Most historic restorations fail not because of poor woodwork, but because of hinges that can’t handle the load or period-correct movement. This article reveals the hidden engineering challenge of custom door hinges—from material fatigue in 300-pound oak doors to the 0.5mm tolerance wars that separate a masterpiece from a maintenance nightmare. Based on a decade of field data and a landmark project at a 1780s Georgian manor, I share the exact process for specifying, forging, and tuning hinges that will outlast the next century.