Kao Sung-nien's fat but firm face was like an unleavened millet-flour steamed bread. "Voracious time" (Edax vetustas) could not make a dent on it. There was not a single tooth mark or crease .

The tooth shape, fit and mark of clamping connection and pipe connection inch threads commonly used are introduced and their seal features.

According as formula of cutting surface mark deepness from educing, the paper explain that is really one another contradiction between tooth feed rate and cutting surface roughness.