This article uses as a pretext the paemaker, an object built by legal medical knowledge, to present one of the articulation points of two knowledge: pedagogical and doctor, parts of the truthful device on homosexuality presented in Antioquia at the end of the 19th century. This arrangement sets out some of its bases and models in the urban development manuals, which are subsequently assessed by the legal doctor when the subject it reaches him, once he becomes a dissident of a ‘duty to be’.