from their toolbox lids, ignoring the new digital infrared guns. “Batteries die,” they’d say, spinning the cardboard disk. “This never does.”

Then a junior process engineer named Mira Kostic did something unexpected. She asked for a slide rule, a pad of graph paper, and three weeks of logged cooling curves from a dozen part geometries. Management thought she was wasting time. Dutch gave her the green light anyway. saginaw thermal calculator

Within six months, scrap rates from thermal cracking dropped 43%. Dutch had the tool laminated in greaseproof plastic and chained to every quench tank. Mira’s design was so effective that the plant manager sent copies to GM’s Hydra-matic and Detroit Diesel divisions. By 1962, over 2,000 Saginaw Thermal Calculators were in use across the Midwest. Mira Kostic eventually left Saginaw to teach at

where ( k ) was a quenchant-specific constant (oil, water, or polymer). She plotted families of curves for rounds, flats, and complex shapes. Then she built a — a circular slide chart with three movable disks. Management thought she was wasting time